- Email: [email protected]
Organogels based on the polyglyceryl fatty acid ester and sunflower oil: Macroscopic property, microstructure, interaction force, and application
LWT - Food Science and Technology 116 (2019) 108590
Contents lists available at ScienceDirect
LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt
Organogels based on the polyglyceryl fatty acid ester and sunflower oil: Macroscopic property, microstructure, interaction force, and application
T
Zong Menga,b, Ying Guob, Yong Wangc, Yuanfa Liub,∗ a Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing, 100048, People's Republic of China b State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, People's Republic of China c Department of Food Science and Engineering, Guangdong Saskatchewan Oilseed Joint Laboratory, Jinan University, Huangpu Rd. West 601, Guangzhou, 510632, Guangdong, People's Republic of China
A R T I C LE I N FO
A B S T R A C T
Keywords: Organogels PGE Macroscopic properties Space-spanning networks Crystalline structure
Polyglyceryl fatty acid ester (PGE) was used as organogelator to structure sunflower oil. Macroscopic properties, microstructures, interaction force of organogels were systematic analysed using rheometer, pulsed nuclear magnetic resonance (pNMR), differential scanning calorimetry (DSC), polarizing light microscope (PLM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR), respectively. In addition, organogels were evaluated as a shortening replacer applied in bread. Macroscopic properties were related to the space-spanning networks formed through surface interactions among crystalline such as hydrogen bonds and electrostatic interaction. Higher organogelators concentration resulted in more compact network which provided lower oil loss, higher firmness and G'. Melting and collapsing of crystalline structure resulted in the transformation of organogel from solid-like state to liquid state. In bread making process, the crystalline network formed by PGE could imitated the functions of crystalline network structures formed by triacylglycerol. This investigation was beneficial for expanding potential applications of PGE in organgels.
1. Introduction Processed foods, such as chocolates, whipped creams, and some bakery products, contain high amounts of solid fats consisting primarily of saturated or even contain trans fats because of their positive influences on product performances in terms of texture, sensory characteristics, and shelf-life. The realization of these functions is based on the crystal network composed of saturated fats and which was responsible for viscoelastic and elastic properties of specialty fats (Maciasrodriguez & Marangoni, 2017). However, excess consumption of trans and saturated fatty acids has been found to show deleterious health effects including obesity issues, cardiovascular diseases, Type II diabetes and other related diseases (Gayet-Boyer et al., 2014; Lichtenstein, 2014; Makarewicz-Wujec, Dworakowska, & Kozlowska-Wojciechowska, 2018; Ruiz-Nunez, Dijck-Brouwer, & Muskiet, 2016). Most countries have already placed a ban or strict legislative limits on using of artificial trans fats in processed foods like the United States, the European Union,
and Canada. Moreover, nutritional guidelines have suggested that reducing the trans and saturated fats in diet and replacing them with unsaturated fats from vegetable sources (Aranceta & Pérezrodrigo, 2012). Therefore, novel oil structuring methods to prepared fat alternatives with zero trans and low saturated fatty acids, and closely resemble conventional fat structured systems have been receiving increased attentions from researchers of food industries. Organogelation of liquid oil is one of the most promising strategies to design new soft matter structures with the functionality of traditional plastic fat, zero trans and low saturated fatty acids (Dassanayake, Kodali, & Ueno, 2011; Singh, Auzanneau, & Rogers, 2017; Fan C.; Wang, Gravelle, Blake, & Marangoni, 2016). Organogel was achieved through adding single or combination of organogelator molecules into the liquid oil. In organogel systems, liquid oil was immobilized by the three-dimensional network of supramolecular structure formed by organogelators, which resulted in a solid-like material in macroscopic features.
∗
Corresponding author. State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China E-mail addresses: [email protected] (Z. Meng), yfl[email protected] (Y. Liu). https://doi.org/10.1016/j.lwt.2019.108590 Received 18 April 2019; Received in revised form 1 September 2019; Accepted 4 September 2019 Available online 05 September 2019 0023-6438/ © 2019 Elsevier Ltd. All rights reserved.
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
PGE completely dissolved in the oil, and then obtained a homogeneous dispersion system. Finally, mixtures were cooled under static conditions at room temperature for 24 h, and then stored at 20 °C incubator for further tests.
Wax-based organogels has been studied and exploited to fully or partially replace the saturated fat in fat-based food formulations such as shortenings, margarines, and creams (Gomez-Estaca et al., 2019). Several studies have already been reported wax-based organogels such as rice bran wax in rice bran oil (Wijarnprecha, Aryusuk, Santiwattana, Sonwai, & Rousseau, 2018), and candelilla wax in high oleic safflower oil (Sanchez-Becerril et al., 2018). However, natural and edible wax have fewer sources. Some articles reported γ-oryzanol and β-sitosterol based organogels (Calligaris, Mirolo, Da Pieve, Arrighetti, & Nicoli, 2014; Sawalha et al., 2015), but relatively high-prices limited the use of those gelling agent in the food industry. Small molecule emulsifier has been attracted attention of scholars because of edible, safety, and wide source. Much research was concentrated on the monoglyceride as a structure agent (Palla, Giacomozzi, Genovese, & Elena Carrin, 2017; Valoppi et al., 2017). On the contrary, PGE as a gelling agent to structured vegetable oil has not yet been intensively studied at our knowledge. This investigation was beneficial for expanding the type of organogelator of small molecule emulsifier and providing a new idea for potential applications of PGE organogels. Polyglycerol fatty acid ester (PGE), formed from esterification of polyglycerol and fatty acids, is a non-ionic surfactant with edible and high safety. A PGE molecule contains a hydrophilic head group of nglycerol units and one or two hydrophobic alkyl chains which determines excellent amphiphilic properties. Therefore, PGE was widely used in cosmetics, food, medicine and other fields. PGE formed a lamellar gel in the presence of water, and this type of self-assembled supramolecular aggregates formed by surfactants in water had been studied both fundamental and applied research over the past few decades (Kunieda, Aramaki, Nishimura, & Ishitobi, 2009; Wakisaka, Nakanishi, & Gohtani, 2014). PGE successively forms a lamellar liquid crystalline and a lamellar gel phase when heated and cooled the mixture of surfactant and water above the Krafft temperature (TK). In lamellar gel phase, the water layer was trapped between the bilayer structures of glycerol head groups by hydroxyl groups (Duerrauster et al., 2007). Macroscopic property, microstructure, interaction force, and application of the organogels formed by a mixture of PGE and sunflower oil at various concentration were investigated using a combination of DSC, PLM, rheometer, XRD, FTIR as well as physical property analyser. The combination of these techniques has allowed a detailed description of the semi-solid structure formed by crystalline structure which trapped liquid oil. In addition, the effects of different lipid matrices on breads were determined by assessing the fatty acid composition, water activity, moisture, specific volume, and texture characteristics. This study offers the essential information about PGE and sunflower oil based organogels, and provided a reference for its baking application.
2.3. Oil loss (OL) determination The method reported by Da Pieve et al. (Da Pieve, Calligaris, Co, Nicoli, & Marangoni, 2010) was adapted to measure the oil loss of organogels. First, a plastic centrifuge tube (1.5 mL) was weighted and the mass of tube was recorded as “a”. Then, approximately 1 g sample was filled in tube whose mass was recorded as “b”, and then tubes with simple were centrifuged at 10621 g for 15 min. The released liquid oil drained out of tube after centrifugation and the mass was recorded as “c”. Triplicate measurements were obtained, and OL values were calculated by Equation (1): OL= (b-c)/b-a
(1)
2.4. Texture analysis The firmness of organogel samples was measured by penetration test using a Texture Analyser (Stable Microsystems, Surrey, UK) equipped with a cylindrical probe (P/5) of 12.7 mm diameter. Samples were melted completely at 75 °C and approximately 30 mL samples were poured into 50 mL flat-bottomed plastic centrifuge tubes and stand at room temperature for 24 h to test firmness. The test settings including the pre-test speed, test speed, and post-test speed were 2.0 mm/s, 1.0 mm/s, and 2.0 mm/s, respectively, and the penetration depth of 15 mm (Yilmaz & Ogutcu, 2014). The measurements were performed in triplicate. Texture exponent v.6.1.1.0 software (Stable Microsystems, Surrey, UK) on the instrument was used to analyse the date. 2.5. Rheological measurements The rheology properties of organogels were measured by using a DHR-3 rotary rheometer (TA Instruments, New Castle, USA) attached with a temperature control system. Tests were performed by a parallel plate with diameter of 40 mm, and the geometry gap was set to 1000 μm (Meng, Qi, Guo, Wang, & Liu, 2018). To determine the linear viscoelastic region (LVR) for the samples, strain sweep tests were conducted at strain amplitude varying from 0.001% to 10%, and applying a constant frequency of 3 Hz. Frequency sweeps were conducted in frequency ranging from 0.1 to 100 Hz, and a fixed strain value determined by LVR. Using the same geometry, temperature sweep measurements were carried out at temperature range of 0–65 °C, and the rate of heating and cooling was 5 °C/min. Strain sweeps and frequency sweeps were carried out at 25 °C, respectively.
2. Material and methods 2.1. Materials Sunflower oil and ingredients of bread, including high-gluten flour, milk powder, eggs, and yeast were purchased from the local market. PGE was a generous gift from Danisco (Danisk Co., Ltd, Suzhou, China). This commercial mixture of PGE was consisted predominantly of stearic acid (57.54%) and palmitic acid (40.83%).
2.6. Solid fat content (SFC) The SFC of organogels was carried out by the IPC-610 pulsed nuclear magnetic resonance (pNMR, Niumag Electronic Technology Co., Ltd, Shang Hai, China), which attached an external water bath to control temperature. The modified method reported by Bin Sintang, Rimaux, Van de Walle, Dewettinck, and Patel (2017) was used. Approximately 3.5 mL of melted samples were transferred into pNMR glass tubes, and then placed in a water bath at 80 °C at least 30 min to eliminate crystal memory. Subsequently, all the tubes were transferred into the auxiliary low temperature water bath of pNMR analyser at 0 °C for 1 h to solidification. The test was measured at temperature range of 0–50 °C, increased 5 °C each time. Before measured, keep the tube at the measured temperature for 30 min. Triplicate measurements were obtained.
2.2. Preparation of organogels Organogels were prepared by mixing sunflower oil and PGE in proportions ranging from 7% PGE to 15% PGE (w/w) with 2% increments, and the preparation method refers to the article published by Alfutimie et al. (Alfutimie, Curtis, & Tiddy, 2014). Firstly, weighing appropriate amounts of PGE and sunflower oil into clean and dry beakers. Then, mixtures were heated and stirred by a multi-point magnetic stirrer (TA Instruments, New Castle, USA) at 75 °C until the 2
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
it, the dough was cut into small pieces and every small dough was kneaded into round shape, and then placed into the proofer (Shuangmai bakery equipment Co., Ltd, Wuxi, China) setting a temperature of 38 °C and a humidity of 75% to perform the second fermentation for 30 min. The bread doughs were baked in a preheated oven (Shuangmai bakery equipment Co., Ltd, Wuxi, China) at 200 °C for 12 min. After cooling to room temperature, five slices of 15 mm thickness were cut from the central portion of each loaf by a SAM-302 slicing machine (Shuangmai bakery equipment Co., Ltd, Wuxi, China), packed in sample bag, and then stored at room temperature until analysis.
2.7. Differential scanning calorimetry (DSC) Thermal analysis was carried out using a TA Q2000 DSC instrument (TA Instruments, New Castle, USA). The experimental method refers to the article published by Lupi et al. (Francesca R. Lupi et al., 2016). An aluminum pan was filled with 7–8 mg organogels and then was sealed by the pressure machine, and an empty pan was used as a reference. In order to exclude the effect of the existing crystalline structure, the sample was rapidly heated to 80 °C and maintained for 10 min, followed by a cooling step to −10 °C. The sample was then kept isothermal for 5 min before heating to 80 °C. The rate of heating and cooling was 10 °C/min. The program Universal Analysis 2000 (TA Instruments, New Castle, DE) was used to plot and analysed the thermal data.
2.11.2. Properties of product Texture properties of bread slices were carried out using TA-XT Plus (Stable Microsystems, Surrey, UK). Measurement was performed with texture profile analysis (TPA) mode at pre-test speed of 5.0 mm/s, test speed of 2.0 mm/s, post-test speed of 5.0 mm/s, and the compression ratio was set at 75% (Alvarez-Jubete, Auty, Arendt, & Gallagher, 2009). The specific volume of breads were measured by millet displacement modified based on the method approved by Liu (Liu, Meng, Liang, Jin, & Wang, 2010). Crumb in the middle of several bread slices was used for following analysis. The moisture content was measured using by a MB120 moisture tester (OHAUS, New Jersey, America) preformed at 105 °C. Water activity was determined using a portable water activity meter (Novasina, Zurich, Switzerland). Each experiment was carried out in triplicate. Fatty acid composition of bread was determined by GC-2010PLUS (Shimadzu, Tokyo, Japan) equipped with a flame ionization detector and a fused-silica capillary column (CP-Sil88, 60 m × 0.25 mm × 0.2 μm. The column was heated to 60 °C and held for 3 min, then programmed at 5 °C/min to 175 °C and held for 15 min, then the temperature was increased to 220 °C at 2 °C/min and held for 10 min.
2.8. Microstructure observation The microstructure of organogels was observed at room temperature by using Leica DM2700P microscope (Leica Microsystems, Wetzlar, Germany) equipped with a Charge-coupled Device (CCD) camera. Organogels were melted in a water bath at 75 °C to eliminate crystal memory before microscope observation. A spot of melted organogels was dropped onto a glass slide and covered with a glass slip. The microscopy slides were conditioned in an incubator (Binder, Neckarsulm, Germany) at 20 °C for 24 h. Slides were observed under 500 × magnification by using polarized light. 2.9. X-ray diffraction (XRD) The molecular organization of the organogels were explored with a D2 Phaser X-Ray Diffractometer (Bruker AXS GmbH, Karlsruhe, Germany) equipped with scintillation counter and 1-dimensional LynxEye detector. The standard ceramic sealed tube using Cu as the Xray source was operated at 30 mA and 40 kV to produce X-ray of 1.54 Å wavelength. Sample holder was filled with organogels, and samples were smoothed before sweeping. Angular scans from 1° to 35° were performed by using a step size of 0.3 and at a rate of 0.03 s/step at environment temperature (Meng et al., 2018). Experiment was carried out in duplicate. The MDI Jade 6 software (Materials Data Inc., Livermore, USA) was used for data processing and analyses.
2.12. Statistical analysis Statistical analysis was completed using Origin 2016 and Sigma Plot 12.5, respectively. All measurement data were presented as means with standard deviation and differences were considered significant at 5% (P < 0.05). Analysis of variance (ANOVA) with Duncan's multiple range test was carried out by the Statistical Analysis System software (SAS, Cary, NC).
2.10. FTIR analysis 3. Results and discussion A FTIR spectrometer (IS10, Nicolet, USA) was used to record the infrared absorption spectra of the samples and the experimental method refers to the article published by our research team (Meng et al., 2018). The FTIR instrument equipped with an attenuated total reflectance (ATR) crystal (ZnSe). Organogels or sunflower oil was directly placed on the crystal, respectively, and the spectra were collected within the range of wavenumber 400 and 4000 cm−1, each with 16 scans at a resolution of 4 cm−1. All spectra erased the effect of the background spectrum measured against a background of air, and were analysed by the software OMNIC (Thermo, v8.0). The measurement was carried out in duplicate.
3.1. Oil loss (OL) and firmness The ability of network to trap liquid oil reflecting by OL and mechanical strength of organogel samples were characterized by texture analysis. Learn from Table. 1S, the proportion of PGE played a positive effect on increasing firmness of organogels and reducing OL. The sample at 7% concentration of PGE lost more than 60% liquid oil while the sample at 15% concentration lost less than 30% liquid oil after centrifuging. It was found that both OL and firmness were benefited from the network formed by PGE.
2.11. Baking application
3.2. Rheological properties
2.11.1. Bread production The basic recipes of bread consisted of high-gluten powder 250 g, water 135 g, sugar 50 g, shortening 35 g, skimmed milk powder 10 g, yeast 2.5 g and salt 2.5 g. Lipid matrix (shortening or organogels) did not add until other materials were blended to a smooth dough at low speed in the pastry blender (Shuangmai bakery equipment Co., Ltd, Wuxi, China). Continue stirring until the mixture came together at low speed, subsequently, blending at high speed until the dough became very elastic and could be pulled out the translucent film. Then, first fermentation was carried out at room temperature for 60 min. Followed
Amplitude sweep tests were used in determination the linear viscoelastic region (LVR) of organogels. Fig. 1S and fig1 displayed the results of LVR and frequency sweep teats respectively. Learned from Fig. 1S, the LVR of all organogel samples has a stress range of approximately 0.001%–1%. As seen from Fig. 1, all organogel samples behaved as “solid” with storage modulus (G′) higher than the loss modulus (G″). Solid-like property of organogels was also attribute to the network structure formed by PGE crystal. Fig. 1 clearly showed that both G′ and G″ were increased as the concentration of organogelators. Additionally, a frequency independent behavior was observed which 3
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
indicated a structured connection of the network (Bin Sintang et al., 2017; Ojijo, Neeman, Eger, & Shimoni, 2010). Temperature ramp tests were performed to evaluate the effect of temperature on the crystalline structure of the organogel. Rheological parameters as a function of temperature were plotted and displayed in Fig. 2. Organogels at all PGE concentration exhibited a typical thermally reversible behavior during the heating and cooling cycle. As the temperature raise, the system gradually melting and completely melting at high temperatures. A sudden decrease in G′ was observed between 40 and 60 °C indicating the melting and collapse of the organogel networks that provided the elasticity property, and the organogel systems exhibited a viscous behavior when continued to raise the temperature. Cooling the samples, a slope increasing in G′ suggested that crystalline aggregates gradually formed and stretched into entire sample, which resulting in the formation of a solid-like organogel material again (F. R. Lupi et al., 2016). The effect of temperature on the solid content in the organogel systems were also characterized by referring to the SFC, and the results
Fig. 1. Frequency sweep curves of organogel (solid marks are representative elastic modulus, hollow marks are representative viscous modulus).
Fig. 2. Temperature sweep curves of organogels at different concentration. 4
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
Fig. 3. DSC profiles of heating process (a) and cooling process (b) of organogels.
of SFC presented in Fig. 2S. A suddenly drop of SFC appeared between 40 and 50 °C indicating the crystalline in organogles began to melt, which was similar with temperature ramp tests. The solid-like property of organogels at low temperature was mainly due to the ability of small molecule gelling agents to entrap liquid oil. As well know, hydrogenation significantly increased SFC through the method of changing in the saturation of the fatty acids. Fig. 2S clearly showed that SFC for all organogel samples were below 12%, and not significantly increase with addition of gelling agents, which indicating that organogelation bound liquid oil to the network structure through physical actions (Rogers, 2009).
Fig. 4. Polarized light images of organogels at concentration of 7% (a), 9% (b), 11% (c), 13% (d), 15% (e).
4.26 J/g, respectively. For cooling scans (Fig. 3b), a single peak appeared in the crystallization curves for all samples, and peaks slightly moved to high temperature with the increasing PGE, which were 42.43 °C (1.48 J/g), 43.34 °C (2.20 J/g), 43.95 °C (2.82 J/g), 44.02 °C (3.27 J/g) and 44.55 °C (4.02 J/g), respectively. It was found that the temperature of endothermic peak for all samples was closed to those of exothermic peak which suggesting that those peaks respected the melting and crystallization of PGE crystals.
3.3. DSC In order to detailed investigate thermal properties of organogel systems, DSC was performed and the typical results collated in Fig. 3. An endothermic peak was observed in heating scans for all samples (Fig. 3a). Peak temperatures were 49.57 °C, 49.76 °C, 49.67 °C, 49.50 °C, and 49.54 °C corresponding to the PGE concentration of 7%, 9%, 11%, 13% and 15% (w/w) respectively which were closed to each other. There was no significant changes in the temperature at around 49 °C for all samples which coincided with the previous research on gel phase formed by PGE in water (Curschellas et al., 2013). Enthalpy change (ΔΗ) as calculated from the peak area was increased with the PGE addition, which were 0.90 J/g, 1.31 J/g, 2.53 J/g, 3.28 J/g and
3.4. Microstructure of organogels Polarized light microscopy were carried out to observe the microstructure of the organogels, and images were displayed in Fig. 4. As 5
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
in the patterns. Two peaks appeared at 5.46° (16.19 Å) and 21.49° (4.13 Å) in the pattern of PGE powder (Fig. 3S), which closed to the small peak at 21.93 Å and the sharp peak at 4.15 Å in the organogel patterns, respectively. PGE with long chain fatty acid (C16–C18) esters of a low degree of glycerol polymerization (3–5 glycerols) be able to self-assemble into the stable α crystalline structure in the presence of water whose XRD parameter was 4.1 Å (Duerrauster et al., 2007; Izquierdo et al., 2006). The broad peak appeared at an angle of 19.47° corresponding to distance of 4.56 Å of organogels which closed to the parameter of α crystalline structure of PGE in water and in accordance with the typical diffraction peaks of liquid crystalline state of the hydrocarbon chain (Shrestha et al., 2006). It was speculated that the PGE also formed α crystalline structure in sunflower oil. Heating the mixture of PGE and sunflower oil above TK allowed liquid oil penetrated and organized into lamellar crystalline structures. Cooling the liquid crystal below TK, α crystalline structure was obtained. According previous study, wider peaks appeared because of disorder into the system which was introduced by liquid oil (Zetzl, Ollivon, & Marangoni, 2009). The XRD patterns of PGE at various concentration suggesting that the concentration of PGE did not affect the lamellar structure spacing.
Fig. 5. XRD pattern of organogels at different concentration.
3.6. FTIR The FTIR measurements were carried out to investigate the structural information about the molecular interaction in organogels. Infrared spectra of organogels collected from the experiment were displayed in Fig. 6. As seen from Fig. 6, broad peaks were observed at around 3300-3400 cm−1 for all organogel samples. The broad peak was the characteristic absorption peak of –OH stretching vibrations from polyglycerol head group in PGE molecular. It was found that intramolecular or intermolecular hydrogen bonding between the PGE molecular contributed to the formation of networks. Obviously, the transmittance of organogels was increased with the addition of PGE, because of more intermolecular interactions. Hydrogen bonds have been reported to present in the organogels of the polymer and monoglyceride (Abdullatif et al., 2014; Meng et al., 2018). Hydrogen bonds may were responsibility for the formation of the semi-crystalline structure that trapped the sunflower oil and provided elastic properties of PGE organogel systems (F. C. Wang & Marangoni, 2016a). A strong peak around 1000-1200 cm−1 corresponded to C–O stretching vibration, and the peaks observed at 2925 cm−1 and 2856 cm−1 indicated C–H stretching vibration of the CH3 and CH2, respectively. The sharp absorption peak at around 1735 cm−1 was attributed to C=O related to ester bond (Baran et al., 2014). Commercial PGE mixture was shown to contain a small amount of free fatty acids which preserved the stability of the lamellar gel phase via the electrostatic interaction (Duerrauster et al., 2007). Coexistence of surface interactions among crystalline particles played an important role in formation of space-spanning network and providing the characteristic properties of organogels.
Fig. 6. FTIR spectra of organogels at different concentration.
seen from the images, PGE formed needle-like crystals appeared as birefringent against a dark background which represented sunflower oil. The spatial distribution of crystals in the organogels were effective retain and limit the migration of oil. The crystal morphology of PGE at low concentration were similar to that at high concentration, and the crystals grown in size and overlapped with the increasing PGE concentration. Ojijo et al. (Ojijo et al., 2010) held the view that high gelling agent concentrations causing a higher degree of the supersaturation, which accelerating the nucleation and the subsequent gelation, thus forming a more compact of organogel network. A denser crystal distribution was conducive to forming a more structured network which contribution to the solid-like properties of organogels and has positive impact on the macroscopic properties of systems. (Patel, Schatteman, De Vos, Lesaffer, & Dewettinck, 2013).
3.7. Baking trials The organogel prepared with 9% PGE was used to obtain sweet breads, while control samples were prepared by using commercial shortenings alone. The pictures of bread appearance and slices were shown in Fig. 4S. Observed the images, sweet breads prepared with organogels or shortening showed similar appearance with a well leavened structure. Table.2S given the results of the specific volume, moisture and water activity (Aw). No significant differences of crumb Aw between the organogel bread and shortening bread, while the moisture and specific volume of shortening breads were higher than that of organogel breads. The texture properties of the bread slices were evaluated by TPA of physical property analyser, and various parameters were shown in Table. 3S. Data on firmness, springiness, cohesiveness, gumminess, chewiness, and resilience of experimental samples were
3.5. XRD XRD were carried out to obtain more information about crystalline microstructure of PGE organogels. The diffraction patterns showed the profiles recorded of PGE powder (Fig. 3S) and organogels (Fig. 5) at room temperature with the 2θ range of 1–35°. Seen from Fig. 5, the patterns clearly showed that diffraction peaks of organogels structured by PGE at all concentration were almost same. A small peak at 21.93 Å, a broad peak at 4.56 Å, and a sharp little peak at 4.15 Å were appeared 6
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
doi.org/10.1016/j.lwt.2019.108590.
similar to that of control samples. In the process of stirring lipid material and dough, crystalline network structures formed by triacylglycerols formed a thin film between the interface of starch and the gluten, which improved the organization of the bread, provided soft and lubricious mouthfeels, and slowed the loss of water. It was found that PGE organogels replacing the typical functionality of crystalline network structures of shortenings (Calligaris, Manzocco, Valoppi, & Nicoli, 2013). In addition, samples containing organogels allowed a saturated fat reduction of about 28% as show in Table. 4S. Above findings were very promising, as they confirmed that organogels could indeed be modified to behave as a laminate fat replacement. This was followed by more explorative research about functional substances released.
References Alfutimie, A., Curtis, R., & Tiddy, G. J. T. (2014). Gel phase (Lβ) formation by mixed saturated and unsaturated monoglycerides. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 456, 286–295. Alvarez-Jubete, L., Auty, M., Arendt, E. K., & Gallagher, E. (2009). Baking properties and microstructure of pseudocereal flours in gluten-free bread formulations. European Food Research and Technology, 230(3), 437–445. Aranceta, J., & Pérezrodrigo, C. (2012). Recommended dietary reference intakes, nutritional goals and dietary guidelines for fat and fatty acids: A systematic review. British Journal of Nutrition, 107(Suppl 2), S8–S22 S2. Baran, N., Singh, V. K., Pal, K., Anis, A., Pradhan, D. K., & pramanik, K. (2014). Development and characterization of soy lecithin and palm oil-based organogels. Polymer-Plastics Technology, 53(9), 865–879. Bin Sintang, M. D., Rimaux, T., Van de Walle, D., Dewettinck, K., & Patel, A. R. (2017). Oil structuring properties of monoglycerides and phytosterols mixtures. European Journal of Lipid Science and Technology, 119(3), 517–519. Calligaris, S., Manzocco, L., Valoppi, F., & Nicoli, M. C. (2013). Effect of palm oil replacement with monoglyceride organogel and hydrogel on sweet bread properties. Food Research International, 51(2), 596–602. Calligaris, S., Mirolo, G., Da Pieve, S., Arrighetti, G., & Nicoli, M. C. (2014). Effect of oil type on formation, structure and thermal properties of γ-oryzanol and β-sitosterol based organogels. Food Biophysics, 9(1), 69–75. Curschellas, C., Kohlbrecher, J., Geue, T., Fischer, P., Schmitt, B., Rouvet, M., et al. (2013). Foams stabilized by multilamellar polyglycerol ester self-assemblies. Langmuir, 29(1), 38–49. Da Pieve, S., Calligaris, S., Co, E., Nicoli, M. C., & Marangoni, A. G. (2010). Shear nanostructuring of monoglyceride organogels. Food Biophysics, 5(3), 211–217. Dassanayake, L. S. K., Kodali, D. R., & Ueno, S. (2011). Formation of oleogels based on edible lipid materials. Current Opinion in Colloid & Interface Science, 16(5), 432–439. Duerrauster, N., Kohlbrecher, J., Zuercher, T., Gunde, R., Fischer, A. P., & Windhab, E. (2007). Microstructure and stability of a lamellar liquid crystalline and gel phase formed by a polyglycerol ester mixture in dilute aqueous solution. Langmuir, 23(26), 12827–12834. Gayet-Boyer, C., Tenenhaus-Aziza, F., Prunet, C., Marmonier, C., Malpuech-Brugère, C., Lamarche, B., et al. (2014). Is there a linear relationship between the dose of ruminant trans-fatty acids and cardiovascular risk markers in healthy subjects: Results from a systematic review and meta-regression of randomised clinical trials. British Journal of Nutrition, 112(12), 1914–1922. Gomez-Estaca, J., Herrero, A. M., Herranz, B., Alvarez, M. D., Jimenez-Colmenero, F., & Cofrades, S. (2019). Characterization of ethyl cellulose and beeswax oleogels and their suitability as fat replacers in healthier lipid pates development. Food Hydrocolloids, 87, 960–969. Izquierdo, P., Acharya, D. P., Hirayama, K.c., Asaoka, H., Ihara, K., Tsunehiro, T., & Kunieda, H. (2006). Phase behavior of pentaglycerol monostearic and monooleic acid esters in water. Journal of Dispersion Science and Technology, 27(1), 99–103. Kunieda, K., Aramaki, K., Nishimura, T., & Ishitobi, M. (2009). Phase behavior of polyglycerin fatty acid ester in a water-oil system and formulations of gel-emulsions stabilized by the cubic phase. Journal of Oleo Science, 49(6), 617–624. Lichtenstein, A. H. (2014). Dietary trans fatty acids and cardiovascular disease risk: Past and present. Current Atherosclerosis Reports, 16, 433. https://doi.org/10.1007/ s11883-014-0433-1. Liu, Y., Meng, Z., Liang, S., Jin, Q., & Wang, X. (2010). Preparation of specialty fats from beef tallow and canola oil by chemical interesterification: Physico-chemical properties and bread applications of the products. European Food Research and Technology, 230(3), 457–466. Lupi, F. R., Greco, V., Baldino, N., Cindio, B. D., Fischer, P., & Gabriele, D. (2016). The effects of intermolecular interactions on the physical properties of organogels in edible oils. Journal of Colloid and Interface Science, 483, 154–164. Maciasrodriguez, B. A., & Marangoni, A. A. (2017). Linear and nonlinear rheological behavior of fat crystal networks. Critical Reviews in Food Science and Nutrition, 58(14), 2398–2415. Makarewicz-Wujec, M., Dworakowska, A., & Kozlowska-Wojciechowska, M. (2018). Replacement of saturated and trans-fatty acids in the diet CVD risk in the light of the most recent studies. Public Health Nutrition, 21(12), 1–10. Meng, Z., Qi, K., Guo, Y., Wang, Y., & Liu, Y. (2018). Macro-micro structure characterization and molecular properties of emulsion-templated polysaccharide oleogels. Food Hydrocolloids, 77, 17–29. Ojijo, N. K., Neeman, I., Eger, S., & Shimoni, E. (2010). Effects of monoglyceride content, cooling rate and shear on the rheological properties of olive oil monoglyceride gel networks. Journal of the Science of Food and Agriculture, 84(12), 1585–1593. Palla, C., Giacomozzi, A., Genovese, D. B., & Elena Carrin, M. (2017). Multi-objective optimization of high oleic sunflower oil and monoglycerides oleogels: Searching for rheological and textural properties similar to margarine. Food Structure, 12, 1–14. Patel, A. R., Schatteman, D., De Vos, W. H., Lesaffer, A., & Dewettinck, K. (2013). Preparation and rheological characterization of shellac oleogels and oleogel-based emulsions. Journal of Colloid and Interface Science, 411(6), 114–121. Rogers, M. A. (2009). Novel structuring strategies for unsaturated fats - meeting the zerotrans, zero-saturated fat challenge: A review. Food Research International, 42(7), 747–753. Ruiz-Nunez, B., Dijck-Brouwer, D. A., & Muskiet, F. A. (2016). The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease. The Journal of Nutritional Biochemistry, 36, 1–20.
4. Conclusion The objective of this study was systematic analysed macroscopic properties, microstructure, interaction force of organogels based on the PGE and sunflower oil. Baking experiment was carried out to achieve a better understanding of the possibility of food application. In organogel systems, space-spanning networks formed by crystalline of PGE through interactions among crystalline particles, which entrapped sunflower oils and provide a solid-like behavior. Higher concentration of PGE led to more compact network structure which resulted in lower OL, higher SFC, firmness and G'. Results of XRD showed that α crystalline structure was formed in organogels. Characteristic absorption peak of –OH appeared in FTIR spectra of organogels suggesting that hydrogen bonds played an important role in the formation of space-spanning networks. Temperature ramp tests and DSC confirmed that the organogels has thermoreversible properities. Organogels was melted into liquid state at around 50 °C, while organogel systems would become a solid-like state again at around 40 °C. Results of baking experiment reported in this study highlighted that the organogels prepared by PGE had the potential to replace the baking shortenings. The organogels based on PGE needs to be investigated further in regard to the relationship between the microstructure and macroproperties, and potential applications in foods. Author agreement/declaration All authors have seen and approved the final version of the manuscript being submitted. They warrant that the article is the authors' original work, hasn't received prior publication and isn't under consideration for publication elsewhere. Conflict of interest The authors declare no competing financial interest. Notes The authors declare no competing financial interest. Acknowledgments This research was supported by the National Natural Science Foundation of China (31772008, 31972112, 31471678), the National Key Research and Development Program of China (2016YFD0401404), and also supported by General Projects of China Postdoctoral Science and Foundation (2018M640458), Special Funding from China Postdoctoral Science Foundation (2019T120391), Qing Lan Project, Suqian City Science and Technology Project (L201810) and Jiangsu Planned Projects for Postdoctoral Research Funds (2018K028B). Appendix A. Supplementary data Supplementary data to this article can be found online at https:// 7
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
Wakisaka, S., Nakanishi, M., & Gohtani, S. (2014). Phase behavior and formation of o/w nano-emulsion in vegetable oil/mixture of polyglycerol polyricinoleate and polyglycerin fatty acid ester/water systems. Journal of Oleo Science, 63(3), 229–237. Wang, F. C., Gravelle, A. J., Blake, A. I., & Marangoni, A. G. (2016). Novel trans fat replacement strategies. Curr. Opin Food Sci. (7), 27–34. Wang, F. C., & Marangoni, A. G. (2016a). Advances in the application of food emulsifier alpha-gel phases: Saturated monoglycerides, polyglycerol fatty acid esters, and their derivatives. Journal of Colloid and Interface Science, 483, 394–403. Wijarnprecha, K., Aryusuk, K., Santiwattana, P., Sonwai, S., & Rousseau, D. (2018). Structure and rheology of oleogels made from rice bran wax and rice bran oil. Food Research International, 112, 199–208. Yilmaz, E., & Ogutcu, M. (2014). Properties and stability of hazelnut oil organogels with beeswax and monoglyceride. J. Am. Oil Chem. Soc. 91(6), 1007–1017. Zetzl, A., Ollivon, M., & Marangoni, A. G. (2009). A coupled differential scanning calorimetry and X-ray study of the mesomorphic phases of monostearin and stearic acid in water. Crystal Growth & Design, 9(9), 3928–3933.
Sanchez-Becerril, M., Marangoni, A. G., Perea-Flores, M. J., Cayetano-Castro, N., Martinez-Gutierrez, H., Andraca-Adame, J. A., et al. (2018). Characterization of the micro and nanostructure of the candelilla wax organogels crystal networks. Food Structure, 16, 1–7. Sawalha, H., Venema, P., Bot, A., Flöter, E., Adel, R. D., & Linden, E. V. D. (2015). The phase behavior of γ-oryzanol and β-sitosterol in edible oil. J. Am. Oil Chem. Soc. 92(11), 1651–1659. Shrestha, L. K., Acharya, D. P., Sharma, S. C., Aramaki, K., Asaoka, H., Ihara, K., & Kunieda, H. (2006). Aqueous foam stabilized by dispersed surfactant solid and lamellar liquid crystalline phase. Journal of Colloid and Interface Science, 301(1), 274–281. Singh, A., Auzanneau, F. I., & Rogers, M. A. (2017). Advances in edible oleogel technologies - a decade in review. Food Research International, 97, 307–317. Valoppi, F., Calligaris, S., Barba, L., Segatin, N., Poklar Ulrih, N., & Nicoli, M. C. (2017). Influence of oil type on formation, structure, thermal, and physical properties of monoglyceride-based organogel. European Journal of Lipid Science and Technology, 119(2), 1500549. https://doi.org/10.1002/ejlt.201500549.
8
Contents lists available at ScienceDirect
LWT - Food Science and Technology journal homepage: www.elsevier.com/locate/lwt
Organogels based on the polyglyceryl fatty acid ester and sunflower oil: Macroscopic property, microstructure, interaction force, and application
T
Zong Menga,b, Ying Guob, Yong Wangc, Yuanfa Liub,∗ a Beijing Advanced Innovation Center for Food Nutrition and Human Health, Beijing Technology and Business University (BTBU), Beijing, 100048, People's Republic of China b State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi, 214122, Jiangsu, People's Republic of China c Department of Food Science and Engineering, Guangdong Saskatchewan Oilseed Joint Laboratory, Jinan University, Huangpu Rd. West 601, Guangzhou, 510632, Guangdong, People's Republic of China
A R T I C LE I N FO
A B S T R A C T
Keywords: Organogels PGE Macroscopic properties Space-spanning networks Crystalline structure
Polyglyceryl fatty acid ester (PGE) was used as organogelator to structure sunflower oil. Macroscopic properties, microstructures, interaction force of organogels were systematic analysed using rheometer, pulsed nuclear magnetic resonance (pNMR), differential scanning calorimetry (DSC), polarizing light microscope (PLM), X-ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR), respectively. In addition, organogels were evaluated as a shortening replacer applied in bread. Macroscopic properties were related to the space-spanning networks formed through surface interactions among crystalline such as hydrogen bonds and electrostatic interaction. Higher organogelators concentration resulted in more compact network which provided lower oil loss, higher firmness and G'. Melting and collapsing of crystalline structure resulted in the transformation of organogel from solid-like state to liquid state. In bread making process, the crystalline network formed by PGE could imitated the functions of crystalline network structures formed by triacylglycerol. This investigation was beneficial for expanding potential applications of PGE in organgels.
1. Introduction Processed foods, such as chocolates, whipped creams, and some bakery products, contain high amounts of solid fats consisting primarily of saturated or even contain trans fats because of their positive influences on product performances in terms of texture, sensory characteristics, and shelf-life. The realization of these functions is based on the crystal network composed of saturated fats and which was responsible for viscoelastic and elastic properties of specialty fats (Maciasrodriguez & Marangoni, 2017). However, excess consumption of trans and saturated fatty acids has been found to show deleterious health effects including obesity issues, cardiovascular diseases, Type II diabetes and other related diseases (Gayet-Boyer et al., 2014; Lichtenstein, 2014; Makarewicz-Wujec, Dworakowska, & Kozlowska-Wojciechowska, 2018; Ruiz-Nunez, Dijck-Brouwer, & Muskiet, 2016). Most countries have already placed a ban or strict legislative limits on using of artificial trans fats in processed foods like the United States, the European Union,
and Canada. Moreover, nutritional guidelines have suggested that reducing the trans and saturated fats in diet and replacing them with unsaturated fats from vegetable sources (Aranceta & Pérezrodrigo, 2012). Therefore, novel oil structuring methods to prepared fat alternatives with zero trans and low saturated fatty acids, and closely resemble conventional fat structured systems have been receiving increased attentions from researchers of food industries. Organogelation of liquid oil is one of the most promising strategies to design new soft matter structures with the functionality of traditional plastic fat, zero trans and low saturated fatty acids (Dassanayake, Kodali, & Ueno, 2011; Singh, Auzanneau, & Rogers, 2017; Fan C.; Wang, Gravelle, Blake, & Marangoni, 2016). Organogel was achieved through adding single or combination of organogelator molecules into the liquid oil. In organogel systems, liquid oil was immobilized by the three-dimensional network of supramolecular structure formed by organogelators, which resulted in a solid-like material in macroscopic features.
∗
Corresponding author. State Key Laboratory of Food Science and Technology, Collaborative Innovation Center of Food Safety and Quality Control in Jiangsu Province, National Engineering Research Center for Functional Food, National Engineering Laboratory for Cereal Fermentation Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, People's Republic of China E-mail addresses: [email protected] (Z. Meng), yfl[email protected] (Y. Liu). https://doi.org/10.1016/j.lwt.2019.108590 Received 18 April 2019; Received in revised form 1 September 2019; Accepted 4 September 2019 Available online 05 September 2019 0023-6438/ © 2019 Elsevier Ltd. All rights reserved.
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
PGE completely dissolved in the oil, and then obtained a homogeneous dispersion system. Finally, mixtures were cooled under static conditions at room temperature for 24 h, and then stored at 20 °C incubator for further tests.
Wax-based organogels has been studied and exploited to fully or partially replace the saturated fat in fat-based food formulations such as shortenings, margarines, and creams (Gomez-Estaca et al., 2019). Several studies have already been reported wax-based organogels such as rice bran wax in rice bran oil (Wijarnprecha, Aryusuk, Santiwattana, Sonwai, & Rousseau, 2018), and candelilla wax in high oleic safflower oil (Sanchez-Becerril et al., 2018). However, natural and edible wax have fewer sources. Some articles reported γ-oryzanol and β-sitosterol based organogels (Calligaris, Mirolo, Da Pieve, Arrighetti, & Nicoli, 2014; Sawalha et al., 2015), but relatively high-prices limited the use of those gelling agent in the food industry. Small molecule emulsifier has been attracted attention of scholars because of edible, safety, and wide source. Much research was concentrated on the monoglyceride as a structure agent (Palla, Giacomozzi, Genovese, & Elena Carrin, 2017; Valoppi et al., 2017). On the contrary, PGE as a gelling agent to structured vegetable oil has not yet been intensively studied at our knowledge. This investigation was beneficial for expanding the type of organogelator of small molecule emulsifier and providing a new idea for potential applications of PGE organogels. Polyglycerol fatty acid ester (PGE), formed from esterification of polyglycerol and fatty acids, is a non-ionic surfactant with edible and high safety. A PGE molecule contains a hydrophilic head group of nglycerol units and one or two hydrophobic alkyl chains which determines excellent amphiphilic properties. Therefore, PGE was widely used in cosmetics, food, medicine and other fields. PGE formed a lamellar gel in the presence of water, and this type of self-assembled supramolecular aggregates formed by surfactants in water had been studied both fundamental and applied research over the past few decades (Kunieda, Aramaki, Nishimura, & Ishitobi, 2009; Wakisaka, Nakanishi, & Gohtani, 2014). PGE successively forms a lamellar liquid crystalline and a lamellar gel phase when heated and cooled the mixture of surfactant and water above the Krafft temperature (TK). In lamellar gel phase, the water layer was trapped between the bilayer structures of glycerol head groups by hydroxyl groups (Duerrauster et al., 2007). Macroscopic property, microstructure, interaction force, and application of the organogels formed by a mixture of PGE and sunflower oil at various concentration were investigated using a combination of DSC, PLM, rheometer, XRD, FTIR as well as physical property analyser. The combination of these techniques has allowed a detailed description of the semi-solid structure formed by crystalline structure which trapped liquid oil. In addition, the effects of different lipid matrices on breads were determined by assessing the fatty acid composition, water activity, moisture, specific volume, and texture characteristics. This study offers the essential information about PGE and sunflower oil based organogels, and provided a reference for its baking application.
2.3. Oil loss (OL) determination The method reported by Da Pieve et al. (Da Pieve, Calligaris, Co, Nicoli, & Marangoni, 2010) was adapted to measure the oil loss of organogels. First, a plastic centrifuge tube (1.5 mL) was weighted and the mass of tube was recorded as “a”. Then, approximately 1 g sample was filled in tube whose mass was recorded as “b”, and then tubes with simple were centrifuged at 10621 g for 15 min. The released liquid oil drained out of tube after centrifugation and the mass was recorded as “c”. Triplicate measurements were obtained, and OL values were calculated by Equation (1): OL= (b-c)/b-a
(1)
2.4. Texture analysis The firmness of organogel samples was measured by penetration test using a Texture Analyser (Stable Microsystems, Surrey, UK) equipped with a cylindrical probe (P/5) of 12.7 mm diameter. Samples were melted completely at 75 °C and approximately 30 mL samples were poured into 50 mL flat-bottomed plastic centrifuge tubes and stand at room temperature for 24 h to test firmness. The test settings including the pre-test speed, test speed, and post-test speed were 2.0 mm/s, 1.0 mm/s, and 2.0 mm/s, respectively, and the penetration depth of 15 mm (Yilmaz & Ogutcu, 2014). The measurements were performed in triplicate. Texture exponent v.6.1.1.0 software (Stable Microsystems, Surrey, UK) on the instrument was used to analyse the date. 2.5. Rheological measurements The rheology properties of organogels were measured by using a DHR-3 rotary rheometer (TA Instruments, New Castle, USA) attached with a temperature control system. Tests were performed by a parallel plate with diameter of 40 mm, and the geometry gap was set to 1000 μm (Meng, Qi, Guo, Wang, & Liu, 2018). To determine the linear viscoelastic region (LVR) for the samples, strain sweep tests were conducted at strain amplitude varying from 0.001% to 10%, and applying a constant frequency of 3 Hz. Frequency sweeps were conducted in frequency ranging from 0.1 to 100 Hz, and a fixed strain value determined by LVR. Using the same geometry, temperature sweep measurements were carried out at temperature range of 0–65 °C, and the rate of heating and cooling was 5 °C/min. Strain sweeps and frequency sweeps were carried out at 25 °C, respectively.
2. Material and methods 2.1. Materials Sunflower oil and ingredients of bread, including high-gluten flour, milk powder, eggs, and yeast were purchased from the local market. PGE was a generous gift from Danisco (Danisk Co., Ltd, Suzhou, China). This commercial mixture of PGE was consisted predominantly of stearic acid (57.54%) and palmitic acid (40.83%).
2.6. Solid fat content (SFC) The SFC of organogels was carried out by the IPC-610 pulsed nuclear magnetic resonance (pNMR, Niumag Electronic Technology Co., Ltd, Shang Hai, China), which attached an external water bath to control temperature. The modified method reported by Bin Sintang, Rimaux, Van de Walle, Dewettinck, and Patel (2017) was used. Approximately 3.5 mL of melted samples were transferred into pNMR glass tubes, and then placed in a water bath at 80 °C at least 30 min to eliminate crystal memory. Subsequently, all the tubes were transferred into the auxiliary low temperature water bath of pNMR analyser at 0 °C for 1 h to solidification. The test was measured at temperature range of 0–50 °C, increased 5 °C each time. Before measured, keep the tube at the measured temperature for 30 min. Triplicate measurements were obtained.
2.2. Preparation of organogels Organogels were prepared by mixing sunflower oil and PGE in proportions ranging from 7% PGE to 15% PGE (w/w) with 2% increments, and the preparation method refers to the article published by Alfutimie et al. (Alfutimie, Curtis, & Tiddy, 2014). Firstly, weighing appropriate amounts of PGE and sunflower oil into clean and dry beakers. Then, mixtures were heated and stirred by a multi-point magnetic stirrer (TA Instruments, New Castle, USA) at 75 °C until the 2
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
it, the dough was cut into small pieces and every small dough was kneaded into round shape, and then placed into the proofer (Shuangmai bakery equipment Co., Ltd, Wuxi, China) setting a temperature of 38 °C and a humidity of 75% to perform the second fermentation for 30 min. The bread doughs were baked in a preheated oven (Shuangmai bakery equipment Co., Ltd, Wuxi, China) at 200 °C for 12 min. After cooling to room temperature, five slices of 15 mm thickness were cut from the central portion of each loaf by a SAM-302 slicing machine (Shuangmai bakery equipment Co., Ltd, Wuxi, China), packed in sample bag, and then stored at room temperature until analysis.
2.7. Differential scanning calorimetry (DSC) Thermal analysis was carried out using a TA Q2000 DSC instrument (TA Instruments, New Castle, USA). The experimental method refers to the article published by Lupi et al. (Francesca R. Lupi et al., 2016). An aluminum pan was filled with 7–8 mg organogels and then was sealed by the pressure machine, and an empty pan was used as a reference. In order to exclude the effect of the existing crystalline structure, the sample was rapidly heated to 80 °C and maintained for 10 min, followed by a cooling step to −10 °C. The sample was then kept isothermal for 5 min before heating to 80 °C. The rate of heating and cooling was 10 °C/min. The program Universal Analysis 2000 (TA Instruments, New Castle, DE) was used to plot and analysed the thermal data.
2.11.2. Properties of product Texture properties of bread slices were carried out using TA-XT Plus (Stable Microsystems, Surrey, UK). Measurement was performed with texture profile analysis (TPA) mode at pre-test speed of 5.0 mm/s, test speed of 2.0 mm/s, post-test speed of 5.0 mm/s, and the compression ratio was set at 75% (Alvarez-Jubete, Auty, Arendt, & Gallagher, 2009). The specific volume of breads were measured by millet displacement modified based on the method approved by Liu (Liu, Meng, Liang, Jin, & Wang, 2010). Crumb in the middle of several bread slices was used for following analysis. The moisture content was measured using by a MB120 moisture tester (OHAUS, New Jersey, America) preformed at 105 °C. Water activity was determined using a portable water activity meter (Novasina, Zurich, Switzerland). Each experiment was carried out in triplicate. Fatty acid composition of bread was determined by GC-2010PLUS (Shimadzu, Tokyo, Japan) equipped with a flame ionization detector and a fused-silica capillary column (CP-Sil88, 60 m × 0.25 mm × 0.2 μm. The column was heated to 60 °C and held for 3 min, then programmed at 5 °C/min to 175 °C and held for 15 min, then the temperature was increased to 220 °C at 2 °C/min and held for 10 min.
2.8. Microstructure observation The microstructure of organogels was observed at room temperature by using Leica DM2700P microscope (Leica Microsystems, Wetzlar, Germany) equipped with a Charge-coupled Device (CCD) camera. Organogels were melted in a water bath at 75 °C to eliminate crystal memory before microscope observation. A spot of melted organogels was dropped onto a glass slide and covered with a glass slip. The microscopy slides were conditioned in an incubator (Binder, Neckarsulm, Germany) at 20 °C for 24 h. Slides were observed under 500 × magnification by using polarized light. 2.9. X-ray diffraction (XRD) The molecular organization of the organogels were explored with a D2 Phaser X-Ray Diffractometer (Bruker AXS GmbH, Karlsruhe, Germany) equipped with scintillation counter and 1-dimensional LynxEye detector. The standard ceramic sealed tube using Cu as the Xray source was operated at 30 mA and 40 kV to produce X-ray of 1.54 Å wavelength. Sample holder was filled with organogels, and samples were smoothed before sweeping. Angular scans from 1° to 35° were performed by using a step size of 0.3 and at a rate of 0.03 s/step at environment temperature (Meng et al., 2018). Experiment was carried out in duplicate. The MDI Jade 6 software (Materials Data Inc., Livermore, USA) was used for data processing and analyses.
2.12. Statistical analysis Statistical analysis was completed using Origin 2016 and Sigma Plot 12.5, respectively. All measurement data were presented as means with standard deviation and differences were considered significant at 5% (P < 0.05). Analysis of variance (ANOVA) with Duncan's multiple range test was carried out by the Statistical Analysis System software (SAS, Cary, NC).
2.10. FTIR analysis 3. Results and discussion A FTIR spectrometer (IS10, Nicolet, USA) was used to record the infrared absorption spectra of the samples and the experimental method refers to the article published by our research team (Meng et al., 2018). The FTIR instrument equipped with an attenuated total reflectance (ATR) crystal (ZnSe). Organogels or sunflower oil was directly placed on the crystal, respectively, and the spectra were collected within the range of wavenumber 400 and 4000 cm−1, each with 16 scans at a resolution of 4 cm−1. All spectra erased the effect of the background spectrum measured against a background of air, and were analysed by the software OMNIC (Thermo, v8.0). The measurement was carried out in duplicate.
3.1. Oil loss (OL) and firmness The ability of network to trap liquid oil reflecting by OL and mechanical strength of organogel samples were characterized by texture analysis. Learn from Table. 1S, the proportion of PGE played a positive effect on increasing firmness of organogels and reducing OL. The sample at 7% concentration of PGE lost more than 60% liquid oil while the sample at 15% concentration lost less than 30% liquid oil after centrifuging. It was found that both OL and firmness were benefited from the network formed by PGE.
2.11. Baking application
3.2. Rheological properties
2.11.1. Bread production The basic recipes of bread consisted of high-gluten powder 250 g, water 135 g, sugar 50 g, shortening 35 g, skimmed milk powder 10 g, yeast 2.5 g and salt 2.5 g. Lipid matrix (shortening or organogels) did not add until other materials were blended to a smooth dough at low speed in the pastry blender (Shuangmai bakery equipment Co., Ltd, Wuxi, China). Continue stirring until the mixture came together at low speed, subsequently, blending at high speed until the dough became very elastic and could be pulled out the translucent film. Then, first fermentation was carried out at room temperature for 60 min. Followed
Amplitude sweep tests were used in determination the linear viscoelastic region (LVR) of organogels. Fig. 1S and fig1 displayed the results of LVR and frequency sweep teats respectively. Learned from Fig. 1S, the LVR of all organogel samples has a stress range of approximately 0.001%–1%. As seen from Fig. 1, all organogel samples behaved as “solid” with storage modulus (G′) higher than the loss modulus (G″). Solid-like property of organogels was also attribute to the network structure formed by PGE crystal. Fig. 1 clearly showed that both G′ and G″ were increased as the concentration of organogelators. Additionally, a frequency independent behavior was observed which 3
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
indicated a structured connection of the network (Bin Sintang et al., 2017; Ojijo, Neeman, Eger, & Shimoni, 2010). Temperature ramp tests were performed to evaluate the effect of temperature on the crystalline structure of the organogel. Rheological parameters as a function of temperature were plotted and displayed in Fig. 2. Organogels at all PGE concentration exhibited a typical thermally reversible behavior during the heating and cooling cycle. As the temperature raise, the system gradually melting and completely melting at high temperatures. A sudden decrease in G′ was observed between 40 and 60 °C indicating the melting and collapse of the organogel networks that provided the elasticity property, and the organogel systems exhibited a viscous behavior when continued to raise the temperature. Cooling the samples, a slope increasing in G′ suggested that crystalline aggregates gradually formed and stretched into entire sample, which resulting in the formation of a solid-like organogel material again (F. R. Lupi et al., 2016). The effect of temperature on the solid content in the organogel systems were also characterized by referring to the SFC, and the results
Fig. 1. Frequency sweep curves of organogel (solid marks are representative elastic modulus, hollow marks are representative viscous modulus).
Fig. 2. Temperature sweep curves of organogels at different concentration. 4
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
Fig. 3. DSC profiles of heating process (a) and cooling process (b) of organogels.
of SFC presented in Fig. 2S. A suddenly drop of SFC appeared between 40 and 50 °C indicating the crystalline in organogles began to melt, which was similar with temperature ramp tests. The solid-like property of organogels at low temperature was mainly due to the ability of small molecule gelling agents to entrap liquid oil. As well know, hydrogenation significantly increased SFC through the method of changing in the saturation of the fatty acids. Fig. 2S clearly showed that SFC for all organogel samples were below 12%, and not significantly increase with addition of gelling agents, which indicating that organogelation bound liquid oil to the network structure through physical actions (Rogers, 2009).
Fig. 4. Polarized light images of organogels at concentration of 7% (a), 9% (b), 11% (c), 13% (d), 15% (e).
4.26 J/g, respectively. For cooling scans (Fig. 3b), a single peak appeared in the crystallization curves for all samples, and peaks slightly moved to high temperature with the increasing PGE, which were 42.43 °C (1.48 J/g), 43.34 °C (2.20 J/g), 43.95 °C (2.82 J/g), 44.02 °C (3.27 J/g) and 44.55 °C (4.02 J/g), respectively. It was found that the temperature of endothermic peak for all samples was closed to those of exothermic peak which suggesting that those peaks respected the melting and crystallization of PGE crystals.
3.3. DSC In order to detailed investigate thermal properties of organogel systems, DSC was performed and the typical results collated in Fig. 3. An endothermic peak was observed in heating scans for all samples (Fig. 3a). Peak temperatures were 49.57 °C, 49.76 °C, 49.67 °C, 49.50 °C, and 49.54 °C corresponding to the PGE concentration of 7%, 9%, 11%, 13% and 15% (w/w) respectively which were closed to each other. There was no significant changes in the temperature at around 49 °C for all samples which coincided with the previous research on gel phase formed by PGE in water (Curschellas et al., 2013). Enthalpy change (ΔΗ) as calculated from the peak area was increased with the PGE addition, which were 0.90 J/g, 1.31 J/g, 2.53 J/g, 3.28 J/g and
3.4. Microstructure of organogels Polarized light microscopy were carried out to observe the microstructure of the organogels, and images were displayed in Fig. 4. As 5
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
in the patterns. Two peaks appeared at 5.46° (16.19 Å) and 21.49° (4.13 Å) in the pattern of PGE powder (Fig. 3S), which closed to the small peak at 21.93 Å and the sharp peak at 4.15 Å in the organogel patterns, respectively. PGE with long chain fatty acid (C16–C18) esters of a low degree of glycerol polymerization (3–5 glycerols) be able to self-assemble into the stable α crystalline structure in the presence of water whose XRD parameter was 4.1 Å (Duerrauster et al., 2007; Izquierdo et al., 2006). The broad peak appeared at an angle of 19.47° corresponding to distance of 4.56 Å of organogels which closed to the parameter of α crystalline structure of PGE in water and in accordance with the typical diffraction peaks of liquid crystalline state of the hydrocarbon chain (Shrestha et al., 2006). It was speculated that the PGE also formed α crystalline structure in sunflower oil. Heating the mixture of PGE and sunflower oil above TK allowed liquid oil penetrated and organized into lamellar crystalline structures. Cooling the liquid crystal below TK, α crystalline structure was obtained. According previous study, wider peaks appeared because of disorder into the system which was introduced by liquid oil (Zetzl, Ollivon, & Marangoni, 2009). The XRD patterns of PGE at various concentration suggesting that the concentration of PGE did not affect the lamellar structure spacing.
Fig. 5. XRD pattern of organogels at different concentration.
3.6. FTIR The FTIR measurements were carried out to investigate the structural information about the molecular interaction in organogels. Infrared spectra of organogels collected from the experiment were displayed in Fig. 6. As seen from Fig. 6, broad peaks were observed at around 3300-3400 cm−1 for all organogel samples. The broad peak was the characteristic absorption peak of –OH stretching vibrations from polyglycerol head group in PGE molecular. It was found that intramolecular or intermolecular hydrogen bonding between the PGE molecular contributed to the formation of networks. Obviously, the transmittance of organogels was increased with the addition of PGE, because of more intermolecular interactions. Hydrogen bonds have been reported to present in the organogels of the polymer and monoglyceride (Abdullatif et al., 2014; Meng et al., 2018). Hydrogen bonds may were responsibility for the formation of the semi-crystalline structure that trapped the sunflower oil and provided elastic properties of PGE organogel systems (F. C. Wang & Marangoni, 2016a). A strong peak around 1000-1200 cm−1 corresponded to C–O stretching vibration, and the peaks observed at 2925 cm−1 and 2856 cm−1 indicated C–H stretching vibration of the CH3 and CH2, respectively. The sharp absorption peak at around 1735 cm−1 was attributed to C=O related to ester bond (Baran et al., 2014). Commercial PGE mixture was shown to contain a small amount of free fatty acids which preserved the stability of the lamellar gel phase via the electrostatic interaction (Duerrauster et al., 2007). Coexistence of surface interactions among crystalline particles played an important role in formation of space-spanning network and providing the characteristic properties of organogels.
Fig. 6. FTIR spectra of organogels at different concentration.
seen from the images, PGE formed needle-like crystals appeared as birefringent against a dark background which represented sunflower oil. The spatial distribution of crystals in the organogels were effective retain and limit the migration of oil. The crystal morphology of PGE at low concentration were similar to that at high concentration, and the crystals grown in size and overlapped with the increasing PGE concentration. Ojijo et al. (Ojijo et al., 2010) held the view that high gelling agent concentrations causing a higher degree of the supersaturation, which accelerating the nucleation and the subsequent gelation, thus forming a more compact of organogel network. A denser crystal distribution was conducive to forming a more structured network which contribution to the solid-like properties of organogels and has positive impact on the macroscopic properties of systems. (Patel, Schatteman, De Vos, Lesaffer, & Dewettinck, 2013).
3.7. Baking trials The organogel prepared with 9% PGE was used to obtain sweet breads, while control samples were prepared by using commercial shortenings alone. The pictures of bread appearance and slices were shown in Fig. 4S. Observed the images, sweet breads prepared with organogels or shortening showed similar appearance with a well leavened structure. Table.2S given the results of the specific volume, moisture and water activity (Aw). No significant differences of crumb Aw between the organogel bread and shortening bread, while the moisture and specific volume of shortening breads were higher than that of organogel breads. The texture properties of the bread slices were evaluated by TPA of physical property analyser, and various parameters were shown in Table. 3S. Data on firmness, springiness, cohesiveness, gumminess, chewiness, and resilience of experimental samples were
3.5. XRD XRD were carried out to obtain more information about crystalline microstructure of PGE organogels. The diffraction patterns showed the profiles recorded of PGE powder (Fig. 3S) and organogels (Fig. 5) at room temperature with the 2θ range of 1–35°. Seen from Fig. 5, the patterns clearly showed that diffraction peaks of organogels structured by PGE at all concentration were almost same. A small peak at 21.93 Å, a broad peak at 4.56 Å, and a sharp little peak at 4.15 Å were appeared 6
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
doi.org/10.1016/j.lwt.2019.108590.
similar to that of control samples. In the process of stirring lipid material and dough, crystalline network structures formed by triacylglycerols formed a thin film between the interface of starch and the gluten, which improved the organization of the bread, provided soft and lubricious mouthfeels, and slowed the loss of water. It was found that PGE organogels replacing the typical functionality of crystalline network structures of shortenings (Calligaris, Manzocco, Valoppi, & Nicoli, 2013). In addition, samples containing organogels allowed a saturated fat reduction of about 28% as show in Table. 4S. Above findings were very promising, as they confirmed that organogels could indeed be modified to behave as a laminate fat replacement. This was followed by more explorative research about functional substances released.
References Alfutimie, A., Curtis, R., & Tiddy, G. J. T. (2014). Gel phase (Lβ) formation by mixed saturated and unsaturated monoglycerides. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 456, 286–295. Alvarez-Jubete, L., Auty, M., Arendt, E. K., & Gallagher, E. (2009). Baking properties and microstructure of pseudocereal flours in gluten-free bread formulations. European Food Research and Technology, 230(3), 437–445. Aranceta, J., & Pérezrodrigo, C. (2012). Recommended dietary reference intakes, nutritional goals and dietary guidelines for fat and fatty acids: A systematic review. British Journal of Nutrition, 107(Suppl 2), S8–S22 S2. Baran, N., Singh, V. K., Pal, K., Anis, A., Pradhan, D. K., & pramanik, K. (2014). Development and characterization of soy lecithin and palm oil-based organogels. Polymer-Plastics Technology, 53(9), 865–879. Bin Sintang, M. D., Rimaux, T., Van de Walle, D., Dewettinck, K., & Patel, A. R. (2017). Oil structuring properties of monoglycerides and phytosterols mixtures. European Journal of Lipid Science and Technology, 119(3), 517–519. Calligaris, S., Manzocco, L., Valoppi, F., & Nicoli, M. C. (2013). Effect of palm oil replacement with monoglyceride organogel and hydrogel on sweet bread properties. Food Research International, 51(2), 596–602. Calligaris, S., Mirolo, G., Da Pieve, S., Arrighetti, G., & Nicoli, M. C. (2014). Effect of oil type on formation, structure and thermal properties of γ-oryzanol and β-sitosterol based organogels. Food Biophysics, 9(1), 69–75. Curschellas, C., Kohlbrecher, J., Geue, T., Fischer, P., Schmitt, B., Rouvet, M., et al. (2013). Foams stabilized by multilamellar polyglycerol ester self-assemblies. Langmuir, 29(1), 38–49. Da Pieve, S., Calligaris, S., Co, E., Nicoli, M. C., & Marangoni, A. G. (2010). Shear nanostructuring of monoglyceride organogels. Food Biophysics, 5(3), 211–217. Dassanayake, L. S. K., Kodali, D. R., & Ueno, S. (2011). Formation of oleogels based on edible lipid materials. Current Opinion in Colloid & Interface Science, 16(5), 432–439. Duerrauster, N., Kohlbrecher, J., Zuercher, T., Gunde, R., Fischer, A. P., & Windhab, E. (2007). Microstructure and stability of a lamellar liquid crystalline and gel phase formed by a polyglycerol ester mixture in dilute aqueous solution. Langmuir, 23(26), 12827–12834. Gayet-Boyer, C., Tenenhaus-Aziza, F., Prunet, C., Marmonier, C., Malpuech-Brugère, C., Lamarche, B., et al. (2014). Is there a linear relationship between the dose of ruminant trans-fatty acids and cardiovascular risk markers in healthy subjects: Results from a systematic review and meta-regression of randomised clinical trials. British Journal of Nutrition, 112(12), 1914–1922. Gomez-Estaca, J., Herrero, A. M., Herranz, B., Alvarez, M. D., Jimenez-Colmenero, F., & Cofrades, S. (2019). Characterization of ethyl cellulose and beeswax oleogels and their suitability as fat replacers in healthier lipid pates development. Food Hydrocolloids, 87, 960–969. Izquierdo, P., Acharya, D. P., Hirayama, K.c., Asaoka, H., Ihara, K., Tsunehiro, T., & Kunieda, H. (2006). Phase behavior of pentaglycerol monostearic and monooleic acid esters in water. Journal of Dispersion Science and Technology, 27(1), 99–103. Kunieda, K., Aramaki, K., Nishimura, T., & Ishitobi, M. (2009). Phase behavior of polyglycerin fatty acid ester in a water-oil system and formulations of gel-emulsions stabilized by the cubic phase. Journal of Oleo Science, 49(6), 617–624. Lichtenstein, A. H. (2014). Dietary trans fatty acids and cardiovascular disease risk: Past and present. Current Atherosclerosis Reports, 16, 433. https://doi.org/10.1007/ s11883-014-0433-1. Liu, Y., Meng, Z., Liang, S., Jin, Q., & Wang, X. (2010). Preparation of specialty fats from beef tallow and canola oil by chemical interesterification: Physico-chemical properties and bread applications of the products. European Food Research and Technology, 230(3), 457–466. Lupi, F. R., Greco, V., Baldino, N., Cindio, B. D., Fischer, P., & Gabriele, D. (2016). The effects of intermolecular interactions on the physical properties of organogels in edible oils. Journal of Colloid and Interface Science, 483, 154–164. Maciasrodriguez, B. A., & Marangoni, A. A. (2017). Linear and nonlinear rheological behavior of fat crystal networks. Critical Reviews in Food Science and Nutrition, 58(14), 2398–2415. Makarewicz-Wujec, M., Dworakowska, A., & Kozlowska-Wojciechowska, M. (2018). Replacement of saturated and trans-fatty acids in the diet CVD risk in the light of the most recent studies. Public Health Nutrition, 21(12), 1–10. Meng, Z., Qi, K., Guo, Y., Wang, Y., & Liu, Y. (2018). Macro-micro structure characterization and molecular properties of emulsion-templated polysaccharide oleogels. Food Hydrocolloids, 77, 17–29. Ojijo, N. K., Neeman, I., Eger, S., & Shimoni, E. (2010). Effects of monoglyceride content, cooling rate and shear on the rheological properties of olive oil monoglyceride gel networks. Journal of the Science of Food and Agriculture, 84(12), 1585–1593. Palla, C., Giacomozzi, A., Genovese, D. B., & Elena Carrin, M. (2017). Multi-objective optimization of high oleic sunflower oil and monoglycerides oleogels: Searching for rheological and textural properties similar to margarine. Food Structure, 12, 1–14. Patel, A. R., Schatteman, D., De Vos, W. H., Lesaffer, A., & Dewettinck, K. (2013). Preparation and rheological characterization of shellac oleogels and oleogel-based emulsions. Journal of Colloid and Interface Science, 411(6), 114–121. Rogers, M. A. (2009). Novel structuring strategies for unsaturated fats - meeting the zerotrans, zero-saturated fat challenge: A review. Food Research International, 42(7), 747–753. Ruiz-Nunez, B., Dijck-Brouwer, D. A., & Muskiet, F. A. (2016). The relation of saturated fatty acids with low-grade inflammation and cardiovascular disease. The Journal of Nutritional Biochemistry, 36, 1–20.
4. Conclusion The objective of this study was systematic analysed macroscopic properties, microstructure, interaction force of organogels based on the PGE and sunflower oil. Baking experiment was carried out to achieve a better understanding of the possibility of food application. In organogel systems, space-spanning networks formed by crystalline of PGE through interactions among crystalline particles, which entrapped sunflower oils and provide a solid-like behavior. Higher concentration of PGE led to more compact network structure which resulted in lower OL, higher SFC, firmness and G'. Results of XRD showed that α crystalline structure was formed in organogels. Characteristic absorption peak of –OH appeared in FTIR spectra of organogels suggesting that hydrogen bonds played an important role in the formation of space-spanning networks. Temperature ramp tests and DSC confirmed that the organogels has thermoreversible properities. Organogels was melted into liquid state at around 50 °C, while organogel systems would become a solid-like state again at around 40 °C. Results of baking experiment reported in this study highlighted that the organogels prepared by PGE had the potential to replace the baking shortenings. The organogels based on PGE needs to be investigated further in regard to the relationship between the microstructure and macroproperties, and potential applications in foods. Author agreement/declaration All authors have seen and approved the final version of the manuscript being submitted. They warrant that the article is the authors' original work, hasn't received prior publication and isn't under consideration for publication elsewhere. Conflict of interest The authors declare no competing financial interest. Notes The authors declare no competing financial interest. Acknowledgments This research was supported by the National Natural Science Foundation of China (31772008, 31972112, 31471678), the National Key Research and Development Program of China (2016YFD0401404), and also supported by General Projects of China Postdoctoral Science and Foundation (2018M640458), Special Funding from China Postdoctoral Science Foundation (2019T120391), Qing Lan Project, Suqian City Science and Technology Project (L201810) and Jiangsu Planned Projects for Postdoctoral Research Funds (2018K028B). Appendix A. Supplementary data Supplementary data to this article can be found online at https:// 7
LWT - Food Science and Technology 116 (2019) 108590
Z. Meng, et al.
Wakisaka, S., Nakanishi, M., & Gohtani, S. (2014). Phase behavior and formation of o/w nano-emulsion in vegetable oil/mixture of polyglycerol polyricinoleate and polyglycerin fatty acid ester/water systems. Journal of Oleo Science, 63(3), 229–237. Wang, F. C., Gravelle, A. J., Blake, A. I., & Marangoni, A. G. (2016). Novel trans fat replacement strategies. Curr. Opin Food Sci. (7), 27–34. Wang, F. C., & Marangoni, A. G. (2016a). Advances in the application of food emulsifier alpha-gel phases: Saturated monoglycerides, polyglycerol fatty acid esters, and their derivatives. Journal of Colloid and Interface Science, 483, 394–403. Wijarnprecha, K., Aryusuk, K., Santiwattana, P., Sonwai, S., & Rousseau, D. (2018). Structure and rheology of oleogels made from rice bran wax and rice bran oil. Food Research International, 112, 199–208. Yilmaz, E., & Ogutcu, M. (2014). Properties and stability of hazelnut oil organogels with beeswax and monoglyceride. J. Am. Oil Chem. Soc. 91(6), 1007–1017. Zetzl, A., Ollivon, M., & Marangoni, A. G. (2009). A coupled differential scanning calorimetry and X-ray study of the mesomorphic phases of monostearin and stearic acid in water. Crystal Growth & Design, 9(9), 3928–3933.
Sanchez-Becerril, M., Marangoni, A. G., Perea-Flores, M. J., Cayetano-Castro, N., Martinez-Gutierrez, H., Andraca-Adame, J. A., et al. (2018). Characterization of the micro and nanostructure of the candelilla wax organogels crystal networks. Food Structure, 16, 1–7. Sawalha, H., Venema, P., Bot, A., Flöter, E., Adel, R. D., & Linden, E. V. D. (2015). The phase behavior of γ-oryzanol and β-sitosterol in edible oil. J. Am. Oil Chem. Soc. 92(11), 1651–1659. Shrestha, L. K., Acharya, D. P., Sharma, S. C., Aramaki, K., Asaoka, H., Ihara, K., & Kunieda, H. (2006). Aqueous foam stabilized by dispersed surfactant solid and lamellar liquid crystalline phase. Journal of Colloid and Interface Science, 301(1), 274–281. Singh, A., Auzanneau, F. I., & Rogers, M. A. (2017). Advances in edible oleogel technologies - a decade in review. Food Research International, 97, 307–317. Valoppi, F., Calligaris, S., Barba, L., Segatin, N., Poklar Ulrih, N., & Nicoli, M. C. (2017). Influence of oil type on formation, structure, thermal, and physical properties of monoglyceride-based organogel. European Journal of Lipid Science and Technology, 119(2), 1500549. https://doi.org/10.1002/ejlt.201500549.
8