- Email: [email protected]
Evaluation of the Consistency of Low-Fat Mayonnaise by Squeezing Flow Viscometry
Available online at www.sciencedirect.com Available online at www.sciencedirect.com
Procedia Food Science
Procedia – Food Science Procedia Food Science001 (2011) (2011) 000–000 1997 – 2002 www.elsevier.com/locate/procedia
11th International Congress on Engineering and Food (ICEF11)
Evaluation of the consistency of low-fat mayonnaise by squeezing flow viscometry Apostolos S. Thomareisa*, Soumela Chatziantoniou Laboratory of Food Statistics and Quality Assurance, Department of Food Technology, Alexander Technological Educational Institute (A.T.E.I.) of Thessaloniki, 57400 Thessaloniki, Greece
Abstract Lubricated squeezing flow viscometry was applied for the evaluation of the consistency of mayonnaise samples of 50% w/w oil content. Mayonnaise samples were prepared with the addition of four stabilizers: sodium alginate, xanthan gum, guar gum and carboxymethyl cellulose (CMC). Each stabilizer was added individually at concentrations from 0.5 to 2% w/w. In addition, a series of nine mayonnaise samples was prepared with mixtures of xanthan gum and guar gum in various ratios, at 1.5% w/w total concentration, aiming to determine synergistic effects between the two stabilizers. All samples were characterized as pseudoplastic since flow behavior index was shown to be lower than unity. Biaxial elongational viscosity, expressed as stress growth coefficient, was determined at specimen’s compressive deformation 50%, because larger deformations lead to structural breakdown of highly viscous samples. Using the present method, the determination of stress growth coefficient was possible in the range from 40 to 300kPa·s. In all samples, stress growth coefficient was shown to increase with increasing concentrations of stabilizers. At concentrations ranging from 1.0 to 1.5%, CMC provided the most viscous emulsions, followed by those with xanthan gum and sodium alginate, while those with guar gum appeared as the least viscous. Conversely, at concentration of 0.75%, CMC was shown to be unable to form a sufficient network, thus providing a less viscous emulsion than the one by xanthan gum. All mixtures of xanthan gum and guar gum revealed synergistic action, where the highest stress growth coefficient values were observed in samples with xanthan gum/guar gum ratios of 30:70 and 40:60. The above mentioned values were higher by two or threefold (p<0.05) compared to those of samples of equal concentration (1.5%) prepared with the addition of xanthan gum or guar gum alone, respectively. ©© 2011 Published by Elsevier Selection Ltd. and/or peer-review responsibility of 11th under International Congress 2011 Published byB.V. Elsevier Selection under and/or peer-review responsibility onExecutive EngineeringCommittee and Food (ICEF 11) Executive Committee. Members
of ICEF11
Keywords: Squeezing flow; Mayonnaise; Stabilizers; Synergy
* Corresponding author. Tel.: +30 2310791353; fax: +30 2310 791360. E-mail address: [email protected].
2211–601X © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of 11th International Congress on Engineering and Food (ICEF 11) Executive Committee. doi:10.1016/j.profoo.2011.09.294
1998 2
Apostolos S. Thomareis and Soumela Chatziantoniou / Procedia Food Science000–000 1 (2011) 1997 – 2002 A.S. Thomareis, S. Chatziantoniou / Procedia – Food Science 00 (2011)
1. Introduction Mayonnaise, a semi-solid oil-in-water emulsion is traditionally prepared from a mixture of egg yolk, vinegar, oil (70-80%, w/w), which may also include salt, sugar or sweeteners and other optional ingredients [1]. Low-fat mayonnaises are products of increasing interest, since consumer tendency continuously points towards products of low caloric content. Addition of modified starch and other hydrocolloids is permitted in mayonnaises and are essential in products of decreased fat content (light) [2], due to their stabilizing and/or thickening properties, which increase emulsion stability, particularly towards creaming [3]. Knowledge of the rheological properties of food products is essential for product development, quality control, sensory evaluation and design and evaluation of the process equipment [4]. The viscosity of mayonnaise can be determined using various viscometers and rheometers. However, such techniques present slippage between contact surfaces and product, which leads to irreproducible results [5]. Lubricated squeezing flow viscometry was introduced to foods testing in mid 1980s and has since been applied to a variety of food products [6-8]. It is based on squeezing a specimen between parallel plates of the same diameter. Since the specimen under the plates maintains a cylindrical shape the test’s geometry is clearly defined. Also, because the specimen is mounted when the plates are separated, structural disruption is dramatically reduced, if not totally eliminated. Thus, the problems created by the forced insertion of the specimen into the narrow gap of a conventional viscometer can, to a great extent, be avoided. Lubricated squeezing flow was also chosen against other methods, due to being the sole viscometric method in which the expected slippage is not considered a disadvantage, but is a prerequisite. Pure elongational flow can be obtained by the lubricated squeezing flow technique, in which slip at the plate-product interface is maximized by applying lubricants. Lubrication ensures that the results for biaxial compression are uncomplicated by any shear components [6, 9]. Lubricated squeezing flow was used in the present study for the determination of rheological properties of different types of mayonnaise. Scope of the present study was to investigate the effect of some commonly used stabilizers, namely xanthan gum, guar gum, sodium alginate and carboxymethyl cellulose (CMC) on the rheological characteristics of low-fat mayonnaise. Objectives of this research were the elucidation of the effect of type and content of stabilizer on the consistency of mayonnaise, as well as synergistic effects of xanthan and guar gum added as blends of different ratios. 2. Materials and Methods A series of twenty eight low-fat mayonnaise samples were prepared in 1kg batches, using a domestic mixer. Ingredients used were soybean oil (500 g), pasteurized egg yolk (90g) vinegar (50 g), sugar (10 g), stabilizer and deionized water. Stabilizers, namely sodium alginate, xanthan gum, guar gum and carboxymethyl cellulose (CMC), were added individually at concentrations of 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2% w/w. An additional series of nine samples was prepared using different blends of xanthan gum and guar gum, at a final concentration of 1.5% w/w, in order to determine synergistic effects of these stabilizers. Stabilizers were obtained from Sigma-Aldrich (Saint-Louis, USA) and all other added ingredients were purchased from a local supermarket. Instron UTM model 5542 (Instron Corp., USA), equipped with a 500 Newton load cell, was the rheometer used. Specimens were subjected to compressive deformation 90% under constant area (67.9 cm2) and constant speed (5mm/min), at 20±1oC, between two parallel lubricated Teflon plates, from 10mm initial height to 1mm final height. Biaxial strain rate (εb) was calculated from the measured forcedisplacement data and used to determine stress growth coefficients (η+ε). All tests were performed using at least three replicates of every sample.
Apostolos A.S. S. Thomareis andS.Soumela Chatziantoniou / Procedia Food Science 1 (2011) 1997 – 2002 Thomareis, Chatziantoniou / Procedia – Food Science 00 (2011) 000–000
One-way analysis of variance (ANOVA), using Student, Newman and Keuls’ multiple range test of mean comparisons was performed using Statistica version 9.0 software (Statsoft Inc., USA). Differences were considered significant at p<0.05. 3. Results and Discussion Lubricated squeezing flow of low-fat mayonnaise samples with different stabilizers added could not be employed to some samples containing insufficient or excessive amounts of stabilizers, due to exhibited sample viscosities outside the range of measurement of the specific method. Samples containing 0.5 and 0.75% guar gum, as well as 0.5% sodium alginate and CMC were shown to be fluid and could not withhold self-supporting networks. Also, addition of 2% guar gum led to excessive oil separation, failing to produce stable emulsions possibly due to high concentration polymer incompatibility. In the case of protein-polysaccharide incompatibility, the mixed solution is unstable and separates into two solvent-rich phases (demixing), one containing mainly the protein and the other one mainly the polysaccharide [10]. On the contrary, samples containing 1.75 and 2% CMC, as well as 2% sodium alginate could not be measured since they were hard and spongy. For all other samples effectively measured by lubricated squeezing flow, results produced flow behavior index values (n) lower than unity, ranging from 0.653 to 0.883, thus characterizing samples as pseudoplastic. This range of n is consistent with the calculated values for mayonnaise and custard [9, 11, 12], as well as mustard [13], at room temperatures. Other researchers have also reported thickened aqueous phases which included pseudoplastic properties for CMC concentrations <2.3% in emulsion gels [14], as well as for xanthan, guar gum concentrations <0.6% [15] and alginate concentrations <0.15% [16] in aqueous solutions. Biaxial elongational viscosity, expressed as stress growth coefficient (η+ε), was determined at biaxial strain rate (εb) of 8.3×10-7 s-1 corresponding to 50% deformation of specimens, because larger deformations lead to structural breakdown of highly viscous samples. Coefficient of variation was in the order of less than 10%, revealing that the test had a high reproducibility. Results expressed as η+ε of lowfat mayonnaise samples with different types and contents of stabilizers are shown in Figure 1. 300
XANT HAN GUAR ALGI NATE CMC
250
η+ε (kPa·s)
200 150 100 50 0
0,50
0,75
1,00
1,25
1,50
1,75
2,00
Y Fig. 1. Stress growth coefficient (η+ε), as affected by type and concentration of stabilizer. Vertical bars denote standard deviations
1999 3
2000 4
Apostolos S. Thomareis and Soumela Chatziantoniou / Procedia Food Science000–000 1 (2011) 1997 – 2002 A.S. Thomareis, S. Chatziantoniou / Procedia – Food Science 00 (2011)
Using the present method, the determination of stress growth coefficient was possible in the range from 40 to 300kPa·s. Similar results, at the same compression rates, ranging from 150 to 200kPa·s, were reported for commercial low-fat mayonnaises by other researchers using the same method [8] or ranging from 80 to 100kPa·s for commercial full-fat mayonnaises, using imperfect lubricated squeezing flow [9]. Also, elongational viscosities ranging from 130 to 150kPa·s were reported for commercial mayonnaises determined by imperfect squeezing flow geometry with a compression rate of 0.01mm/min [13]. As shown in Figure 1, η+ε statistically differed for all concentrations of each stabilizer (p<0.05). All samples containing xanthan gum were effectively measured, which revealed xanthan gum’s ability to form sufficient network at moderate concentrations. Xanthan gum’s ability to form consistent and stable emulsions at 0.5% was also demonstrated by other researchers [11, 17]. Xanthan gel-forming inability and high pseudoplasticity may have led to consistent and stable emulsions at relatively high concentrations such as 2%, due to reduced depletion flocculation effects [10]. Additional reports have shown that full-fat mayonnaise exhibited weak gel-like properties, whereas gel strength increased with increasing xanthan gum concentrations [11]. Stress growth coefficient, therefore, consistency of samples was shown to increase with increasing concentration of all stabilizers used, which was in accordance with results by other researchers [15, 16]. Samples prepared with added xanthan gum, guar gum and sodium alginate presented a similar increasing rate with stabilizer concentration, whereas in samples with CMC the corresponding rate was more rapid. At concentrations ranging from 1 to 1.5%, CMC provided the most viscous emulsions, followed by those with xanthan gum and sodium alginate, while those with guar gum appeared as the least viscous. Conversely, at concentration of 0.75%, CMC was shown to be unable to form a sufficient network, thus providing a less viscous emulsion than the one by xanthan gum. Synergy between xanthan gum and guar gum was investigated by varying xanthan contents in blends of the above mentioned stabilizers, since guar gum was shown to produce the least viscous and less stable emulsions. As shown in Figure 2, all mixtures of xanthan gum and guar gum revealed synergistic action, since consistency of blends were higher than those of samples containing individual stabilizers. The observed synergy indicated that intermolecular binding occurred between galactomannan’s backbone and disordered segments of xanthan [18] at all ratios.
300
η+ε (kPa·s)
250
200
150
100
50
0
0
10
20
30
40
50
60
70
80
90
100
Y Fig. 2. Stress growth coefficient (η+ε), as affected by concentration of xanthan gum (%) in xanthan gum/guar gum blends. Vertical bars denote standard deviations
Apostolos A.S. S. Thomareis andS.Soumela Chatziantoniou / Procedia Food Science 1 (2011) 1997 – 2002 Thomareis, Chatziantoniou / Procedia – Food Science 00 (2011) 000–000
Consistency was shown to be statistically different amongst most samples (p<0.05), except samples with xanthan gum/guar gum ratios of 50:50 and 20:80, as well as 80:20 and 10:90. Stress growth coefficient values increased with increasing incorporation of xanthan in xanthan gum/guar gum mixtures and then were shown to continuously decrease. Specifically, the highest stress growth coefficient values were observed in samples with xanthan gum/guar gum ratios of 30:70 and 40:60. The above mentioned values were higher by two or threefold compared to those of samples of equal concentration (1.5%) prepared with the addition of xanthan gum or guar gum alone, respectively. Previously reported results in aqueous gum solutions also showed highest xanthan gum/guar gum synergistic effect at 40:60 ratio, by the use of oscillatory rheometry [19]. Type and concentration of stabilizer was shown to affect low-fat mayonnaise’s consistency which revealed that product properties can be effectively manipulated by addition of various stabilizers. Guar gum addition led to the production of the least viscous samples, followed by sodium alginate and xanthan gum, while CMC produced the most viscous. Synergistic effects between xanthan gum and guar gum were prominent in xanthan gum/guar gum blends of 30:70. Lubricated squeezing flow viscometry was shown to be successfully employed for the evaluation of the consistency of low-fat mayonnaise samples of 50% oil content. Using this method, a wide range of stress growth coefficient values could be effectively determined. Furthermore, viscosity differences between samples with various types or concentrations of stabilizers were in fact distinguished. Synergistic effects between two or more stabilizers could also be studied so as to attain low-fat products of improved consistency. Conclusively, this method can be used as a basic tool for the development and quality control of similar products. References [1] Depree JA, Savage GP. Physical and flavour stability of mayonnaise. Trends Food Sci Tech 2001;12:157-163. [2] Nor Hayati I, Che Man YB, Tan CP, Nor Aini I. Droplet characterization and stability of soybean oil/palm kernel olein o/w emulsions with the presence of selected polysaccharides. Food Hydrocolloid 2009;23:233-243. [3] Euston SR, Finnigan SR, Hirst RL. Kinetics of droplet aggregation in heated whey-protein stabilized emulsions: Effect of polysaccharides. Food Hydrocolloid 2002;16:499-505. [4] Wendin K, Aaby K, Edris A, Risberg-Ellekjaer M, Albin R, Bergenstahl B et al. Low-fat mayonnaise: Influences of fat content, aroma compounds and thickeners. Food Hydrocolloid 1997;11:87-99. [5] Derkach SR. Rheology of emulsions. Adv Colloid Interfac 2009;151:1-23. [6] Campanella OH, Peleg M. Squeezing flow viscosimetry of peanut butter. J Food Sci 1987;52:180-184. [7] Huang H, Kokini JJ. Measurement of biaxial extensional viscosity of wheat flour doughs. J Rheol 1993;37:879-891. [8] Corradini MG, Stern V, Suwonsichon T, Peleg M. Squeezing flow of semi liquid foods between parallel Teflon coated plates. Rheol Acta 2000;39:452-460. [9] Terpstra MEJ, Jansen AM, Van der Linden E. Exploring imperfect squeezing flow measurements in a Teflon geometry for semisolid foods. J Food Sci 2007;72:492-502. [10] Dumay E, Laligant A, Zasypkin D, Cheftel JC. Pressure- and heat-induced gelation of mixed β-lactoglobulin /polysaccharide solutions: Scanning electron microscopy of gels. Food Hydrocolloid 1999;13:339-351. [11] Ma L, Barbosa-Cánovas GV. Rheological characterization of mayonnaise. Part II: Flow and viscoelastic properties at different oil and xanthan gum concentrations. J Food Eng 1995;25:409-425. [12] Izidoro D, Sierakowski MR, Waszczynskyj N, Haminiuk CWI, de Paula Scheer A. Sensory evaluation and rheological behavior of commercial mayonnaise. Int J Food Eng 2007;3:1-15. [13] Hoffner B, Gerhards C, Peleg M. Imperfect lubricated squeezing flow viscometry for foods. Rheol Acta 1997;36:686-693. [14] Marquardt D, Sucker H. Oil-in-water-emulsion gels: Determination and mathematical treatment of flow properties. Eur J Pharm Biopharm 1998;46:115-124. [15] de Vicente J, Stokes JR, Spike HA. Soft lubrication of model hydrocolloids. Food Hydrocolloid 2006;20:483-491.
2001 5
2002 6
Apostolos S. Thomareis and Soumela Chatziantoniou / Procedia Science 1 (2011) 1997 – 2002 A.S. Thomareis, S. Chatziantoniou / Procedia – Food ScienceFood 00 (2011) 000–000
[16] Gómez-Díaz D, Navada JM. Rheology of aqueous solutions of food additives. Effect of concentration, temperature and blending. J Food Eng 2003;56:387-392. [17] Sun C, Gunasekaran S, Richards MP. Effect of xanthan gum on physicochemical properties of whey protein isolate stabilized oil-in-water emulsions. Food Hydrocolloid 2007;21:555-564. [18] Schorsch C, Gamier C, Doublier JL. Microscopy of xanthan/galactomannan mixtures. Carbohyd Polym 1995;28:319-323. [19] Wang F, Wang YJ, Sun Z. Conformational role of xanthan in its interaction with guar gum. J Food Sci 2002;67:3289-3294.
Presented at ICEF11 (May 22-26, 2011 – Athens, Greece) as paper EPF875.
Procedia Food Science
Procedia – Food Science Procedia Food Science001 (2011) (2011) 000–000 1997 – 2002 www.elsevier.com/locate/procedia
11th International Congress on Engineering and Food (ICEF11)
Evaluation of the consistency of low-fat mayonnaise by squeezing flow viscometry Apostolos S. Thomareisa*, Soumela Chatziantoniou Laboratory of Food Statistics and Quality Assurance, Department of Food Technology, Alexander Technological Educational Institute (A.T.E.I.) of Thessaloniki, 57400 Thessaloniki, Greece
Abstract Lubricated squeezing flow viscometry was applied for the evaluation of the consistency of mayonnaise samples of 50% w/w oil content. Mayonnaise samples were prepared with the addition of four stabilizers: sodium alginate, xanthan gum, guar gum and carboxymethyl cellulose (CMC). Each stabilizer was added individually at concentrations from 0.5 to 2% w/w. In addition, a series of nine mayonnaise samples was prepared with mixtures of xanthan gum and guar gum in various ratios, at 1.5% w/w total concentration, aiming to determine synergistic effects between the two stabilizers. All samples were characterized as pseudoplastic since flow behavior index was shown to be lower than unity. Biaxial elongational viscosity, expressed as stress growth coefficient, was determined at specimen’s compressive deformation 50%, because larger deformations lead to structural breakdown of highly viscous samples. Using the present method, the determination of stress growth coefficient was possible in the range from 40 to 300kPa·s. In all samples, stress growth coefficient was shown to increase with increasing concentrations of stabilizers. At concentrations ranging from 1.0 to 1.5%, CMC provided the most viscous emulsions, followed by those with xanthan gum and sodium alginate, while those with guar gum appeared as the least viscous. Conversely, at concentration of 0.75%, CMC was shown to be unable to form a sufficient network, thus providing a less viscous emulsion than the one by xanthan gum. All mixtures of xanthan gum and guar gum revealed synergistic action, where the highest stress growth coefficient values were observed in samples with xanthan gum/guar gum ratios of 30:70 and 40:60. The above mentioned values were higher by two or threefold (p<0.05) compared to those of samples of equal concentration (1.5%) prepared with the addition of xanthan gum or guar gum alone, respectively. ©© 2011 Published by Elsevier Selection Ltd. and/or peer-review responsibility of 11th under International Congress 2011 Published byB.V. Elsevier Selection under and/or peer-review responsibility onExecutive EngineeringCommittee and Food (ICEF 11) Executive Committee. Members
of ICEF11
Keywords: Squeezing flow; Mayonnaise; Stabilizers; Synergy
* Corresponding author. Tel.: +30 2310791353; fax: +30 2310 791360. E-mail address: [email protected].
2211–601X © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of 11th International Congress on Engineering and Food (ICEF 11) Executive Committee. doi:10.1016/j.profoo.2011.09.294
1998 2
Apostolos S. Thomareis and Soumela Chatziantoniou / Procedia Food Science000–000 1 (2011) 1997 – 2002 A.S. Thomareis, S. Chatziantoniou / Procedia – Food Science 00 (2011)
1. Introduction Mayonnaise, a semi-solid oil-in-water emulsion is traditionally prepared from a mixture of egg yolk, vinegar, oil (70-80%, w/w), which may also include salt, sugar or sweeteners and other optional ingredients [1]. Low-fat mayonnaises are products of increasing interest, since consumer tendency continuously points towards products of low caloric content. Addition of modified starch and other hydrocolloids is permitted in mayonnaises and are essential in products of decreased fat content (light) [2], due to their stabilizing and/or thickening properties, which increase emulsion stability, particularly towards creaming [3]. Knowledge of the rheological properties of food products is essential for product development, quality control, sensory evaluation and design and evaluation of the process equipment [4]. The viscosity of mayonnaise can be determined using various viscometers and rheometers. However, such techniques present slippage between contact surfaces and product, which leads to irreproducible results [5]. Lubricated squeezing flow viscometry was introduced to foods testing in mid 1980s and has since been applied to a variety of food products [6-8]. It is based on squeezing a specimen between parallel plates of the same diameter. Since the specimen under the plates maintains a cylindrical shape the test’s geometry is clearly defined. Also, because the specimen is mounted when the plates are separated, structural disruption is dramatically reduced, if not totally eliminated. Thus, the problems created by the forced insertion of the specimen into the narrow gap of a conventional viscometer can, to a great extent, be avoided. Lubricated squeezing flow was also chosen against other methods, due to being the sole viscometric method in which the expected slippage is not considered a disadvantage, but is a prerequisite. Pure elongational flow can be obtained by the lubricated squeezing flow technique, in which slip at the plate-product interface is maximized by applying lubricants. Lubrication ensures that the results for biaxial compression are uncomplicated by any shear components [6, 9]. Lubricated squeezing flow was used in the present study for the determination of rheological properties of different types of mayonnaise. Scope of the present study was to investigate the effect of some commonly used stabilizers, namely xanthan gum, guar gum, sodium alginate and carboxymethyl cellulose (CMC) on the rheological characteristics of low-fat mayonnaise. Objectives of this research were the elucidation of the effect of type and content of stabilizer on the consistency of mayonnaise, as well as synergistic effects of xanthan and guar gum added as blends of different ratios. 2. Materials and Methods A series of twenty eight low-fat mayonnaise samples were prepared in 1kg batches, using a domestic mixer. Ingredients used were soybean oil (500 g), pasteurized egg yolk (90g) vinegar (50 g), sugar (10 g), stabilizer and deionized water. Stabilizers, namely sodium alginate, xanthan gum, guar gum and carboxymethyl cellulose (CMC), were added individually at concentrations of 0.5, 0.75, 1, 1.25, 1.5, 1.75 and 2% w/w. An additional series of nine samples was prepared using different blends of xanthan gum and guar gum, at a final concentration of 1.5% w/w, in order to determine synergistic effects of these stabilizers. Stabilizers were obtained from Sigma-Aldrich (Saint-Louis, USA) and all other added ingredients were purchased from a local supermarket. Instron UTM model 5542 (Instron Corp., USA), equipped with a 500 Newton load cell, was the rheometer used. Specimens were subjected to compressive deformation 90% under constant area (67.9 cm2) and constant speed (5mm/min), at 20±1oC, between two parallel lubricated Teflon plates, from 10mm initial height to 1mm final height. Biaxial strain rate (εb) was calculated from the measured forcedisplacement data and used to determine stress growth coefficients (η+ε). All tests were performed using at least three replicates of every sample.
Apostolos A.S. S. Thomareis andS.Soumela Chatziantoniou / Procedia Food Science 1 (2011) 1997 – 2002 Thomareis, Chatziantoniou / Procedia – Food Science 00 (2011) 000–000
One-way analysis of variance (ANOVA), using Student, Newman and Keuls’ multiple range test of mean comparisons was performed using Statistica version 9.0 software (Statsoft Inc., USA). Differences were considered significant at p<0.05. 3. Results and Discussion Lubricated squeezing flow of low-fat mayonnaise samples with different stabilizers added could not be employed to some samples containing insufficient or excessive amounts of stabilizers, due to exhibited sample viscosities outside the range of measurement of the specific method. Samples containing 0.5 and 0.75% guar gum, as well as 0.5% sodium alginate and CMC were shown to be fluid and could not withhold self-supporting networks. Also, addition of 2% guar gum led to excessive oil separation, failing to produce stable emulsions possibly due to high concentration polymer incompatibility. In the case of protein-polysaccharide incompatibility, the mixed solution is unstable and separates into two solvent-rich phases (demixing), one containing mainly the protein and the other one mainly the polysaccharide [10]. On the contrary, samples containing 1.75 and 2% CMC, as well as 2% sodium alginate could not be measured since they were hard and spongy. For all other samples effectively measured by lubricated squeezing flow, results produced flow behavior index values (n) lower than unity, ranging from 0.653 to 0.883, thus characterizing samples as pseudoplastic. This range of n is consistent with the calculated values for mayonnaise and custard [9, 11, 12], as well as mustard [13], at room temperatures. Other researchers have also reported thickened aqueous phases which included pseudoplastic properties for CMC concentrations <2.3% in emulsion gels [14], as well as for xanthan, guar gum concentrations <0.6% [15] and alginate concentrations <0.15% [16] in aqueous solutions. Biaxial elongational viscosity, expressed as stress growth coefficient (η+ε), was determined at biaxial strain rate (εb) of 8.3×10-7 s-1 corresponding to 50% deformation of specimens, because larger deformations lead to structural breakdown of highly viscous samples. Coefficient of variation was in the order of less than 10%, revealing that the test had a high reproducibility. Results expressed as η+ε of lowfat mayonnaise samples with different types and contents of stabilizers are shown in Figure 1. 300
XANT HAN GUAR ALGI NATE CMC
250
η+ε (kPa·s)
200 150 100 50 0
0,50
0,75
1,00
1,25
1,50
1,75
2,00
Y Fig. 1. Stress growth coefficient (η+ε), as affected by type and concentration of stabilizer. Vertical bars denote standard deviations
1999 3
2000 4
Apostolos S. Thomareis and Soumela Chatziantoniou / Procedia Food Science000–000 1 (2011) 1997 – 2002 A.S. Thomareis, S. Chatziantoniou / Procedia – Food Science 00 (2011)
Using the present method, the determination of stress growth coefficient was possible in the range from 40 to 300kPa·s. Similar results, at the same compression rates, ranging from 150 to 200kPa·s, were reported for commercial low-fat mayonnaises by other researchers using the same method [8] or ranging from 80 to 100kPa·s for commercial full-fat mayonnaises, using imperfect lubricated squeezing flow [9]. Also, elongational viscosities ranging from 130 to 150kPa·s were reported for commercial mayonnaises determined by imperfect squeezing flow geometry with a compression rate of 0.01mm/min [13]. As shown in Figure 1, η+ε statistically differed for all concentrations of each stabilizer (p<0.05). All samples containing xanthan gum were effectively measured, which revealed xanthan gum’s ability to form sufficient network at moderate concentrations. Xanthan gum’s ability to form consistent and stable emulsions at 0.5% was also demonstrated by other researchers [11, 17]. Xanthan gel-forming inability and high pseudoplasticity may have led to consistent and stable emulsions at relatively high concentrations such as 2%, due to reduced depletion flocculation effects [10]. Additional reports have shown that full-fat mayonnaise exhibited weak gel-like properties, whereas gel strength increased with increasing xanthan gum concentrations [11]. Stress growth coefficient, therefore, consistency of samples was shown to increase with increasing concentration of all stabilizers used, which was in accordance with results by other researchers [15, 16]. Samples prepared with added xanthan gum, guar gum and sodium alginate presented a similar increasing rate with stabilizer concentration, whereas in samples with CMC the corresponding rate was more rapid. At concentrations ranging from 1 to 1.5%, CMC provided the most viscous emulsions, followed by those with xanthan gum and sodium alginate, while those with guar gum appeared as the least viscous. Conversely, at concentration of 0.75%, CMC was shown to be unable to form a sufficient network, thus providing a less viscous emulsion than the one by xanthan gum. Synergy between xanthan gum and guar gum was investigated by varying xanthan contents in blends of the above mentioned stabilizers, since guar gum was shown to produce the least viscous and less stable emulsions. As shown in Figure 2, all mixtures of xanthan gum and guar gum revealed synergistic action, since consistency of blends were higher than those of samples containing individual stabilizers. The observed synergy indicated that intermolecular binding occurred between galactomannan’s backbone and disordered segments of xanthan [18] at all ratios.
300
η+ε (kPa·s)
250
200
150
100
50
0
0
10
20
30
40
50
60
70
80
90
100
Y Fig. 2. Stress growth coefficient (η+ε), as affected by concentration of xanthan gum (%) in xanthan gum/guar gum blends. Vertical bars denote standard deviations
Apostolos A.S. S. Thomareis andS.Soumela Chatziantoniou / Procedia Food Science 1 (2011) 1997 – 2002 Thomareis, Chatziantoniou / Procedia – Food Science 00 (2011) 000–000
Consistency was shown to be statistically different amongst most samples (p<0.05), except samples with xanthan gum/guar gum ratios of 50:50 and 20:80, as well as 80:20 and 10:90. Stress growth coefficient values increased with increasing incorporation of xanthan in xanthan gum/guar gum mixtures and then were shown to continuously decrease. Specifically, the highest stress growth coefficient values were observed in samples with xanthan gum/guar gum ratios of 30:70 and 40:60. The above mentioned values were higher by two or threefold compared to those of samples of equal concentration (1.5%) prepared with the addition of xanthan gum or guar gum alone, respectively. Previously reported results in aqueous gum solutions also showed highest xanthan gum/guar gum synergistic effect at 40:60 ratio, by the use of oscillatory rheometry [19]. Type and concentration of stabilizer was shown to affect low-fat mayonnaise’s consistency which revealed that product properties can be effectively manipulated by addition of various stabilizers. Guar gum addition led to the production of the least viscous samples, followed by sodium alginate and xanthan gum, while CMC produced the most viscous. Synergistic effects between xanthan gum and guar gum were prominent in xanthan gum/guar gum blends of 30:70. Lubricated squeezing flow viscometry was shown to be successfully employed for the evaluation of the consistency of low-fat mayonnaise samples of 50% oil content. Using this method, a wide range of stress growth coefficient values could be effectively determined. Furthermore, viscosity differences between samples with various types or concentrations of stabilizers were in fact distinguished. Synergistic effects between two or more stabilizers could also be studied so as to attain low-fat products of improved consistency. Conclusively, this method can be used as a basic tool for the development and quality control of similar products. References [1] Depree JA, Savage GP. Physical and flavour stability of mayonnaise. Trends Food Sci Tech 2001;12:157-163. [2] Nor Hayati I, Che Man YB, Tan CP, Nor Aini I. Droplet characterization and stability of soybean oil/palm kernel olein o/w emulsions with the presence of selected polysaccharides. Food Hydrocolloid 2009;23:233-243. [3] Euston SR, Finnigan SR, Hirst RL. Kinetics of droplet aggregation in heated whey-protein stabilized emulsions: Effect of polysaccharides. Food Hydrocolloid 2002;16:499-505. [4] Wendin K, Aaby K, Edris A, Risberg-Ellekjaer M, Albin R, Bergenstahl B et al. Low-fat mayonnaise: Influences of fat content, aroma compounds and thickeners. Food Hydrocolloid 1997;11:87-99. [5] Derkach SR. Rheology of emulsions. Adv Colloid Interfac 2009;151:1-23. [6] Campanella OH, Peleg M. Squeezing flow viscosimetry of peanut butter. J Food Sci 1987;52:180-184. [7] Huang H, Kokini JJ. Measurement of biaxial extensional viscosity of wheat flour doughs. J Rheol 1993;37:879-891. [8] Corradini MG, Stern V, Suwonsichon T, Peleg M. Squeezing flow of semi liquid foods between parallel Teflon coated plates. Rheol Acta 2000;39:452-460. [9] Terpstra MEJ, Jansen AM, Van der Linden E. Exploring imperfect squeezing flow measurements in a Teflon geometry for semisolid foods. J Food Sci 2007;72:492-502. [10] Dumay E, Laligant A, Zasypkin D, Cheftel JC. Pressure- and heat-induced gelation of mixed β-lactoglobulin /polysaccharide solutions: Scanning electron microscopy of gels. Food Hydrocolloid 1999;13:339-351. [11] Ma L, Barbosa-Cánovas GV. Rheological characterization of mayonnaise. Part II: Flow and viscoelastic properties at different oil and xanthan gum concentrations. J Food Eng 1995;25:409-425. [12] Izidoro D, Sierakowski MR, Waszczynskyj N, Haminiuk CWI, de Paula Scheer A. Sensory evaluation and rheological behavior of commercial mayonnaise. Int J Food Eng 2007;3:1-15. [13] Hoffner B, Gerhards C, Peleg M. Imperfect lubricated squeezing flow viscometry for foods. Rheol Acta 1997;36:686-693. [14] Marquardt D, Sucker H. Oil-in-water-emulsion gels: Determination and mathematical treatment of flow properties. Eur J Pharm Biopharm 1998;46:115-124. [15] de Vicente J, Stokes JR, Spike HA. Soft lubrication of model hydrocolloids. Food Hydrocolloid 2006;20:483-491.
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Apostolos S. Thomareis and Soumela Chatziantoniou / Procedia Science 1 (2011) 1997 – 2002 A.S. Thomareis, S. Chatziantoniou / Procedia – Food ScienceFood 00 (2011) 000–000
[16] Gómez-Díaz D, Navada JM. Rheology of aqueous solutions of food additives. Effect of concentration, temperature and blending. J Food Eng 2003;56:387-392. [17] Sun C, Gunasekaran S, Richards MP. Effect of xanthan gum on physicochemical properties of whey protein isolate stabilized oil-in-water emulsions. Food Hydrocolloid 2007;21:555-564. [18] Schorsch C, Gamier C, Doublier JL. Microscopy of xanthan/galactomannan mixtures. Carbohyd Polym 1995;28:319-323. [19] Wang F, Wang YJ, Sun Z. Conformational role of xanthan in its interaction with guar gum. J Food Sci 2002;67:3289-3294.
Presented at ICEF11 (May 22-26, 2011 – Athens, Greece) as paper EPF875.