Physicochemical properties of waxy corn starch after three-stage modification

Physicochemical properties of waxy corn starch after three-stage modification

Accepted Manuscript Physicochemical properties of waxy corn starch after three-stage modification Marzena Włodarczyk-Stasiak, Artur Mazurek, Radosław ...

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Accepted Manuscript Physicochemical properties of waxy corn starch after three-stage modification Marzena Włodarczyk-Stasiak, Artur Mazurek, Radosław Kowalski Urszula, Pankiewicz, Jerzy Jamroz PII:

S0268-005X(16)30349-6

DOI:

10.1016/j.foodhyd.2016.08.010

Reference:

FOOHYD 3540

To appear in:

Food Hydrocolloids

Received Date: 27 March 2016 Revised Date:

1 August 2016

Accepted Date: 3 August 2016

Please cite this article as: Włodarczyk-Stasiak, M., Mazurek, A., Urszula, Pankiewicz, R.K., Jamroz, J., Physicochemical properties of waxy corn starch after three-stage modification, Food Hydrocolloids (2016), doi: 10.1016/j.foodhyd.2016.08.010. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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hydrothermal treatment

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VALUE INCREASE

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WAI; FAI

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VALUE DECREASE

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WAI; FAI

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S BET

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MERIGEL (Pre-gelatinisation)

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Degree of crosslinking WAI [%]

FAI [%]

SBET ads [m2/g]

SBET des [m2/g]

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Degree of crosslinking WAI [%]

FAI [%]

SBET ads [m2/g]

SBET des [m2/g]

Influence the degree of cross-linking on selected physicochemical properties of modified starch.

S BET

RESISTAMYL (Cook-up)

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PHYSICOCHEMICAL PROPERTIES OF WAXY CORN STARCH AFTER THREE-STAGE MODIFICATION

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Corresponding author. Tel .: +48 (81) 462 33 31

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E-mail address: [email protected] (M. Włodarczyk-Stasiak)

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Abstract

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The paper presents a study on the functional properties of waxy corn starches, physicochemically

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modified. The physical modifications (hydrothermal treatment) allowed to obtain pre-gelatinised

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starch (Merigel) or untreated starch, of cook-up type (Resistamyl). The chemical modification of

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starches differentiated them in terms of the degree of cross-linking (low, medium and high) and the

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level of substitution (medium).

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The characteristics of changes in the viscosity of starch gels were determined in the function of

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temperature and time. It was found that with an increase of the degree of cross-linking (low
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temperature of +20°C starch gels of the Merigel type are characterised by a high level of transparency,

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which may indicate intensively hindered retrogradation at +4°C, while measurements for samples of

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the Resistamyl type indicate transmittance values close to zero, similar to those for waxy corn starch.

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The tendency to syneresis was tested at +4°C and -22°C. At +4°C, the modified starch gels, type

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Merigel, are characterised by nearly three-fold higher degree of syneresis compared to those from the

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Resistamyl group. The degree of syneresis of cook-up type gels is small after storage at 22°C. Starches

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of the pre-gelatinisation type are characterised by WAI (Water Adsorption Index) values in the range

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of 981-1207%, and starches of the cook-up type - 196-205%. Higher values of FAI (Fat Adsorption

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Index) are also noted in the case of the pre-gelatinisation starches (FAI: 194-222%) in relation to the

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cook-up type starches (FAI: 170-174%). Cook-up starches do not form emulsions. The medium degree

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of cross-linking of pre-gelatinisation type starches causes a lowering of the value of their specific

34

surface area (SBET), while for the cook-up type starches an increase of that value was observed.

Marzena Włodarczyk-Stasiak, Artur Mazurek, Radosław Kowalski, Urszula Pankiewicz, Jerzy Jamroz

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Department of Analysis and Evaluation of Food Quality, University of Life Sciences in Lublin, Faculty of Food Science and Biotechnology, Skromna Street 8 20-704 Lublin, Poland

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Keywords: degree of cross-linking, waxy corn starch, chemical modification, viscosity, functional

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properties

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1. Introduction 1

ACCEPTED MANUSCRIPT Modified starches, as food additives, are used to control the texture and the rheological

2

properties of the product (Cousidine, 1982; Davies, 1995). Starch modification can be effected on the

3

chemical, physical or enzymatic pathways, and as a result of combining those processes. The products

4

obtained constitute an important addition in the production processes in various branches of the food

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industry. Modified starches exhibit diverse and strongly varied properties relative to native starch.

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Most frequently, the modification affects such functional properties of starch as solubility, water

7

binding capacity, gelatinisation temperature and viscosity, transparency and rheological stability of

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gels, rate of retrogradation, emulsification ability and chemical reactivity.

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Chemical modification can be effected through esterification, etherification, oxidation, and

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the insertion of functional groups into starch molecule, which makes its physicochemical properties

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change considerably (Czerwińska, Leszczyński, & Pałasiński, 2011; Singh, Kaur, & McCarthy, 2007;

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Zdybel, 2006). Reaction conditions (concentration of the reagents, time, pH and the presence of a

13

catalyst during the modification, the kind of substituent and its share – degree of substitution) are the

14

factors that shape the new functional properties of starches of diverse botanical origins (Hirsch &

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Kokini, 2002; Kavitha & BeMiller, 1998; Rutenberg & Solarek, 1984; Steeneken & Woortman, 1994).

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The products of esterification include e.g. phosphorylated or acetylated starches.

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Phosphorylation of starch is most frequently conducted with the use of POCl3, phosphates, or tetra

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acid anhydrides that are used for the production of cross-linked starches. Esterification conducted with

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acetic anhydride, adipic anhydride and vinyl acetate leads to the obtainment of acetylated starches.

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The inserted acetyl groups cause a reorganisation of starch at the structural level through steric

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hindrance. When acetyl groups are built into the starch molecule their mutual repelling effect is

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observed, which facilitates the penetration of water molecules in the newly formed amorphous areas

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(Lawal, 2004). Studies conducted on the acetylation of starch indicate an increase in its solubility and

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water absorption, and the presence of acetyl groups hinders gelatinisation and formation of an ordered

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structure, and thus delays starch retrogradation (Gonzalez & Perez, 2002; Lawal, 2004; Singh, Kaur,

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& Singh, 2004; Singh, Chawla, & Singh, 2004).

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Starch modified through esterification and etherification forms intermolecular bonds between

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hydroxyl groups in the process of cross-linking (Rutenberg & Solarek, 1984; Würzburg, 1986). The

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reagents used most frequently for starch cross-linking include sodium trimetaphosphate, sodium

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phosphate, sodium tripolyphosphate, epichlorohydrin, phosphoryl chloride, as well as adipic and

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acetic acid anhydrides and vinyl chloride (Wattanchant, Muhammad, & Hashim, 2003; Woo & Seiba,

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1997; Wu & Seiba, 1990; Yeh & Yeh, 1993; Yook, Pek, & Park, 1993). In the course of cross-linking,

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intermolecular bonds are formed in a random manner and they are located on the inner and outer

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surfaces of starch granules (Acquarone & Rao, 2003; Singh, Kaur, & McCarthy, 2007). The slower the

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cross-linking agents (SMTP, EPI) act, the deeper their penetration into the granules, which results in a

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higher degree of cross-linking (Gluck-Hirsch & Kokini, 1997; Huber & BeMiller, 2001).

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ACCEPTED MANUSCRIPT Most often cross-linking is applied to wax starches, in the structure of which amylopectin

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dominates, which permits the obtainment of reversible gels (Katzback, 1972). The newly formed

3

structure inhibits starch interactions with water, which is attributed to the high stability of cross-linked

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starches in the water environment (El-Tahlawy, Venditti, & Pawlak, 2007). Cross-linked starches also

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display reduced solubility compared to their native counterparts, decreasing with an increasing level of

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cross-linking. The probable causes of this phenomenon are given as increased cross-linking density

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and reduced accessibility of hydrophilic groups (Reddy & Seiba, 1999; Rutenberg & Solarek, 1984).

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Cross-linking leads also to an increase in peak viscosity of both normal and waxy starches (Acquarone

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& Rao, 2003).

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Cross-linked starches are characterised by an increased stability of gels during freezing and

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defreezing at low ranges of medium pH and under the effect of shearing forces (Delville, et al., 2002;

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Ellis, Cochrane, & Daley, 1998; Evans & Haisman, 1979; Simkovic, 1996).

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Modified starches are commonly used for soups, sauces, infant food, water and milk-based fruit

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desserts fillers and for deep frozen and deep-fried food products (Rutenberg & Solarek, 1984).

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Starches forming viscous, transparent and stable structures are obtained also through physical

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modification. Modification based on pre-gelatinisation facilitates water diffusion into the starch

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granules, improving their swelling ability. The most frequently applied hydrothermal treatment

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leading to the acquisition of pre-gelatinisation type starches is drum drying (starch suspension or

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paste), less often - extrusion and spray-drying. Pre-gelatinisation starches are used for the preparation

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of sauces, puddings, creams; they play the function of a texture-forming additive in ready meals that

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do not require thermal treatment, and forming irreversible gels they stabilise the structure of meals

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consumed after heating. Pre-gelatinisation can also be a preliminary treatment preceding the chemical

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modification of starches. The available literature does not provide many reports on the effect of the

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process (pre-gelatinisation) on the functional properties of starch prior to chemical modification. One

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can suppose that pre-gelatinisation will be beneficial for the chemical modification of starch.

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However, precise elucidation of the effect of the combined modification will require further multi-

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directional research.

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The objective of the study was to estimate the functional properties of waxy corn starches

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obtained through physicochemical modification. Analyses were conducted for starches after

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hydrothermal treatment such as pre-gelatinisation (Merigel), and for those not subjected to

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hydrothermal treatment, such as cook-up type starch (Resistamyl). Chemically modified starches

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differed in the degree of cross-linking (low, medium, high) and in the level of substitution (medium).

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The functional properties (water absorption, fat absorption capacity, activity and stability of

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emulsions), the rheological properties (viscosity, susceptibility to syneresis and retrogradation) and the

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specific surface area of the modified starches were analysed.

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2. Material and methods

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2.1. Materials The research material consisted of modified corn starches with medium degree of substitution

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and various levels of cross-linking, supplied by the company TATE&LYLE (Brenntag) (Tab.1).

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According to the producer, starches of the cook-up type (Resistamyl) require thermal treatment, while

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starches of the Merigel type had been subjected to pre-gelatinisation. Table 2 presents the chemical

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composition of the samples of the starches.

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2.2. Methods 2.2.1. Rheological properties

Measurements of viscosity of the modified starch gels were performed on a Reothest 2 tester

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(VEB MLW Prüfgeräte-Werk Medingen, Germany), according to the Winkler method after certain

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necessary modifications (Fortuna, Gałkowska, & Juszczak, 2004; Winkler, Luckowi, & Donic, 1971).

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For 5% (w/w) starch dispersions the S/S-1 cylinder systems were applied. The viscosity characteristics

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of the dispersions were determined by heating within the temperature range from 20oC to 96oC

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(1oC/min), keeping them for 20 minutes at Tconstans=96oC, and then cooling them down from 96oC to

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20oC (1oC/min). Viscosity measurements were taken at 5 minute intervals, at shearing rate of 145.8 (s-

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) which corresponds to rotational speed of 27 rev/min.

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2.2.2. Functional properties

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2.2.2.1. Degree of syneresis

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The degree of syneresis was determined following the procedure described by Cisse et al.

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(2013). Solutions of the 5% (w/w) starch dispersions were gelatinised at 100oC. After cooling down,

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the samples were stored for 4 weeks at +4oC and -22oC. The degree of syneresis was determined from

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the volume of liberated water (ml / 10 ml gel; %). The samples were adjusted to 20°C and

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measurements were taken on days 7, 14, 21 and 28.

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2.2.2.2. Paste clarity

1% (w/w) starch dispersions were prepared and subjected to gelatinisation for 30 min. at

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100oC. The gels were then stored for 4 weeks at +4oC and +20oC. Measurements of transmittance (T)

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were taken at 7-day intervals, at temperature of 20oC and at λ=650 nm, referenced to distilled water

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(Cisse et al., 2013; Lin, Wang, & Chang, 2008).

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2.2.2.3. Water absorption index (WAI)

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The determination of the water absorption index (WAI) of the modified starches was

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performed according to the procedure of Anderson et al. (1969), Rutkowski & Kozłowska (1981). 4

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Samples of the starches were flooded with distilled water, centrifuged, unbound water was drained off,

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and the thimbles were dried.

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Water absorption (WAI) was calculated on the basis of the formula (1):

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WAI =

m − m ⋅100% m

(1)

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WAI - percentage content of bound water per 1 g of the material [%,w/w] mm - weight of test tube with wet sediment [g] m - weighed portion, converted to value per 1 gram of dry matter [g]

2.2.2.4. Fat absorption index (FAI)

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Fat absorption index (FAI) was determined according to the method of Beuchat (1977), Rutkowski &

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Kozłowska (1981). Weighed portions of starch were mixed with oil, and unbound oil was removed

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after centrifuging. Fat absorption (FAI) was calculated from the formula (2): FAI =

m − m ⋅100% m m

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FAI - percentage content of bound oil per 1 g of the material [%,w/w] mm - weight of test tube with wet sediment [g] m - weighed portion, converted to value per 1 gram of dry matter [g]

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2.2.2.5. Emulsification activity (EA)

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adaptation of the procedure described by Rutkowski & Kozłowska (1981), Yasumatsu et al. (1972). Starch samples were mixed in a water-oil emulsion (1:1) and then centrifuged, and emulsion volume measurements were made. Emulsification activity was calculated from the formula (3): EA =

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The determination of the emulsification activity (EA) was performed according to an

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EA- emulsification activity [%] e- volume of emulsified layer [cm3] f- total volume of sample [cm3]

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(2)

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Samples prepared in an analogous manner were used for the determination of emulsion

stability (EAc). Prior to centrifuging emulsified samples were heated for 5 minutes at 100oC.

2.2.2.6. Specific surface area calculated by the isotherms of water vapour sorption (SBET)

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Specific surface area of the starches (SBET) was determined from the isotherms of water vapour

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adsorption and desorption according to the procedure of Włodarczyk-Stasiak & Jamroz (2008). The

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calculation of those values was made with the use of the BET multi-layer adsorption theory, within the

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range of p/p0 0-0,35.

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The data reported in all the results are an average of triplicate observations. In the study the

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mean values (x) and the standard deviation (σ) were calculated, from the range (x-2σ; x+2σ). The data

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were subjected to statistical analysis using Minitab Statistical Software.

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3. Results and discussion The behaviour of the paste viscosity was analysed as a function of temperature and time for

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the modified starch gels. The shapes of the curves of viscosity differ fundamentally for the modified

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starches of the Merigel – pre-gelatinisation type (Fig.1) and the Resistamyl - cook-up type (Fig.2). The

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viscosity change curves obtained (viscosity vs. temperature and viscosity vs. time) indicate a decrease

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of the values of viscosity of the Merigel type starches up to the point of attaining the minimum

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viscosity (10-90 mPa·s), followed by an increase due to the cooling down of the gels (Fig.1). It was

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also noted that with an increase in the degree of cross-linking (low ML
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viscosity of the gels under analysis decreases. A similar relation between the increase of cross-linking

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and decrease of viscosity was found by Prochaska et al. (2009) for acetylated distarch adipate.

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Kurakake et al. (2009) demonstrated also that corn starch gels with a higher degree of cross-linking

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are characterised by lower viscosity than starches with lower levels of cross-linking. Acetylated rice

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starches were studied by González & Pérez (2002), who noted an increase in the viscosity of the gels

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after acetylation, and attributed this phenomenon to increased water absorption, more intensive

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swelling of granules, and increased solubility. According to those authors the presence of acetyl

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groups weakens the forces of association in amorphous areas and the intermolecular hydrogen bonds

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stabilising the structure. Hoover & Sosulski (1985) suggest that acetylation is the cause of increase of

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the viscosity of bean starch at 90°C.

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Irrespective of the type of chemical modification, in the case of samples of starches of the Merigel

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type, a violent increase of viscosity was observed during their cooling (Fig.1). The increase of

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viscosity may result from the joining of amylose chains, and increase of molecular mass, which may

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lead to accelerated retrogradation. According to the research results obtained by González & Pérez

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(2002), the occurrence of acetyl groups causes a weakening of retrogradation of cooled solutions,

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which is not supported in the study by Kurakake et al. (2009).

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Starches of the Resistamyl type (cook-up) have viscosity close to zero below the temperature

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range of their gelatinisation (Fig.2). After attaining the gelatinisation temperature and with further

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temperature increase the value of viscosity increases in relation to the degree of cross-linking, until the

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maximum value is reached. The varied ranges of gelatinisation temperature and the maximum

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viscosity of the gels depend on the degree of cross-linking of a given starch (low RL
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RM
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both the gelatinisation and the heating temperatures (96°C). Most of the samples of starch of the

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Resistamyl type gelatinise at a slightly lower temperature (75-85°C). In the course of cooling the 6

ACCEPTED MANUSCRIPT 1

viscosity of the gels decreases significantly, with a tendency to retrogradation. A decrease in the

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viscosity of acetylated starches was demonstrated also by González & Pérez (2002).

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Kapelko et al. (2015) claim that the stronger the process of cross-linking, the more starch is resistant to

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high temperature and shear forces, and the attainment of the maximum viscosity requires a longer time

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of heat treatment. The effect of cross-linking of starch on changes in the viscosity of gels can be attributed to

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two opposing mechanisms. Cross-linking prevents the loss of amylose liberated from granules and

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stabilises the newly-formed structure, which results in an increase in gel viscosity. On the other hand,

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the inhibition of penetration of water molecules into the newly-formed structure slows down the

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swelling of granules and reduces viscosity. Increase in the number of cross-linking bonds may cause

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diffusion resistance in the penetration of water (Hirsch & Kokini, 2002).

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Retrogradation is an undesirable phenomenon causing a change in the texture and stability of

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starch food products. The intensity of retrogradation was determined by measuring the transmittance

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of starch gels at +4°C (Fig.3) and +20°C (Fig.4); higher values of transmittance [%] indicate more

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intensive retrogradation. At the temperature of +20°C the gels of starches of the Merigel type were

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characterised by high transmittance after the 7th day of analysis, which can be attributed to a high

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intensity of retrogradation. Gels of acetylated starches of the Resitamyl type, at temperature of 20°C,

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throughout the whole analysis displayed a constant close-to-zero transmittance, similar to that of waxy

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corn starch. A similar relation is confirmed by the results obtained by the authors Krysińska,

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Gałkowska & Fortuna (2008), who studied gels of acetylated and hydroxypropylated waxy corn

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starches, and their results also indicate negligible retrogradation after 21 days of experiment at 6°C.

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Kaur, Sing & Singh (2004), presenting factors affecting the rheological properties of gels of modified

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potato starches, demonstrated that cross-linking and substitution delay retrogradation during storage. It

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was also demonstrated that the substitution of hydroxyl groups with acetyl groups in the structure of

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starch precludes parallel orientation of starch chains initiating retrogradation. The presence of acetyl

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groups is also conducive to the delay of crystallisation of amylopectin and to the retention of water in

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starch molecules. Singh, Kaur & McCarthy (2007) indicate that stronger cross-linking causes a slow-

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down of retrogradation, and attribute that phenomenon to reduced mobility of amorphous chains in

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starch granules due to the formation of intermolecular bridges.

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A high transmittance of gels of Merigel type starches was demonstrated at the temperature of

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+4°C, which indicates intensive retrogradation (Fig.3). At that temperature, after 21 days of the

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experiment a distinct decrease was noted in the transmittance of gels prepared from starches of the

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Resistamyl type, as well as for the waxy corn starch. After 28 days, the measurements of gels of

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Resistamyl type starches and waxy corn starch displayed transmittance close to zero. The sudden drop

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in the clarity of solutions of the Resistamyl type starch may be the cause of the change in the structure

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of that starch, after 21 days of observation at +4°C. This phenomenon was not observed to such an

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extent in starches of the Merigel type. Fortuna and Juszczak (1998) demonstrated a stronger 7

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retrogradation of wheat starch gels relative to waxy corn starch, and low temperature was a factor

2

facilitating retrogradation. According to Sodhi & Singh (2005), gels of acetylated rice starches became

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opaque after storage at +4°C, and an eluate appeared on their surface, indicating syneresis. The tendency of hydrocolloids to syneresis leads to retrogradation. The susceptibility of the

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modified corn starches was analysed after storage at +4°C (Fig.5) and -22°C (Fig.6). At +4°C the

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modified starches of the Merigel type were characterised by nearly three-fold greater eluation than

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those from the Resistamyl group (Fig. 5). Sample M is characterised by the least eluation among all

8

other pre-gelatinised starches. Starches RM and RH are characterised by the least eluation compared

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to the waxy corn starch. The degree of syneresis of the modified corn starches is low after storage at -

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22°C. Starches of both Merigel and Resistamyl types are characterised by increased eluation relative

11

to the waxy corn starch. Research results (Krysińska, Gałkowska & Fortuna (2008) indicate negligible

12

syneresis of acetylated rice starches during storage. Singh, Kaur & McCarthy (2007) attribute the

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weakening of syneresis to acetyl groups, due to the retention of water in starch molecules. According

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to Perera & Hoover (1999), syneresis is an effect of interaction between amylopectin and leached

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amylose, which leads to the creation of areas with traits of turbidity.

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A distinct correlation was noted between the ability of absorbing water (WAI) and the type of

17

modified starch (Fig 7). Samples of Merigel type starches display over five-fold higher water

18

absorption than Resistamyl (cook-up) starches. Samples of Resistamyl starches display a slight

19

increase of the WAI index relative to the waxy corn starch. González & Pérez (2002) attribute the

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increased water absorption of acetylated rice starches to the substitution of acetyl groups which,

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weakening the hydrogen bonds, facilitate water access to amorphous areas.

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Interesting results were obtained as concerns the ability of fat binding (FAI) by starches of the

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Merigel and Resistamyl types (Fig.8). Starches of the Resistamyl type display a slight increase of the

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FAI index relative to that of waxy corn starch. A correlation was also noted between the degree of

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cross-linking and the decrease of the index in question. For the Merigel samples an increase of FAI

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was demonstrated with increasing level of cross-linking of the starch (low ML < medium MM< high

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MH), while stronger cross-linking of starch of the Resistamyl types caused a decrease of fat absorption

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(high RH < medium RM< low RL). Phosphorylated starches (M, R) display higher values of FAI than

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acetylated starches. Murúa-Pagola, Beristain-Guevara & Martínez-Bustos (2009) noted an increase of

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oil retention by starches after chemical modification and additional extrusion, and found that

32

phosphate groups cause a stronger retention of oil than acetyl groups. Thiebaud et al. (1997) and

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Zhang et al. (1997) report elongation of carbon chains and increased levels of substitution as the

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causes of increased hydrophobicity due to chemical modification.

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Discussed WAI and FAI indices indicate that the hydrothermal treatment differentiated the

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investigated starches more strongly than the chemical modification in terms of the degree of cross-

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linking (low, medium, high). 8

ACCEPTED MANUSCRIPT 1 Fig. 9 presents changes in emulsification activity and the stability of emulsions for starches

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Merigel and Resistamyl. Starches of the Resistamyl type do not display any properties of emulsion

4

formation, whereas all starches of the Merigel type are characterised by a capability of forming and

5

stabilising emulsions. Sample ML is characterised by the greatest ability of forming and stabilising

6

emulsions. Starches of Merigel type show higher values of the functional properties (AE, WAI and

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FAI) are therefore may be useful in the food industry as a texture-creating additive in dishes that do

8

not require heat treatment or that are meant for direct consumption.

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Water vapour adsorption and desorption was conducted on the modified corn starches and on

10

the native material at 20°C. The results obtained permitted the calculation of specific surface area

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(SBET) in both processes, within monolayer, aw 0-0.4. Specific surface area determined in the process

12

of adsorption (SBET ads) is ca. 5-20% greater than that determined from the desorption isotherm (SBET

13

des) (Tab.3). Only in the case of two samples (MM, R) the specific surface area determined is smaller

14

relative to the native material. It was found that the medium level of cross-linking of the modified

15

starches (MM, RM) causes a differentiation of their sorption properties. In the case of starch MM,

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with a medium level of cross-linking, a decrease of the specific surface areas (SBET ads, SBET des) was

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observed, while for the cook-up type starch (RM) an increase of those values was noted.

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Modified starches of the Merigel and Resistamyl types with low, medium and high degrees of

19

cross-linking were analysed. It was found that with increasing level of cross-linking the starches were

20

characterised by lower values of viscosity (Fig. 10). At the same time it was also noted that, in the case

21

of the Merigel type starches, with an increase in the degree of cross-linking there was a decrease of the

22

temperature at which the highest viscosity of the gels was observed. The presented correlation

23

between the temperature at which a sample attains the maximum viscosity and the degree of cross-

24

linking is not as apparent in the case of starches of the Resistamyl type. Samples of the Resistamyl

25

type starches behave somewhat differently. Starches with the lowest degree of cross-linking attain

26

maximum viscosity at the temperature of ca. 90°C, while an increase in the degree of cross-linking

27

(RM, RH) causes that the maximum viscosity is displayed at a lower temperature (ca. 80°C).

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The degree of cross-linking had a significant effect on the functional properties of the starches, such as

30

water absorption (WAI), fat absorption (FAI) and specific surface area determined from the sorption

31

isotherms (SBETads, SBETdes). The analyses of starches of the Resistamyl (cook-up) type (Fig. 11)

32

revealed a strong correlation, R2=1 (Tab. 4), between the degree of cross-linking and the values of the

33

WAI index and specific surface areas (SBETads, SBETdes). An increase of those values was noted for

34

samples with low (RL) and high (RH) degree of cross-linking, while a significant decrease of WAI

35

and specific area at medium cross-linking of starch (RM). Mathematical interpretation of function

36

f(degree of cross-linking) vs. (WAI or SBETads or SBETdes) is observed when the values of variable (x2),

37

defining the degree of the polynomial assume positive values. In the case of samples of the Merigel 9

ACCEPTED MANUSCRIPT 1

type equally strong correlations, R2=1, were found between f(degree of cross-linking) vs. (WAI or

2

SBETads or SBETdes) (Fig. 11, Tab. 4). Starch with medium degree of cross-linking (MM) is characterised

3

by the highest values of these indices, while the low (ML) and high (MH) cross-linking caused a

4

decrease of their values.

5 6

4. Conclusions The study was focussed on waxy corn starches of the pre-gelatinisation (Merigel) and cook-up

8

(Resistamyl) types, with different degrees of cross-linking and medium degree of substitution. The

9

hydrothermal treatment (pre-gelatinisation) differentiated the most strongly the functional and

10

physicochemical properties of the starch as opposed to the cook-up type starch, not subjected to any

11

preliminary treatment. Next to the pre-gelatinisation, the medium degree of cross-linking caused the

12

strongest differentiation of the properties of the Resistamyl and Merigel starches. It was demonstrated

13

that the process of starch pre-gelatinisation (Merigel), with its medium degree of substitution, causes

14

an increase in the values of WAI, AE and SBET, while cook-up type starches with the same degree of

15

substitution are characterised by decreased values of those indices. The different functional properties

16

of the two types of starches permit their application in food products of various compositions, destined

17

for long storage within a broad range of temperatures. Preliminary modification of starch of the

18

Merigel type permits its application in food products that do not require culinary treatment or for

19

which such treatment can be omitted, e.g. cooking, that can be used for direct consumption, with

20

simultaneous possibility of achieving the kind of texture that meets the expectations of the consumer.

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Acknowledgements

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We wish to thank the company TATE&LYLE (Brenntag) for providing samples.

25 26

28 29 30 31 32 33 34 35 36 37 38 39 40

References

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Acquarone, V. M., & Rao, M. A. (2003). Influence of sucrose on the rheology and granule size of cross-linked waxy maize starch dispersions heated at two temperatures. Carbohydate Polymers, 51, 451–458. Anderson, R. A., Conway, H. F., Pfeifer, V. F., & Griffin, L. E. J. (1969). Gelatinization of corn grits by roll and extrusion cooking. Cereal Science, Today, 14, 4. Approved methods of the AACC. (1990. 2000). St Paul. MN: The Association. Beuchat, L.R. (1977). Functional and electrophoretic characteristic of succinylated peanut flour proteins. Journal of Agricultural and Food Chemistry, 25, 258–260. Cisse, M., Zoue, L.T., Soro, Y.R., Megnanou, R., & Niamke, S. (2013). Physicochemical and functional properties of starches in quality protein maize. Journal of Applied Biosciences, 66, 5130-5139. Cousidine, D. M. (1982). Foods and food production encyclopedia. NY: John Wiley Inc. p. 142.

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Czerwińska, D. (1995). Starches modification – characteristics, used in cereal products. Cereal and Milling Review, 12, 10-11 (in Polish). Davies, L. (1995). Starch-composition. Modifications. Applications and nutritional value in foodstuffs. Food Technology Europe, 6/7, 44-52. Delville, J., Joly, C., Dole, P., & Bliard, C. (2002). Solid state photo-cross-linked starch based films: A new family of homogeneous modified starches. Carbohydrate Polymers, 49, 71–81. Dybel, E. (2006). The properties of potato starch preparations subjected to chemical modifications and roasting. Food, 4, 49 (in Polish). Ellis, R. P., Cochrane, P. M., & Daley, M. F. B. (1998). Starch production and industrial use. Journal of Science Food and Agriculture, 77, 289–311. El-Tahlawy, K., Venditti, R. A., & Pawlak, J. J. (2007). Aspects of the preparation of starch microcellular foam particles crosslinked with glutaraldehyde using a solvent exchange technique. Carbohydrate Polymers, 67, 319–331. Evans, I. D. & Haisman, D. R. (1979). Rheology of gelatinized starch suspensions. Journal of Texture Studies, 10, 347–370. Fortuna, T., Gałkowska, D., & Juszczak, L. (2004). Comparison of rheological properties of some preparations of modified starch. Acta Scientiarum Polonorum. Technologia Alimentaria, 3(1), 21-32 (in Polish). Fortuna, T. & Juszczak, L. (1998). Starch retrogradation sorted by particle size. Science Book AR in Crakow, 342, 31-39 (in Polish). Gluck-Hirsch, J. B., & Kokini, J. L. (1997). Determination of the molecular weight between crosslinks of waxy maize starches using the theory of rubber elasticity. Journal of Rheology, 41, 129. González, Z. & Pérez, E. (2002). Effect of acetylation on some properties of rice starch. Starch/Stärke, 54, 148–154. Hirsch, J. B. & Kokini, J. L. (2002), Understanding the mechanism of cross -linking agents (POCl3, STMP, and EPI) through swelling behavior and pasting properties of cross -linked waxy maize starches. Cereal Chemistry, 79, 102-107. Hoover, R. & Sosulski, F. (1985). A comparative study of the effect of acetylation on starches of phaseolus vulgaris Biotypes. Starch/Stärke, 37, 397–404. Huber, K.C., & BeMiller, J.N. (2001). Channels of maize and sorghum starch granules. Carbohydrate Polymers, 41, 269-276. Kapelko, M., Zięba, T., Michalski, A., & Gryszkin A. (2015). Effect of cross-linking degree on selected properties of retrograded starch adipate. Food Chemistry, 167, 124–130. Katzback, W. (1972). Phosphate cross-bonded waxy corn starches solve many food application problems. Food Technology, 4, 32-36. Kavitha, R., & BeMiller, J. N. (1998). Characterization of hydroxy-propylated potato starch. Carbohydrate Polymers, 37, 115-121. Krysińska, P., Gałkowska, D., & Fortuna, T. (2008). Features of the system of modified starch derived from waxy maize. Food. Science. Technology. Quality, 5, 60, 9 – 23 (in Polish). Kurakake, M., Akiyama, Y., Hagiwara, H. & Komaki T. 92009). Effects of cross-linking and low molecular amylose on pasting characteristics of waxy corn starch. Food Chemistry, 116, 66–70. Kaur, L., Singh, N., & Singh, J. (2004). Factors influencing the properties of hydroxypropylated potato starches. Carbohydrate Polymers, 55, 211–223. Lawal, O. S., Adebowale, K. O. & Oderinde, R. A. (2004). Functional properties of amylopectin and amylose fractions isolated from Bambarra groundnut (Voandzeia subterranean) starch. African Journal of Biotechnology, 3(8), 399-404. Lin, J.H., Wang, S.W.,& Chang, Y.H. (2008). Effect of molecular size on gelatinization thermal properties before and after annealing of rice starch with different amylose contents. Food Hydrocolloids, 22,156–63. Murúa-Pagola, M., Beristain-Guevara, C.I., & Martínez-Bustos, F. (2009). Preparation of starch derivatives using reactive extrusion and evaluation of modified starches as shell materials for encapsulation of flavoring agents by spray drying. Journal of Food Engineering, 91, 380–386. Perera, C. & Hoover, R. (1999). Influence of hydroxypropylation on retrogradation properties of native. defatted and heat moisture treated potato starches. Food Chemistry, 64, 361–375.

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ACCEPTED MANUSCRIPT Table 1 Characteristics of modified corn starches. Degree of crosslinkin Code g Distarch phosphate 0b high M low ML Merigel pregelatinisation Acetylated distarch adipate medium a medium MM high MH high Distarch phosphate 0b R low Resistamyl RL cook-up Acetylated distarch adipate medium a medium RM high RH Waxy corn starch Waxy corn starch WCS a Acetyl groups not more than 2.5% and adipate groups not more than 0.135% [Compendium of Food Additive Specifications] b Phosphate not more than 0.5% [Compendium of Food Additive Specifications] Type of modification

Degree of substitution

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Trade name

ACCEPTED MANUSCRIPT Table 2 Chemical composition of modified corn starches. Carbohydrate

Moisture

94 94 92 92 86,5 86,5 86,5 86,5

5,9 5,8 7,0 7,0 12,4 12,6 12,0 12,6

Protein

Fat

Ash

<0,35 <0,35 <0,35 <0,35 <0,35 <0,35 <0,35 <0,35

<0,08 <0,08 <0,08 <0,08 <0,10 <0,10 <0,10 <0,10

<0,7 <0,7 <0,7 <0,7 <0,4 <0,4 <0,4 <0,4

pH

[%] 5,8 5,7 5,7 5,9 5,8 6,2 5,8 5,9

RI PT

Trade name M ML MH MR R RL RM RH

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Protein determined by AACC (Method 46-08), dry mass counting up water determined by AACC (Method 4415A), fat determined by AACC (Method 30-16, 26), ash determined by AACC (Method 08-01).

ACCEPTED MANUSCRIPT Table 3 Specific surface area calculated by the sorption isotherms of vapour water (SBET). Specific surface area (g/m2) Desorption (SBET des)

217.07±3.76d 203.28±2.42c 145.97±1.82b 282.95±4.63g 190.30±4.70a 276.70±3.60f 279.02±3.37f 230.51±4.59e 199.50±3.83

205.55±4.24d 180.08±1.87b 112.94±3.10a 224.77±4.36e 187.09±3.73c 256.08±3.41f 262.65±2.99g 229.21±4.25e 190.53±3.81

RI PT

M ML MM MH R RL RM RH Waxy corn starch

Adsorption (SBET ads)

SC

Sample

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The same letters in columns indicate values that are not significantly different at α = 0.05

ACCEPTED MANUSCRIPT Table 4 The mathematical description functional properties versus degree of crosslinking. Mathematical expression Model Resistamyl

Merigel

19.4x - 76.65x + 260 R2 = 1 1.79x2 - 6.95x + 176.74 FAI= f(x) R2 = 1 97.5x2 – 350.5x + 456 SBET ads= f(x) R2 = 1 89.43x2 - 335.4x + 425.96 SBET des= f(x R2 = 1 f(x) = degree of cross-linking

-190.42x + 797.4x + 373.8 R2 = 1 -42.6x2 + 184.61x + 51.91 R2 = 1 -41.5x2 + 141.5x + 179 R2 = 1 -48x2 + 213x + 22 R2 = 1

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WAI= f(x)

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ACCEPTED MANUSCRIPT 500

100 ML MM

90

400

MH Temperature

80

350

70

300

60

250

50

200

40

150

30 20

SC

100 50

0

10

20

30

40

50

60

M AN U

0 70

80 90 100 110 120 130 140 150 160 170 Time [min]

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Fig. 1. Viscosity of modified waxy corn starches type of Merigel.

10 0

Temperature [ oC]

450

RI PT

Viscosity [mPas]

M

ACCEPTED MANUSCRIPT 100

450 400

300 250

90

RL RM

80

RH Temperature

70 60

RI PT

Viscosity [mPas]

350

R

200

50

150

40

100

0 10

20

30

40

50

60

70

80

90 100 110 120 130 140 150 160 170

M AN U

0

SC

30

50

Time [min]

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Fig. 2. Viscosity of modified waxy corn starches type of Resistamyl.

20

Temperature [ oC]

500

ACCEPTED MANUSCRIPT 100 90

70

M

60

ML

RI PT

Transmittance in +4°C[%]

80

MM

50

MH

40

Waxy corn starch

30

R

SC

20 10

0

7

14

M AN U

0 21

28

days

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Fig. 3. Modified starch retrogradation at a temperature of +4°C.

RL

RM RH

ACCEPTED MANUSCRIPT 100 90

70

M

60

ML

RI PT

Transmittance in +20°C[%]

80

MM

50

MH

40

Waxy corn starch

30

R

SC

20 10

0

7

14

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28

days

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Fig. 4. Modified starch retrogradation at a temperature of +20°C.

RL

RM RH

ACCEPTED MANUSCRIPT 100 90

70

M

60

RI PT

ML MM

50

MH

40

Waxy corn starch

30

R

20

RL

SC

Degree of syneresis in +4°C

80

10

7

14

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0 21

28

days

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Fig. 5. Syneresis modified starch at a temperature of +4°C.

RM RH

ACCEPTED MANUSCRIPT 100 90

70 M 60

RI PT

ML

50

MM MH

40

Waxy corn starch

30

R

20

RL

10 0 14

21

28

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SC

Degree of syneresis in -22°C

80

days

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Fig. 6. Syneresis modified starch at a temperature of -22°C.

RM RH

ACCEPTED MANUSCRIPT 1400 1207 c

1200

1000

1052 b

M

981 b

ML

800

MH R RL

600

RM RH

400

RI PT

MM

200

0 1

SC

Waxy corn starch

196 a 203 a 199 a 205 a 184

M AN U

Water absorption index [%]

1062 b

Fig. 7. Water adsorption index modified starch.

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ACCEPTED MANUSCRIPT 240 230

222 f

M

208 e

210

ML

203 d

200

RI PT

MM MH

194 c

R

190

RL

174 b 172 ab 171 ab170 a

180 170

RM RH

Waxy corn starch

SC

Fat absorption index [%]

220

163

150 1

M AN U

160

Fig. 8. Fat adsorption index modified starch.

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ACCEPTED MANUSCRIPT 70

Stability of emulsification activity [%] 36

53

52

30

50

RI PT

25 40

20

31 30

15

10

SC

20 10

M AN U

6

10

0

0

0

0

M

ML

MM

MH

R

0

RL

EP

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Fig. 9. Emulsification activity and stability modified starch.

AC C

Stability of emulsification activity [%]

35

60

Emulsification activity [%]

40

Emulsification activity [%] 60

0

0

0 RM

0 RH

10

5

4 2

0 Waxy corn starch

ACCEPTED MANUSCRIPT 500

y = 6x 2 - 28x + 110 R2 = 1 y = -15x 2 + 40x + 65 R2 = 1

300

60

40 2

2

100

y = 35x - 175x + 220 R2 = 1

RI PT

200 y = 92,5x - 562,5x + 915 R2 = 1

20

0

0 Medium

High

Degree of crosslinking

SC

Low

M AN U

Sample type Merigel Sample type Resistamyl Temperature of peak viscosity Max viscosity

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Fig. 10. Viscosity vs degree of cross-linking.

Temperature [°C]

80

400 Viscosity [mPas]

100

300

Merigel

Resistam yl

1250 250

M AN U

1050

SC

1450

RI PT

ACCEPTED MANUSCRIPT

200

850

WAI (%) FAI (%) SBET ads (m2/g) SBET des (m2/g)

650 450

150

WAI (%) FAI (%) SBET ads (m2/g) SBET des (m2/g)

250 50 Low 1

2

Medium 2

3

High 3

EP

1

TE D

100

4

AC C

Fig. 11. Functional properties (WAI, FAI, SBET) versus degree of cross-linking.

50 1

Low

2

Medium 3

High 4

ACCEPTED MANUSCRIPT •

Chemically modified corn starches of by various degrees of cross-linking and medium substitution The hydrothermal treatment most differentiates the samples properties



The cross-linking of less than differentiate samples of pre-gelatinisation



The modified starches can be used for the non-processed food cooking



The modified starches can be used in food destined for long storage

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ACCEPTED MANUSCRIPT WAI =

m − m ⋅100% m

(1)

FAI =

m − m ⋅100% m m

(2)

EA =

e f

⋅ 100%

(3)

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m