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Research Paper
Effect of sucrose on Water Chestnut (Trapa bispinosa) starchhydrocolloids mixtures
Z. Lutfi* and A. Hasnain
Department of Food Science & Technology,
University of Karachi, Karachi-75270, Pakistan
*Corresponding author
Zubala Lutfi
Research Fellow
Department of Food Science & Technology,
University of Karachi. Karachi, Pakistan.
Tel: +92 21 4823115, Fax: +91 21 9243206
E mail: zubala.lutfi7@gmail.com
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ABSTRACT
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Effect of sucrose on Water Chestnut (Trapa bispinosa) starchhydrocolloids mixtures
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Food industry has a vast application of starch-gum interactions in different bakery
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products as well as low calorie food formulations. Present study was carried out to
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observe the effect of sugar (sucrose) on interactions of water chestnut starch-xanthan and
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water chestnut starch-guar combinations, using Brabender Amylograph. Water chestnut
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starch (5% w/v) was mixed individually with guar (0-0.3% w/v) and xanthan (0-0.3%
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w/v) and heated in a Brabender Amylograph. Significant change in gelatinization
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temperature and peak viscosity was observed. Peak viscosity increased by the addition of
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guar as well as xanthan gum while gelatinization temperature decreased in comparison
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with the controls. This behavior can provide ease in processing of confectionery,
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especially those which are high in sugar / sugar syrup under high temperatures. As the
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concentration of sugar in sugar-starch-water system was increased, the gelatinization
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temperature of the starch also increased. Gelatinization of the starch is critical in building
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structure and texture of bakery products. These results can be used in starch based
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products which can provide different benefits: suspension of particulates (as in muffin
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mixes); reduces the dough stickiness; improved handling and machinability; increased
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cake volume; improved water binding for increased moistness; and softer textures.
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Keywords: Water Chestnut, Brabender Viscoamylograph.
By Zubala Lutfi & Abid Hasnain
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Introduction:
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Starch plays an important role in developing the different food products by contributing
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alone or with different ingredients. It acts as a thickener, stabilizer or texture enhancer. In
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addition it is also used to improve the moisture retention to make the water mobility
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restricted so that the product can be prevented from spoilage during storage.
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Starch products are mixture of different ingredients as well as taste enhancers and the
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interactions of these ingredients or taste enhancers with each other are very important in
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maintaining the quality of the product. In Pakistan, water chestnut locally known as
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“SINGHARA” is an edible aquatic angiosperm which belongs to the Trapaceae family in
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the genus of Trapa bispinosa Roxb. This variety is native to Asia, where it is used in
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cooking. Few South-East Asian countries import Water Chestnut from China for food. In
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both Asia and Europe, the dried nuts are often eaten raw, though more usually they are
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boiled or roasted. The high carbohydrate content of water chestnut makes it a very good
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source of starch for both domestic and industrial uses. Application of starches in food
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systems are primarily governed by gelation, gelatinization, pasting, solubility, swelling,
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paste clarity and freeze thaw stability
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Uses of native unmodified starches have certain shortcomings which limit their wider
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application and industrial uses. Functional starches available in the commercial market
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are usually obtained from corn or other cereals. The physical modification (mainly
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gelatinization) or simple chemical modifications are sometimes used to fulfill the specific
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needs of food and technical allied industries. Modified food starches generally show
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better paste clarity and stability, increases resistance to retrogradation and freeze thaw
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stability (Be Miller, 1997). The functional properties of the starch such as viscosity,
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dispersibility, solubility and stability are significantly influenced by this taste enhancer
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thus it is necessary to determine the effect of these taste substances on viscoelastic
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properties of starch.
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Among these taste substances and sweet substances, sucrose are the most widely added to
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starch products. The effect of sucrose on the viscoelastic properties of starches has been
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investigated by many researchers (Abu-Jdayil et al., 2001; Ahmad et al., 1999; Campbell
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et al., 1957; Cheer et al., 1983; Chungcharoen et al., 1987; D’Appolonia 1972; Eliasson
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1992; Evageliou et al., 2000; Sudhakar et al., 1995; Hirashima et al., 2005; Spies et al.,
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1982; Bean et al., 1959; Bean et al., 1978; Savage et al., 1978).
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Sugar is also known to retard gelatinization by inhibiting swelling of starch granules in
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water system. As a consequence, however the overall outcome of sugar addition to a
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specific food product is by far unpredictable.
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Hydrocolloids such as xanthan and guar gum also added to enhance the properties of
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starch and also improve the textural and overall acceptability of the product (Christianson
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et al., 1981). Investigation of starch-gum interactions showed that it significantly
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increased the viscosity of starch that can be desirable for the use in different bakery
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products.
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During this study the effect on gelatinization temperature and peak viscosity of water
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chestnut starch by the interaction with sucrose and gums were investigated. Water
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chestnut starch has potential to be used in the food industry. Sucrose is widely used as an
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ingredient or a taste enhancer in the food industry and in home cooking.
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Material and Methods:
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Water chestnut starch (WCS) was isolated from dried Water chestnuts; food grade
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xanthan gum (XG) and guar gum (GG) were purchased from the local market of Karachi,
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Pakistan. Water chestnut starch (moisture content of 12%) at 5% (w/v) level was mixed
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with 0-0.3% w/v xanthan gum (XG) and 0-0.3% w/v guar gum (GG) in sucrose solution
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(0-30% w/v). The mixture was then heated in a Brabender Viscograph (Model D- 47055)
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from 35 °C to 95 °C at a rate of 1.5 °C/min at 75 rpm, held for 10 min at 95 °C and then
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cooled back to 40 °C. The change in behavior was interpreted with respect to
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gelatinization temperature and peak viscosity.
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Statistical Analysis
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The results reported are means of triplicate determinations. The statistical analysis of the
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results was conducted by the analysis of variance (ANOVA) and LSD test using SPSS
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version 11.0 for Windows program. Significant differences were reported for P≤ 0.05.
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Result and Discussion:
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The effect on peak viscosity and gelatinization temperature of WCS – XG and WCS -
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GG was investigated at varying concentrations of sucrose. Initially, as shown in Table 1,
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an increase in peak viscosity of WCS at 5% concentration was observed in the presence
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of sucrose. This viscosity increased from 72 BU at 10% sucrose concentration to 114 BU
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at 30% sucrose concentration, where as it was decreased to 101 BU at 50% sucrose
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concentration. The same results were obtained by Kulkarni et al. (1995) according to
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which an increase in the peak viscosity of WCS was recorded as the concentration of
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sucrose increased up to 30%.
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The increase in viscosity is due to the swelling of starch granules accompanied by
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leaching of amylose whereas granules may rupture during further heating. The
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equilibrium point between the swelling and rupture of starch granules is defined as peak
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viscosity (Ikeda et al., 2002).
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The reason for the increase in peak viscosity by the addition of sucrose at different
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concentration is may be due to the interaction of sucrose with polysaccharide which made
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starch granules restricted and tightened that will result in a slow leaching of amylose
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chain. Due to the tightened structure, the swelling of granule will enhance further
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(Pongsawatmanit Rungnaphar et al., 2007).
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While larger amount of sucrose decreased the degree of swelling for starch granules
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(Hirashima et al., 2005), it also known that the rate of increase in viscosity is slower at
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higher concentration of sugar than at low concentration (Kulkarni et al., 1995). However
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the starch granule could be swollen even at high concentration of sucrose (Hirashima et
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al., 2005). Hence the details on the trend of increase in viscosity by the addition of sugar
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up to 50% concentration have yet to be worked out.
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The effect on WCS-GG combinations by using varying concentration of sucrose are
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reported in table 2. The increase in peak viscosity at constant starch and gum
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concentrations were observed. When the concentration of sucrose was increased at 10%
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to 30% at 5% WCS and 0.1% GG, the viscosity increased from 153BU to 193 BU at 10%
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and 30% respectively.
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This result is observed at all concentrations of GG. Similarly, at a constant sucrose and
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starch concentrations, the viscosity is increased when the concentration of gum was
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increased at 0-0.5% while the sucrose concentration ranges from 10% to 30%.
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The increase in viscosity is due to polymer-polymer interactions, as sucrose concentration
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increases it binds with water to make it unavailable for polymers and enhances the
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interaction of leached amylose to the gums resulting in the increase in viscosity. This
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result is in agreement to the (Be Miller et al., 2002) according to which the polymer-
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polymer interactions increased apparent molecular size and viscosity.
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In the absence of sucrose as shown in (Tables 3 and 4) the viscosity is increased by the
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addition of gums but significant increase was observed by the addition of sugar which
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favored the gums interactions with starch. It is also reported that GG is protected by sugar
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against hydrolysis and subsequent loss of viscosity (Carlson et al., 1965).
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The effect on WCS- XG combinations by using varying concentration of sucrose are
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reported in table 5. The increase in peak viscosity at constant starch and gum
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concentrations were observed. When the concentration of sucrose was increased at 10%
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to 30% for example at 5% starch and 0.1% XG the viscosity is increased from 129BU to
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165 BU at 10% and 30% respectively.
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This result is observed at all concentrations of XG. Similarly, at a constant sucrose and
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starch concentrations, the viscosity is increased when the concentration of gum was
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increased at 0-0.5% while the sucrose concentration ranges from 10% to 30%.
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At higher concentrations of XG (0.1- 0.3%) the significant increase in viscosity is not
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observed particularly at concentration of 0.3% XG. This can be due to inefficient
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hydration of gums and starch. For the efficient interaction it was supposed that gums and
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starch must be completely hydrated. As shown in Table 4, in sugar free environment they
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both get completely hydrated and results in significant increase in viscosity but in
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presence of sugar the hydration is limited due to which the marked increase was not
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observed. Some reports support the observed results. While keeping the sugar and starch
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concentration constant the peak viscosity is increased with increase in gum concentration
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from 0.1 – 0.3%.
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The gelatinization is delayed by the addition of sugar. (Bean et al., 1959, Bean et al.,
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1978a, D’Appolonia 1972, Miller et al., 1965, Spies et al., 1982) shown in Table 1. The
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sugar or any other solute added to water decreased the availability of water in the system
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which therefore requires the higher energy to interact with other components in the
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system (Spies et al., 1982). Osman (1978) found that sugar inhibit swelling of corn starch
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in water and retard gelatinization. The delay in gelatinization temperature is lower in the
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presence of gums and hence the gums bring the gelatinization temperature of WCS –
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sucrose combinations to almost that of starch alone (Table 2 & 5) due to two different
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effects. First the gelatinization temperature of WCS is decreased by the increases of gums
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concentration and this decreased is much higher with XG as compared to guar. Secondly
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the gelatinization temperature of WCS is increased in the presence of sucrose, which is
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the agreement of earlier studies (Slade et al., 1989; Kim et al., 1992). This combined
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effect tends to bring the gelatinization temperature of WCS close to starch alone.
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These results can be used in starch based products which can provide different benefits
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such as suspension of particulates (as in muffin mixes), reduce the dough stickiness;
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improved handling and machinability, increased cake volume, improved water binding
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for increased moistness and softer textures.
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References
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Carlson, W. A., Ziegenfuss, E. M. 1965. The effect of sugar on guar gum as thickening
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fructose on gelation of oxidezied starch. Carbohydrate Polymers, 42: 261-272.
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Table 1: Effect of sucrose on the peak viscosity (PV) gelatinization temperature of 5% (WCS)
Ingredients
Peak viscosity
(BU)
Gelatinization
temperature °C
5% WCS
72a
77.2a
5% WCS + 10%
sucrose
95b
78.8b
5% WCS + 20%
sucrose
103c
80.2c
5% WCS + 30%
sucrose
114d
81.7d
5% WCS + 50%
sucrose
101e
91.5e
Assays were performed in triplicate. Mean values followed by different superscripts with in
the same column are significantly different (P ≤ 0.05).
Table 2. Effect of sucrose on the peak viscosity (PV) and gelatinization temperature of WCS-GG combinations
Ingredients
10%
sucrose
20%
sucrose
30%
sucrose
PV
Gel.
PV
Gel.
PV
(BU)
Temp. °C
(BU)
Temp. °C
(BU)
Gel.
Temp.
°C
5% WCS + 0.1% GG
153a
68.1a
149a
76.8a
193a
79.2a
5% WCS + 0.2% GG
155b
72.8b
189b
76.7b
273b
78.3b
5% WCS + 0.3% GG
220c
72.7c
277c
65.1c
412c
Assays were performed in triplicate. Mean values followed by different superscripts with in
the same column are significantly different (P ≤ 0.05).
59.7c
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Table 3. Effect of addition of (GG) on the peak viscosity (PV) and gelatinization temperature of 5% (WCS).
Ingredients
Peak
viscosity
(BU)
Gelatinization
temperature
°C
5% WCS
72a
77.2a
5% WCS + 0.1% GG
79b
77.5b
5% WCS + 0.2% GG
135c
70.9c
5% WCS + 0.3% GG
172d
66d
Assays were performed in triplicate. Mean values followed by different superscripts with in
the same column are significantly different (P ≤ 0.05).
Table 4. Effect of addition of XG on the peak viscosity (PV) and gelatinization temperature of 5% (WCS).
Ingredients
Peak
viscosity
(BU)
Gelatinization
temperature
°C
5% WCS
72a
77.2a
5% WCS + 0.1% XG
98b
71.1b
5% WCS + 0.2% XG
159c
69.4c
5% WCS + 0.3%
XG
170d
70.6d
Assays were performed in triplicate. Mean values followed by different superscripts with in
the same column are significantly different (P ≤ 0.05).
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Table 5. Effect of sucrose on the peak viscosity (PV) and gelatinization temperature of WCS-XG combinations.
Ingredients
10%
sucrose
20%
sucrose
30%
sucrose
PV
Gel.
PV
Gel.
PV
(BU)
Temp. °C
(BU)
Temp. °C
(BU)
Gel.
Temp.
°C
5% WCS + 0.1% XG
129a
76a
165a
76.8a
165a
5% WCS + 0.2%
XG
197b
71.7b
203b
75.2b
252b
5% WCS + 0.3%
XG
259c
64.5c
325c
67c
326c
Assays were performed in triplicate. Mean values followed by different superscripts with in
the same column are significantly different (P ≤ 0.05).
77.6a
65.1b
74c
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