Effect of Sucrose on Glass Transition, Gelatinization, and Retrogradation of Wheat Starch

Abstract

Cereal Chem. 78(2): [186][187][188][189][190][191][192] Differential scanning calorimetry (DSC) was used to study the effect of sucrose on wheat starch glass transition, gelatinization, and retrogradation. As the ratio of sucrose to starch increased from 0.25:1 to 1:1, the glass transition temperature (T g , T g ′) and ice melting enthalpy (∆H ice ) of wheat starch-sucrose mixtures (with total moistures of 40-60%) were decreased to a range of -7 to -20°C and increased to a range of 29.4 to 413.4 J/g of starch, respectively, in comparison with wheat starch with no sucrose. The T g ′ of the wheat starch-sucrose mixtures was sensitive to the amount of added sucrose, and detection was possible only under conditions of excess total moisture of >40%. The peak temperature (T m ) and enthalpy value (∆H G ) for gelatinization of starch-sucrose systems within the total moisture range of 40-60% were increased with increasing sucrose and were greater at lower total moisture levels. The T g ′ of the starchsucrose system increased during storage. In particular, the significant shift in T g ′ ranged between 15 and 18°C for a 1:1 starch-sucrose system (total moisture 50%) after one week of storage at various temperatures (4, 32, and 40°C). At 40% total moisture, samples with sucrose stored at 4, 32, and 40°C for four weeks had higher retrogradation enthalpy (∆H) values than a sample with no sucrose. At 50 and 60% total moisture, there were small increases in ∆H values at storage temperature of 4°C, whereas recrystallization of samples with sucrose stored at 32 and 40°C decreased. The peak temperature (T p ), peak width (δT), and enthalpy (∆H) for the retrogradation endotherm of wheat starch-sucrose systems (1:0.25, 1:0.5, and 1:1) at the same total moisture and storage temperature showed notable differences with the ratio of added sucrose. In addition, T p increased at the higher storage temperature, while δT increased at the lower storage temperature. This suggests that the recrystallization of the wheat starch-sucrose system at various storage temperatures can be interpreted in terms of δT and T p .The phase transitions associated with ordering and disordering, such as glass transition, gelatinization, and retrogradation in starch systems have been intensively investigated with differential scanning calorimetry (DSC) (Donovan 1979; Zeleznak and Hoseney 1987a,b;Slade and Levine 1988;Kalichevsky et al 1992).The glass transition temperature (T g , T g ′) in starch decreases with increasing water content due to the plasticization effect of water (Slade and Levine 1987). The T g of starch systems with water contents >20% drops below room temperature (Zeleznak and Hoseney 1987a) and below 0°C for water contents ≥50% (Slade and Levine 1988). At temperatures below T g , the material becomes a glassy solid and molecular motion is so slow that crystallization does not occur in a realistic period of time. At temperatures above T g , however, the material is a rubbery liquid and sufficient motion of the polymer can occur, allowing a retro...

Application of Retrogradation-retardation Technology to Korean Rice Cake, Garaedduk Made from Non-waxy Rice

“…So far, related studies have mainly focused on chemical ways to use emulsifiers or other materials with high moisture retention (Kim et al, 2007, Jang et al, 2004. Unlike those studies, the present study was conducted in light of the processing methods for traditional Korean foods with a variety of properties in which the same grain is used, such as cooked glutinous rice, sticky rice cakes, and traditional cookies (Wu et al, 2009, Yoo et al, 2001.…”

Effect of sugar and water contents on non-expanded cassava flour extrudates

“…Carvalho and Mitchell (2000) found that the sectional expansion of wheat flour extrudates was less affected by sucrose than by corn grit extrudates, which was attributed to the starch molecular integrity of wheat being lower than corn starch under severe shear condition. Structural changes have also been attributed to competition for water (HSIEH;PENG;HUFF, 1990) and inhibition of starch gelatinization (JANG et al, 2001). The modification of the extrudate texture as a consequence of increasing the sucrose concentration has been attributed to the plasticization of starch-based products by decreasing the glass transition temperature, increasing product density, and reducing sectional expansion (FAN; MITCHELL; BLANSHARD, 1996).…”

Microstructure of high-pressure vs. atmospheric frozen starch gels

“…Solutions of low molecular weight sugars have T g ' values below normal frozen storage temperatures (e.g. T g ' of a sucrose/water solution is around − 46°C), but for a gelatinized starch water system the T g ' is according to a number of studies around − 5°C (Ferrero, Martino, & Zaritzky, 1996;Jang, Lee, Cho, & Pyun, 2001;Levine & Slade, 1986;Lim, Wu, & Reid, 2000;Roos & Karel, 1991;Wang & Jane, 1994). The reported T g ' value for a starch/ water system is well above the storage temperature (− 24°C) used in this study and therefore the observed storage stability is not surprising.…”