Inhibition of wheat starch retrogradation by tea derivatives

Highlights

• Inhibitory effects of four industrial tea derivatives on wheat starch retrogradation were compared.

• Inhibition of wheat starch retrogradation by tea derivatives was investigated by TPA, RVA and DSC.

• The retrogradation kinetics of the starch additive mixtures were well modeled by the Avrami theory.

Abstract

The effect of four industrial tea derivatives (tea polyphenols [TPS], tea water-soluble extracts [TSE], tea polysaccharides [TSS], and green tea powder [GTP]), on the retrogradation of wheat starch was investigated using texture profile analysis (TPA), differential scanning calorimetry (DSC), rapid viscosity analysis (RVA), and the α-amylase–iodine method. The addition of the four tea derivatives resulted in decreased hardness and increased cohesiveness of the starch gel as shown by the TPA test. The DSC data demonstrated an increase in the enthalpy change of starch gelatinization and a decrease in the enthalpy change of starch recrystallite dissociation. The RVA results indicated that the peak viscosity, representing the intermolecular forces of wheat starch, was reduced after addition of TPS, TSE, and TSS, respectively, but was increased by GTP. Furthermore, the half crystallization time in the Avrami equation almost doubled after the separate addition of the tea derivatives.

Introduction

Tea is produced from the plant Camellia sinensis, which mainly grows in China and in Southeast Asia. Tea provides many health benefits, such as antioxidant properties, hypertension prevention, ultraviolet radiation protection, and bodyweight management (Cao, 2013, Pinto, 2013). These health benefits have been attributed to the bioactive components in tea, mainly polyphenols and polysaccharides. Due to these health benefits, tea is currently the most popular beverage in worldwide after water, and is thought to be the most promising natural product for health in the 21st century (Bansal et al., 2013, Narotzki et al., 2012, Thielecke and Boschmann, 2009). However, when tea is incorporated into foods, its components often interact with other food ingredients, including starch. From the literature, tea polyphenols or tea polysaccharides have been shown to have the ability to modify the thermodynamic, paste, and retrogradation properties of starch (Ananingsih et al., 2013, Guo et al., 2011, Guo et al., 2013, Zhu et al., 2009). It is thought that the modifications by TSS may result from increased electrostatic repulsion and decreased association among the macromolecules, as well as synergistic interactions among these polysaccharides. As for TPS, its polyhydric structures could have resulted in the increased enthalpy of starch gelatinization and decreased starch retrogradation (Wu et al., 2009, Zhu et al., 2008). Furthermore, it is likely that tea protein and/or fiber, as well as other tea components, can affect the physicochemical properties of starch, though there is little published data on these theories. In the previous studies, many factors and compounds are thought to be able to eliminate or reduce starch retrogradation in both short- or long-term retrogradation, including β-cyclodextrin (Tian et al., 2009a, Tian et al., 2009b), anionic polysaccharides (Funami et al., 2008), and food hydrocolloids (Funami et al., 2005).

Recently, bakery products contained tea components were privilege in the market for its healthy benefits. However, the quality especially the storage properties of this kind high-starch products was decreased by starch retrogradation. The objective of this research, therefore, was to give a scientific insight of four typically industrial tea derivatives (TPS; tea water-soluble extracts (TSE); TSS; and green tea powder (GTP)) as potential anti-retrogradation additives in food industry. The retarding effect of above four typically industrial tea derivatives on both the short- and long-term retrogradation of wheat starch (WS) were evaluated and compared, using texture profile analysis (TPA), differential scanning calorimetry (DSC), rapid viscosity analysis (RVA), and the α-amylase–iodine method.