Effect of preparation method on the properties of potato starch acetates with an equal degree of substitution

Abstract

Acetylated retrograded starch is one of the forms of resistant starch (RS3/4). Apart from the known resistance to amylolysis, it is characterized by the capability to form viscous pastes. Properties of this type of acetates are mainly determined by the degree of substitution and raw material used for esterification.

The objective of this study was to produce starch acetates with a degree of substitution DS = 0.1 from native potato starch and retrograded potato starch, and to compare selected properties of the resultant preparations.

Retrograded starch was produced by freezing pastes with concentrations of 1, 4, 10, 18 or 30 g/100 g. Starch acetates with a degree of substitution DS ∼ 0.1 were produced from native or retrograded starch through acetylation with various doses of acetic acid anhydride (6.5–26.0 cm³/100 g of starch). The preparations produced were characterized by various properties. A positive correlation was observed between resistance to amylolysis and the number of acetyl groups at C2 and C3 the produced starch acetates.

Introduction

Starch – as one the most abundant polysaccharides in nature – has been widely applied in both the food and non-food industries. Yet, in its native form starch has low industrial applicability. Depending on demands and mode of utilization, most of the starch produced is subjected to successive physical and chemical modifications. These modifications enable obtaining starch preparations with different structure and properties. The change of starch structure by means of physical and chemical modifications may affect a decrease in its susceptibility to amylolytic degradation. One of the groups of modified preparations used in recent years as food additives includes preparations of resistant starch that have been reported to play a health-promoting role (Laguna et al., 2011, Perera et al., 2010), as the so-called prebiotics (Angioloni and Collar, 2011, Scarminio et al., 2012). One of the forms of resistant starch is retrograded starch (RS3) produced as a result of physical modification of starch (Haralampu, 2000, Zhou and Lim, 2012). Retrogradation is a process defined as the linking of starch chains into ordered structures being crystalline in character. Properties of the resultant retrograded starch are determined by, among other things, the origin and type of starch, conditions of retrogradation and presence of other compounds (Funami et al., 2008, Korus et al., 2008, Silverio et al., 2000, Zhou et al., 2008). The chemical modification of starch also leads to the production of resistant starch which is referred to as RS4 fraction. Acetylation, hydroxypropylation, phosphorylation, roasting with glycine, cross-linking with epichlorohydrin or saturation with iron ions are chemical modifications that increase starch resistance to amylolysis (Juansang et al., 2012, Leszczyński, 2004). Acetylation of retrograded starch has bee shown to enable obtaining preparations of resistant starch RS3/4 with high resistance to the activity of amylolytic enzymes (Kapelko et al., 2012a, Zięba et al., 2011b) and characterized by the capability to form viscous pastes (Kapelko et al., 2012a, Zięba et al., 2011). The process of starch acetylation is determined by a number of factors. Both the degree and site of substitution with acetyl groups depend on, among other things, the origin (Mirmoghtadaie, Kadivar, & Shahedi, 2009) and form of starch (Kapelko, Zięba, Golachowski, & Gryszkin, 2012), size of starch granules (Mirmoghtadaie et al., 2009), degree of crystallinity (Golachowski, 2003), amylose content (Mirmoghtadaie et al., 2009), and conditions of the acetylation process (González & Pérez, 2002).

The objective of this study was to preparation starch acetates with a degree of substitution DS = 0.1 from native potato starch and retrograded potato starch, and to compare selected properties of the resultant preparations.