Wheat starch crosslinking

Table 10.13 Effect of degree of crosslinking on pasting properties of large granule wheat starch at 10% solids27...

Monosubstitution of wheat starch by acetyl or hydroxypropyl groups27 without crosslinking yields products with a reduced pasting temperature, and yields pastes with enhanced clarity and viscosity but with increased stringiness (Table 10.14). The usefulness of this product is somewhat limited and requires special applications. Amylose has been found to be hydroxypropylated —20% more than amylopectin in corn and potato starches at a molar substitution level of 0.1 (3.5% hydroxypropyl).425,426... 

Acetylated wheat distarch phosphate pastes had improved clarity and better storage stability than the pastes of unmodified and crosslinked alone starches when 1% aqueous dispersions were heated in a boiling water bath for 30 minutes and stored at two different temperatures (4°C and 25°C) for 9 days.27 Storage at 4°C of 5% pastes of native and crosslinked wheat starch revealed that both were unstable after one day, the soft texture of the initial pastes being transformed into an opaque and rigid gel that exhibited syneresis. In contrast, the acetylated distarch phosphate was stable for at least... 

The extent of mixing of polymer blends on a nanometer scale can be determined by examining the spin-lattice relaxation performance of the H nuclei. This has been achieved previously in blends of cellulose/poly(vinyl alcohol) (PVOH) [14], wheat proteins/PVOH [15], starch/poly(caprolactone) (PCL) [16] and starch/crosslinked poly(acrylic acid) [17]. 

Englyst et al.248 classified starch into three types RSI, RS2 and RS3. RSI is a starch protected from digestion in the small intestine by a food matrix, such as the intact endosperm of a wheat kernel. RS2 is simply unswollen granular starch. RS3 is starch that was gelatinized, but then retrograded to become enzyme-resistant. Chemically modified (e.g. crosslinked) starch (RS4) has been added to the list.242 The four forms of resistant starch and their measurement are described by Nugent246 and Sajilata et al.249... 

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