The molecular size of amylopectin (AP) and amylose (AM), AP chain length distribution, crystallinity and granular structure (morphology and granule size distribution) of five wild type potato starches (wtps), five AM free potato starches (amfps), four high-AM potato starches (haps), one wild type cassava starch (wtcs) and one AM free cassava starch (amfcs) were investigated and related to their gelatinisation characteristics. Starches with higher levels of short chains [degree of polymerisation (DP) 6-9 and DP 10-14)] had lower gelatinisation onset (T o), peak (T p) and conclusion (T c) temperatures, whereas higher contents of longer chains (DP 18-25 and DP 25-80) led to higher gelatinisation temperatures. Gelatinisation enthalpies (DH) increased with degree of crystallinity. The granules of wtps were larger than those of amfps and haps, respectively. No differences in morphology were observed between wtps and amfps granules, but the haps granules had more irregular surfaces and showed multi-lobed granules.

Monodisperse short-chain amorphous or semicrystalline amylose-glycerol monostearate (GMS) complexes, or, as a reference, pure GMS, were added to starch dispersions which were gelatinized and allowed to cool. The largest impacts on rheological properties were observed when GMS or amorphous GMS complexes were added. The controlled release of the short amylose chains of the latter induced double helix and, thus, network formation, resulting in higher viscosity readings. As the lipid is set free after starch gelatinization, it is assumed that it complexes with amylose leached outside the granule, whereas additional pure GMS can probably to a greater extent complex inside the granule. Semicrystalline complexes could be considered as inert mass in the starch systems as their melting temperature exceeded the temperature reached during the experiment. The additives also impacted starch's sensitivity to enzymatic degradation. GMS addition reduced the resistant starch (RS) content of the gels and increased their hydrolysis index (HI). Added amorphous or semicrystalline complexes, on the other hand, yielded gels with a higher RS content and a lower HI. Addition of amylose-lipid complexes to starch suspensions impacts starch gel characteristics and decreases its digestion rate, possibly by releasing short amylose chains in a controlled way that then participate in amylose crystallization and, hence, RS formation.

Starch, an essential component of an equilibrated diet, is present in cereals such as common and durum wheat, maize, rice, and rye, in roots and tubers such as potato and cassava, and in legumes such as peas. During food processing, starch mainly undergoes nonchemical transformations. Here, we focus on the occurrence of starch in food raw materials, its composition and properties, and its transformations from raw material to final products. We therefore describe a number of predominant food processes and identify research needs. Nonchemical transformations that are dealt with include physical damage to starch, gelatinization, amylose-lipid complex formation, amylose crystallization, and amylopectin retrogradation. A main focus is on wheat-based processes. (Bio)chemical modifications of starch by amylolytic enzymes are dealt with only in the context of understanding the starch component in bread making.

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To obtain detailed knowledge on possible changes in the properties of starch, proteins, and arabinoxylan as a result of field preharvest sprouting (PHS), three wheat varieties were harvested at maturity and several weeks later when severe PHS had occurred. Falling number values of flour dropped from 306 to 147 s (Sahara), 382 to 155 s (Forum), and 371 to 230 s (Tobak). Blocking of α-amylase activity demonstrated that the decline in falling number and changes in RVA pasting and gelation properties were not caused by changes in intrinsic starch properties as a result of PHS. PHS had no influence on the SDS-extractability and molecular weight distribution of the proteins. For arabinoxylan, incipient breakdown was noticed, leading to a higher amount and average degree of polymerization of water extractable arabinoxylan. Results show that strategies to cope with severely PHS in wheat should focus on blocking enzyme activities.