In vitro amylolysis of pulse and hylon VII starches explained in terms of their composition, morphology, granule architecture and interaction between hydrolysed starch chains

Physicochemical characteristics, ATR-FTIR molecular interactions and in vitro starch and protein digestion of thermally-treated whole pulse flours

Hydrothermal treatments, annealing (ANN) and heat moisture treatment (HMT) were applied to four whole pulse flours (black bean, broad bean, chickpea and lentil) with the aim to increase their slow digestible (SDS) and resistant starch (RS) fractions. In order to assess differences in their molecular interactions, they were analyzed and compared by ATR-FTIR before and after in vitro digestion. Both hydrothermal treatments promoted changes on starch granular architecture, being reflected on their thermal and pasting properties, that where positively correlated with their amylose and protein contents (R=0.96, P<0.01). Overall, the proposed hydrothermal treatments increased their SDS and RS fractions, but they had different effect on their in vitro protein digestion. The ATR-FTIR analysis of cooked flours before and after digestion showed that thermal treatments promoted new physical interactions at molecular scale between starch and proteins, that were correlated with the amount of RS fraction. The outcomes of this study could help to understand the slow digestion properties and possible interactions of the flour components in these four pulses.

Impact of molecular structure on the physicochemical properties of starches isolated from different field pea (Pisum sativum L.) cultivars grown in Saskatchewan, Canada

The objective of this study was to determine the molecular structure and properties of recently released cultivars of field peas [CDC Golden (CDCG), Abarth (ABAR), CDC Patrick (CDCP) and CDC Amarillo (CDCA)] grown at different locations in Saskatchewan, Canada. Starch yield (on whole seed basis), apparent amylose, total lipid and specific surface area were in the range 34-37%, 38.2-42.6%, 1.07-1.38% and 0.31-0.38m2/g, respectively. The proportion of short (DP 6-12) amylopectin chains, amylopectin branching density, molecular order, crystallinity, crystalline heterogeneity, gelatinization transition temperatures, pasting temperatures, peak viscosity, extent of acid hydrolysis, and resistant starch content were higher in CDCG and ABAR. However, amylopectin long chains (DP 13-26), average chain length and thermal stability were higher in CDCP and CDCA. The results of this study showed that differences in physicochemical properties among cultivars were mainly influenced by amylopectin chain length distribution, amylopectin branching density and co-crystallization of amylose with amylopectin.