Molecular structure characteristics, functional parameters and in vitro protein digestion of pressure‐cooked soya bean flours with different amounts of water

Abstract

When a food product is cooked at high temperature with different proportions of water, the differential degradation that occurs in the molecular structure promotes changes in their functional characteristics. In this study, water and soya bean flour (dry base) were mixed in different ratios (3:1, 2:1, 1:1, 0.25:1 and 0:1) and pressure cooked at 130°C, 1.5 kg cm À2 for 30 min, cooled down to 40°C and air dried for 24 h. Protein changes due to thermal process were determined with the ATR-FTIR, as well as some functional parameters and in vitro protein digestibility. At higher water:soya bean flour ratios (3:1 and 2:1), the protein digestibility increased due to denaturation of tertiary structures, while urease activity (UA) and the functional characteristics of water absorption index (WAI) and water solubility index (WSI) decreased. Pearson's correlation analysis revealed that molecular changes on amide I, II and in a-helix: b-sheet ratios were directly related with the amount of added water.

Physicochemical, functional andATR‐FTIR molecular analysis of protein extracts derived from starchy pulses

“…On the other hand, raw protein extracts from white bean and broad bean showed the lowest digestion values (80.59% and 82.35%, respectively), while chickpea and lentil showed 92.41% and 91.47%, respectively, that could be related to the absence of protease inhibitors and other seed components, as well as the possibly partial thermal denaturation of protease inhibitors during its processing. Previous reports have shown similar in vitro digestion values in thermal processed protein isolates (Hsu et al ., ; Ng & Ng, ), inferring that under such conditions there was an affective decrease on the protease inhibitors that are present in most legumes (Ma et al ., ; de la Rosa‐Millán et al ., ).…”

“…c). Other authors have found that thermal processing is positively correlated with protein denaturation as well as higher in vitro digestion (Krintiras et al ., ; de la Rosa‐Millán et al ., ).…”

“…This is due to the significantly less 'pure' nature of the amide I band, where only 60% of the absorbance contribution is from N-H bending, while the C-N stretching accounts for the remaining 40% (Jackson & Mantsch, 1995). It is well known that the functional and digestion properties of proteins are directly related to their molecular conformation, in which the proportion of ahelix and b-sheet structures are correlated with their performance in food systems, especially with their water absorption and in vitro digestion (Susi & Byler, 1986;de la Rosa-Mill an et al, 2015).…”

“…Other studies have found that valuable structural characteristics related to the interaction between components within flours as well as in animal-derived proteins that can be obtained from the amide I (AI) and amide II (AII) zones; the AI zone is related to the macromolecular organisation of proteins and may reflect the denaturation extent of the materials (Barth, 2007;Kong & Yu, 2007; Rosa-Mill an et al, 2015). On the other hand, the AII group has been related to the conformation of the secondary protein structures (Vedantham et al, 2000;Cai & Singh, 2004).…”

Deodorization of Arthrospira platensis biomass for further scale‐up food applications

“…Protein digestibility is an important quality assessment in food. Compared with vegetable protein sources, A. platensis digestibility was 70%, which is higher than the value of 58% reported for soybean flour but lower than values reported by Caballero de la Peña for casein, whey protein‐concentrate and soybean‐maize germ protein isolate (98%, 90% and 86%, respectively). Compared with non‐animal sources, cyanobacteria digestibility was higher given the lack of fiber in the cell walls .…”