Nutritional quality and techno-functional changes in raw, germinated and fermented yellow field pea (Pisum sativum L.) upon pasteurization

Yellow field peas were subjected to soaking (SY), germination (SGY), fermentation (SFY), fermentation and pasteurization (SFPY), combined germination and fermentation (SGFY), as well as SGFY upon pasteurization (SGFPY). Soaking generally had a negligible impact on the proximate composition and nutritive quality of field peas except that a 23.4% reduction in trypsin inhibitor activity (TIA) was observed. Both germination and fermentation led to a significant reduction in starch content by 11.2-11.7%. Processed peas including SFY, SFPY, SGFY, and SGFPY exhibited higher in vitro protein digestibility (IVPD) values (P < 0.05) of 87.80-89.16%, which was further strengthened by the negative correlation between IVPD and antinutrients including tannin and TIA. The electrophoretic profile of their protein hydrolysates confirmed the IVPD results where the above four treatments resulted in an extensive degradation and breakdown of pea seed's storage proteins with the peptide subunits appeared at molecular weight < 16 kDa. SFY, SFPY, SGFY, and SGFPY also showed higher levels of digestible starch (114.1-257.7 g/kg) which agreed with their DSC gelation temperatures and the most distinguishable alternations on their microstructure. The fermentation of germinated peas led to an enhanced nutritional property, the following pasteurization process further changed the starch crystalline organization and protein resembling structure of field peas.