Improvement of nutrifunctional properties of chickpea (Cicer arietinum l.) flour by fermentation with selected lactic acid bacteria

Abstract

Chickpea (Cicer arietinum L.) is an important pulse crop used in human nutrition with potential application to the development of novel functional and gluten-free foods. Like other legumes, it is a good source of high quality proteins, dietary fiber, low glycemic index carbohydrates, unsaturated fatty acids, vitamins and minerals and many bioactive phytochemicals associated with positive effects on human health such as a decreased risk of cardiovascular disease, diabetes and metabolic syndrome, among others. Therefore, researches on novel applications and development of legumes derived products have raised significantly. However, beside their benefits, legume plants synthesize antinutritional factors (ANF) as defense against predators that cause adverse physiological effects to humans and animals. These substances, include enzyme inhibitors, phytic acid, tannins, lectins and α-galactosides which affect the digestibility and bioavailability of nutrients and cause gastrointestinal discomfort. Fermentation has been proposed as an effective technological strategy for improving nutritional and nutraceutical properties of legumes as it has proven to remove ANF with the simultaneous release of bioactive compounds. Since fermentation performed with an autochthonous starter culture would be better than a spontaneous uncontrolled one, the aim of this work was to improve the technofunctional quality of chickpea flour by fermentation with selected LAB isolated from legumes cultivated and consumed in northwestern Argentina. For this purpose a Randomized Complete Block Design was carried out to assess the influence of some fermentation variables such as the addition of Lactiplantibacillus plantarum CRL 2211 and/or Weissella paramesenteroides CRL 2182 (0-7 Log CFU/g), temperature (30-37 ºC), time (8-24 h) and dough yield (160-200) on LAB population, acidification, ANF and total phenolic contents (TPC). To explain LAB enzymes behaviour during fermentation, a modelling approach including molecular docking and dynamics simulations of tannase-phenols (gallocatechin) and protease-inhibitor (Bowman-Birk and Kunitz type) complexes were performed. Fermentation of chickpea flour with both strains for 24 h at 37ºC led to an increase in LAB, acidity, TPC and contributed to tannins and trypsin inhibitors removal. Tannases from LAB present in chickpea showed a relevant affinity for gallocatechin (-5.4 to -8.9 Kcal/mol) and their interaction mechanism involves polar contacts between catalytic residues GLU, ASP, HIS, and LYS from the active sites with oxygen atoms from hydroxyl groups of catechin, epicatechin and procyanidins. Regarding interactions between LAB proteases and trypsin inhibitors higher relative affinity and binding energy values (-40.4 kcal/mol) were observed for L. plantarum endopeptidases. The results suggest that the combination of experimental and simulation data may lead to a better understanding of food fermentation to enhance nutrifunctional properties.