Enhanced nutritional value of chickpea protein concentrate by dry separation and solid state fermentation

Abstract

Abstract A sustainable dry processing method to obtain nutritional and functional chickpea products was developed, yielding protein concentrates suited to prepare products without additives. Chickpeas were milled and air-classified into protein and starch-enriched concentrates. Subsequently, spontaneous solid state fermentation (SSF) with daily back-slopping was performed at 37 °C. The dominant autochthonous lactic acid bacteria (LAB) strains in chickpea flour and enriched fractions were Pediococcus pentosaceus and Pediococcus acidilactici. Strains were selected on their ability to metabolise flatulence-causing α-galactosides. SSF reduced the pH of the doughs in 24h from 6.6 to 4.2. After 72 h, concentrations of raffinose and stachyose were reduced by 88.3–99.1%, while verbascose became undetectable. Moreover, phytic acid reduced with 17% while total phenolic contents increased with 119%. Besides the observed differences in smell, texture and colour, the sourdoughs showed 67% higher water-holding capacity. This natural route to produce chickpea concentrates thus increases both the nutritive and technical functionality. Industrial relevance Increasing the sustainability of our food production is required to meet the demand for food of our growing world population. A processing route combining dry fractionation and solid state fermentation is developed to prepare chickpea concentrates with improved nutritional properties. This route is more sustainable as the use of water and thus energy-intensive drying steps are minimised. Moreover, it provides more natural ‘clean-label’ foods, i.e., foods with less additives and minimally processed. Solid state fermentation is used to reduce the presence of anti-nutritional factors, i.e., α-galactosides and phytic acid. Autochthonous LAB were accumulated via back-slopping and employed as starter culture as an alternative to the use of a commercial starter culture. Chickpea sourdoughs with enhanced nutritional quality of chickpea were obtained. The sourdough may be used directly to fortify cereal products like chickpea protein enriched bread or can be dried into a chickpea ingredient for many other applications as well.