Abstract
In order to determine the impact of fermentation on protein quality, pea protein concentrate (PPC) was fermented with Lactobacillus plantarum for 11 h and total phenol and tannin contents, protease inhibitor activity, amino acid composition and in vitro protein digestibility were analyzed. Phenol levels, expressed as catechin equivalents (CE), increased on dry mass basis from 2.5 at 0 h to 4.9 mg CE per 1 g of PPC at 11 h. Tannin content rose from 0.14 at 0 h to a maximum of 0.96 mg CE per 1 g of PPC after 5 h, and thereafter declined to 0.79 mg/g after 11 h. After 9 h of fermentation trypsin inhibitor activity decreased, however, at all other fermentation times similar levels to the PPC at time 0 h were produced. Chymotrypsin inhibitor activity decreased from 3.7 to 1.1 chymotrypsin inhibitory units (CIU) per mg following 11 h of fermentation. Protein digestibility reached a maximum (87.4%) after 5 h of fermentation, however, the sulfur amino acid score was reduced from 0.84 at 0 h to 0.66 at 11 h. This reduction in sulfur content altered the in vitro protein digestibility-corrected amino acid score from 67.0% at 0 h to 54.6% at 11 h. These data suggest that while fermentation is a viable method of reducing certain non-nutritive compounds in pea protein concentrate, selection of an alternative bacterium which metabolises sulfur amino acids to a lesser extent than L. plantarum should be considered.
Highlights
Pulses represent a nutritionally and economically viable protein source in developing countries where the consumption of animal proteins is scarce and expensive [1]
Lactobacillus plantarum fermentation of pea protein concentrate (PPC) influenced the non-nutritive compounds while causing a decrease in protein quality
Protein digestibility was increased, the alteration of sulfur amino acid content resulted in an overall reduction in protein quality
Summary
Pulses represent a nutritionally and economically viable protein source in developing countries where the consumption of animal proteins is scarce and expensive [1]. With respect to amino acid content, pulses tend to have limited amount of thiol-containing amino acids (i.e. cysteine and methionine) and are rich in lysine compared to human nutritional requirements, whereas cereals have limited lysine content and high sulfur amino acid content [2] For this reason, pulse crops are often consumed alongside cereal grains as the two provide complementary amino acid profiles. The FAO/WHO defines protein quality in terms of the amino acid profile and digestibility of a protein source based on an in vivo bioassay [3] This definition of protein quality could be broadened further to include protein functionality, as in addition to their nutritional attributes, it is essential for protein ingredients to perform well in food product design
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
