Potential prebiotic effect of whey protein and spent brewer yeast hydrolysates by enzymes of Cynara cardunculus extract

Biologically active peptides are of particular interest to food science and health since they have demonstrated beneficial physiological roles upon ingestion. These biopeptides can be released and/or activated in vivo during gastrointestinal digestion or otherwise via enzyme-mediated proteolysis throughout food processing. The survival of many bacterial species inhabiting the large bowel depends essentially on the substrates made available to them, most of which come directly from the diet. Some of these substrates can be selectively considered asprebiotics - which are nondigestible food ingredients that can stimulate beneficial bacteria such as lactobacilli or bifidobacteria growth in the colon. Thus, the major objective of this research work was to study the potential prebiotic activity of peptide extracts obtained via hydrolysis of whey proteins from a mixture of milk (cow, ewe and goat) and spent brewer yeast extracts achieved by cardosins present in Cynara cardunculus aqueous extract. The strains tested were probiotic strains viz. Lactobacillus acidophillus Ki and Bifidobacterium lactisBb12 and Frutooligosacharides were used as positive control of prebiotic activity. From whey protein hydrolysates two fractions were tested, the ultrafitration permeate (PM >1000 Da and < 20000 Da) and a nano-permeate (1000 Da) and nano-permeate (1000 and >20000 Da). Incorporation of the extracts in media without glucose did not produce such good results, but the better activity was obtained for the ultrafiltration permeate of whey hydrolyzate (>1000 and >20000 Da); this result was expected since both extracts stimulate mainly the bacterial growth through the nitrogen compounds: peptides and aminoacids.