Naturally Occurring Peptides
In current research, peptides have been identified and characterized in bovine milk and bovine colostrum [12, 94]. Some peptides are able to perform specific biological functions (bioactive peptides), which makes them useful in the growing market of functional foods and as nutraceuticals . Such purported bioactive properties include anti-cancer effects against certain tumors, cell growth activity, wound healing effects, ACE-inhibitory effects, ileum stimulation and contraction, anti-thrombotic and antimicrobial effects . Membrane technology seems to be a promising industrial scale recovery technique for peptides, as they can permeate ultrafiltration membranes thus being separated from macromolecules. Nanofiltration is then applied to concentrate peptides based on their molecular weight and electrostatic properties .
Whey Permeate As Substrate for Bacteriocin Production
Both nisin and pediocin are of great interest as food preservatives due to their antimicrobial activities and further characteristics like heat and pH stability. The bacteriocin nisin is produced by lactic acid bacteria (LAB), whereas pediocin is produced by Pediococcus strains . Currently, bacteriocins can be produced with high yields. However, the growth media used are expensive and often not food-grade. As LAB grows good on whey permeate, this makes whey permeate a suitable medium for food-grade bacteriocin production [96, 97]. Research has been conducted using whey permeate as a food-grade medium for the production of bacteriocins [98-100], with yields as high as 5x104 AU/mL in continuous culture . Another advantage of using whey permeate as substrate for bacteriocin production is the presence of minerals and vitamins, which are important co-factors for Lactobacillus lactis. However, additional nutrients such as casein hydrolysates must be added to increase the yield due to the low nitrogen content of whey permeate (97). In general, bacteriocin production can be conducted on food-grade material, but the yields are lower and their purification is expensive. Lab-scale experiments demonstrated that with optimal process conditions and proper nutrient addition, respectable product yields can be achieved. However, pilot-scale validation is necessary for commercialization of bacteriocin production using whey permeate.