Research Projects

Gut microbiome has been found to influence human health by maintaining immune and metabolic homeostasis and protecting against pathogens. It is desirable to selectively promote the growth of useful or probiotic bacteria to have beneficial effect on human health. Over more than 1000 microbial species that inhabit in the colon, only 1.5-9% are the probiotic bacteria such as Lactobacilli and Bifidobacteria. Consuming live probiotics has limited efficacy due to constraints of survival through processing, shelf life and digestion of the food itself. Therefore, in addition to taking probiotic loaded foods, it is imperative to promote their growth in the colon by providing conducive environment in the colon including prebiotics which are selectively delivered into the colon. The ability of probiotic bacteria to utilize oligosaccharides is due to the unique sugar binding proteins present in the membrane of probiotic bacteria. They selectively recognize the oligosaccharides and facilitate their uptake by the bacterial cells. The main food components used as prebiotics are the indigestible carbohydrates. However, all the present prebiotic supplements used to modulate gut microbiota lack protein source which is an important nitrogen source for the bacterial growth. Owing to the absorption of amino acids and peptides in the small intestine, only small amount is available to the colonic bacteria. Therefore, need arises to deliver nitrogen sources like peptides and amino acids to the colonic probiotic bacteria which are resistant to human digestive enzymes. In this project we propose an approach to covalently conjugate the whey protein hydrolysate (WPH) with prebiotic carbohydrates to produce controlled Maillard reaction products that enable the protein moiety to successfully resist host digestive enzymes and reach colon. Prior treatment of the protein with pepsin and trypsin will hardly leave any peptide linkages available for the digestive enzymes and the conjugate formed will provide a spatial shield to the protein core hence making it less prone to the digestive enzymes. β-glucan has been reported to have tremendous health benefits including antioxidant, antiproliferative, immune modulatory and known to act as prebiotic for the colonic bacteria. It is the polymer of β-D-glucopyranose units linked through (1→4) and (1→3) glycosidic bonds in cereals and (1→6) glycosidic bonds in fungal sources. Maillard reaction involves condensation between a carbonyl group of reducing sugars and an amino group of proteins. It is a natural and non-toxic process that can be employed to modify food proteins and reducing polysaccharides and improves the functional properties of proteins. β-glucan can be covalently linked with whey protein hydrolysates produced by sequential treatment of pepsin and trypsin to produce whey protein-β-glucan conjugates which can act as novel prebiotics therefore, supplying peptides into the colon for use by probiotic bacteria.