Microbial and enzymatic hydrolysis of dromedary whey proteins and caseins: techno-functional, radical scavenging, antimicrobial properties and incorporation in beverage formulation

Abstract

Comparative study of functional properties, radical scavenging and antimicrobial activities of dromedary whey protein and casein hydrolysates was investigated. Dromedary protein hydrolysates were prepared by treatment with digestive proteases (pepsin and pancreatin) and by the proteolytic system of two lactic acid bacteria (Streptococcus thermophilus and Lactobacillus bulgaricus). Solubility and interfacial properties like emulsifying capacity are improved after enzymatic hydrolysis of both whey protein and casein. Whereas, foam capacity and stability are more important in whey protein hydrolysates than casein hydrolysates and are widely influenced by the method of hydrolysis. All hydrolysates showed radical scavenging activities. The highest antioxidant activity is exhibited by WPHE (whey protein hydrolysated by gastro-intestinal enzymes “pepsin and pancreatin”) for DPPH (2,2-diphenyl-1-picrylhydrazyl) test and CNHE (casein hydrolysated by pepsin and pancreatin) for ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay. Further, whey protein hydrolysates displayed antibacterial activity and WPHE was the most effective, particularly against Escherichia coli and Staphylococcus epidermidis. Based on the results, we conclude that WPHE has great technological applicability in food ingredients, as a promising source of functional hydrolysate with antioxidant and antimicrobial activities. For this reason, WPHE was added to the dromedary milk based beverage and chemical, microbiological and sensory properties of the resulting product were investigated. Formulated beverage flavored with strawberry or banana possessed a good microbiological quality. The sensory analysis demonstrated a good acceptance mainly in taste and consistency of the beverage samples. There is only significant difference in the color of the different formulated beverages.