Physico-chemical properties and antioxidant efficacy of whey protein isolate and casein hydrolyzate stabilized nano-vesicular vehicle systems containing curcumin

Abstract Text:

Development of stable nano-emulsion systems, designed for efficient delivery of hyper-active natural antioxidants, nutraceuticals, and other bioactive compounds is crucial for effective enhancement of dairy product shelf-life as well as to alleviate the detrimental biological consequences caused by the reactive oxygen species. This study investigated the physico-chemical and antioxidant properties of a nanoemulsion system, developed as nano-vesicular vehicles (NVVs) for efficient delivery of curcumin (CU), a highly potent generally recognized as safe (GRAS) antioxidant. Coarse emulsions were first produced by dispersing whey protein isolate (WPI) (1%, w/v - primary emulsifier), tween-20 (20% w/v of WPI - secondary emulsifier), chymotryptic hydrolyzate of casein (CH) (1:50 w/w of WPI) and CU (0.22%, w/v) in 200 mM phosphate buffer with a pH of 8.0 (the continuous phase) for three hours with gentle stirring at 22˚C. The NVVs were generated by subjecting the coarse emulsion to single-pass ultra-high pressure homogenization (UHPH) at 140 and 210 MPa. Physico-chemical and antioxidative properties of the CU-loaded-NVVs containing CH (CU+CH-NVVs) were analyzed and compared to the NVVs without CH (CU-NVVs) for 16 days of storage at 4^OC. Increasing the trace amount of CH resulted in a significant enhancement (P<0.05) of both short and long term antioxidative properties [antioxidant activity (AA) and persistence (AP), respectively], in all CU+CH-NVVs throughout the study compared to CU-NVVs.  The CU+CH-NVVs generated using 210 MPa showed 497 and 567% enhancement of AA and AP, respectively, relative to the CU- NVVs on the 16^thday of storage. The former also showed 6222 and 11278% enhancement of AA and AP compared to the control (buffer alone). The CU+CH-NVVs generated at 210 MPa exhibited a considerable (7.4%) reduction in mean globular particle diameter as well as a substantial increase (17%) in zeta potential compared to the CU-NVVs formulated using the same UHPH at the final day of storage indicating the efficacy of even a minute quantity of CH to remarkably enhance the stability of NVVs. 

Keywords: Nanoemulsion, neutraceutical, free radical.