Effect of spray drying and freeze drying on the immunomodulatory activity, bitter taste and hygroscopicity of hydrolysate derived from whey protein concentrate

Abstract

The main aim of the present work was to obtain microencapsulated whey protein concentrate hydrolysate (WPCH) in order to reduce its bitter taste and resistance to hygroscopicity without impairing its immunoregulatory activity by spray drying or freeze drying with whey protein concentrate (WPC) and sodium alginate (SA) as carriers. To attenuate its bitter taste, the WPCH were encapsulated with WPC or the mixture of WPC and sodium alginate (WPC/SA). The splenocyte proliferation activity, hygroscopicity, bitter taste and morphology of non-encapsulated WPCH and encapsulated WPCH were evaluated. Results revealed that WPCH could significantly enhance splenocyte proliferation activity compared with WPC itself. Both spray drying and freeze drying with or without carrier material addition did not exert negative effect on the immunomodulatory activity of WPCH. The bitterness, determined by taste dilution analysis method, of both WPC-encapsulated WPCH and WPC/SA-encapsulated WPCH was significantly lower than that of the original non-encapsulated WPCH. Morphological analysis showed that freeze drying process could not encapsule WPCH as spray drying did. All of these indicated that spray drying with WPC or the mixture of WPC and SA (WPC/SA) as carriers was beneficial for reducing the bitter taste and hygroscopicity without impairing the immunoregulatory activity of whey protein hydrolysate.