Development of a spray-dried conjugated whey protein hydrolysate powder with entrapped probiotics

Bifidobacterium animalis ssp. lactis ATCC27536 and Lactobacillus acidophilus ATCC4356 were encapsulated in a conjugated whey protein hydrolysate (WPH10) through spray drying. Probiotic cultures were added at the ratio of 1:1 into the conjugated WPH10 solution at a spiking level of about 10 log(10) cfu/mL. The mixture was spray dried in a Niro drier with inlet and outlet temperatures of 200 degrees C and 90 degrees C, respectively. The final dried product was determined for cell viability and further stored for 16 wk at 25 degrees, 4 degrees, and -18 degrees C to monitor viability and functionality. Micro images showed the presence of link bridges in non-conjugated WPH10, whereas, in the case of conjugated WPH10, round particles with pores were observed. The mean probiotic counts before and after spray drying were 10.59 log(10) cfu/mL and 8.98 log(10) cfu/g, respectively, indicating good retention of viability after spray drying. The solubility and wetting time of the WPH10-maltodextrin (MD) encapsulated probiotic powder were 91.03% and 47 min, whereas for WPH10, the solubility and wetting time were 82.03% and 53 min, respectively. At the end of storage period, the counts were 7.18 log(10) cfu/g at 4 degrees C and 7.87 log(10) cfu/g at -18 degrees C, whereas at 25 degrees C the counts were significantly reduced, to 3.97 log(10) cfu/g. The solubility of WPH-MD powder was 82.36%, 83.1%, and 81.19% at -18 degrees C, 4 degrees C, and 25 degrees C, respectively, and wetting times were 61 min, 60 min, and 63 min at -18 degrees C, 4 degrees C, and 25 degrees C, respectively. By contrast, for WPH10 powder, the solubility significantly reduced to 69.41%, 69.97%, and 68.99% at -18 degrees C, 4 degrees C, and 25 degrees C, and wetting times increased to 71 min, 70 min, and 72 min at -18 degrees C, 4 degrees C, and 25 degrees C, respectively. The conjugated WPH10 is thus demonstrated as a promising carrier for probiotics and can be further used as an ingredient for developing functional foods, to harness their enhanced functionality and health benefits derived from both WPH and probiotics.