Abstract

The antimicrobial and immunostimulatory properties of colostrum have been known and valued for a long time. Due to the beneficial influence on health, colostrum was considered to be a nutraceutical. The aim of this research was to investigate the influence of colostrum addition (one was defatted and spray dried and the other was only lyophilized) on a kinetics of microbial acidification of milk and on quality of the final product. To this end, four different technological variants of yoghurts were produced accounting for different moment of colostrum addition (before and after incubation), as well as the amount of colostrum introduced (0.5% and 1%).

Acidification rate increased with colostrum addition. Colostrum did not inhibit a growth of St. thermophilus and L. bulgaricus. Addition of colostrum which was defatted and spray dried lifted diauxic growth of yoghurt culture due to delivery of high amount easily hydrolysed (unfolded) proteins. Yoghurts with lyophilized colostrum had higher content of myristic (C14:0), pentadecanoic (C15:0), palmitic (C16:0), margarine (C17:0), heptadecanoic (C17:1), stearic (C18:0), oleic (cis) (C18:1Δc), linoleic (C18:2) and conjugated linoleic acids (C18:2 CLA). What is more, colostrum addition accounted for smaller gel particles in prepared yoghurts. Rheological analysis of yoghurts fortified with lyophilized colostrum revealed that there was a slight increase in apparent viscosity within a range of shear stress up to 101/s. It was found that 1% of colostrum addition assured better water biding capacity of yoghurts. All yoghurts remained stable under storage at 4˚C for 28 days.