N Vakili - Department of food hygiene, Science and Research Branch, Islamic Azad University, Tehran, Iran
M Ataee - Department of food hygiene, Science and Research Branch, Islamic Azad University, Tehran, Iran
S Kakoolaki - Iranian Fisheries Science Research Institute, Agriculture Research Education and Extension Organization (AREEO), Tehran, Iran
H Ahari - Department of Food Science and Technology, Science and Research Branch, Islamic Azad University, Tehran, Iran
A Ghorbanzadeh - Department of Aquatic Health and Disease, Veterinary Science Faculty, Islamic Azad University, Tehran, Iran

The aim of the present study was to evaluate the physico-chemical criteria of yogurt fortified with fish protein hydrolysate (FPH) obtained from Fresh Abu mullet (Planiliza abu) fish weighing ۴۰ g during ۲۱-day refrigeration. A hundred milliliters of final milk were inoculated with starter culture, and fermented for ۴-۵ hours until the pH reached to ۴.۶. The yogurts were divided in two groups in triplicate and each group was prepared in triplicate. Yogurts supplemented with nanoencapsulated hydrolysates exhibited a slight reduction in pH and augmented acidity particularly up to three weeks of refrigeration. The pH of nanoemulsion-FPH yogurt was initially ۴.۵۲ and reached ۴.۰۱ in third week with a significant difference (p<۰.۰۵) compared with that of the control at the same time (۳.۸۰). The pH value of the fortified yogurt showed acceptable limit on day ۷ (۴.۳۵) but it was remarkably decreased on day ۱۴ (۴.۱۹, p<۰.۵). The upmost and the least values of viscosity of nano-FPH yogurt samples were respectively ۴۱۸۷.۳ and ۴۰۴۶.۶ (cps) on days ۱ and ۲۱. The viscosity values of control were ranged from ۳۷۱۶.۰ to ۴۰۴۲.۰, respectively in ۲۱ and ۱ days of refrigeration. Moreover, the maximum and minimum water holding capacity (WHC) value of nano-FPH yogurt samples ۹۲.۵% and ۸۶.۲%, respectively on days ۱ and ۲۱. It is concluded that the incorporation of the FPH in the form of nanoencapsulation offered superior physico-chemical advantages than those of control yogurt samples.

Yogurt, Nanoemulsion, Fish protein hydrolysate, Physico-Chemical parameters