Physicochemical properties of enriched yogurt with pistachio nut pellet

Background: The improvement of structural characteristics of low-fat functional dairy products has always been of great importance. The purpose of the present study was to evaluate the physicochemical properties of low-fat probiotic yogurt fortified with pistachio-pellet. Materials and Methods: Kalle-Ghuchi pistachio kernel residue (pellet) was prepared after extracting the oil through cold-pressing. Probiotic starter (ABT-10) was then added to low-fat milk and the sample was divided into three portions (T1-T3). T1 was the control. T2 and T3 were treated with 2% and 4% pistachio-pellet, respectively. After incubation at 42°C, the products were kept at 4°C for 14 days. During this period, the products‟ physicochemical properties were investigated. The results were analyzed using a one-way ANOVA (P<0.05). Results: A direct relationship was observed between the amount of pellet and the product acidity. Additionally, spontaneous syneresis reduction was detected during this period. Water holding capacity (WHC) of the fortified portions of yogurt was not affected by pellet treatment. Regarding yogurt color changes, lightness (L*) reduction, greenness (a*), and yellowness (b*) enhancement were observed compared to the control portion. Conclusions: Enriching yogurt with the proteins of pistachio pellet not only improves the physical structure of low-fat yogurt gel but may also enhance its functional properties, including bioactivity and being satisfactory for cardiovascular health.