Abstract:The contents of dietary fiber and polyphenols in pine nut skin were measured, and then pine nut skin was added to yogurt products to determine its effects on the physicochemical characteristics and sensory properties of the yogurt. The results showed that the contents of total dietary fiber and polyphenols in pine nut skin were 72.14% and 16.7 mg/g, respectively, and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability was up to 97.8%, suggesting that pine nut skin could be used as antioxidant dietary fiber. Through single factor and orthogonal experiments, the determined optimal process conditions to prepare pine nut skin yogurt were 7 h fermentation at 45 ℃ with 8.0 g/100 g sucrose, 1.9 g/100 g pine nut skin, 0.1 g/100 g starter culture, and 2.0 g/100 g milk powder. Compared to the yogurt without addition of pine nut skin, the whey precipitation rate, water holding capacity, titratable acidity, pH, and texture and product acceptance of pine nut skin yogurt did not show significant differences (p>0.05), whereas DPPH radical scavenging ability, hydroxyl radical scavenging ability, and reducing power, as well as taste, flavor, and color were significantly improved (p<0.05). The application of pine nut skin to yogurt products could increase the dietary fiber content and the antioxidant activity of yogurt, without compromising the quality.
