Lutein as a functional ingredient in sheep milk yogurt: development, characterization and extraction recovery

Abstract The research aimed to evaluate the behavior of different concentrations of lutein added in sheep milk yogurt. The work verified the effect on acidity, pH, color, lutein degradation, and recovery during storage. Different added lutein concentration into yogurt were compared: 0.00 mg; 3.0 mg; 3.45 mg; and 3.9 mg (·100 mL-1). Analyzes were performed on days 1st, 15th, 30th, and 45th of refrigerated storage (5 °C). Lutein did not influence fermentation patters, but post acidification was observed, mainly in groups with the highest lutein concentrations. The amount of lutein recovered was different between groups (P < 0.05) due to treatment. Some differences (P < 0.05) in the same treatment occurred over time, tending to decrease lutein recovery. For all treatments, up to the end of storage, the final amount of lutein characterized the product as a nutritional source of this element. However, lutein recovery in G4 has reached the minimum daily intake recommended by researchers for health benefits. Recovery ranged from 81.9 ± 0.76·100-1 (w·w-1) to 76.31 ± 1.07·100-1 (w·w-1) on the storage period. L* has no difference (P > 0.05) between groups with different added lutein concentrations. In contrast, a*, b*, c*, and YI (yellowness index) were different (P < 0.05).

摘要 本研究旨在评估羊乳酸奶中添加不同浓度叶黄素（lutein）的品质变化规律。实验验证了5 ℃冷藏储存（refrigerated storage）过程中，叶黄素添加量对酸奶酸度、pH值、色泽、叶黄素降解情况及保留率（recovery）的影响。本研究设置了4组叶黄素添加浓度：0.00 mg/100 mL、3.0 mg/100 mL、3.45 mg/100 mL及3.9 mg/100 mL，并分别于冷藏储存的第1、15、30和45天开展指标分析。结果显示，叶黄素添加量未对发酵模式产生显著影响，但各组均出现后酸化（post acidification）现象，且该现象在叶黄素浓度最高的组别中最为显著。不同处理组的叶黄素保留率存在显著差异（P < 0.05），且同一处理组的保留率随储存时间延长亦存在显著差异（P < 0.05），整体呈下降趋势。截至储存结束，所有处理组的最终叶黄素含量均使该产品成为该营养元素的膳食来源。但G4组的叶黄素保留率已达到研究者推荐的健康获益每日最低摄入量。储存期内，产品的叶黄素保留率范围为81.9 ± 0.76·100^-1（质量比，w·w^-1）至76.31 ± 1.07·100^-1（质量比，w·w^-1）。L*值在不同叶黄素添加浓度的组别间无显著差异（P > 0.05）；与之相反，a*、b*、c*值及黄度指数（Yellowness Index，YI）则存在显著差异（P < 0.05）。