Szajnar K, Pawlos M, Znamirowska A
Department of Dairy Technology, University of Rzeszow, Cwiklinskiej St. 2D, Rzeszow 35-601, Poland.
Int J Food Sci. 2021 Jul 11;2021:7928745. doi: 10.1155/2021/7928745. eCollection 2021.
The global market for sheep's milk and its products is increasing due to higher demand for cheese and traditional dairy products, and as a novelty, sheep's milk is an ingredient in infant formulas and nutraceuticals. The aim of this study was to determine the properties of fermented sheep's milk, which combines probiotic benefits with increased dietary fiber content. The influence of the applied dose of chokeberry fiber on the growth of living cells of and in fermented sheep's milk was also evaluated. Sheep milk with the addition of 0% (control sample), 1.5%, and 3.0% chokeberry fiber was fermented by two different probiotic monocultures and . In the fermented milk, pH value, syneresis (%), color, and texture were determined. Furthermore, the microbiological analysis and an organoleptic evaluation were performed. With the increasing dose of chokeberry fiber, the pH value decreased already before the fermentation process. After fermentation, the milk's pH values with fiber were still lower than those in the control sample. Presumably, more acidic metabolites were produced by , causing a more intense reduction of the pH value than both in control milk and in milk with the addition of fiber. The addition of chokeberry fiber affected the stimulation of the growth of both types of bacteria. In the milk sample without fiber addition, a more significant number of viable cells were counted for by 0.5 log CFU g more than the milk fermented with . Furthermore, in milk fermented by with 1.5% chokeberry fiber (LA1), the number of viable bacterial cells was higher than that in milk fermented by with the same addition of fiber (LR1). However, in sample LA3, the number of viable bacterial cells was lower than that in sample LR3. Tested fermented sheep milk met the Recommendation of the International Dairy Federation's requirements regarding the number of live bacterial cells for dairy probiotics. The addition of chokeberry fiber increased syneresis in each fermented milk group, regardless of the bacteria used for fermentation. Moreover, the use of fiber caused a significant reduction in brightness ∗, an increase of red color, and a decrease of yellow color. Milk fermented with was characterized by a harder gel, compared to their analogues fermented with . The addition of fiber intensified the sour taste and the taste of the additive in both types of fermented sheep milk.
由于对奶酪和传统乳制品的需求增加，羊奶及其产品的全球市场正在扩大。此外，作为一种新奇产品，羊奶还是婴儿配方奶粉和营养保健品的一种成分。本研究的目的是确定发酵羊奶的特性，这种羊奶兼具益生菌益处和更高的膳食纤维含量。同时还评估了所添加的黑加仑纤维剂量对发酵羊奶中嗜酸乳杆菌和鼠李糖乳杆菌活细胞生长的影响。添加了0%（对照样品）、1.5%和3.0%黑加仑纤维的羊奶分别由两种不同的益生菌单培养物嗜酸乳杆菌和鼠李糖乳杆菌进行发酵。测定了发酵乳中的pH值、脱水收缩率（%）、颜色和质地。此外，还进行了微生物分析和感官评价。随着黑加仑纤维剂量的增加，在发酵过程开始前pH值就已下降。发酵后，添加纤维的牛奶的pH值仍低于对照样品。据推测，嗜酸乳杆菌产生了更多酸性代谢物，导致对照牛奶和添加纤维的牛奶中的pH值下降幅度都比鼠李糖乳杆菌更大。添加黑加仑纤维对两种细菌的生长均有促进作用。在未添加纤维的牛奶样品中，嗜酸乳杆菌的活菌数比用鼠李糖乳杆菌发酵的牛奶多0.5 log CFU g。此外，在添加1.5%黑加仑纤维（LA1）的嗜酸乳杆菌发酵牛奶中，活菌数高于添加相同纤维量的鼠李糖乳杆菌发酵牛奶（LR1）。然而，在LA3样品中，活菌数低于LR3样品。经测试，发酵羊奶符合国际乳品联合会关于益生菌乳制品活菌数的建议要求。无论使用哪种细菌进行发酵，添加黑加仑纤维都会使每个发酵乳组的脱水收缩率增加。此外，使用纤维会使亮度L*显著降低，红色增加，黄色减少。与用鼠李糖乳杆菌发酵的类似物相比，用嗜酸乳杆菌发酵的牛奶具有更硬的凝胶质地。在两种发酵羊奶中，添加纤维都会增强酸味和添加剂的味道。
