Plant proteases used in cheesemaking are easily available and could increase the acceptability of cheeses, otherwise hindered by ethical issues (e.g., religions, dietary habits, aversion to genetically engineered food and food ingredients). The milk clotting potential of Onopordum tauricum (Willd.) aqueous extract as an alternative to animal rennet was assessed for the first time in milk of different species (ewe, goat, cow). Among the aerial anatomical parts, i.e., receptacle, leaves, stems, and flowers, only the latter ones showed clotting properties. A response surface methodology (RSM) was used to explore the effects of three independent variables (temperature, pH, volume of coagulant) on the milk clotting activity (MCA) of the flower extract. A second-order polynomial model adequately described the experimental data and predicted a temperature value of 55 °C, a pH value of 4.9–5.7, and a volume of coagulant of 300–500 μL (added to 5 mL of milk) as optimal conditions to maximize the MCA. At a 35 °C temperature and natural milk pH of 6.7–6.8, the estimated MCA of the O. tauricum extract was 72–87, 69–86, and 75–151, in goat’s, ewe’s, and cow’s milk, respectively. In comparison, the MCA of calf rennet was 5.4–4.9, 3.3–14.7, and 4.9–16.7 times higher than that of the plant extract in goat’s, ewe’s, and cow’s milk, respectively.

中文翻译：

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不同种类的牛奶中牛头草（Wild。）水提物的凝结特性。

奶酪制造中使用的植物蛋白酶很容易获得，并且可以提高奶酪的可接受性，否则会受到道德问题（例如宗教，饮食习惯，对基因工程食品和食品成分的厌恶）的阻碍。牛肝菌的凝乳潜力（Willd。）首次在不同种类（母羊，山羊，牛）的牛奶中评估了水提取物作为动物凝乳酶的替代品。在空中解剖部分中，即容器，叶子，茎和花，只有后者具有凝结特性。使用响应面方法（RSM）来研究三个独立变量（温度，pH，凝结剂体积）对花提取物的牛奶凝结活性（MCA）的影响。二阶多项式模型可以充分描述实验数据，并预测温度为55°C，pH值为4.9-5.7，凝结剂体积为300-500μL（添加到5 mL牛奶中）是最佳条件最大化MCA。在35℃的温度和天然乳pH值为6.7-6.8，所述的估计的MCA O. tauricum山羊奶，母羊奶和牛奶中的提取物分别为72–87、69–86和75–151。相比之下，小牛凝乳酶的MCA分别是山羊，母羊和牛奶中植物提取物的MCA的5.4-4.9、3.3-14.7和4.9-16.7倍。