Abstract：
BACKGROUND: Aspergillus sp. has been used in traditional Japanese fermented foods. Protease-containing culture products of A. oryzae have been applied as the adjunct enzyme source to enrich the flavor in ripened cheese. Although proteolysis was stimulated, the increase of free fatty acids (FFA) was recognized in some products. Since an excess amount of FFA accumulation can cause rancidity in cheese products, the assessment of lipase activity was considered to be essential for the cheese adjunct preparation.
RESULTS: Although an equal lipase activity from the adjunct materials of A. kawachii NBRC 4308, A. luchuensis RIB 2604 and A. oryzae AHU 7139 was applied to semi-hard cheese, the FFA level was significantly higher in A. oryzae cheese than in the others. Furthermore, the profiles of volatile components were different in experimental cheeses. An in vitro study with experimental curds demonstrated that the high FFA might not depend on the lipase retainability on curds. On the contrary, the pronounced activation of the lipases occurred in A. oryzae after incubation with the curds. Moreover, incubation of the insoluble lipase that had been attached to the cells with skim milk curd extracts allowed the release of lipases from the cells into the medium with remarkable activation.
CONCLUSIONS: A. oryzae AHU 7139 possessed a complex lipolytic system comprising extracellular and cell-binding lipases that were attributed to the increase in FFA in A. oryzae cheese. © 2022 Society of Chemical Industry.
RESULTS: Although an equal lipase activity from the adjunct materials of A. kawachii NBRC 4308, A. luchuensis RIB 2604 and A. oryzae AHU 7139 was applied to semi-hard cheese, the FFA level was significantly higher in A. oryzae cheese than in the others. Furthermore, the profiles of volatile components were different in experimental cheeses. An in vitro study with experimental curds demonstrated that the high FFA might not depend on the lipase retainability on curds. On the contrary, the pronounced activation of the lipases occurred in A. oryzae after incubation with the curds. Moreover, incubation of the insoluble lipase that had been attached to the cells with skim milk curd extracts allowed the release of lipases from the cells into the medium with remarkable activation.
CONCLUSIONS: A. oryzae AHU 7139 possessed a complex lipolytic system comprising extracellular and cell-binding lipases that were attributed to the increase in FFA in A. oryzae cheese. © 2022 Society of Chemical Industry.
摘要：
背景：曲霉属。已用于传统的日本发酵食品。含蛋白酶的米曲霉培养产物已被用作辅助酶源，以丰富成熟奶酪的风味。尽管刺激了蛋白水解，在某些产品中发现游离脂肪酸（FFA）的增加。由于过量的FFA积累会导致奶酪产品酸败，脂肪酶活性的评估被认为是奶酪助剂制备所必需的。
结果：尽管将来自A.kawachiiNBRC4308，A.luchuensisRIB2604和A.oryzaeAHU7139的辅助材料的脂肪酶活性相同，米曲霉奶酪的FFA水平明显高于其他奶酪。此外，实验干酪中挥发性成分的分布不同。对实验凝乳的体外研究表明，高FFA可能不依赖于凝乳上的脂肪酶保持性。相反,与凝乳一起孵育后，在米曲霉中发生了脂肪酶的明显激活。此外，将附着在细胞上的不溶性脂肪酶与脱脂乳凝乳提取物一起孵育，可以使脂肪酶从细胞中释放到培养基中，并具有明显的活化作用。
结论：A.米曲霉AHU7139具有复杂的脂肪分解系统，该系统包含细胞外和细胞结合脂肪酶，这归因于米曲霉奶酪中FFA的增加。©2022化学工业学会。
结果：尽管将来自A.kawachiiNBRC4308，A.luchuensisRIB2604和A.oryzaeAHU7139的辅助材料的脂肪酶活性相同，米曲霉奶酪的FFA水平明显高于其他奶酪。此外，实验干酪中挥发性成分的分布不同。对实验凝乳的体外研究表明，高FFA可能不依赖于凝乳上的脂肪酶保持性。相反,与凝乳一起孵育后，在米曲霉中发生了脂肪酶的明显激活。此外，将附着在细胞上的不溶性脂肪酶与脱脂乳凝乳提取物一起孵育，可以使脂肪酶从细胞中释放到培养基中，并具有明显的活化作用。
结论：A.米曲霉AHU7139具有复杂的脂肪分解系统，该系统包含细胞外和细胞结合脂肪酶，这归因于米曲霉奶酪中FFA的增加。©2022化学工业学会。
