Vitamin menaquinone-7 (MK-7) supplementation improves bone health and reduces the incidence of osteoporosis. Despite the recent developments in MK-7 fermentation using Bacillus subtilis natto, low fermentation yields, as well as complicated downstream processing steps, are still the main reasons for the expensive final product. To overcome these issues, developing a fermented dairy-based product rich in MK-7 by avoiding costly downstream steps and optimising the fermentation operating conditions to enhance the MK-7 concentration would be an alternative approach. The present study, therefore, aims to evaluate the role of agitation and aeration as the key operating conditions on MK-7 production by Bacillus subtilis natto using a milk media. The agitation and aeration rates of 525 RPM and 5 VVM were found to be the optimum levels leading to the production of 3.54 mg/L of MK-7. Further, the sensory evaluation was performed to compare the sensory properties of the freeze-dried fermented samples with non-fermented milk samples. The results illustrated that the fermented samples had a significant saltiness with intense aroma resulting in the less acceptability of them by the panellists.

中文翻译：

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曝气和混合在开发富含甲基萘醌7的乳制品功能食品中的作用。

维生素甲萘醌 7 (MK-7) 补充剂可改善骨骼健康并降低骨质疏松症的发病率。尽管最近使用纳豆枯草芽孢杆菌发酵 MK-7 取得了进展，但发酵产量低以及下游加工步骤复杂仍然是最终产品价格昂贵的主要原因。为了克服这些问题，通过避免昂贵的下游步骤和优化发酵操作条件以提高 MK-7 浓度来开发富含 MK-7 的发酵乳制品将是一种替代方法。因此，本研究旨在评估搅拌和曝气作为关键操作条件对纳豆枯草芽孢杆菌使用牛奶培养基生产 MK-7 的作用。发现 525 RPM 和 5 VVM 的搅拌和通气速率是产生 3.54 mg/L MK-7 的最佳水平。此外，进行感官评价以比较冷冻干燥发酵样品与非发酵乳样品的感官特性。结果表明，发酵样品具有明显的咸味和浓郁的香气，导致小组成员对它们的接受度较低。