Fermentation of Menaquinone-7: The Influence of Environmental Factors and Storage Conditions on the Isomer Profile

Abstract

Menaquinone-7 (MK-7) provides significant health gains due to its excellent pharmacokinetic properties. However, MK-7 occurs at low concentrations in mainstream foods, heightening the demand for nutritional supplements. MK-7 exists as geometric isomers, and only all-trans MK-7 is bioactive. Exposure to certain environments impacts the isomer profile. Knowledge of these factors and their influence on the isomer composition is important, as the efficacy of fermented MK-7 end products is solely determined by the all-trans isomer. This investigation aimed to evaluate the short- and long-term effect of atmospheric oxygen, common temperatures, and light on the isomer profile. From the short-term study, it was ascertained that MK-7 is moderately heat-stable but extremely light-sensitive. The stability of all-trans MK-7 was then examined during 8 weeks of storage at a low temperature with minimal oxygen exposure in the absence of light. Negligible change in the all-trans MK-7 concentration occurred, suggesting it is reasonably stable during prolonged storage in this environment. These findings will aid the development of optimal storage conditions to preserve bioactive MK-7 in fermented nutritional supplements, the large-scale availability and consumption of which will help compensate for the dietary deficit of this essential vitamin and provide consumers with better health outcomes.