高品质红曲米固态发酵机理微观表征及规模放大准则的研究

Functional food is revival of the ancient Chinese concept “Medicine and food share a common origin”. Red yeast rice is a kind of fermented functional food; the acid form of lovastatin is an effective cholesterol-lowering component of red yeast rice, which is capable of reducing cholesterol by inhibiting the activity of HMG-CoA reductase enzyme, a rate-limiting enzyme of endogenous cholesterol synthesis. Monascin and ankaflavin are also responsible for the cholesterol-lowering activity besides the acid form of lovastatin. Functional red yeast rice, containing a variety of known functional components, has significant advantages of multi-component and multi-target regulation of blood lipids. Currently the scale-up of the functional red yeast rice solid-state fermentation is a bottleneck restricting its safe production and wide application as functional fermented foods. This project will focus on the interaction between microscopic matrix of substrate particles and Monascus, to study the mechanism of solid-state fermentation of red yeast rice for production of acid-form lovastatin and Monascin. The effects of microscopic features of substrate particles on the heat and mass transfer, Monascus biomass and metabolism will be investigated during the fermentation process, and the mechanism of targeted products related with the fermentation micro-environmental changes will be analyzed in multi-scale and multi-level. Consequently, multi-parameter fermentation kinetic equations and process scale-up similarity criteria will be developed, providing key parameter characterization, testing and control technology bases for red yeast solid-state fermentation process.

功能食品是中国自古提倡“药食同源”概念的复兴。红曲米是一种发酵功能食品，酸型洛伐他汀是红曲米中一种高效的降胆固醇物质，它通过抑制胆固醇合成限速酶HMGCR的活性，降低人体内源性胆固醇的合成，从而达到降胆固醇的功效。除了酸型洛伐他汀，红曲素和安卡黄素也具有显著的降血脂功效。红曲拥有多种明确的功效成分，具备多组分和多靶点调控血脂的显著优势。目前功能红曲固态发酵技术规模放大是瓶颈，制约了其作为功能性发酵食品的安全生产和推广应用。本项目将从大米基质颗粒与红曲菌相互影响的微观特性变化为研究切入点，开展产酸型洛伐他汀和红曲素红曲米固态发酵机理的研究。主要研究发酵基质特性对发酵过程传质传热，红曲菌生物量以及红曲菌代谢的影响，多尺度、多层面地解析发酵目标产物与发酵微环境变化的规律，建立多参数发酵动力学方程和规模放大相似准则，为红曲固态发酵规模化生产提供工艺关键参数表征、检测与调控技术基础。

含有洛伐他汀的红曲米是一种发酵功能食品，除了酸型洛伐他汀，红曲素和安卡黄素也具有显著的降血脂功效。本项目采用扫描电镜、菌丝体重量测量、低场核磁共振分析和检测手段研究了大米基质及添加豆渣对红曲菌微观结构、生物量的影响、自由水和束缚水在基质中的分布变化规律，通过柱层析结合制备色谱技术分离纯化了6种红曲色素，建立色素定量检测方法，替代了多波长的色价分析方法。色素定量检测方法更真实准确地反映目标色素产物的产量。多尺度、多层面地解析了红曲发酵产物中的洛伐他汀及红曲色素等目标产物产量与发酵微环境变化的规律，使含有洛伐他汀功能红曲的色价达到2700u/g,其中的主要色素成分包括红曲素和红斑红曲素。将转化后的各类红斑红曲素氨基酸衍生物进行光稳定性评价结果显示：亮氨酸、天冬酰胺、半胱氨酸、谷氨酸、缬氨酸、丝氨酸、甘氨酸7种红斑红曲素氨基酸衍生物光稳定性明显优于红斑红曲胺。因此，对于上述富含红斑红曲素的功能红曲产品，将其转化为光稳定性强的氨基酸衍生物是实现高品质功能红曲的有效技术手段。