不同品种大米发酵紫色红曲霉产色素的特性分析

该研究以一株色素产量稳定的紫色红曲菌为试验菌株，采用不同品种的大米（粳米、籼米、糯米）作为基质进行液态摇瓶发酵，通过测定生物量、葡萄糖含量、大米成分，分析红曲霉生长状况，借助高效液相色谱、薄层色谱和色差仪对发酵所产红曲色素的颜色特性及安全性进行评价。结果表明：粳米发酵的胞外色价最高，于505 nm处最高可达19.07 U/mL，是籼米的2.28倍，糯米的2.53倍；发酵3~4 d籼米的红曲菌胞内色价可达947.46 U/g（505 nm），分别是糯米的1.24倍和粳米的1.33倍；发酵6~7 d粳米的胞内色价较高，于505 nm处可达1762.80 U/g，分别是籼米的1.41倍和糯米的1.86倍，粳米的后期发酵更利于M9的色素累积。HPLC分析六种主要红曲色素产量表明，籼米和糯米发酵显著促进了两种橙色素O1、O2在胞内积累，发酵第7 d的产量分别是粳米的5.00倍和6.31倍，粳米发酵更有利于红色素（R1、R2）及黄色素（Y1、Y2）产生；三种大米相比，粳米发酵所产桔霉素最低，安全性更高。总体而言，以粳米为基质发酵更利于M9产红、黄色素，而糯米和籼米更利于红曲菌M9产橙色素。

Characteristics of Pigment Production from Fermentation of Different Varieties of Rice by Monascus purpureus

A Monascus purpureus strain with a stable pigment yield was used to examine pigment production in different varieties of rice (namely, japonica, indica, and glutinous), which were used as substrates for shaking flask fermentation. Growth of Monascus was analyzed by measuring biomass, glucose content, and rice composition. In addition, the color characteristics and consumption safety of the produced pigments were evaluated by chromatographic methods such as HPLC and TLC. The results showed that the extracellular color value of Monascus during fermentation of japonica rice was the highest, reaching 19.07 U/mL at 505 nm, which was 2.28 and 2.53 times that of indica and glutinous rice, respectively. The intracellular color value of Monascus was 947.46 U/g (505 nm) in indica rice after 3~4 days of fermentation, which was 1.24 and 1.33 times that of glutinous and japonica, respectively. On the 6~7th day, the intracellular color value of Monascus after fermentation of japonica was higher, reaching 1762.80 U/g at 505 nm, which was 1.41 and 1.86 times that of indica and glutinous rice, respectively. The late-stage fermentation of japonica rice was more conducive to the accumulation of M9 pigments. The yield of six main Monascus pigments was measured by HPLC. It was found that fermentation of indica and glutinous rice significantly promoted the accumulation of two orange pigments, O1 and O2, in the cell, yielding 5.00 and 6.31 times that of japonica rice on the 7th day of fermentation, respectively. Furthermore, fermentation of japonica rice was found to be more conducive to the production of red (R1, R2) and yellow pigments (Y1, Y2). Among the three rice varieties, japonica exhibited the lowest citrinin content during fermentation; therefore, it might be safer to use japonica rice for fermentation and pigment production. In general, when japonica rice was used as the substrate for fermentation, yields of the red and yellow pigments were higher, while higher yields of orange pigment were obtained for glutinous and indica rice.