基于微生物发酵的低糖型桑椹精粉制备工艺研究

以改善桑椹精粉的加工特性(粒径、粉体特性、色泽)和保持脱氧野尻霉素(DNJ)、总多酚、总黄酮和花青素等活性成分为目标,通过微生物发酵技术研究营养和外观品质俱佳的低糖型桑椹精粉的制备工艺。将桑椹原浆经肠膜明串珠菌(Leuconstoc mesenteroides)和葡萄酒高活性干酵母(Saccharomyces cerevisiae)发酵、冻干后制备低糖型桑椹精粉,并以干桑椹直接粉碎后的桑椹原粉为对照,比较桑椹原粉、桑椹精粉和添加黄豆辅料的桑椹精粉的加工特性以及活性成分含量。与桑椹原粉相比,2种低糖型桑椹精粉的葡萄糖和果糖含量、水分含量、水分活度、吸湿性、堆密度、休止角、粒径都明显降低,色泽、流动性等加工特性显著改善。桑椹原粉的DNJ含量为0.68mg/g,发酵后DNJ含量显著提高,为2.07mg/g,冻干处理后为1.39mg/g,冻干并添加辅料处理后其含量为1.03mg/g。发酵、冻干以及添加黄豆辅料对总多酚、总黄酮含量没有显著影响；桑椹原粉、桑椹发酵液、桑椹精粉、添加黄豆辅料的桑椹精粉的总多酚含量分别为27.70、28.55、25.83、25.85mg/g,总黄酮含量分别为1.24、1.01、1.16、1.30mg/g。发酵处理造成花青素含量显著下降,而冻干和添加黄豆辅料对花青素含量没有显著影响。桑椹经发酵、添加黄豆冻干处理后,其加工特性得到改善,DNJ含量增加,花青素含量降低,而总多酚和总黄酮含量没有明显变化。

Study on Preparation of Low-Sugar Mulberry Extract Powder Based on Microbial Fermentation

In order to improve the processing characteristics (particle size, powder characteristics, color) and maintain the active substances such as deoxynojirimycin(DNJ), total polyphenols, total flavonoids and anthocyanins, the low-sugar mulberry extract powder with good nutrition and appearance quality was prepared by microbial fermentation technology. Two kinds of low-sugar mulberry extract powders (with or without soybean addition) were prepared by fermentation of mulberry protoplasm through Leuconstoc mesenteroides and Saccharomyces cerevisiae and freeze-drying. The processing characteristics and active substance contents of the low-sugar mulberry extract powder were compared with that of the mulberry powder directly crushed by dry mulberry. Compared with mulberry powder, the glucose content, fructose content, water content, water activity, hygroscopicity, bulk density, resting angle and particle size of two kinds of low-sugar mulberry extract powder were significantly decreased after fermentation and freeze-drying, and their processing properties such as color and fluidity were significantly improved. The DNJ content of mulberry powder was 0.68mg/g, which was significantly increased to 2.07mg/g after fermentation, 1.39mg/g after freezing-drying, and 1.03mg/g after freezing-drying and addition of soybean. The contents of total polyphenols and total flavonoids were not significantly affected by fermentation, freezing-drying and addition of soybean. The total polyphenols contents of mulberry powder, fermented mulberry, freeze-dried fermented mulberry, freeze-dried fermented mulberry with soybean addition were 27.70,8.55,5.83, and 25.85mg/g, and the contents of total flavonoids were 1.24,1.01,1.16 and 1.30mg/g, respectively. The content of anthocyanin decreased significantly after fermentation, while the content of anthocyanin did not change significantly after freezing-drying and soybean addition. After fermentation and freezing-drying, the processing characteristics of low-sugar mulberry extract powder were improved. The content of DNJ was increased, and the content of anthocyanin was decreased. However the contents of total polyphenols and total flavonoids were not significantly changed.