复合益生菌协同发酵葡萄汁菌种筛选与工艺优化

为增强葡萄汁的保健功能,以巨玫瑰葡萄为原料,选择21株益生菌对葡萄汁进行发酵,经过初筛和复筛,得到适宜葡萄汁发酵的植物乳杆菌21802和短乳杆菌6239,并将两株菌进行复配,以活菌数和感官评分为指标,对复合益生菌协同发酵葡萄汁工艺进行优化。结果表明,复合益生菌协同发酵葡萄汁最佳发酵工艺条件为:植物乳杆菌21802与短乳杆菌6239的菌种比例1:2,葡萄汁料水比2:1,接种量5%,发酵温度36 ℃,发酵时间60 h。此条件下发酵所得益生菌发酵葡萄汁的活菌数可达到8.98×10⁹ CFU/mL,感官评分为91.1分。     

Enhancement of functional characteristics of mixed lactic culture producing nisin z and exopolysaccharides during continuous prefermentation of milk with immobilized cells

Antagonistic phenomena between strains often occur in mixed cultures containing a bacteriocinogenic strain. A nisin Z producer (Lactococcus lactis ssp. lactis biovar. diacetylactis UL719) and 2 nisin-sensitive strains for acidification (Lactococcus lactis ssp. cremoris ATCC19257) and exopolysaccharide (EPS) production (Lactobacillus rhamnosus RW-9595M) were immobilized separately in gel beads and used to continuously preferment milk at different temperatures, with pH controlled at 6.0 by fresh milk addition. The process showed high volumetric productivity, with an increase from 8.0 to 12.5 L of prefermented milk per liter of reactor volume and hour as the temperature was increased from 27 to 35°C. Lactococcus lactis ssp. lactis biovar. diacetylactis UL719 counts in prefermented and fermented (22-h batch fermentation) milks were stable during 3 wk of continuous fermentation (8.1 ± 0.1 and 8.9 ± 0.2 log cfu/mL, respectively). The L. lactis ssp. cremoris population (estimated with real-time quantitative PCR) decreased rapidly during the first week of continuous culture to approximately 4.5 log cfu/mL and remained constant afterward. Lactobacillus rhamnosus counts in prefermented and fermented milks significantly increased with prefermentation time, with no temperature effect. Nisin Z reached high titers in fermented milks (from 177 to 363 IU/mL), with EPS concentration in the range from 43 to 178 mg/L. Immobilization and continuous culture led to important physiological changes, with Lb. rhamnosus becoming much more tolerant to nisin Z, and Lb. rhamnosus and L. lactis ssp. lactis biovar. diacetylactis UL719 exhibiting large increases in milk acidification capacity. Our data showed that continuous milk prefermentation with immobilized cells can stimulate the acidification activity of low-acidifying strains and produce fermented milks with improved and controlled functional properties.     

AB益生菌纤维咀嚼片加工工艺的研究

以玉米皮为主要原料,采用酸碱与酶复合法制成玉米膳食纤维基料。建立双歧杆菌、嗜酸乳杆菌混合发酵工艺。通过正交实验确定了AB益生菌咀嚼片的最佳处方及最佳工艺条件,经混合、造粒、干燥、压片等工序加工后,制成具有保健功能的AB益生菌纤维咀嚼片。     

海藻酸钠和乳清蛋白作为益生菌包埋壁材的比较

利用海藻酸钠和乳清蛋白分别制备包埋有两歧双歧杆菌的微胶囊,测定了不同微胶囊的粒径、包埋效率、缓冲能力和外观形态,同时还考察了不同微胶囊对两歧双歧杆菌保护效果的影响。结果表明：乳清蛋白微胶囊的粒径和包埋效率均要高于海藻酸钠微胶囊,分别为202.5 μm,87.8%和118.3 μm,48.1%;虽然在高胆盐环境中两种微胶囊对两歧双歧杆菌的保护效果没有显著差别,但在低酸环境、模拟胃液和常温贮藏期中,相比于海藻酸钠微胶囊,乳清蛋白微胶囊将两歧双歧杆菌的存活量分别提高了大约5、2、0.5（lg（CFU/mL））。乳清蛋白微胶囊在pH值偏中性的环境中具有较高的缓冲能力;在外观形态上,由高浓度乳清蛋白溶液制备而来的微胶囊具有较好的呈球性和致密度,这些可能是乳清蛋白微胶囊具有较高保护效果的原因。     

关于二元连续函数为凸函数的两个条件

推广和改进了连续函数为凸函数的条件。     

混菌发酵苹果浊汁的益生菌筛选及其发酵动力学模型构建

为筛选得到苹果浊汁发酵的较佳复合益生菌,以苹果浊汁为原料,从10 种常见益生菌菌株中筛选出具有耐酸、耐胆盐特性及良好发酵性能的优良菌株,并进行复合菌株间拮抗实验以及复合菌株较佳比例的研究。此外,根据筛选得到的复合菌株较佳比例发酵苹果浊汁,构建菌体生长、产物生成及底物消耗动力学模型,研究确定模型的动力学参数,并进行验证。结果表明：发酵苹果浊汁的较佳复合菌株组合为嗜酸乳杆菌6005、植物乳杆菌21805、发酵乳杆菌21828,根据感官评定及活菌数得到3 株菌株复合比例为111时,发酵苹果浊汁口感风味最佳,活菌数最高;建立复合菌株发酵苹果浊汁的菌体生长、产物生成和底物消耗动力学模型,模型理论值与实验值误差均小于10%,拟合较好,建立的动力学模型能够较好地预测复合益生菌发酵苹果浊汁发酵过程变化。     

杏皮渣膳食纤维片剂的配方及制备工艺

在单因素试验基础上,采用Design Expert 8.0设计软件,根据Box-Behnken的原理设计,以杏皮渣膳食纤维量、微晶纤维素量、木糖醇添加量为响应因素,片剂综合指标为响应值,采用三因素三水平设计进行杏皮渣膳食纤维片制备工艺优化的响应面试验。结合实际生产条件确定最佳组合为:杏皮渣膳食纤维添加量33.55%、微晶纤维素添加量49.25%、木糖醇添加量8.55%、添加1%硬脂酸镁作为润滑剂,此条件下制得的杏皮渣膳食纤维片子表面光滑,色泽均匀,有淡淡的清凉感,不易裂片、碎片。混合物料的临界相对湿度测定表明该产品的最适生产环境相对湿度为75.91%。     

浅析连续平压法生产中/高密度纤维板工艺控制要点

近年来,连续平压法已经是中/高密度纤维板生产企业首选技术。笔者结合多年的工作经验,介绍了连续平压机生产中/高密度纤维板过程中工艺控制要点,并针对如何稳定产品质量提出了工艺控制思路。     

A selective medium for the enumeration and differentiation of Lactobacillus delbrueckii ssp. bulgaricus

Modified reinforced clostridial medium (mRCM) was developed and evaluated for the differential enumeration of Lactobacillus delbrueckii ssp. bulgaricus. Lactobacillus bulgaricus, an important species of lactic acid bacteria with health benefits, is used in the production of yogurt and other fermented foods. Our results showed that supplementing reinforced clostridial medium with 0.025% CaCl₂, 0.01% uracil, and 0.2% Tween 80 (mRCM) significantly enhanced the growth rate of L. bulgaricus RR and ATCC 11842 strains as measured by the optical densities of these strains after 12 h of incubation at 42°C. The bacterial populations (plate count) of the RR and ATCC 11842 strains were 0.76 and 0.77 log cfu/g higher in mRCM than in de Man, Rogosa, and Sharpe and reinforced clostridial medium media, respectively. Conversely, the population counts for other bacterial species (Bifidobacterium, Lactobacillus rhamnosus, and Lactobacillus reuteri) were significantly inhibited in the mRCM medium. The addition of aniline blue dye to mRCM (mRCM-blue) improved the selectivity of L. bulgaricus in mixed lactic bacterial cultures compared with de Man, Rogosa, and Sharpe medium and lactic agar with regard to colony appearance and morphology. The mRCM-blue performed better than the conventional medium in culturing, enumerating, and differentiating L. bulgaricus. Therefore, mRCM-blue could be used as a selective medium to enhance the growth and differentiation of L. bulgaricus in order to meet the increasing demand for this beneficial species of bacteria.