嗜酸乳杆菌发酵大豆酸凝乳的研究

本文研究了嗜酸乳杆菌在豆乳中的生长情况,考察了温度、接种量、木瓜汁添加、嗜酸乳杆菌与植物乳杆菌复配比例对发酵的影响,最后根据发酵豆乳的感官指标,确定了嗜酸乳杆菌发酵豆乳的最佳工艺。结果表明,发酵温度为39℃、接种量为6%、木瓜汁添加量为10%、嗜酸乳杆菌与植物乳杆菌配比为1:2是制作木瓜发酵豆乳的最佳工艺条件。产品中嗜酸乳杆菌的活菌数达到3.0×109CFU/mL,且产品口感良好。     

Fermentation characteristics and transit tolerance of Lactobacillus casei Zhang in reconstituted mare milk during storage

The fermentation characteristics of Lactobacillus casei Zhang in mare milk and transit tolerance during refrigerated storage for 28 days were evaluated. There were no dramatic changes in the viable counts of L. casei Zhang in the fermented mare milk samples during storage at various inoculation levels. L. casei Zhang showed good tolerance to the simulated transit juice and maintained high viability in mare milk (above 10⁸cfu/g) during storage. Our results showed that L. casei Zhang had good probiotic properties, and suggest that mare milk could serve as the vehicle for the delivery of L. casei Zhang.     

Chemometric analysis of minerals and trace elements in raw cow milk from the community of Navarra,Spain

The concentrations of protein, fat, five minerals (Na, K, P, Ca and Mg) and nine trace elements (Fe, Zn, Cu, Mn, Se, Al, Cd, Cr and Pb) have been determined in 347 samples of raw cow milk from the community of Navarra, north Spain, using infrared analysis, atomic absorption spectrometry (flame and electrothermal atomisation) and inductively coupled plasma atomic emission spectroscopy. A preliminary chemometric study with the use of pattern recognition methods was carried out in order to characterise, classify and distinguish the different collected samples on the basis of their contents. Principal component analysis (PCA) has permitted the reduction of 16 variables to five principal components which interpret reasonably well the correlations of these studied variables. These variable associations may be attributed to intrinsic (lactogenesis) and other extrinsic factors, such as seasonal variation, animal feeding or geographical situation. Changes in these contents during different seasons were also assessed and consistently interpreted. Linear discriminant analysis (LDA) was used to explore cow milk samples, classifying according to season or geographical location, providing complementary information to PCA. This work shows that PCA and LDA are useful chemometric tools for the multivariate characterisation of raw cows’ milk.     

Adaptation of Escherichia coli O157:H7 to acid in traditional and commercial goat milk amasi

Acid resistance of Escherichia coli O157:H7 strains UT 10 and UT 15 were determined in traditional Amasi fermented for 3 days at ambient temperature (ca 30 °C) and commercial Amasi fermented at 30 °C for 24 h and stored at 7 °C for 2 days. Escherichia coli O157:H7 counts in commercial Amasi were detected at 2.7 log₁₀ cfu/ml after 3 days while those in traditional Amasi could not be detected after the same period. There was no significant difference (p ? 0.05) in the survival of acid adapted (AA) and non-adapted (NA) E. coli O157:H7 in traditional Amasi, while in commercial Amasi, the NA strain survived significantly (p ? 0.05) better than its AA counterpart. Regardless of prior adaptation to acid, E. coli O157:H7 can survive during fermentation and storage of fermented goat milk Amasi. Also, the fermentation time, pH and storage temperature affects the survival of E. coli O157:H7 in the fermented milk.     

黄酒酿造中米浆水回用技术的研究

对浸米过程中米浆水的变化情况及不同添加浆水量对黄酒质量的影响进行了分析.结果表明,随浸米时间的延长,米浆水中总酸和COD含量逐渐增加;浸米温度越低,酸含量越少.黄酒发酵过程中用新鲜米浆水替代部分投料用水,可以起到"以酸制酸"的作用,最适宜的浆水添加量为40%.     

Effects of reverse CO2 acidification cycles,calcium supplementation,pH adjustment and chilled storage on physico-chemical and rennet coagulation properties of reconstituted low- and medium-heat skim milk powders

The reversibility extent of one and two reverse CO₂ acidification cycles on the physico-chemical and rennet coagulation properties of milks reconstituted from low- (LH) or medium- (MH) heat skim powder, enriched or not with calcium and pH adjusted or not was investigated. The ionized calcium concentration, buffering properties and average casein micelle size of untreated and CO₂-treated milks were evaluated before and after a chilled storage for 2 days. The ionized calcium concentration and buffering properties have been modified by the CO₂-treatment, particularly after a second CO₂-cycle. These modifications were highly dependent on the initial milk properties and chilled storage. Inversely, the average casein micelle size was not significantly changed. In addition, the rennet-clotting behaviour checked by near infrared spectroscopy (NIR-S) and rheology (SAOR) indicated the main factors responsible for changes in the casein micelles environment and dynamic casein micellar calcium phosphate reorganization, especially after two CO₂-cycles. A single CO₂-cycle induced a better rennetability for non Ca-enriched milk reconstituted from MH-powder. A second CO₂-cycle was particularly efficient to improve Ca-enriched pH-adjusted milks.     

发酵型功能早籼米乳饮料的制备

以早籼米为原料,开发出了具有发酵风味的米乳饮料.首先对保加利亚乳杆菌和嗜热链球菌的培养特性进行了研究,结果表明,经过驯化的乳酸菌产酸效果明显高于未驯化菌种.通过实验确定了发酵型功能米乳饮料的具体生产工艺:大米→浸泡→磨浆→过滤→添加辅料→糊化→高压灭菌→冷却→发酵→成品.具体的最佳工艺参数如下:料液比为1:18,浸泡时间为2 h,菊糖添加量为5%,奶粉添加量为1%,接菌量为3%,发酵温度为37℃,发酵时间为8 h.     

醇法花生浓缩蛋白改性工艺研究

对醇法花生浓缩蛋白产品进行物理改性,探讨了热水温度、溶液pH、超声波处理时间对产品功能特性的影响.通过正交实验得出优化的改性工艺条件为:将醇法花生浓缩蛋白加入100℃热水中溶解,固液比1:9,调pH为9,超声波功率300 W,频率25 kHz,超声波处理时间30 min.改性产品的蛋白含量为65.86%(N×6.25,干基),氮溶解指数(NSI)为64.68%.     

可溶性大豆多糖在花生蛋白奶中的应用研究

花生蛋白奶制品风味独特,含有丰富的营养,但其产品稳定性差,常出现乳液分层,甚至沉淀,严重影响产品质量.本文通过离心沉淀率,乳化分层现象来研究可溶性大豆多糖等几种乳化稳定剂对花生蛋白奶(由m花生仁:V水=1 1:13制成)稳定性的影响,结果表明可溶性大豆多糖可作为营养强化剂和稳定剂加入到花生蛋白奶中,其合理添加量为0. 3%.     

加压碳化体系对纳米碳酸钙粒度和分散性的影响

利用加压碳化体系制备粒径均一、高分散性纳米碳酸钙材料。考察氢氧化钙浓度、表面活性剂添加量、反应温度、CO2压力对制备纳米CaCO3粒子尺寸和分散程度的影响,采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、Zeta电位和傅立叶变换红外光谱(FT-IR)对制备的纳米碳酸钙粒子进行表征。结果表明,最优加压碳化反应条件是Ca(OH)2质量浓度为2%、表面活性剂添加量为3%(占碳酸钙理论产量的百分比)、反应温度为40℃、CO2压力为6 MPa,所得立方形碳酸钙平均粒径为117 nm,晶型为方解石型碳酸钙。碳化反应加入表面活性剂十六烷基三甲基溴化铵(CTAB)使CaCO3表面形成的正电荷增大至+37.7 mV并高于标准值30 mV,表明制备的CaCO3产品具有良好的分散性且稳定。通过FT-IR和Zeta电位对CTAB改性前后CaCO3纳米粒子进行表征,探讨了CTAB对合成纳米CaCO3分散性的影响机理,为纳米碳酸钙制备提供了一种新的方法。