瑞士乳杆菌发酵牛乳产生抗ACE活性条件的优化

本实验探讨了发酵条件对瑞士乳杆菌发酵牛乳产生抗ACE活性的影响。在单因素试验的基础上,进行正交试验,得出能产生较高抗ACE活性的最佳工艺条件是:发酵温度为37℃,发酵时间为12h,无脂乳固形物浓度12%(W/V)。

Diagnosis and Treatment of Yeast Mastitis in Dairy Cattle

[Objective] Study on the yeast mastitis in dairy cattle cases which have been ineffectively treated by multiple antibiotics through traditional Chinese medicine prescription. [ Method] The isolated pathogenic fungi from milk were used for drug sensitivity testing and the ones proved were clinically treated by self-made traditional Chinese medicine prescription ＂Ruxiaotang＂. [ Result] 19 cases of 20 selected dairy cattle cases were diagnosed as yeast mastitis and cured with the except of a Candida tropicalis case. [ Conclusion] The results provide a new reference for curing yeast mastitis.

Fermented Goat Milk and Cow Milk Produced by Different Starters of Lactic Acid Bacteria： Quality Studies

Lactic acid bacteria （LAB） is widely used as culture starters in dairy fermentation. The aim of this study was to investigate the quality of fermented goat milk and cow milk, as well as the viability of LAB in the same products. Fermentations were performed with pasteurized goat milk or cow milk added with skim milk （18% of solids） using three separately different starters; yoghurt starter （a combination of Streptococcus thermophilus FNCC-0040 and Lactobacillus bulgaricus FNCC-0041）, single starter of Lactobacillus acidophilus FNCC-0029 and Lactobacillus casei FNCC-0051. The parameters observed were pH, acidity, nutritional quality including protein, fat and lactose content and product＇s viscosity. Acidity, pH and viability of LAB were also monitored during storage at refrigerated temperature （4 ℃） for 28 days. Results show that the different LAB starters did not affect the pH, acidity, lactose and protein content. Differences on LAB starters affected fat content and viscosity. The highest score of viscosity （30.00 Pa.s ± 7.02 Pa.s） was observed on products fermented by yoghurt starters, followed by products obtained using starter of L. acidophilus （17.7 ±11.4） and L. casei （8.62 ±0.35）. Protein content, acidity, pH and viscosity were not significantly different between products obtained from goat milk and cow milk. Fat content in fermented goat milk was higher （5.03% ±0.62%） than in fermented cow milk （3.52% ±0.37%）, however, lactose content was higher in fermented cow milk （5.16% ±0.40%） than in fermented goat milk （4.53% ±0.35%）. Total LAB concentration in fermented cow milk during storage was 8.03± 0.52 logt0 cfu/mL, while in fermented goat milk was 7.81 loglo cfu/mL ± 0.67 loglo cfu/mL. There was a 10.83% decrease in LAB viability in fermented cow milk and 11.40% in fermented goat milk after 28 days of storage. In conclusion, quality of fermented milk is affected by the starters applied, raw milk source and storage period.

Effect of TMF （Total Mixed Fiber） as Roughage Source on Rumen Fermentation in Lactating Dairy Cows

This experiment was conducted using by-products from agro-industry as dairy cows feed. Bagasse, pineapple peel, corn cob, corn stover and vinasses were used to produce TMF （total mixed fiber） for dairy cow feed. Fifteen multiparous Holstein Friesian dairy cows with an initial body weight of 417.88± 52.60 kg and 83.31 ± 26.47 DIM （days in milk） were randomly allocated to three treatments （TI = rice straw and 1 kg of vinasses; T2 = SCWS （sweet corn waste silage）; T3 = TMF （total mixed fiber）） under completely randomized design. The results showed that the chemical composition of TMF was in the normal range of pH and VFA （volatile fatty acids） on silage. However, cows fed TMF and SCWS tended to yield higher level of NH3-N. For volatile fatty acid in rumen fluid, acetate in group of cows fed rice straw with vinasse tended to be the highest. Moreover, propionate in cows fed TMF was found to be the highest among all treatments （P 〉 0.05）. In conclusion, the TMF can be used to feed dairy cow without affecting rumen parameter.

Viability of Bifidobacteria in frozen yogurt made from camel milk

The purpose of this research was to incorporate Bifidobacterium angulatum and Bifidobacterium infantis in frozen fermented dairy desserts made from camel or cow milk and to determine their viability during freezing and storage at .20℃. To meet this objective, ice cream mixtures were formulated using camel or cow milk constituents, inoculated with regular yogurt starter （Lactobacillus delbruecldi ssp bulgaricus and streptococcus thermophilus） and incubated at 42℃ till a pH value of 5.0 was attained. The fermented mixes were heated to 80℃ for 5 min in water bath to inhibit yogurt organisms. Bifidobacteria were then added at 2 g/kg mix （1 gram from each Bifidobacterium strain）. The results showed that the initial counts of Bifidobacteria before freezing were 7.3 × 10^8 and 7.1 × 108 cfu/g for camel and cow mix respectively and decreased to 1.06× 10^8 and 1.1×10^8 in the same order （about 0.8 log reduction in the count of Bifidobacteria was observed） after freezing and storage for one day. No significant changes in counts of Bifidobaeteria were found during storage at -20℃ for 17 weeks. Changes in pH and titratable acidity were also studied. No significant changes in titratable acidities of frozen yogurt made from camel or cow milk constituents during storage period were observed.