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新型酸奶发酵剂的研究 总被引:12,自引:3,他引:9
研究了具有不同粘度,风味和保健功能的新型酸奶发酵剂,首先通过对专用酸奶菌种嗜热链球菌和保加利亚乳杆菌不同菌株的组合筛选,优选出具有不同粘度和风味的3种组合;其次,酸奶的疗效保健作用来源于嗜酸乳杆菌,通过研究缓冲盐,生长促进物质对该菌生长的影响,确定了适宜的培养基成分和发酵剂中菌种的配比。 相似文献
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西藏牧区自然发酵牦牛酸奶的乳酸菌菌种筛选及工艺优化 总被引:1,自引:0,他引:1
采用从西藏、川西青藏高原牧区自然发酵牦牛酸奶中筛选出的发酵性能优良的4 株乳酸菌(LP1、LP2、LP3、LP4)进行组合发酵试验,经过纸片法筛选出优势发酵组合,以及其发酵牦牛酸奶的凝乳时间、滴定酸度、感官评价可以得出(LP1和LP2)组合为本试验的最佳发酵菌种组合。因此选用此菌种组合发酵牦牛酸奶,经过L16(44)正交试验得出牦牛酸奶发酵的最佳工艺条件为:发酵温度42 ℃、接种量6%、加糖量4 g/100 mL、菌种LP1与LP2浓度比为2∶1,此条件下发酵的牦牛酸奶凝固均匀,组织结构光滑细腻,无乳清析出,具有浓郁的酸奶风味。 相似文献
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在使用传统发酵剂的基础上研究了添加双歧杆菌发酵对羊酸奶食用品质的影响情况,通过用单因素实验和正交实验,以羊酸奶的滴定酸度、保水力、感官评分和质构特性为指标,优化出双歧杆菌羊酸奶的最佳发酵工艺条件。结果表明:当加糖量为7%,接种量为6%(均为质量分数),菌种比例为1∶1∶2,培养温度为42℃时,双歧杆菌羊酸奶的食用品质最好。 相似文献
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Strain-specific PCR primers for Lactococcus lactis subsp. cremoris FC were developed using the randomly amplified polymorphic DNA (RAPD) technique. RAPD was used to generate strain-specific markers. A 1164-bp RAPD marker found to be strain-specific was sequenced, and a primer pair specific for L. lactis subsp. cremoris FC was designed. The specificity of this primer pair was tested with 23 L. lactis subsp. cremoris strains and 20 intestinal bacterial species, and was found to be strain-specific. Subsequently, this primer pair was subjected to the quantification of L. lactis subsp. cremoris FC in the feces of subjects fed fermented milk containing this strain. After administration, L. lactis subsp. cremoris FC was detected in the feces of all 7 subjects, with the maximum number being between 10(5) and 10(9) cells g(-1) of feces. Furthermore, this strain was detected in only one feces sample 2 weeks after administration was stopped. These results suggest that L. lactis subsp. cremoris FC can survive passage through the gastrointestinal tract. 相似文献
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Evidence of a relationship between autolysis of starter bacteria and lipolysis in cheddar cheese during ripening 总被引:2,自引:0,他引:2
Cell viability, autolysis and lipolysis were studied in Cheddar cheese made using Lactococcus lactis subsp. cremoris AM2 or Lactococcus lactis subsp. cremoris HP. Cheddar cheese was made in triplicate over a 3 month period and ripened for 238 days at 8 degrees C. Cell viability in cheese was lower for AM2 (a non-bitter strain) than for strain HP (a bitter strain). Autolysis, monitored by the level of the intracellular marker enzyme, lactate dehydrogenase (EC 1.1.1.27) in cheese 'juice' extracted by hydraulic pressure, was much greater in the cheese made using AM2 than that made with HP. Lipolysis was determined by the increase during ripening of individual free fatty acids (FFA) from butyric (C4:0) to linolenic acid (C18:3) measured using a high performance liquid chromatographic technique. Levels of individual FFA from butyric (C4:0) to linolenic (C18:3) acids increased significantly (P<0.05) during ripening in cheeses made with either starter culture. Palmitic (C16:0) and oleic (C18:1) acids were the most abundant FFA throughout ripening in all cheeses. Levels of caprylic (C8:0), myristic (C14:0), palmitic (C16:0) and stearic (C18:0) acids were significantly higher (P<0.05) in cheeses manufactured with Lc. lactis subsp. cremoris AM2 than in cheeses manufactured with Lc. lactis subsp. cremoris HP. Differences in levels of lipolysis between strains was not due to differences in the specific lipolytic or esterolytic activities in cell free extracts of the strains as measured by activity on triolein (lipase) and p-nitrophenylbutyrate (esterase) substrates. Therefore, evidence is provided for a relationship between the extent of starter cell autolysis and the level of lipolysis during Cheddar cheese ripening. 相似文献
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Govindasamy-Lucey S Gopal PK Sullivan PA Pillidge CJ 《The Journal of dairy research》2000,67(4):585-596
The autolysin, N-acetyl muramidase (AcmA), of six commercial Lactococcus lactis subsp. cremoris starter strains and eight Lc. lactis subsp. cremoris derivatives or plasmid-free strains was shown by renaturing SDS-PAGE (zymogram analysis) to be degraded by the cell envelope proteinase (lactocepin; EC 3.4.21.96) after growth of strains in milk at 30 degrees C for 72 h. Degradation of AcmA was less in starter strains and derivatives producing lactocepin I/III (intermediate specificity) than in strains producing lactocepin I. This supports previous observations on AcmA degradation in derivatives of the laboratory strain Lc. lactis subsp. cremoris MG1363 (Buist et al. Journal of Bacteriology 180 5947-5953 1998). In contrast to the MG1363 derivatives, however, the extent of autolysis in milk of the commercial Lc. lactis subsp. cremoris starter strains in this study did not always correlate with lactocepin specificity and AcmA degradation. The distribution of autolysins within the cell envelope of Lc. lactis subsp. cremoris starter strains and derivatives harvested during growth in milk was compared by zymogram analysis. AcmA was found associated with cell membranes as well as cell walls and some cleavage of AcmA occurred independently of lactocepin activity. An AcmA product intermediate in size between precursor (46 kDa) and mature (41 kDa) forms of AcmA was clearly visible on zymograms, even in the absence of lactocepin I activity. These results show that autolysis of commercial Lc. lactis subsp. cremoris starter strains is not primarily determined by AcmA activity in relation to lactocepin specificity and that proteolytic cleavage of AcmA in vivo is not fully defined. 相似文献
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藏灵菇中高产胞外多糖乳酸菌的筛选及其发酵性能的研究 总被引:2,自引:0,他引:2
本研究采用高通量筛选技术和苯酚-硫酸法获得高产胞外多糖的乳酸菌菌株,并对其发酵性能和酸奶品质进行测试。筛选的八株菌均具有高产胞外多糖和良好的发酵性能。其菌种鉴定结果是:菌株KTx、 KL1、J1为干酪乳杆菌(Lactobacillus casei),菌株Tx为嗜热链球菌(Streptococcus thermophilus),菌株KS4、J4、Pl、P5为乳酸乳球菌乳酸亚种(Lactococcus lactis subsp.1actis),其中嗜热链球菌Tx制备发酵剂的粘度最高,凝乳时间最短,感官综合评分最高,可利用此菌株进一步开发研制具有良好稳定性的功能性酸奶。 相似文献
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Effects of milk products fermented by Bifidobacterium longum on blood lipids in rats and healthy adult male volunteers 总被引:1,自引:0,他引:1
Xiao JZ Kondo S Takahashi N Miyaji K Oshida K Hiramatsu A Iwatsuki K Kokubo S Hosono A 《Journal of dairy science》2003,86(7):2452-2461
The effects of milk products fermented by Bifidobacterium longum strain BL1, a probiotic strain, on blood lipids in rats and humans were studied. Rats were fed a cholesterol-enriched experimental diet, supplemented with lyophilized powders of 1) acid milk (control), 2) milk fermented with a mixed culture of ordinary yogurt starters composed of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus (SL), and 3) bifidobacterium milk fermented with the probiotic B. longum strain BL1, respectively. The bifidobacterium milk feeding brought about significant lowering of the serum concentrations of total cholesterol, low-density lipoprotein cholesterol, and triglycerides, in comparison with the control, while no change in high-density lipoprotein cholesterol concentration was observed. On the other hand, supplementation with SL milk resulted in only slight, nonsignificant decreases in serum lipid concentrations in comparison with the control. In the human study, 32 subjects with serum total cholesterol ranging from 220 to 280 mg/dl were randomly assigned to two treatments: 1) intake of a low-fat drinking yogurt prepared with ordinary yogurt starters composed of S. thermophilus and L. delbrueckii subsp. bulgaricus (P-group) and 2) intake of a low-fat drinking yogurt prepared with the two ordinary yogurt starters plus B. longum strain BL1 (B-group). After intake for 4 wk at 3 x 100 ml/day, reduction of serum total cholesterol was observed in approximately half of the B-group subjects; a particularly significant decrease in serum total cholesterol was found among subjects with moderate hypercholesterolemia (serum total cholesterol > 240 mg/dl). However, the serum lipid concentrations in the P-group subjects were almost stable during the experimental periods. The present results indicate the potential of the probiotic B. longum strain BL1 in serum lipid improvement. 相似文献
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高加索酸奶中乳酸菌的分离与鉴定 总被引:1,自引:0,他引:1
从自然发酵的5份酸奶样品中,通过平板划线等方法分离筛选乳酸菌。经形态特征,生理生化特性及糖发酵试验等,筛选到12株乳酸菌,分别为:乳杆菌7株,其中:3株德氏乳杆菌保加利亚亚种(Lactobacillus delbrueckii subsp.bulgaricus),3株瑞士乳杆菌(Lactobacillus hel-veticus),1株罗伊氏乳杆菌(Lactobacillus reuteri);乳酸球菌5株,包括3株嗜热链球菌(Streptococcus thermophilus),2株乳酸乳球菌乳脂亚种(Lactococcus lactis subsp.Cremoris)。 相似文献
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Subarna Makhal Suresh Kumar Kanawjia Apurba Giri 《International Journal of Dairy Technology》2014,67(4):530-538
The effects of plain and fermented curd dressing ripened by single (Lactococcus lactis subsp. lactis biovar. diacetylactis) as well as mixed‐strain starter cultures (L. lactis subsp. lactis; L. lactis subsp. cremoris; L. lactis subsp. lactis biovar. diacetylactis:: 1:1:1), different levels of fat (18–24%) in curd dressing and inoculation rate (1–5%) on direct acidified Cottage cheese were observed. Ripened curd dressing containing 22% fat and mixed‐strain starter cultures at 3% imparted a pleasant acidic note, delicate overtones of diacetyl, improved the body and texture, visual appearance and thereby enhanced the overall quality of the product. 相似文献
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