新型酸奶发酵剂的研究

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。     

鹅肉发酵香肠菌种发酵性能与应用研究

通过对3种适合肉制品发酵的菌种:植物乳杆菌、嗜酸乳杆菌、戊糖片球菌发酵性能的研究,筛选出两种较优的组合发酵剂。再通过正交试验确定鹅肉发酵香肠组合发酵剂的最优配比,最后对鹅肉发酵香肠成熟过程和贮藏过程中的pH值和感官品质等方面进行综合分析。结果表明,由戊糖片球菌和植物乳杆菌按1∶1(V∶V)比例混合、接种量为3%(V/m)时所构成的鹅肉香肠发酵剂,其发酵性能最佳。     

介绍一种长寿型酸奶菌种

由上海明厚食品有限公司乳酸菌种培育中心从国外引进的长寿型复合式酸奶发酵剂菌株(可继代使用)。该菌种是由留学丹麦学者,国务院特别津贴获得者,中国乳品专家刘明厚教授在长期训化、筛选、培育下,形成适合于中国人口味的酸奶发酵剂,该发酵剂优点是:1.每瓶发酵剂菌种可继20代以     

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

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。     

双歧杆菌发酵对羊酸奶食用品质的影响

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。     

不同发酵剂对切达干酪成熟期间品质的影响

应用乳酸乳球菌乳酸亚种LA、乳酸乳球菌乳脂亚种LC以及不同比例混合菌(LA∶LC=1∶1,LA∶LC=1∶2,LA∶LC=2∶1)制作切达干酪,研究这5种发酵剂在干酪成熟过程中对其质构、感官、风味物质形成及蛋白水解程度等方面的影响。结果表明:3种不同比例组合菌株发酵剂的蛋白水解能力适中,生产出的干酪口味清淡,其中按1∶1接种制作的干酪具有良好的成熟度、质地和风味,具有一定的商业应用价值,可将其用于切达干酪的生产。     

酸奶菌种组合保存及混合发酵法探讨

本文介绍了酸奶菌种筛选,纯菌种的组合保存及混合制备母发酵剂的方法及其应用情况。     

果味黑豆酸奶的研制

将芒果、菠萝果汁按1∶1混合制成混合果汁,在黑豆浆中加入一定比例的混合果汁进行乳酸菌发酵,制成果味黑豆酸奶。试验采用L9(34)正交试验法确定加工工艺参数,筛选出最优组合。研究结果表明以黑豆浆为基料,添加10%混合果汁、7%蔗糖和4%发酵剂(StLb=2∶1),在40℃发酵4h,制得的酸豆奶色、香、味甚佳,具有营养保健功能。     

活性百合双歧酸奶的加工工艺研究

研究了以百合、鲜牛奶为主要原料 ,添加蔗糖、低聚果糖、低聚异麦芽糖等辅料 ,利用双歧杆菌、保加利亚乳杆菌和嗜热链球菌为混合发酵剂 ,生产活性百合双歧酸奶的加工工艺 ,并对百合浆料液化和脱苦工艺条件等进行了探讨。试验结果表明 ,活性百合双歧酸奶的发酵条件为 ,接入菌种比例 :双歧杆菌∶保加利亚乳杆菌∶嗜热链球菌 =2∶1∶1,工作发酵剂接种量为 3 % ,发酵温度为 3 9± 1℃ ,发酵时间约 6～ 8h。     

混料设计在无花果汁乳酸菌发酵剂配比研究中的应用

为了寻求无花果汁乳酸菌发酵剂中各菌种的最佳组合,采用混料设计法研究了乳酸菌的不同组合对无花果发酵液总活菌数和产酸量的影响,建立了发酵剂中各菌种配比与发酵液总活菌数和产酸量的回归模型,考察了发酵剂中各菌种的互作效应,获得了最佳菌种配比为干酪乳杆菌(Y5-2b)、植物乳杆菌(Yj)和嗜酸乳杆菌(NCFM)1∶1∶2,此时,发酵液总活菌数为1.86×109 CFU/m L,产酸量为7.41 g/L。     

Monitoring the cell number of Lactococcus lactis subsp. cremoris FC in human feces by real-time PCR with strain-specific primers designed using the RAPD technique

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.     

新型高效降胆固醇酸奶的研制

以分离自新疆酸马奶,具有高效降胆固醇活性的发酵乳杆菌SM-7和1株乳酸乳球菌乳亚种LB12菌株发酵制备酸奶,通过单因素试验研究混菌比例、接种量、发酵时间和发酵温度对酸奶品质的影响。通过结合感官评定为指标的正交试验,确定酸奶最佳发酵条件是:菌种配比1∶1(发酵乳杆菌:乳酸乳球菌),接种量6%,发酵温度42℃,发酵时间8h。利用该条件发酵的酸奶,组织状态较粘稠,乳清析出少,香气较好,酸甜适宜。其胆固醇降解率达44.86%,比优化前提高了4.29%。     

Evidence of a relationship between autolysis of starter bacteria and lipolysis in cheddar cheese during ripening

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.     

弱后酸化酸奶发酵剂菌株的筛选及复配

以典型的酸奶发酵剂菌株:德氏乳杆菌保加利亚亚种和嗜热链球菌为实验材料,进行了单菌株产酸特性的测定,并研究了后酸程度不同的球杆菌按照不同比例混合后产酸特性。结果显示:筛选到2株后酸化弱的菌株,当这两株菌的复配比例为100:1时,后酸程度较弱,在42℃放置24h酸度仅上升了10°T,与科汉森的酸奶发酵剂YF-L822相比后酸更弱。     

Varying influence of the autolysin, N-acetyl muramidase, and the cell envelope proteinase on the rate of autolysis of six commercial Lactococcus lactis cheese starter bacteria grown in milk

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.     

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

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。     

Effects of milk products fermented by Bifidobacterium longum on blood lipids in rats and healthy adult male volunteers

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.     

高加索酸奶中乳酸菌的分离与鉴定

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)。     

Process for improving the quality of direct acidified Cottage cheese

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.     

发酵剂对双蛋白干酪理化特性及风味的影响

在牛乳和添加豆乳(质量分数10%)的牛乳中分别使用筛选发酵剂与商品发酵剂进行切达干酪生产,并对成熟干酪的理化成分、质地、风味成分和感官特性进行分析。结果表明,豆乳的添加对干酪的质地、风味和感官特性均无不良影响,而应用筛选发酵剂L. lactis subsp. cremoris QH27-1和L. lactis subsp. lactis XZ3303生产双蛋白切达干酪对干酪的品质有一定的改善作用,可将其应用于双蛋白干酪生产中。