锡盟蒙古族传统发酵马乳中功能性特征肽段的研究

乳基中的小分子活性肽的相关研究,近几年被重点关注,它可以提高机体免疫能力,是调节生理代谢的功能成分。发酵马乳已被证实具有较高的营养价值和医疗保健作用。该研究针对锡盟蒙古族传统发酵马乳,用高效凝胶过滤色谱与超高效液相色谱-电喷雾串联三重四极杆质谱分析发酵马乳样品中蛋白水解物的分子质量分布,并对主要的功能二肽进行定性定量检测。研究结果表明,发酵后马乳的分子质量在1000 Da以下的蛋白水解物比例有显著提升,检测出24条具有潜在血管紧张素转化酶(angiotensin-converting enzyme,ACE)抑制功能的二肽,标记含量较高且有功能活性的肽段VP、AF为该发酵马乳样品的特征肽段,并对以上功能肽段的构效关系进行探讨。该研究为进一步开发来源于蒙古族传统发酵食品中的功能乳肽提供参考。     

In vitro investigation of anticancer,antihypertensive, antidiabetic,and antioxidant activities of camel milk fermented with camel milk probiotic: A comparative study with fermented bovine milk

This study aimed to investigate in vitro anticancer activity by antiproliferative activity, antihypertensive activity by angiotensin-converting enzyme inhibition, antidiabetic activity by α-amylase and α-glucosidase inhibitions, and antioxidant activities of camel milk fermented with camel milk probiotic compared with fermented bovine milk. The camel milk probiotic strain Lactococcus lactis KX881782 (Lc.K782) and control Lactobacillus acidophilus DSM9126 (La.DSM) were used to prepare fermented camel and bovine milks separately. The proteolytic activities of water-soluble extract (WSE) in all fermented camel milk were higher than those in fermented bovine milk. The α-glucosidase inhibitions in both milk types fermented by Lc.K782 ranged from 30 to 40%. Camel milk fermented by Lc.K782 had the highest antioxidant activity by 2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulphonic acid). The highest angiotensin-converting enzyme inhibition of WSE in camel milk fermented by Lc.K782 was >80%. The proliferations of Caco-2, MCF-7, and HELA cells were more inhibited when treated with WSE of fermented camel milk extracts.     

Fermented milk retains beneficial effects on skeletal muscle protein anabolism after processing by centrifugation and supernatant removal

Lactobacillus-fermented milk can stimulate anabolic effects in skeletal muscle. Fermented milk containing Lactobacillus produces aqueous molecules, such as free AA and lactate. This study aimed to investigate how processing fermented milk by centrifugation and removal of supernatant affects AA absorption and postprandial skeletal muscle protein synthesis (MPS) when mice are fed fermented milk. We gavaged male Sprague-Dawley rats with skim milk (S), fermented milk (F), or processed fermented milk (P), and examined the total AA content in portal vein blood (reflecting AA absorption) and plantaris muscle MPS at 30, 60, and 90 min following administration. Relative to fasted rats, at 30 min the total AA concentration in portal vein blood from rats in the P groups was significantly higher, followed by F and S, respectively. The MPS rates were higher for the F or P groups compared with the S group. Phosphorylation levels of p70S6 kinase in the P and F groups were significantly higher than those for the S group 30 min after administration, although the level of Akt phosphorylation was similar among the groups. These results suggested that fermentation improves AA absorption that in turn enhances postprandial MPS via Akt-independent mechanisms, and that processed fermented milk retains these favorable effects on MPS.     

罗汉果发酵乳冰淇淋的开发研究

以罗汉果汁为主要原料,利用正交试验对罗汉果发酵乳冰淇淋的生产工艺进行了研究。结果表明,罗汉果发酵乳冰淇淋的最佳配方为罗汉果汁25%,复合稳定剂0.4%,赤藓糖醇14%,发酵乳30%,以此得到营养价值高,结合了酸奶和冰淇淋的双重特点和风味独特的冰淇淋制品。     

Survival of Escherichia coli O157:H7 in traditional African yoghurt fermentation

Growth and survival of a nontoxigenic strain of Escherichia coli O157:H7 (ATCC 43888) was determined in traditionally fermented pasteurized milk. Preheated milk was inoculated with 1% (v/v) of a mixed culture of Lactobacillus delbrueckii ssp. bulgaricus (NCIMB 11778) and Streptococcus salivarius ssp. thermophilus (NCIMB 110368) and incubated at 25, 30, 37 or 43 degrees C for 24 h. E. coli O157:H7 (10(5) CFU/ml) were introduced into the milk pre- and post-fermentation. Fermented milk samples were subsequently stored at either 4 degrees C (refrigerator temperature) or 25 degrees C (to mimic African ambient temperature) for 5 days. After 24 h of fermentation, the pH of the samples fermented at the higher temperatures of 37-43 degrees C decreased from 6.8 to 4.4-4.0 ( +/- 0.2) whereas at the lower temperature of 25 degrees C, the pH decreased to pH 5.0 +/- 0.1. During this period, viable counts for E. coli O157:H7 increased from 10(5) to 10(8) - 10(9) CFU/ml except in milk fermented at 43 degrees C wherein viability declined to 10(4) CFU/ml. In fermented (25-30 degrees C) milk stored at 4 degrees C for 5 days, E. coli O157:H7 viability decreased from 10(8-9) to 10(6-7) CFU/ml whereas milk fermented at 43 degrees C resulted in loss of detectable cells. In contrast, storage of fermented milk samples at 25 degrees C for 5 days eventually resulted in complete loss of viability irrespective of fermentation temperature. Stationary phase E. coli O157:H7 inoculated post-fermentation (25 and 43 degrees C) survived during 4 degrees C storage, but not 25 degrees C storage. Fermentation temperature and subsequent storage temperature are critical to the growth and survival of E. coli O157:H7 in traditional fermented products involving yoghurt starter cultures.     

Kefir grains as a starter for whey fermentation at different temperatures: chemical and microbiological characterisation

We report here a comparative analysis of the growth, acidification capacity, and chemical and microbiologic composition between kefir grains after 20 subcultures in whey at 20, 30, and 37°C and the original kefir grains coming from milk along with a determination of the microbiological composition of the fermented whey as compared with that of traditional fermented milk. When fermentation was carried out repeatedly at 30 or 37°C, kefir grains changed their kefir-like appearance, exhibited reduced growth rates, had a lower diversity of yeasts and water content, and a higher protein-to-polysaccharide ratio compared with the original kefir grains. In contrast, at 20°C kefir grains could remain in whey for prolonged periods without altering their acidification capacity, growth rate, macroscopic appearance or chemical and microbiologic composition-with the only difference being a reduction in certain yeast populations after 20 subcultures in whey. At this incubation temperature, the presence of Lactobacillus kefiranofaciens, Lb. kefir, Lb. parakefir, Lactococcus lactis, Kluyveromyces marxianus, Saccharomyces unisporus, and Sac. cerevisiae was detected in kefir grains and in fermented whey by denaturing-gradient-gel electrophoresis (DGGE). In whey fermented at 20°C the number of lactic-acid bacteria (LAB) was significantly lower (P<0·05) and the number of yeast significantly higher (P<0·05) than in fermented milk. Since the DGGE profiles were similar for both products, at this temperature the microbiologic composition of fermented whey is similar to that of fermented milk. We therefore suggest a temperature of 20°C to preserve kefir grains as whey-fermentation starters.     

南瓜胡萝卜发酵乳饮料的工艺研究

以南瓜、胡萝卜为主要原料,经预处理、软化、打浆等工序,添加各种辅料,采用单因素试验和响应面设计,确定南瓜胡萝卜发酵乳饮料生产的最佳配方和工艺条件.结果表明,饮料的最佳配方为南瓜汁70％,胡萝卜汁30％,脱脂乳粉2.5％,安赛蜜0.025％,复合稳定剂0.18％.饮料的最佳工艺条件为接种量3％,发酵温度42℃,发酵时间4h.     

无糖藜麦发酵乳的物化特性及抗氧化活性

目的：开发有益于身体健康的无糖风味发酵乳。方法：在复原乳中添加藜麦浆,以木糖醇替代蔗糖经发酵后得无糖藜麦发酵乳,以酸度、黏度、持水力等物化特性及体外抗氧化为评价指标,探究藜麦浆对无糖发酵乳的影响。结果：添加藜麦浆的发酵乳pH高于普通发酵乳,酸度、黏度、持水力则略低于普通发酵乳,且无糖藜麦发酵乳的DPPH自由基清除率（86.23%）、ABTS自由基清除率（71.32%）、羟基自由基清除率（63.27%）、Fe³⁺还原能力（0.48 mmol/L）均高于普通发酵乳。结论：添加木糖醇和藜麦浆会改变发酵乳的物化性质,同时提高发酵乳的抗氧化活性。     

传统乳制品中乳酸菌的筛选及发酵性能研究

为获得优良发酵性能的乳酸菌,采用传统培养方法从传统发酵乳样品中分离乳酸菌,并将分离菌株制备发酵乳。通过考察发酵乳的感官品质筛选优良菌株,采用形态学观察及16S rDNA序列分析对筛选菌株进行鉴定;并对其生长性能、产酸性能及其制备发酵乳贮藏期内品质变化进行测定。结果显示,共分离得到67株乳酸菌,筛选出5株性能较佳的菌株（编号为C-1、Q164、Q165、Q166和Q167）,均被鉴定为嗜热链球菌（Streptococcus thermophilus）。其中,菌株C-1生长性能和产酸性能最佳,该菌株制备的发酵乳奶香明显,口感细腻顺滑,感官评分最高（93.5分）,30 ℃贮藏21 d后,酸度为86.0 °T,活菌数为7.2×103 CFU/g。综上,嗜热链球菌C-1具备优良发酵性能菌株的应用潜力。     

Rheological, sensorial, and chemopreventive properties of milk fermented with exopolysaccharide-producing lactic cultures

The objective of this research was to evaluate the rheological, sensorial, and chemopreventive properties of milk fermented with different exopolysaccharide (EPS)-producing lactic cultures. Reconstituted skim milk (11% wt/vol) was fermented with single strains of EPS-producing and non-EPS-producing cultures. Whey that collected on the surface of undisturbed fermented milks and after cutting was measured. All EPS-producing cultures reduced the amount of whey present on the surface of the undisturbed samples, whereas only 3 out of 5 strains reduced syneresis measured after cutting. All EPS-producing cultures except a strain of Lactobacillus delbrueckii ssp. bulgaricus reduced viscoelastic moduli in fermented milk. There was a linear correlation between ropiness and smoothness. In the chemoprevention study, 140 male Fisher rats were divided into 7 groups of 20 each. Rats in 6 groups were fed diets supplemented with fermented milks each made with a single strain of EPS-producing or non-producing cultures, whereas rats in group 7 (control) were fed a diet supplemented with milk acidified with glucono-δ-lactone (GDL). All rats were injected with azoxymethane (15 mg/kg, subcutaneous) at wk 7 and 8 of age to induce tumors and fed their respective diets ad libitum throughout the study. After 30 wk of initiation, all rats were anesthetized with ether, and their intestinal tissues were isolated and washed with cold normal saline. The number and size of tumors in the colon and small intestine were recorded. Rats fed diets supplemented with fermented milk made with 2 EPS-positive and 1 EPS-negative strains had significantly lowered incidence of colon tumor and colon tumor multiplicity. Cyclooxygenase-2 enzyme activity (the enzyme implicated in colon tumor development) was significantly lower in the colon tissue of rats fed diets containing milk fermented with 4 EPS-producing and 1 non-producing cultures than that in rats fed diets supplemented with GDL-acidified milk. Different EPS-positive cultures produced fermented milks with distinct rheological characteristics and levels of ropiness. No relationship was found between rheological properties or level of ropiness of fermented milk and its chemopreventive effect.     

Effect of long-term intake of milk products on blood pressure in hypertensive rats

The effect of long-term intake of two fermented milk products on the development of hypertension was compared in young spontaneously hypertensive rats (SHR). The products contained tripeptides isoleucine-proline-proline (IPP) and valine-proline-proline (VPP), which have been shown to possess angiotensin converting enzyme (ACE) inhibitory activity. Six-week-old SHR were divided into four groups to receive orally ad libitum water, skim milk or two fermented milk poducts (fermented milk A or fermented milk B; the latter is commercially available in Japan with trade name Calpis) for 14 weeks. The calculated intake of IPP was 0.4 mg/d and 0.2 mg/d in the groups receiving fermented milk A and B, respectively, whereas the corresponding amounts for VPP were 0.6 mg/d and 0.3 mg/d. Systolic blood pressure (SBP) was monitored weekly by tail-cuff method. The development of hypertension was significantly attenuated in both groups receiving fermented milk products, whereas skim milk did not affect blood pressure. The effect was detectable after 6 weeks of treatment. At the end of the experiment, the lowest blood pressure level was found in the group receiving fermented milk A: the SBP was 21 mm Hg lower than in the group receiving water and 10 mm Hg lower than in the group receiving fermented milk B. This difference could be explained by larger intake of ACE inhibitory tripeptides in the group receiving fermented milk A as compared with fermented milk B.     

无糖藜麦发酵乳复合发酵工艺优化及品质分析

为开发一款具有较高抗氧化能力的无糖藜麦发酵乳,通过单因素实验确定复合菌种发酵比例、木糖醇添加量,并采用响应面法优化无糖藜麦发酵乳的各项发酵工艺参数。结果表明,无糖藜麦发酵乳的最佳工艺为:复合发酵剂比例植物乳杆菌:嗜酸乳杆菌为2:1、木糖醇添加量5%、乳酸菌接种量3%、藜麦浆添加量30%、发酵温度38 ℃、发酵时间8 h,此时发酵乳超氧化物歧化酶（SOD酶）活力最高241.17 U/mL,并且其理化指标和微生物指标均符合国家标准要求。     

AMINO ACID COMPOSITION AND NUTRITIONAL IMPLICATIONS OF MILK FERMENTED BY VARIOUS LACTIC CULTURES

A total of nine milk products were analyzed for total and free amino acids and total and nonprotein nitrogen. The products were: (1) whole milk (WM), (2) skim milk (SM), (3) WM fermented by Streptococcus thermophilus, (4) SM fermented by S. thermophilus, (5) WM fermented by Lactobacillus bulgaricus, (6) SM fermented by L. bulgaricus, (7) WM fermented by L. acidophilus, (8) SM fermented by L. acidophilus and (9) commercially prepared buttermilk. Essential amino acid content of the fermented milk was lower than that of the whole or skim milk. Fermentation of milk by lactic cultures decreased the total lysine (except butter milk) and methionine contents of all the samples. Since these two amino acids are limiting amino acids in protein malnourished areas, lactic fermentation of milk may be undesirable based on the chemical scores of the protein. However, the free amino acid content, including that of lysine and methionine, increases significantly upon lactic fermentation of milk. This predigestion of protein might result in an increased availability of the amino acids to offset the reduction in amino acids during fermentation and may even result in a better quality protein. Biological evaluation of the fermented milk proteins is necessary to evaluate their nutritional quality. L. bulgaricus was the most proteolytic of all the organisms used.     

西藏灵菇菌粒、瑞士乳杆菌LZ-R-5与普通乳酸菌的发酵乳特性对比及低场核磁共振在其储藏期间水分的在线监测应用

分别以西藏灵菇菌粒、瑞士乳杆菌LZ-R-5(分离自西藏灵菇菌粒)和"川秀"牌乳酸菌酸奶发酵粉发酵纯牛奶得到三种发酵乳。研究三种发酵乳发酵和储藏期间的生长特性,并利用低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)技术研究三种发酵乳在发酵和储藏期间的水分分布和迁移规律,结合持水力和流变学特性,探究发酵乳水分迁移变化与流变学特性是否存在相关性。结果显示,发酵期间,三种发酵乳pH逐渐降低,乳酸酸活菌数先增多后减少。三种发酵乳在储藏期间,总水分含量和自由水含量都呈逐渐减少趋势,横向弛豫时间T₂₂先减小后增大;另外,三种发酵乳持水力变化、表观粘度、G'和G″变化一致,呈现先增大后减小的趋势。由此可知,LF-NMR技术可以应用于发酵乳储藏期间水分的在线监测,为发酵乳品质快速判定提供了理论依据。     

基于电子鼻和电子舌技术评价乳酸乳球菌对发酵乳风味品质的影响

目的:探究不同发酵特性的乳酸乳球菌对发酵乳品质的影响。方法:通过电子鼻与电子舌技术,结合多元统计分析对191株乳酸乳球菌所制备的发酵乳进行风味与滋味品质评价。结果:主成分分析表明,具有不同产酸和蛋白水解特性的乳酸乳球菌所制备的发酵乳风味特征呈分离趋势。Mann-Whitney分析结果表明,慢速产酸组的发酵乳芳香成分显著低于中速及快速产酸组,而甲烷、乙醇、有机硫化物则显著高于另外两组(P<0.01)。在滋味方面,慢速产酸组发酵乳的鲜味强烈,而中速和快速产酸组酸味更强烈(P<0.01)。相关性分析结果表明,菌株的产酸速率与蛋白水解程度呈显著负相关(P<0.01)。结论:产酸速率快、蛋白水解能力弱的乳酸乳球菌可赋予发酵乳更多的芳香成分以及更强烈的酸味,而产酸慢、蛋白水解能力强的菌株使得发酵乳具有更多的甲烷、乙醇、有机硫化物成分以及较强的鲜味。     

响应面法优化白首乌发酵乳制备工艺

以白首乌粉、奶粉为主要原料，以德氏乳杆菌保加利亚亚种（Lactobacillus delbruechii subsp. bulgaricus）和嗜热链球菌（Streptococcus thermophilus）为发酵剂，以感官评价和2,2'-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（ABTS）法得到的抗氧化值为评价指标，通过单因素试验和响应面试验对白首乌发酵乳发酵工艺进行优化。结果表明，在白首乌过筛目数为70目、白首乌粉、奶粉和蔗糖添加质量比为1∶2∶2、接种量为4%、发酵温度为30 ℃、发酵时间为11 h条件下，白首乌发酵酸乳感官评分最高为88分，抗氧化值为580.2 mgVCE/L，活菌数达2.2×108 CFU/mL，酸度为85 °T，风味独特、口感柔和细腻、酸甜可口，为白首乌产品的开发提供一种新的思路。     

鼠李糖乳杆菌GG发酵驼乳与牛乳的发酵特性和降糖活性比较

本试验以耐酸、耐氧、定植力强及功能性丰富的鼠李糖乳杆菌GG (Lactobacillus rhamnosus GG,L-GG)单菌发酵的驼乳和牛乳为研究对象,通过鼠李糖乳杆菌GG的生长曲线确定发酵时间,评价不同发酵时间和不同储藏时间下,发酵驼乳与牛乳的发酵特性(pH、滴定酸度和活菌数)、蛋白质水解活性和降糖活性(α-淀粉酶和α-葡萄糖苷酶抑制活性)。结果表明,pH、滴定酸度、活菌数和蛋白质水解活性存在一定的内在联系。随着发酵时间的增加,两种发酵乳的pH下降,滴定酸度上升,活菌数和蛋白质水解活性也在不断增加。在储藏期间,pH、滴定酸度、活菌数和蛋白质水解活性逐渐趋于稳定。发酵驼乳较发酵牛乳的pH低,滴定酸度、活菌数和蛋白质水解活性高,在维持发酵品质和延长货架期方面优于发酵牛乳。经过发酵后的原料乳降糖活性提高,在发酵和储藏期间发酵驼乳和牛乳都表现出很高的α-淀粉酶抑制活性,在储藏期间表现出较高的α-葡萄糖苷酶抑制活性,整体上看发酵驼乳的降糖活性优于发酵牛乳。     

Occurrence of Yersinia enterocolitica in milk and dairy products in Morocco.

A total of 227 samples of milk and dairy products were examined for the presence of Yersinia enterocolitica. Yersinia spp. were recovered from 11 of 30 raw milks (36.6%), one of 20 pasteurized milks (5%), 15 of 63 traditional fermented milks (23.8%), seven of 94 cheeses and one of 20 cream samples (5%). The overall incidence of Y. enterocolitica in milk and dairy products was 6.6%. The other Yersinia species were Y. intermedia, Y. kristensenii, Y. frederiksenii and Y. pseudotuberculosis. Y. enterocolitica was detected only in raw milk (30% of the samples), in traditional fermented milks (6.3%) and in raw milk-made cheese (4%). The majority of the Y. enterocolitica isolates were of biotype 1 (environmental strains). The Celfulodin-Irgasan-Novobiocin (CIN) Agar was found to be more efficient than the Mac Conkey Agar in the isolation of Yersinia organisms.     

Development of a novel milk‐based fermented product fortified with wheat germ

Wheat germ (WG) was mixed with water (1:5), heated (85 °C/15 min), cooled and used to replace 0, 20, 30 and 40% (w/w) of standardised cow's milk (3% fat), supplemented with 2%(w/w) skim milk powder. Yoghurt‐like fermented products were prepared from the different formulations, stored at 7 ± 2 °C for 15 days, and analysed for chemical composition, pH, microbiological quality, texture profile (TPA), viscosity, syneresis and sensory properties. The addition of WG slurry enhanced acid development during fermentation and increased the viscosity of the fermented products. Nutritious milk‐based fermented products of acceptable composition and quality could be prepared from formulations containing 20% (w/w) WG slurry.     

Effect of administration of fermented milk containing whey protein concentrate to rats and healthy men on serum lipids and blood pressure

The effect of fermented milk supplemented with whey protein concentrate on the serum lipid level of rats was investigated. The serum total cholesterol level for the group fed fermented milk with both Lactobacillus casei TMC0409 and Streptococcus thermophilus TMC 1543 was significantly lower than that of the control group (P<0.05) in rats. Furthermore, the effect of the longterm intake of this fermented milk on the serum lipid level of twenty healthy adult men was investigated. During the 8-wk study, the volunteers consumed 200 ml of fermented milk or placebo in the morning and evening. Blood samples were drawn for analysis three times, just before taking the experimental diet, and after 4 wk and 8 wk of consumption. After 8 wk, the high density lipoprotein cholesterol level for the fermented milk group showed a significant rise after 4 wk (P<0.05), whereas that of the placebo group showed no change even after 4 wk (P>0.05). The triglyceride level for the fermented milk group lowered significantly after 4 wk (<0.05), whereas that of the placebo group showed no change even after 4 wk (P>0.05). The atherogenic index [(total cholesterol - high density lipoprotein cholesterol)/high-density lipoprotein cholesterol] for the fermented milk group decreased significantly from 4.24 to 3.52 (P<0.05). The systolic blood pressure lowered significantly by the intake of fermented milk (P<0.05) On the other hand, such effect was not observed in the placebo group (P>0.05). These results indicate potential of the development of fermented milk with multiple therapeutic effects.