乳酸菌对中国传统主食馒头质量的影响

传统馒头发酵剂由多种微生物群体组成,乳酸菌是馒头传统发酵剂中的重要微生物类群,其种类和数量与馒头的品质存在内在联系。该文针对馒头传统发酵剂中乳酸菌菌群的发展过程以及乳酸菌发酵与馒头品质的关系进行了综述,为馒头发酵剂的研究提供参考。 关键词：中图分类号：TS211.4 文献标识码：A 文章编号：0254-5071（20１5）11-0010-04 doi:     

乳酸湿热处理改善大米粉性质及粉条品质的研究

主要研究乳酸湿热处理对大米粉性质及其干粉条和湿粉条品质的影响。以水磨籼米粉为原料,通过不同浓度乳酸、湿热以及乳酸与湿热联用的方法对米粉进行处理,研究不同条件下制备的大米粉的糊化特性、溶解度、膨胀率以及干粉条和湿粉条的蒸煮品质和质构品质。实验结果表明:乳酸湿热处理对大米粉糊化特性影响显著,大米粉通过湿热处理、乳酸处理、乳酸湿热联用处理后,大米粉的峰值黏度、谷值黏度、衰减值、最终黏度、回生值都有所降低。在乳酸处理(pH=4)时,峰值黏度最高。乳酸湿热处理对大米粉的溶解度和膨胀度都有一定的影响,与原样相比,被处理过的样品其溶解度、膨胀度都逐渐降低。在粉条蒸煮品质测定中,乳酸处理(pH=4)后,干粉条和湿粉条的断条率、蒸煮损失率都达到最低。在粉条质构品质测定中,经过湿热处理、乳酸处理和乳酸湿热联用处理三种方法处理以后,湿粉条的硬度、咀嚼性均有所下降,在乳酸处理(pH=4)时,湿粉条的弹性达到最大;在湿热处理、乳酸处理和乳酸湿热联用处理中,干粉条的黏度有所下降,在乳酸(pH=4)时,干粉条的弹性达到最大。最终结果:在乳酸处理(pH=4)时,对改善大米粉性质及粉条品质的效果是最优的。     

反射法测定芦荟制品中乳酸的含量

芦荟制品中乳酸的含量反映芦荟制品加工过程中微生物控制情况,也反映芦荟制品品质的变化情况。本文建立了一种反射计量测定乳酸含量的新方法。实验结果表明,该方法快速灵敏、操作简单、重复性好,可用于芦荟制品生产过程中乳酸含量的测定及其产品质量的评价。     

乳酸黄瓜的腌制

本文对乳酸黄瓜的腌制方法进行了研究和探讨，利用多菌株乳酸菌菌液腌制黄瓜，不仅使酸黄瓜的酸味更加纯正，而且提高营养价值，本方法适合于酸黄瓜等生产企业技术升级和产品内在质量的提高。     

乳酸菌在食用农产品安全生产中的应用研究进展

食用农产品作为食品加工的源头,对食品的质量安全和品质起关键性的作用。作为食品安全的首要环节,食用农产品的安全生产问题已成为近年来各国学者研究的热点。随着对乳酸菌生物特性和安全性能研究的深入,利用乳酸菌减少生产中农药和化学肥料使用过程中带来的危害从而获得绿色食用农产品受到众多消费者的关注。当前,乳酸菌在保障食用农产品质量安全领域发挥了越来越大的作用。本文综述了国内外有关乳酸菌在食用农产品拮抗致病微生物和腐败微生物、重金属和农药残留的去除、真菌毒素降解及果树病虫害防控等领域的最新研究进展,旨在为促进乳酸菌在食用农产品中的应用发展和食用农产品加工质量控制提供新思路,同时提出了乳酸菌未来研究的方向和可能面临的挑战。     

果味活菌乳酸饮料的研制

以新鲜牛乳为原料,在发酵酸奶的基础上,加入稳定剂、蜂蜜、香精、糖类等,通过正交实验,确定了最佳工艺配方、技术参数和产品的质量指标,得到一种营养、风味独特的果味活菌乳酸饮料。     

Action of plasma-activated lactic acid on the inactivation of inoculated Salmonella Enteritidis and quality of beef

This study aimed to investigate the effects of plasma-activated lactic acid (PALA) on Salmonella Enteritidis and beef quality. To improve the antibacterial efficiency of plasma-activated water (PAW), plasma-activated lactic acid (PALA) was prepared by treating lactic acid (0.05–0.20%) with a plasma jet for 40 to 100 s with subsequent application to the surfaces of beef slices (50 × 50 mm, approximately 10 g). Slices were analyzed for changes in surface color, pH, lipid oxidation and odor. In addition, secondary structure (β-sheet and random coil) of the beef protein was determined using Fourier transform infrared spectrometer. We showed that the antibacterial activity of PALA was closely related to the reaction of NO₂⁻ with H₂O₂ as well as the decomposition of NO₂⁻ under acidic conditions. UV-treated fresh beef slices were spot-inoculated with Salmonella Enteritidis (5.67 log CFU/g) and then immersed in PALA solutions for 20 s; leading to a reduction ranging from 1.24 to 3.52 log CFU/g. Data indicated that there was no negative effect of PALA on beef quality parameters. This study not only provided a theoretical basis for developing a novel decontaminant but also enabled PALA to find a way for practical application.Industrial relevanceIn China, a high concentration of lactic acid (2.0–2.5%) is a widely used bactericidal agent in the beef industry. However, it has a negative effect on the odor and protein of the product. The meat industry faces challenges in achieving the balance between the antimicrobial effect on meat and the quality of the product. Based on this, plasma-activated water (PAW) is a hopeful alternative decontaminant for microbial inhibition on meat, made by treating water with non-thermal plasma, containing reactive species, ions and charged particles, which is safe and environmentally friendly. This study demonstrated that plasma-activated lactic acid (PALA) was more effective and stable than PAW. The PALA treatment of beef slices not only led to the reduction of Salmonella Enteritidis but maintained beef quality. PALA appears a promising decontaminant for the meat industry.     

Simultaneous saccharification and fermentation of furfural residues by mixed cultures of lactic acid bacteria and yeast to produce lactic acid and ethanol

In a cellulosic ethanol production system, yeasts cannot be reused, and it is difficult to avoid the formation of lactic acid. A novel mixed fermentation system based on water-rinsed furfural residue was designed to produce lactic acid and ethanol simultaneously by yeast and lactic acid bacteria. The fermentation broth can be used for the production of lactic acid, ethanol, or ethyl lactate, which is a very suitable alternative green solvent. Simultaneous saccharification and fermentation by mixed cultures of lactic acid bacteria and yeast (MSSF) in different conditions were carried out. Acid/alcohol molar ratios (molar ratio of lactic acid to ethanol) were investigated to determine the effects of temperature, substrate concentration, and mass rate of yeast to lactic acid bacterial cells on MSSF. Cellulose conversion rate was also calculated to evaluate the effectiveness of MSSF. The cellulose conversion rate of MSSF was higher than those of ethanol simultaneous saccharification and fermentation and lactic acid simultaneous saccharification and fermentation. The cellulose conversion rate increased with increasing substrate concentration, while the acid/alcohol molar ratio decreased with increasing substrate concentration. These results indicate that yeast cells could provide nutrients for lactic acid bacteria. MSSF at 38 °C is also apt to obtain a low acid/alcohol molar ratio. A 1:1 lactic acid/alcohol molar ratio will be obtained at a fluctuating temperature (38 °C between 0 and 54 h, 42 °C after 54 h) and a substrate concentration of 9%, while keeping a high cellulose conversion rate and final lactic acid concentration. A probable bottleneck for MSSF and its potential solution are also proposed in this paper.     

Bacteriological quality of broiler carcasses as affected by in-plant lactic acid decontamination

In an attempt to improve the bacteriological quality of broiler carcasses the bactericidal effect of treatments with 1% and 2% lactic acid was investigated. Bacterial colonisation was determined immediately after treatment, after the carcasses had been chilled and during storage at 0 degrees C. Examination included numbers of mesophilic aerobic and psychrotrophic aerobic colony-forming units (CFU), CFU of Enterobacteriaceae at 37 degrees C and CFU of Staphylococcus aureus. Immediately after treatment colonisation per gram skin was generally reduced by about 1 log. Initially 2% lactic acid was not found significantly more effective in reducing colony counts than 1%. However, treatment with 2% lactic acid suppressed post-decontamination colonisation with Enterobacteriaceae more effectively than 1% lactic acid, as determined after 15-18 days storage at about 0 degrees C. Lactic acid treatment was most effective when applied shortly before chilling. Successive treatment at three different stages during slaughtering did not increase reduction of colony counts. It is concluded that decontamination with 1-2% lactic acid at pH 2, when applied shortly before chilling, will markedly improve the bacterial safety and increase the refrigerated shelf life of broiler carcasses.     

细菌L-乳酸发酵的研究--耐高糖高酸菌株的选育

本文主要研究了L-乳酸发酵中耐高糖高酸菌株的选育及所选菌株的发酵特性情况.结果表明,出发菌株经离子注入诱变后,其生长的临界乳酸和葡萄糖浓度分别为24g/L和150g/L,并经耐高糖高酸的选育和驯化后,得到一株在产酸速率和最终L-乳酸产量方面都比原始对照菌株高的目的菌株LB1-1,其最终L-乳酸产量达到70g/L,出发菌株为43g/L.     

利用一株凝结芽孢杆菌发酵酸解玉米秸秆生产乳酸

该研究拟考察凝结芽孢杆菌（Bacillus coagulans）利用玉米秸秆生物炼制乳酸的效果。以凝结芽孢杆菌CGMCC No.7635为菌种,利用2%硫酸预处理后的玉米秸秆为碳源、20 g/L酵母粉为氮源,添加20 FPU/g纤维素酶后开展糖化发酵生产乳酸实验。结果表明,发酵65 h后可获得乳酸含量为（38.38±1.03） g/L,其中L-乳酸光学纯度为（99.23±0.22）%。进一步使用补料发酵工艺,添加经预处理的玉米秸秆,可最终获得乳酸含量为（82.56±1.28） g/L。建立的玉米秸秆生物炼制乳酸工艺操作简单、产物浓度高,具有工业应用潜力。     

Inactivation kinetics of Yersinia enterocolitica by citric and lactic acid at different temperatures

Inactivation of Yersinia enterocolitica by citric (1--20% w/v) and lactic (0.3--4.0% v/v) acids at different temperatures (4, 20, 40 degrees C) has been investigated. Inactivation effect of citric and lactic acids was dependent on time and temperature of exposure and acid concentration. Survival curves of Y. enterocolitica suspended in citric acid solutions at 4 and 20 degrees C displayed a shoulder followed by an exponential inactivation, but at 40 degrees C a shoulder was not observed. At all temperatures investigated, survival curves of Y. enterocolitica suspended in lactic acid solutions were linear or slightly concave upwards. A mathematical model based on the Weibull distribution accurately described the kinetics of inactivation of Y. enterocolitica by both acids. The influence of the citric acid concentration on Y. enterocolitica resistance was independent of the treatment temperature. However for lactic acid, the influence of the acid concentration on microbial inactivation depended on the temperature. At any temperature investigated, lactic acid was significantly more effective than citric acid.     

乳酸菌液态发酵兔肉的研究

采用乳酸菌液态发酵法泡制免肉，研制出一种具有泡菜风味的兔肉食品。     

乳酸菌抗真菌活性及其抑制真菌毒素的效果

讨论了乳酸菌抗真菌的活性及其清除真菌毒素的3种可能机制，即①乳酸菌通过对霉菌生长的直接抑制，从而抑制真菌毒素的形成；②通过产生代谢产物抑制真菌菌株或降解真菌毒素到无毒或毒性较低的化合物，以此降低真菌毒素的危害；③借助乳酸菌细胞壁与真菌毒素(黄曲霉毒素B1和玉米赤霉烯酮)的物理结合来清除介质中的毒素危害。乳酸菌的抗真菌活性和清除霉菌毒素的能力显然受到菌株、细胞浓度、细胞处理方式和环境条件的影响。新型发酵乳菌株筛选过程中应该考虑乳酸菌菌株的抗真菌活性及其清除真菌毒素的能力。     

Kinetic analysis and mathematical modeling of growth and lactic acid production of Lactobacillus casei var. rhamnosus in milk whey

Lactobacillus casei is a lactic acid bacterium (LAB) that colonizes diverse ecological niches and that has found broad commercial application. The aim of this study was to characterize the kinetics of biomass production, lactic acid production, and substrate consumption of Lactobacillus casei var. rhamnosus cultured in deproteinized milk whey. Batch culture experiments were performed in an instrumented, 2-L, stirred tank bioreactor using different inoculum concentrations (0.5 to 1.0 g/L) and lactose levels (35 to 70 g/L). The time series of experimental data corresponding to biomass growth, lactose consumption, and lactic acid formation were differentiated to calculate the corresponding kinetic rates. Strong exponentially dependent product inhibition effects were evident at low lactic acid concentrations, and lactic acid production rate was partially associated with biomass growth. A mathematical model is presented that reproduces the experimental lactose, biomass, and lactic acid concentration profiles.     

Decontamination with lactic acid/sodium lactate buffer in combination with modified atmosphere packaging effects on the shelf life of fresh poultry.

The effect of the treatment with various concentrations (2%, 5%, 7.5% and 10% w/v) of lactic acid/sodium lactate buffer (pH 3.0) combined with modified atmosphere packaging (MAP) (90% CO2/10% O2) on the shelf life and organoleptic quality of fresh chicken legs stored at 6 degrees C was investigated. The CO2 concentration of all samples packed in modified atmosphere (MA) decreased during the first 3 days of storage, followed by a gradual increase after the third day, while O2 showed a corresponding decrease. The buffering capacity of the buffer systems seem to be sufficient to maintain a low pH of the skin during storage. Legs treated with 2, 5, 7.5, and 10% (w/v) lactic acid/sodium lactate buffer (pH 3.0) combined with MAP have a shelf life at 6 degrees C of 14, 15, 16 and 17 days, respectively. The shelf life when the product was not treated with lactic acid was 1, 2.3 and 4 days shorter, respectively.     

酸和盐胁迫对乳酸菌活性的影响

该研究以13株食品常见乳酸菌为研究对象,考察酸和盐胁迫对其活性的影响,探究这13株乳酸菌的最适酸、盐生长条件及耐酸、耐盐能力。结果表明,适当的低盐浓度（1%、2%）对部分乳酸菌的生长有促进作用,植物乳杆菌和副干酪乳杆菌的最适盐浓度为1%,保加利亚乳杆菌和嗜酸乳杆菌的最适盐浓度为2%;盐浓度进一步增大,13株乳酸菌的生长受到抑制;盐浓度为10%时,除戊糖片球菌、乳酸乳球菌乳酸亚种、嗜热链球菌和乳酸片球菌外,其余9株菌的生长抑制率都＞95%。当pH值为5～7时,13株乳酸菌都生长良好,pH=6时,7株乳酸菌活性均最高;随着酸胁迫的增强,13株乳酸菌生长受抑制程度增大;pH为1～3时,13株乳酸菌的生长抑制率都＞90%,高盐及高酸对9株杆菌的抑制作用强于4株球菌。     

清香型白酒酒醅中乳酸高产菌株的筛选及乳酸的分离纯化

该研究以分离自清香型白酒酒醅的10株乳酸菌为研究对象，采用溶钙圈法和液体发酵法从中筛选高产乳酸菌株，并对其产乳酸条件进行考察；然后通过活性炭和离子交换柱对乳酸进行分离纯化，并通过高效液相色谱（HPLC）法检测乳酸纯度。结果表明，植物乳杆菌（Lactobacillus plantarum）SL32-2为高产乳酸的菌株，其在高粱糖化液中产乳酸的最佳发酵温度和初始pH值分别为35 ℃和7.0。活性炭对其发酵液的最适处理条件为活性炭添加量1.5 g/100 mL、处理温度60 ℃、处理时间2 h，此时脱色率、脱糖率和脱蛋白率分别为72.65%、3.75%和85.81%。经离子交换柱进一步纯化后，乳酸总得率为51.12%，其中阴离子交换柱的洗脱液中乳酸纯度较高。     

Inhibitors of lactic acid fermentation in Spanish-style green olive brines of the Manzanilla variety

Frequently, a delay or lack of lactic acid fermentation occurs during the processing of Spanish-style green olives, in particular of the Manzanilla variety. Many variables can affect the progress of fermentation such as temperature, nutrients, salt concentration, antimicrobials in brines, and others. In this study, it was demonstrated that an inappropriate alkaline treatment (low NaOH strength and insufficient alkali penetration) allowed for the presence of several antimicrobial compounds in brines, which inhibited the growth of Lactobacillus pentosus. These substances were the dialdehydic form of decarboxymethyl elenolic acid either free or linked to hydroxytyrosol and an isomer of oleoside 11-methyl ester. Olive brines, from olives treated with a NaOH solution of low concentration up to 1/2 the distance to the pit, contained these antimicrobials, and no lactic acid fermentation took place in them. By contrast, a more intense alkaline treatment (2/3 lye depth penetration) gave rise to an abundant growth of lactic acid bacteria without any antimicrobial in brines. Therefore, the precise cause of stuck fermentation in Manzanilla olive brines was demonstrated for the first time and this finding will contribute to better understand the table olive fermentation process.     

酸奶和乳酸奶饮料的高品质甜味剂——蔗糖素

<正> 在我国,酸奶和乳酸奶饮料被认为是具有营养和保健功能的食品,相当流行。然而,这类产品往往很甜,影响了其保健的形象。有鉴于此,许多生产商已在酸奶和乳酸奶饮料中以蔗糖和强力甜味剂混合进行加甜。 1997年3月,一种新型的强力甜味剂—蔗糖素获批准在中国使用,为我国的酸奶和乳酸奶饮料生产商带来了喜讯。这种甜味剂是第一种采用蔗糖制成的强力甜味剂,具有像蔗糖一样的味道,其甜度比蔗糖平均高出600倍,且不会产生热量,不会引起龋齿。