强化发酵对小米淀粉分子结构及老化特性的影响

利用自然发酵液中对淀粉老化特性起主要作用的菌种(乳酸菌:戊糖片球菌、植物乳杆菌、屎肠球菌,酵母菌:酿酒酵母,芽孢菌)强化发酵,研究强化发酵对小米淀粉分子结构及老化特性的影响,为剖析自然发酵对淀粉老化特性的改性机理提供理论基础及数据支持,为开发发酵小米新途径、生产小米发酵剂提供依据。采用0.2 g/100 m L的Na OH提取发酵后的小米淀粉,研究强化发酵对小米淀粉颗粒特性、红外光谱、分子量及老化特性的影响。结果如下:发酵并未改变淀粉的偏光十字;自然发酵后小米淀粉表面被侵蚀,强化发酵后淀粉颗粒表面侵蚀迹象变重,孔道加深且数量增多;自然发酵后小米淀粉官能团区的峰位未变,强化发酵小米淀粉指纹区图谱部分消失,且自然发酵及强化发酵小米淀粉的特征峰强度减弱;强化发酵后I区的重均、数均分子量升高,而自然发酵重均、数均分子量略有降低,但II区二者的重均、数均分子量均降低;自然发酵及强化发酵后淀粉的回生值及最终黏度降低。发酵使淀粉的分子结构发生改变,短期抗老化性能提高。     

自然发酵对小米淀粉分子结构及凝胶特性的影响

研究自然发酵对小米淀粉凝胶特性及分子结构的影响,旨在为发酵小米淀粉改性机理的研究提供理论基础,为实现机械化、产业化生产发酵小米制品提供科学依据。采用内蒙古黄金苗小米自然发酵144 h,研究发酵对小米淀粉分子结构的影响,分析小米淀粉凝胶特性的变化,结果:自然发酵使小米淀粉的颗粒表面遭到侵蚀,但发酵未改变淀粉的A型结晶;发酵后淀粉的基团峰位未发生变化,但峰强减弱;发酵后Ⅰ区(支链淀粉)、Ⅱ区(直链淀粉)的重均分子质量降低,数均分子质量升高,未发酵小米淀粉的重均分子质量为2.5×10~4~5.9×10~5 g/mol,发酵后小米淀粉重均分子质量为2.2×10~4~5.4×10~5 g/mol。发酵后小米淀粉的回生值、最终黏度较未发酵小米淀粉降低425、470 m Pa·s;糊化温度、热焓值分别上升1.62℃、7.05 J/g;发酵后淀粉凝胶的硬度降低60.735 g,弹性降低0.707,且发酵96 h后,淀粉的凝胶特性基本趋于平稳。自然发酵后小米淀粉的分子结构发生变化,淀粉的凝胶特性改变,更适宜生产利用淀粉抗老化特性制得的产品。     

不同乳酸菌发酵剂对发酵红肠品质的影响

为研究乳酸菌发酵对红肠品质的影响,将发酵技术应用于本无发酵工艺的红肠制品中,筛选出能够提高红肠品质的乳酸菌发酵剂。分别将常应用于发酵肉制品的7 种商业乳酸菌发酵剂（木糖葡萄球菌＋戊糖片球菌（THM-17）、木糖葡萄球菌＋清酒乳杆菌＋类植物乳杆菌（PRO-MIX5）、木糖葡萄球菌＋肉葡萄球菌＋清酒乳杆菌（WBL-45）、木糖葡萄球菌＋戊糖片球菌＋植物乳杆菌（VHI-41）、木糖葡萄球菌＋戊糖片球菌＋植物乳杆菌（SHI-59）、肉葡萄球菌＋木糖葡萄球菌（WBX-43）和戊糖片球菌＋木糖葡萄球菌＋肉葡萄球菌＋乳酸片球菌（VBM-60））及8 种单菌（弯曲乳杆菌、戊糖乳杆菌、清酒乳杆菌-1、戊糖片球菌、木糖葡萄球菌、肉葡萄球菌、清酒乳杆菌-2、植物乳杆菌）以107 CFU/g的接种量接种至腌制后的肉馅中,拌馅灌肠后于35 ℃、80%湿度条件下发酵12 h,取样测定发酵后样品的乳酸菌数和细菌总数,再经干燥、蒸煮、烟熏、烘烤制得成品,测定其感官、pH值、色差、质构、亚硝酸盐、硝酸盐、生物胺及N-亚硝胺含量等指标。结果表明：15 种发酵剂中以木糖葡萄球菌和植物乳杆菌2 种乳酸菌发酵剂应用效果较好,所制得产品pH值分别为5.26和5.04,色泽美观,弹性适中,亚硝酸盐残留量（10.84、10.13 mg/kg）低,可显著抑制N-亚硝胺的形成（N-二甲基亚硝胺含量分别为1.29、2.51 μg/kg）,生物胺总量较低。由此说明,木糖葡萄球菌和植物乳杆菌能够显著提高红肠产品的安全品质。     

生物发酵处理对小米淀粉分子结构及糊化特性的影响

采用0.2 g/100 m L NaOH溶液提取发酵后的小米淀粉,研究自然发酵及优势菌(乳酸菌、酵母菌)发酵后对小米淀粉颗粒特性、结晶度、官能团、分子质量、糊化及老化特性的影响。结果如下:乳酸菌、酵母菌发酵后,淀粉颗粒表面有明显的侵蚀迹象,而自然发酵淀粉颗粒表面侵蚀迹象较轻;乳酸菌发酵后小米淀粉的结晶度较自然发酵增加1.49%而酵母菌发酵减少0.33%;发酵并未改变小米淀粉官能团区的峰位,但特征峰强度减弱,乳酸菌、酵母菌发酵后小米淀粉指纹区图谱消失;未发酵小米淀粉重均分子质量为1.5×10~4~5.9×10~5 g/mol,自然发酵分子质量在2.1×10~4~5.4×10~5 g/mol,乳酸菌发酵分子质量为1.6×10~4~5.3×10~5 g/mol,酵母菌发酵分子质量为1.6×10~4~4.7×10~5 g/mol,乳酸菌、酵母菌发酵后支链淀粉长链及直链淀粉比例减少而中间及短支链淀粉的比例相对增加;乳酸菌、酵母菌发酵96 h糊化温度较自然发酵下降0.84℃和1.13℃,热焓值上升1.00 J/g和0.78 J/g;二者的回生值较自然发酵分别下降743、471 mPa·s。自然发酵的优势菌(乳酸菌、酵母菌)使小米淀粉的分子结构、糊化及老化特性发生明显变化,并在小米自然发酵过程中起主导作用。     

自然发酵风干肠中乳酸菌的分离与鉴定

以自然发酵风干肠为研究对象,分析了细菌总数和乳酸菌菌数的变化情况,结果表明,乳酸菌为风干肠发酵过程中的优势菌群.通过对风干肠中乳酸菌的分离鉴定,共分离出戊糖片球菌(Pediococcus pentosaceus)、乳酸乳球菌乳酸亚种(Lactococcus lactis subsp lactis)、短乳杆菌(Lactobacillus brevis)、弯曲乳杆菌(Lactobacillus curvatus)和发酵乳杆菌(Lactobacilus fermentum)5株乳酸菌.24h产酸速率测定结果表明,弯曲乳杆菌＞短乳杆菌＞乳酸乳球菌乳酸亚种＞戊糖片球菌＞发酵乳杆菌.     

中式发酵香肠用发酵剂混合菌种的研究

将玫瑰色微球菌、干酪乳杆菌、植物乳杆菌、戊糖片球菌、嗜酸乳杆菌、木糖葡萄球菌采用正交试验法组合为 9组发酵剂 ,考察了发酵肠的 pH值、水分含量、乳酸菌活菌数、感官品质等的变化规律。结果表明 ,混合球菌更适合于作为发酵肠的发酵剂。经优化组合 ,筛选出了由葡萄球菌、干酪乳杆菌、玫瑰色微球菌、嗜酸乳杆菌、戊糖片球菌等混合菌制备的发酵剂 ,是符合发酵肠GMP要求的快速发酵剂 ,且经济合理 ,并赋予产品良好的风味。发酵条件 :37℃ ,RH >80 % ,2 0h。     

川西藏区牦牛酸醡肉中产蛋白酶和淀粉酶菌株的分离鉴定及其生理特性分析

实验从川西藏区牦牛酸醡肉中分离获得了7株具有产蛋白酶或淀粉酶的菌株。通过16SrDNA和ITS基因测序鉴定为淀粉液化芽孢杆菌、多粘类芽孢杆菌、枯草芽孢杆菌亚种、植物乳杆菌、戊糖片球菌、镰刀霉、黑曲霉;其中淀粉液化芽孢杆菌、多粘类枯草芽孢杆菌、枯草芽孢杆菌亚种可同时产蛋白酶和产淀粉酶,且酶活力较高,属于优质发酵菌。     

5 种乳酸菌对库车小白杏发酵液理化性质及感官评价的影响

用戊糖片球菌、罗伊氏乳杆菌、鼠李糖乳杆菌、植物乳杆菌、嗜酸乳杆菌共5?种乳酸菌发酵库车小白杏，通过比较发酵液在发酵过程中的菌浓度、pH值、总可溶性固形物（total soluble solids，TSS）含量、超氧化物歧化酶（superoxide dismutase，SOD）活性等理化特性及发酵结束后的感官评价，筛选出一种或几种适合发酵库车小白杏发酵液的菌株。结果表明，发酵结束后，戊糖片球菌发酵库车小白杏发酵液的SOD活性达到252.63?U/g，活菌数达到8.07（lg（CFU/mL）），TSS含量降至17.1?°Brix，感官总体评价值最佳达到97%。植物乳杆菌发酵的库车小白杏发酵液的SOD活性达到275.87?U/g，感官总体评价几何平均（geometrical mean，GM）值达到88%。嗜酸乳杆菌发酵的库车小白杏发酵液速度最快，活菌数最终达到9.95（lg（CFU/mL）），TSS含量降至16.6?°Brix，但感官总体评价GM值仅为79%。综上所述，戊糖片球菌是最适合发酵库车小白杏的菌种，而植物乳杆菌和嗜酸乳杆菌的适合度仅次于戊糖片球菌。通过比较5?种乳酸菌发酵的库车小白杏发酵液的理化性质和感官评价，可以得出结论，戊糖片球菌最适合发酵库车小白杏。     

湘西传统酸鱼中乳酸菌的分离及特性研究

对从湘西传统酸鱼4个不同发酵阶段分离的196株乳酸菌种类进行了研究,分离出的乳酸菌主要包括植物乳杆菌、戊糖片球菌、食品乳杆菌、明串珠菌、肠球菌及干酪乳杆菌等,并且这些乳酸菌在发酵过程中呈现出一种动态的变化进程。同时对分离到的乳酸菌进行了一系列的生理生化试验;产酸速率实验,耐食盐、耐亚硝盐实验,耐酸及耐胆盐实验,氨基酸脱羧酶实验以及抑菌实验,选育出具有较好的发酵剂潜力的3株植物乳杆菌和1株戊糖片球菌。     

PCR-DGGE分析吉林市传统发酵豆酱中细菌的多样性

该研究以吉林市农家传统发酵豆酱为试材,利用PCR-DGGE技术分析豆酱不同发酵阶段细菌的生物多样性及变化规律。结果表明,豆酱发酵过程中细菌菌群种类较为丰富,主要有戊糖片球菌（Pediococcus pentosaceu）、乳明串珠菌（Leuconostoc lactis）、葡萄球菌属（Staphylococcus sp.）、屎肠球菌（Enterococcus faecium）、解淀粉芽孢杆菌（Bacillus amyloliquefaciens）、弗氏柠檬酸杆菌（Citrobacter freundii）、霍氏肠杆菌（Enterobacter hormaechei）、产酸克雷伯氏菌（Klebsiella oxytoca）、不可培养杆菌（uncultured bacterium）。其中乳酸菌是发酵过程中的优势菌,对豆酱的风味起着主要作用。传统豆酱发酵过程中菌群有一定的亲缘性,菌落结构变化较小,为传统发酵豆酱的进一步开发和研究提供理论基础。     

南宁地区米酒曲源乳酸菌在糯米汁中氨基酸和有机酸代谢特征研究

该研究采用纯培养技术对广西省南宁地区米酒曲中乳酸菌多样性进行了解析,旨在揭示其分离株在糯米汁中产氨基酸和有机酸的特征。结果表明,11个样品共分离出20株乳酸菌,分别被鉴定为戊糖片球菌（Pediococcus pentosaceus）、融合魏斯氏菌（Weissella confuse）、类肠膜魏斯氏菌（Weissella paramesenteroides）、屎肠球菌（Enterococcus faecium）、台湾乳球菌（Lactococcus taiwanensis）、植物乳杆菌（Lactobacillus plantarum）和戊糖乳杆菌（Lactobacillus pentosus）,其中戊糖片球菌（P. pentosaceus）占分离株的35%,为南宁地区米酒曲中的优势乳酸菌。选取除屎肠球菌（E. faecium）外的16株乳酸菌分离株进行糯米汁纯种发酵,结果发现所有菌株均不产氨基酸,乳酸为糯米汁中主要有机酸。主成分分析（PCA）结果表明,融合魏斯氏菌（W. confuse）HBUAS53367产有机酸的能力较强,可用于后续进一步研究。     

Microbiological and fermentation characteristics of togwa,a Tanzanian fermented food

Selected microbiological and metabolic characteristics of sorghum, maize, millet and maize-sorghum togwa were investigated during natural fermentation for 24 h. The process was predominated by lactic acid bacteria (LAB) and yeasts. The mesophiles, lactic acid bacteria, and yeasts increased and the Enterobacteriaceae decreased to undetectable levels within 24 h. The isolated microorganisms were tentatively identified as Lactobacillus plantarum, Lactobacillus brevis, Lactobacillus fermentum, Lactobacillus cellobiosus, Pediococcus pentosaceus, Weissella confusa, Issatchenkia orientalis, Saccharomyces cerevisiae, Candida pelliculosa and Candida tropicalis. The pH decreased from 5.24-5.52 to 3.10-3.34. Maltose increased initially and then decreased, fructose decreased and glucose levels increased during the first 12 h of fermentation. The organic acids detected during fermentation included DL-lactic, succinic, formic, pyruvic, citric, pyroglutamic and uric acid. Lactate was the predominant acid and increased significantly with time. The volatile organic compounds (VOC) detected included acetaldehyde, 2-methyl-propanal, 2-methyl-butanal, 3-methyl-butanal, ethanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, diacetyl and acetoin. Ethanol was the predominant VOC and it increased significantly with time.     

Use of starter cultures of lactic acid bacteria and yeasts in the preparation of togwa,a Tanzanian fermented food

Starter cultures of lactic acid bacteria (Lactobacillus brevis, Lactobacillus cellobiosus, Lactobacillus fermentum, Lactobacillus plantarum and Pediococcus pentosaceus) and yeasts (Candida pelliculosa, Candida tropicalis, Issatchenkia orientalis and Saccharomyes cerevisiae) isolated from native togwa were tested singly or in combination for their ability to ferment maize-sorghum gruel to produce togwa. All species of bacteria showed an ability to ferment the gruel as judged by lowering the pH from 5.87 to 3.24-3.49 and increasing the titratable acidity from 0.08% to 0.30-0.44% (w/w, lactic acid) in 24 h. Yeasts used singly showed little activity within 12 h, but lowered the pH to 3.57-4.81 and increased the acidity to 0.11-0.21% in 24 h. Yeasts in co-culture with lactic acid bacteria (LAB) had a modest effect on the final acidity (P<0.05). The number of lactic acid bacteria and yeasts increased while the Enterobacteriaceae decreased with fermentation time. The pH was lowered and lactic acid produced significantly (P<0.05) fastest in natural togwa fermentation and in samples fermented by L. plantarum or L. plantarum in co-culture with I. orientalis. The content of fermentable sugars was reduced during fermentation. Most volatile flavour compounds were produced in samples from fermentation by P. pentosaceus and I. orientalis in co-culture with either L. plantarum or L. brevis.     

Characterization of lactic acid bacteria isolated from a Thai low-salt fermented fish product and the role of garlic as substrate for fermentation

Lactic acid bacteria (LAB) isolated from raw materials (fish, rice, garlic and banana leaves) and processed som-fak (a Thai low-salt fermented fish product) were characterized by API 50-CH and other phenotypic criteria. Lactococcus lactis subsp. lactis and Leuconostoc citreum were specifically associated with fish fillet and minced fish, Lactobacillus paracasei subsp. paracasei with boiled rice and Weisella confusa with garlic mix and banana leaves. In addition, Lactobacillus plantarum, Lactobacillus pentosus and Pediococcus pentosaceus were isolated from raw materials. A succession of aciduric, homofermentative lactobacillus species, dominated by Lb. plantarum/pentosus, was found during fermentation. In total, 9% of the strains fermented starch and 19% fermented garlic, the two main carbohydrate components in som-fak. The ability to ferment garlic was paralleled by a capacity to ferment inulin. An increased percentage of garlic fermenting strains was found during fermentation of som-fak, from 8% at day 1 to 40% at day 5. No starch fermenting strains were isolated during fermentation. Three mixed LAB cultures, composed of either starch fermenting Lc. lactis subsp. lactis and Lb. paracasei subsp. paracasei, or garlic fermenting Lb. plantarum and Pd. pentosaceus, or a combination of these strains were inoculated into laboratory prepared som-fak with or without garlic. In som-fak without garlic, pH was above 4.8 after three days, irrespective of addition of mixed LAB cultures. The starch fermenting LAB were unable to ferment som-fak and sensory spoilage occurred after three days. Fermentation with the combined mix of starch and garlic fermenting strains led to production of 2.5% acid and a decrease in pH to 4.5 in two days. The fermentation was slightly slower with the garlic fermenting strains alone. This is the first report describing the role of garlic as carbohydrate source for LAB in fermented fish products.     

The occurrence and growth of microorganisms during the fermentation of fish sausage

Minced fish (mullet) sausage mixes containing added sugar, salt, nitrate, nitrite and spices were fermented (48 h, 30 degrees C) by indigenous flora or by a starter culture (Pediococcus acidilactici) and the microbial ecology and behaviour of various bacteria was monitored. Pediococcus pentosaceus and Lactobacillus plantarum dominated the indigenous fermentation, achieving populations of 10(7)-10(8) cfu/g by 48 h, and decreasing the pH of the mix to 4.5-4.7. Significant growth (10(5)-10(7) cfu/g) of Staphylococcus warneri, Staphylococcus aureus, Staphylococcus epidermidis. Micrococcus varians and Micrococcus luteus also occurred during this fermentation. Less growth was exhibited by Bacillus megaterium and yeasts. Pediococcus acidilactici dominated the fermentation when it was inoculated as a starter culture, but indigenous lactic acid bacteria (P. pentosaceus and L. plantarum) also grew to 10(7)-10(8) cfu/g. The growth of other bacteria and yeasts was restricted during fermentation with starter culture. Inoculated Escherichia coli, Salmonella typhimurium, Salmonella sofia, and Staphylococcus aureus grew to 10(6)-10(7) cfu/g in the sausage mix during indigenous fermentation. Lesser growth occurred for Bacillus cereus, Clostridium perfringens and Vibrio parahaemolyticus. Growth of these bacteria was significantly inhibited in sausage mix fermented with P. acidilactici.     

金鲳鱼发酵菌株筛选及其生物学特性与风味形成评价

为了有效控制发酵鱼的品质及其保质期,从传统发酵金锠鱼中筛选适合作发酵剂的菌株。以过氧化氢酶阳性、耐盐性、抗菌性及不产生组胺为筛选指标,采用稀释分离法分离目标菌株,并对其生物学特性、发酵风味与口感进行评价。结果显示,从发酵金锠鱼中分离到的38株菌株中,筛选出的两株潜在发酵菌株（zh-b和zh-f）经形态鉴定与16S rRNA分析鉴定为戊糖片球菌（Pediococcus pentosaceus）和植物乳杆菌（Lactobacillus planta-ruma）,其最适温度分别为20与30 ℃,最适pH为5、6。两株菌对金黄色葡萄球菌与大肠标杆菌均具有抗菌活性,但植物乳杆菌抗菌活性更好,且产酸能力明显高于戊糖片球菌。电子鼻对发酵产物进行测定,发现戊糖片球菌产生的甲基类、硫化物、氮氧化合物、醇类或醛酮类和有机芳香硫化物响应值（64.10、57.98、44.75、40.22和19.93）高于植物乳杆菌（5.50、34.11、10.68、0和8.95）,是香气成分的主要贡献者。电子舌测定发现,两株菌均具有产生鲜味、鲜回味的能力,且戊糖片球菌的味值分别为14.32、6.64,明显高于植物乳杆菌产生鲜味、鲜回味（3.20、2.90）,但只有植物乳杆菌产生酸味。另外,两株菌也产生非常少量的苦味。研究为两株菌作为发酵剂用于规模化生产发酵金鲳鱼提供依据。     

秭归地区鲊广椒中乳酸菌及细菌多样性研究

该研究在采用纯培养方式对秭归地区鲊广椒中乳酸菌进行分离鉴定的基础上，进一步采用MiSeq高通量测序技术对其细菌多样性进行解析。结果表明，从14个鲊广椒中分离出的43株疑似乳酸菌被鉴定为乳酸杆菌属（Lactobacillus）和屎肠球菌属（Enterococcus），鉴定到的种主要有植物乳杆菌（Lactobacillus plantarum）、敏捷乳杆菌（Lactobacillus alimentarius）和屎肠球菌（Enterococcus faecium），占所有分离株的86.05%，其中L. plantarum占所有分离株的60.74%，为优势菌种。测序结果显示，鲊广椒中主要的细菌类群为隶属于硬壁菌门（Firmicutes）的Lactobacillus和戊糖片球菌属（Pediococcus）以及隶属于变形菌门（Proteobacteria）的假单胞菌属（Pseudomonas），其平均相对含量分别为47.85%、13.29%和21.31%，其中乳酸菌含量累计达61.14%。由此可见，秭归地区鲊广椒中蕴含了较为丰富的乳酸菌资源，但同时也存在Pseudomonas等具有致病性的菌属。