调理预制烤猪肉冷藏过程中微生物生长特性的研究

采用平板培养方法测定微生物的生长特性,结果显示:4℃贮藏过程中托盘包装的样品在贮藏第12天时,细菌总数为7.87 lg cfu/g,发生腐败变质,其优势腐败菌为假单胞菌、热杀索丝菌。真空包装样品的细菌总数显著低于托盘包装,接近腐败,其优势腐败菌为假单胞菌和乳酸菌。聚合酶链式反应-变性梯度凝胶电泳(PCRDGGE)法对微生物生长特性的研究结果表明:托盘包装样品贮藏末期时的电泳条带明显比真空包装的样品更粗、更亮,表明真空包装样品腐败菌的数量少于托盘包装的样品。贮藏期间,从两种包装样品中不仅检测出假单胞菌、热杀索丝菌、葡萄球菌和乳酸菌,而且还检测出节杆菌和气单胞菌。通过菌群相似性分析得知,调理预制烤猪肉在不同包装条件下贮藏0 d与12 d样品的菌群结构相似性较低,而贮藏第9天与第12天样品的菌群结构相似性较高,即贮藏前期和贮藏后期菌落结构有显著性变化(P0.5),说明在贮藏后期优势腐败菌对其它微生物的生长有抑制作用。研究表明:平板培养结合PCR-DGGE方法可使调理预制烤猪肉冷藏过程中微生物生长特性的测定结果更为准确、全面。     

壳聚糖-普鲁兰多糖复合抗菌保鲜膜对冷鲜牛肉的保鲜效果

开发了一种适用于冷鲜牛肉保鲜的具有抗菌功能的可食性抗菌保鲜膜。将4 mg/mL的ε-聚赖氨酸(ε-PL)添加到壳聚糖-普鲁兰多糖溶液中,制备具抗菌功能的可食性复合抗菌保鲜膜,并验证该保鲜膜具有良好的理化特性和抗菌效果。冷鲜牛肉贮藏过程中优势致病菌(大肠O157:H7,单增李斯特菌和沙门氏菌)和菌落总数等指标检测结果表明,贮藏9天,对照组菌落总数就达到8.09 lg(CFU/g),而处理组增长较缓慢,第13天为5.94lg (CFU/g)。贮藏末期,处理组大肠O157:H7、单增李斯特菌和沙门氏菌较对照组分别减少了5.12,4.47 lg(CFU/cm2)和5.54 lg(CFU/cm2)。通过比较分析冷鲜牛肉贮藏过程中感官、质地、挥发性盐基氮(TVBN)、pH值、色度指标(a*/b*)等指标,表明该膜对于减缓冷鲜牛肉品质劣变具有显著效果。该保鲜膜对于控制牛肉品质劣变、延长货架期具有良好效果。     

气调包装酱卤鸭翅贮藏过程中菌群结构分析

运用传统细菌平板培养和聚合酶链式反应-变性梯度凝胶电脉方法研究气调包装酱卤鸭翅15 ℃贮藏过程中微生物菌群结构变化。细菌总数计数结果表明,产品生产的卫生条件较好,细菌初始污染菌数较低（小于2（lg（CFU/g）））,至贮藏第9天左右产品细菌总数超过4（lg（CFU/g））。变性梯度凝胶电脉指纹图谱结果表明,贮藏初期产品的初始污染菌主要为不动杆菌属,至贮藏末期,产品中的主要菌群有嗜冷杆菌、莫拉氏菌、链球菌等,其中嗜冷杆菌属成为产品贮藏末期的优势菌。     

北京烤鸭加工过程中菌相变化规律及其特征

应用微生物选择性培养并结合细菌系统鉴定的方法对北京烤鸭加工过程中的菌相变化规律及其特征进行分析和研究。结果显示:乳酸菌是整个加工过程中的主要微生物为3.41～5.97(lg(CFU/g)),受温度影响较小;假单胞菌属在加工前期(解冻、清洗)分别是4.77(lg(CFU/g))和4.39(lg(CFU/g)),为仅次于乳酸菌的主要微生物,受温度影响较大;肠杆菌科在加工中期(烫皮、晾挂)与乳酸菌达到相同数量级分别是3.18(lg(CFU/g))和5.96(lg(CFU/g)),成为仅次于乳酸菌的主要微生物。烤鸭的烫皮、烤制工序能有效降低各类菌的含量,灭菌后菌含量低于1.00(lg(CFU/g));晾挂工序是整个加工过程中微生物出现增长的阶段,各类菌的数值在4.29～6.36(lg(CFU/g)),因此需严格控制晾挂的温度、湿度和时间,以确保产品的安全性。本研究表明,乳酸菌、假单胞菌属和肠杆菌科是北京烤鸭加工过程中的主要微生物。     

传统四川腊肠及浅发酵香肠调料特性研究

对常用于四川传统酱香型风干腊肠辅料中的调料豆瓣酱、豆豉、醪糟和豆腐乳等进行理化及微生物指标测定,并对其在腊肠中的作用特性进行分析。结果显示:豆瓣酱的乳酸菌、微球菌、酵母菌和霉菌含量分别为5.94,6.31,3.31,2.84lg CFU/g,较丰富的微生物显然利于腊肠通过发酵形成浓郁风味,还可使腊肠在不添加硝盐时仍然呈现较佳色泽;豆豉微生物含量大致为乳酸菌5.67lg CFU/g、微球菌6.05lg CFU/g、酵母菌2.79lg CFU/g、霉菌2.22lg CFU/g;醪糟主要含酵母菌,含量高达5.26lg CFU/g;豆腐乳含酵母菌4.99lg CFU/g、霉菌3.00lg CFU/g,这些调料均具有助发酵和抑制腊肠腐败和酸败,赋予腊肠醇香风味,或部分替代食盐等作用。以此为基础,对开发的一种类似于传统酱香型风干腊肠的"浅发酵香肠"的调料进行了特性分析,其理化和微生物指标为pH 4.64,乳酸菌4.06lg CFU/g,微球菌4.29lg CFU/g,酵母菌3.99lg CFU/g,霉菌2.00lg CFU/g,此特性将对浅发酵香肠风味发挥重要影响。     

流化冰结合静压式挤压技术对冰藏大黄鱼菌相变化的影响

以传统冰藏(碎冰)为对照研究了流化冰以及流化冰结合静压式挤压(300 MPa,10 min)对大黄鱼保鲜效果的影响,并结合细菌16S rDNA PCR扩增和测序以及生理生化鉴定法研究了贮藏过程中菌相的变化。结果显示,希瓦氏菌为大黄鱼贮藏过程中的优势腐败菌。流化冰贮藏抑制了微生物的增长,菌落总数低于同期冰藏组。在贮藏末期,流化冰组鱼肉中发现了一定比例耐盐性的革兰氏阳性菌,如玫瑰小球菌(19.4%)、乳酸菌(2.9%)和葡萄球菌(4.3%),这可能与流化冰含有一定的盐分有关。静压式挤压具有一定的灭菌效果,处理后新鲜大黄鱼鱼肉中的菌落总数减少了0.4 lg CFU/g,对革兰氏阴性菌作用较强,结合流化冰贮藏能够有效降低致腐能力较强的革兰氏阴性菌比例,具有一定的应用前景。     

原料肉贮藏时间对牛肉发酵香肠中微生物菌相变化和蛋白质降解的影响

采用传统微生物计数、高通量测序、凯氏定氮、高效液相色谱等方法,探究牛肉宰后0～4 ℃下不同贮藏时间（0、12、24、36 h）对发酵香肠加工过程中微生物菌相变化、蛋白质降解及其相关性的影响。结果显示,随着牛肉贮藏时间的延长,香肠中菌落总数、大肠菌群数、菌群多样性和丰富度以及蛋白质降解指标均呈上升趋势,总游离氨基酸含量呈下降趋势;香肠成熟阶段中总挥发性盐基氮含量与总生物胺含量之间呈极显著正相关（P＜0.01）。其中,贮藏36 h牛肉加工的香肠与未经贮藏牛肉加工的香肠对比,菌落总数平均值由2.40×107 CFU/g增加到4.03×107 CFU/g（P＜0.05）,反映菌群多样性的Shannon指数平均值由1.39增长至2.89,优势菌群由整个加工阶段均为葡萄球菌变成前期为魏斯氏菌,后期为葡萄球菌;总游离氨基酸含量平均值由7.09 mg/g减少至6.44 mg/g,总生物胺含量平均值由92.14 mg/kg增长为117.42 mg/kg（P＜0.05）。结论：控制原料牛肉贮藏时间可以有效减少香肠中微生物的总量,降低菌群多样性,抑制蛋白质的降解,减缓生物胺的积累,从而保障发酵香肠的安全性。     

低温下鲜切莲藕菌相分析及货架期评价

采用不同选择性培养基分析真空包装鲜切莲藕的菌相组成,并采用菌落形态、显微形态观察及生理生化方法予以鉴定;建立Gompertz模型揭示莲藕主要腐败微生物在4℃恒温贮藏过程中的变化规律;基于感官分析,确定低温条件下鲜切莲藕货架期的微生物限量。结果发现,真空包装鲜切莲藕中主要菌相为乳酸菌属、肠杆菌科、假单胞菌属、酵母菌属,实验鉴定出乳酸菌属、肠杆菌科、假单胞菌属、酵母菌属各2株;经菌落形态、显微形态观察及生理生化鉴定,均符合相关科属特性。整个贮藏过程中,乳酸菌、肠杆菌、假单胞菌和酵母菌的数量变化趋势基本一致,其中乳酸菌延滞期最短,假单胞菌最大比生长率最高,酵母菌数量优势相对较大。该莲藕产品的货架期为10d左右,所对应的微生物数量级约107CFU/g。     

不同高阻隔包装材料对烤鸭微生物及菌群多样性的影响

为研究不同阻隔性包装材料对烤鸭品质影响的差异性,本研究采用3种不同类型高阻隔包装材料(镀氧化硅类、乙烯醇聚合物、聚偏二氯乙烯)对烤鸭进行真空包装,以聚乙烯/尼龙包装为对照,然后在4℃下分别贮藏21 d,检测此期间烤鸭的挥发性盐基氮(total volatile basic nitrogen,TVB-N)含量、肉色、微生物(菌落总数、乳酸菌和肠杆菌数),并用高通量测序技术观察了不同样品的微生物多样性变化。结果表明:镀氧化硅包装可以有效抑制TVB-N的产生,在贮藏第21天时其含量最低,且低于20 mg/kg,并可抑制微生物的生长;通过高通量测序技术观察了不同样品的微生物多样性变化,贮藏时间和包装材料对烤鸭的微生物菌落结构有明显影响,在贮藏过程中,乳酸菌菌属与魏斯氏菌属是镀氧化硅材料包装烤鸭样品的优势菌群;乳酸菌属、魏斯氏菌属、假单胞菌属、类香味菌属、肉食杆菌属是乙烯醇聚合物材料包装烤鸭的优势菌群;乳酸菌属、魏斯氏菌属、热杀索丝菌属、弧菌属是聚偏二氯乙烯材料包装烤鸭的优势菌群。对比发现,镀氧化硅类材料对假单胞菌、类香味菌属、热杀索丝菌等的抑制是其有效保持烤鸭的品质、延长其货架期的主要原因。综...     

不同包装方式对调理预制烤猪肉冰温贮藏中微生物和理化特性影响

本文研究不同包装方式对调理预制烤猪肉冰温(-1℃)贮藏中微生物和理化特性的影响。结果表明,-1℃冰温贮藏28 d后托盘包装样品的细菌总数(7.53 lg cfu/g)显著高于真空包装样品的细菌总数(5.54 lg cfu/g)(P0.05),其优势腐败菌为假单胞菌和热杀索丝菌。真空包装样品优势菌为热杀索丝菌、乳酸菌和假单胞菌。贮藏28 d后,托盘包装的样品红度(a*)值为9.88、p H为6.37、硫代巴比妥酸(TBARS)值达到了3.02 mg/kg、挥发性盐基氮(TVB-N)值为56.6 mg/100 g、感官基本不可接受,而真空包装的a*值为10.87、p H为6.13、TBARS值为1.62 mg/kg、TVB-N值为43.9 mg/100 g、感官仍有一定的可接受性。SDS-聚丙烯酰胺凝胶电泳结果表明贮藏期间真空包装样品的所有蛋白条带的强度强于托盘包装的样品,直到贮藏结束时,真空包装样品的蛋白条带仍然较粗且清晰。研究表明冰温结合真空包装可有效的延长调理预制烤猪肉的保质期。     

Anti-listerial inhibitory lactic acid bacteria isolated from commercial cold smoked salmon

The natural microflora of cold-smoked fish at the end of shelf-life are lactic acid bacteria (LAB). Some of these display a capacity to inhibit spoilage as well as several strains of pathogenic micro-organisms, e.g. Listeria monocytogenes which is isolated frequently from cold-smoked salmon (CSS). Eight batches of sliced vacuum-packed CSS from Norway, Scotland and Spain were collected at retail. Packs were stored at 5 degrees C and examined for chemical and microbiological characteristics, at purchase date and at expiration date. pH, water activity and salt content were similar to available data on lightly preserved fish products. There was a consistent pattern in the development of the microflora on CSS; the initial level of LAB was low on freshly produced CSS (10(2) cfu g(-1)); however, storage in vacuum packaging at refrigeration temperature was elective for LAB. At the end of the stated shelf-life these micro-organisms, represented mainly by Lactobacillus spp., attained ca.10(7) cfu g(-1) while Enterobacteriaceae counts were consistently lower (10(5) cfu g(-1)), which indicates the ability of LAB to grow and compete with few carbohydrates available and in the presence of moderate salt concentrations. L. monocytogenes was not found in any sample. Forty-one percent of LAB strains isolated exhibited inhibitory capacity against Listeria innocua, in a plate assay. A majority of the inhibitory effects were non-bacteriocinogenic, but nevertheless were very competitive cultures which may provide an additional hurdle for improved preservation by natural means.     

Drying Temperature and Time Affect Quality of Chinese-style Sausage Inoculated with Lactic Acid Bacteria

Lactobacillus plantarum, Streptococcus thermophilus and a commercial culture (DS-66) were used as starter culture for manufacturing Chinese-style sausage. The influence of drying temperature and time on the growth of lactic acid bacteria (LAB) and on changes in quality were determined. After drying the sausage at 370 and 45°C for 12 hr, the population of LAB had increased from an initial 10⁶ CFU/g to 10⁸ and 10⁷ CFU/g, respectively. The pH value was the lowest for the sausage dried at 37°C. Nitrite residuals decreased rapidly with increased drying time. Starter cultures increased the amino nitrogen level and suppressed ammonia nitrogen production.     

腌腊肉制品中乳酸菌的筛选鉴定及其在腊肠中的应用

为筛选适合传统腌腊肉制品的优良乳酸菌菌株,从多种农家自制传统腌腊肉制品中分离纯化出9株优势乳酸菌。通过发酵特性筛选,得到一株性状优良菌株10M-7,并制备该菌株的干粉发酵剂,以未接种发酵剂腊肠为对照,分析此发酵剂对腊肠感官品质和微生物变化的影响。结果表明,10M-7菌株具有良好的产酸特性和抑菌性能。根据形态学、生理生化特征和16S rRNA序列分析,鉴定其为植物乳杆菌,采用冷冻干燥法制备纯种发酵剂,并制作人工发酵腊肠。发酵剂组pH值在初期便迅速下降,且始终低于对照组;发酵剂组乳酸菌迅速生长繁殖,且葡萄球菌和大肠杆菌数量与对照组相比明显降低。感官评价表明,当添加量为10~4CFU/g原料肉时,能够很好地保持和改善产品风味,使产品整体感觉更好。     

SODIUM LACTATE EFFECTS ON MICROBIAL, SENSORY, AND PHYSICAL CHARACTERISTICS OF VACUUM-PACKAGED PORK SAUSAGE

Vacuum-packaged fresh meat products held at refrigeration temperatures have limited shelf-life expectancies, often due to growth of anaerobic lactic acid-producing bacteria. Agents that can suppress the growth of this group are beneficial. Fresh pork sausage, formulated to contain 0%, 1%, 2%, or 3% sodium lactate (SL), was vacuum packaged and stored at 4C for 0, 10, 17, 24, and 31 days. A trained sensory panel evaluated pork, salty, sour, and bitter flavors. Aerobic total plate counts (APC), anaerobic total plate counts (AnPC), aerobic lactic acid producers (ALC), anaerobic lactic acid producers (AnLC), TBA values, and pH were determined. SL depressed APC, AnPC, and AnLC. Addition of 1% SL extended shelf-life of vacuum-packaged fresh pork sausage by 1 week compared to controls; samples containing 2% and 3% SL had not reached spoilage level (log₁₀ 7.0 CFU/g) at the conclusion of this study. Addition of SL increased salty taste and prevented loss of pork flavor over time, but had no effect on sour or bitter flavors.     

直投式乳酸菌发酵剂的研制

本研究旨在研制出一种菌活高、使用简单,无需复杂的无菌操作技术与设备的直投式乳酸茵发酵剂,可用于发酵乳、泡菜以及动物饲料发酵和生产。本发酵剂以嗜酸乳杆菌LHlF为菌种,实验过程优化番茄汁增菌培养基的配方,细胞数目达4．25×10^10CFU／mL。最佳的抗冷冻保护剂的配方为：脱脂奶粉2．5％,甘油1％,葡萄糖2．5％,蔗糖1％,Vc2．5％。真空冷冻干燥的条件为4000r／min,20min离心获得菌体后真空冷冻干燥6h。通过优化的直投式乳酸菌发酵剂的活菌教可以i叁到1．27×10^12CFU／g;于4℃存放三个月后,乳酸菌活菌数仍i古互03×10^10CFU／g。因此,经过优化乳酸菌发酵条件及保护剂配方,所得的冻干型直投式菌种可用于乳品及动物饲料的发酵。     

Survival of Lactic Acid Bacteria in Commercial Frozen Yogurt

Survival of constitutive lactic acid bacteria (LAB) was studied in 265 samples from three batches of commercial frozen yogurt stored at -23°C for one year. The total LAB in the three batches was > 10⁷CFU/g, and batch C was comprised exclusively of streptococci. Decreasing LAB counts in batches A and B were very slight. Experimental storage conditions resulted in the survival of LAB even after the 60 to 67 wk period.     

眉山泡菜中乳酸菌的分离鉴定

目的：分析眉山泡菜的基本数据和乳酸菌的菌种构成。方法：从眉山市采集泡菜12 份,测定pH值、总酸度、盐度、乳酸菌计数,用16S rRNA序列分析法鉴定菌种。结果：样品pH值的范围是3.37～3.89,总酸度的范围是0.65～0.92 g/100 g（以乳酸计）,盐度的范围是4.16%～5.28%（以NaCl计）,MRS和M17乳酸菌计数分别是1.71～6.33、1.33～5.78（lg（CFU/g））。总酸度对乳酸菌计数影响最大。共分离鉴定出16 株乳酸菌：Lactobacillus fermentum（2 株）、Lactobacillus plantarum（3 株）、Lactobacillus brevis（2 株）、Lactobacillusacidophilus（1 株）、Lactobacillus casei（1 株）、Lactobacillus pentosus（1 株）、Lactobacillus delbrueckii（1 株）、Lactococcus lactis（3 株）、Pediococcus pentosaceus（2 株）。结论：眉山泡菜中乳酸菌存在多样性,实验结果为工业发酵生产泡菜积累了菌株。     

Survival of Listeria monocytogenes, Listeria innocua, and Lactic Acid Bacteria in Chill Brines

ABSTRACT:  Listeria monocytogenes is the pathogen of concern in ready-to-eat (RTE) meat products. Salt brines are used to chill processed meats. L. monocytogenes and lactic acid bacteria (LAB) can grow under saline conditions, and may compete with each other for nutrients. The objective of this study was to determine the effect of lactic acid bacteria ( Enterococcus faecalis , Carnobacterium gallinarum , and Lactobacillus plantarum ) on the survival of L. monocytogenes and Listeria innocua in brines stored under low temperatures for 10 d. Sterile tap water (STW) and 2 brine solutions (7.9% and 13.2% NaCl) were inoculated with 1 of 5 cocktails ( L. monocytogenes , L. innocua , LAB, L. monocytogenes + LAB, or L. innocua + LAB) at initial concentrations of 7 log CFU/mL. Brines were stored for 10 d at 4 or 12 °C. Three replications of each brine concentration/cocktail/temperature combination were completed. No significant reductions of L. monocytogenes occurred in 7.9%[w/v] or 13.2%[w/v] brines when LAB were present; however, there were significant reductions after 10 d of L. monocytogenes in the STW solution when LAB were present (1.43 log CFU/mL at 4 °C and 3.02 log CFU/mL at 12 °C). L. innocua was significantly less resilient to environmental stresses of the brines than L. monocytogenes , both with and without LAB present ( P ≤ 0.05). These strains of lactic acid bacteria are not effective at reducing L. monocytogenes in brines at low temperatures. Furthermore, use of L. innocua as a model for L. monocytogenes is not appropriate under these environmental conditions.     

不同乳酸菌接种发酵泡菜风味的研究

以新鲜红皮萝卜为原料,分别接种分离自自然发酵泡菜中的乳明串株菌、乳酸乳球菌、食窦魏斯氏、发酵乳杆菌、植物乳杆菌进行纯种乳酸菌发酵制作泡菜。通过测定泡菜的乳酸菌菌相、总酸度、感官评价、挥发性成分及有机酸,对分离自自然发酵泡菜中不同乳酸菌纯种发酵泡萝卜的风味进行研究。结果表明,发酵达到终点时,接种不同乳酸菌发酵的泡菜中大部分乳酸菌的活菌数相差不大,都在7.0lg CFU/m L左右,泡菜液中的乳酸菌几乎全为植物乳杆菌;大部分乳酸菌纯种发酵泡菜中总酸含量>4g/kg;不同乳酸菌发酵的泡菜挥发性成分及有机酸的种类差异不显著。      

Some characteristics of lactic acid bacteria present in commercial sucuk samples

A total of 10 sucuk samples, obtained from Denizli, Turkey were analysed for some physical, chemical and microbiological characteristics. In addition, lactic acid bacteria (LAB) strains producing bacteriocin-like metabolites were isolated and identified. The production of some typical metabolites of the cultures isolated was investigated. At the end of the research, the average values of the pH, water and fat content were 5.1, and 37.2% and 30.5%, respectively. Microbiological analyses results were determined: average 8.34 log CFU/g TAMB, 8.91 log CFU/g LAB (at the MRS agar) and average 8.25 log CFU/g LAB (at the Elliker's lactic agar). The average counts of yeast-mould, coliform and Enterobacteriaceae were found to be 5.0 log CFU/g, 3.28 log CFU/g and 3.27 log CFU/g, respectively. In this study, counts of yeast-mould in the two samples, coliform counts in the five samples, and Enterobacteriaceae counts in the three samples were < 1.0 log CFU/g. A total of 6 of 100 LAB isolates obtained from the sucuk samples were found as a strain producing bacteriocin-like metabolites. These 6 strains were identified as follows; 3 strains Lactobacillus plantarum and 3 strains Pediococcus pentosaceus. According to the findings, these strains have the potential to be used as a sucuk starter culture. Additionally, acid and flavour compounds, other undesirable metabolite-producing activities of the strains, were determined in the model system. From these results it was concluded, after the determination of the toxicological properties, that the 4 strains of LAB identified (L. plantarum 13 P. pentosaceus 15 P. pentosaceus 74 and P. pentosaceus 75) would be useful as the starter and protective culture in the processing of the sucuk and similar fermented products.