自然发酵风干肠中葡萄球菌的筛选与鉴定

以自然发酵风干肠为研究对象,分析了风干肠中细菌总数、葡萄球菌和乳酸菌的变化情况,结果表明,发酵初期葡萄球菌受到乳酸菌的抑制,增长缓慢;发酵后期乳酸菌生长进入衰退期,葡萄球菌开始快速繁殖。通过对风干肠中葡萄球菌的分离筛选,共鉴定出5株符合生产要求的葡萄球菌,分别为模仿葡萄球菌(Staphylococcus simulans),木糖葡萄球菌(Staphylococcus xylosus),腐生葡萄球菌(Staphylococcus saprophyticus),表皮葡萄球菌(Staphylococcus epidermidis)和克氏葡萄球菌(Staphylococcus kloosii)。     

从风干肠中分离出的三株乳酸菌发酵性能的研究

对从自然发酵风干肠中分离出的三株乳酸菌的发酵性能进行研究,主要包括菌种的耐盐性试验、耐亚硝酸盐试验、生长温度的测定、产酸速率的测定、蛋白质及脂肪降解活性试验、拮抗性试验。结果表明:分离乳酸菌1号菌的耐热性强,可能在烘烤后继续发挥产酸效力,因此不适合作为发酵剂使用;2号菌、3号菌则可在6%的食盐浓度下和0.15g/kg的亚硝酸钠下生长,在65℃以上完全不生长,产酸速度快,不分解蛋白质和脂肪,相互之间无拮抗作用,完全符合肉制品发酵剂的要求。     

自然发酵风干肠生产过程中微生物变化及理化性质的分析

以自然发酵风干肠为研究对象,分析了生产过程中微生物数量和理化指标的变化。微生物方面,按总菌数、乳酸菌、葡萄球菌和酵母菌几个大类研究各自的变化以及相互之间的作用关系;理化方面,分析了pH值、水分含量、水分活度及总氮含量几个重要指标,并阐述了各个理化指标之间及其与微生物变化的关系。     

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 subsplactis)、短乳杆菌(Lactobacillus brevis)、弯曲乳杆菌(Lactobacillus curvatus)和发酵乳杆菌(Lactobacillus 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。      

风干肠的生产与质量控制

在传统风干肠加工的基础上采用自配的风干肠调料和新的加工过程,严格质量关键控制点,极大地改善了风干肠的质量,赋予产品以悦目的感官特征.     

微生物在发酵风干肠中的应用

传统发酵风干肠的生产是依赖自然发酵过程完成的。采用人工接种发酵剂开展发酵肠的研究与应用,对风干肠独特风味的形成起决定性的作用,使发酵肠的生产得到了极大的推进。     

发酵风干肠中乳酸菌的发酵性能

对从自然发酵风干肠中分离的6 株乳酸菌的发酵性能进行评价,主要包括测定菌株的生长曲线、产酸能力、对NaCl及NaNO2的耐受能力,同时通过吲哚实验和抗生素敏感性测定对菌株的安全性进行初步评价。结果表明：6 株乳酸菌生长趋势接近,均在8 h左右进入生长稳定期,pH值在0～8 h下降最快,清酒乳杆菌和发酵乳杆菌的产酸能力更强;所有菌株均可在6 g/100 mL NaCl和0.015 g/100 mL NaNO2条件下生长,植物乳杆菌和弯曲乳杆菌的NaCl耐受能力最优,清酒乳杆菌和发酵乳杆菌则对NaNO2具有最强的耐受能力;吲哚实验中6 株乳酸菌的反应结果均为阴性,对实验所选抗生素无耐药性,说明6 株乳酸菌具有较好的发酵性能和安全性,可作为功能性发酵剂用于发酵肉制品的生产。     

清酒乳杆菌对发酵风干肠品质的影响

该研究采用清酒乳杆菌（Lactobacillus sakei，L. sakei）作为发酵菌株制备发酵风干肠，研究其对发酵风干肠品质的影响，以自然发酵产品作为对照组，在发酵成熟过程中的第0、3、6、9天测定产品的菌落总数、乳酸菌数、pH值、水分含量、水分分布、嫩度、色差、过氧化物值（Peroxide Value，POV）、硫代巴比妥酸值（Thiobarbituric Acid Value，TBARS）、脂肪酸含量和感官评分等指标，研究发酵菌株对风干肠品质的影响。试验表明，L. sakei接种组的乳酸菌数和菌落总数显著高于对照组（P<0.05），L*值、a*和b*显著低于对照组（P<0.05）；L. sakei接种组在发酵终点时，水分含量降至32.15%，pH值降至4.41，保证了发酵风干肠的安全性；POV值和TBARS值显著低于对照组（P<0.05），表明L. sakei具有较好的抑制脂肪氧化作用；L. sakei接种组的总体可接受性更高，发酵后期酯类物质种类和含量均高于对照组。综上，L. sakei的添加改善了产品的品质和风味。     

风干肠在成熟过程中理化特性及微生物状况的研究

对风干肠风干过程中理化及微生物指标变化的研究结果表明，水分的除去主要在第一周内完成，风干半成品的水分含量为２０．４％；ＮａＣｌ含量随水分的逸失而升高，ＴＢＡ值在风干过程中一直上升；总挥发性盐基氮（ＴＶＢＮ）在风干的前１１天一直上升，以后开始下降。细菌总数在风干前期迅速下降，而１周后趋于稳定，优势菌群为乳酸菌。试验结果还表明，用传统工艺生产的风干肠属于发酵肠类，这和人工烘烤生产的干肠有着本质上的区别。自然风干的适宜时间为８～１０天。     

脂肪添加量对发酵风干肠品质的影响

研究不同脂肪添加量（0%～30%）对发酵风干肠品质的影响,考察发酵0、3、6、9 d发酵风干肠的pH值、水分含量、硬度、咀嚼性、黏聚性、色差及感官品质。结果表明：随着发酵时间的延长,发酵风干肠的pH值呈现先降低后升高的趋势,水分含量逐渐降低,且pH值和水分含量随着脂肪添加量的增加而下降;硬度和咀嚼性随着发酵时间延长呈升高趋势,黏聚性呈下降趋势,但脂肪添加量对硬度和咀嚼性影响不显著;亮度值（L*）和红度值（a*）随着发酵时间延长均呈显著降低的趋势,脂肪添加量20%～30%组的L*最优,a*则与脂肪添加量呈负相关;感官评价结果表明,脂肪添加量10%和20%组较优且差异不显著,结合理化指标总体评价,脂肪添加量10%组发酵风干肠具有较好的品质。     

自然发酵中式香肠加工成熟过程中乳酸菌菌群研究

研究自然发酵川味、广味香肠加工成熟过程中乳酸菌菌群,旨在探明乳酸菌在香肠加工成熟过程中菌群分布及其变化规律。结果表明:(1)发酵初期两种香肠中乳酸菌数量均在104cfu/g水平,2d后不断增加,广味香肠中乳酸菌数量增加更快,第12天两者趋于一致,达到106cfu/g,第21天数量均跃升至107cfu/g,第30天达最大值,接近108cfu/g,40d后数量开始下降。(2)香肠中水分含量和pH值在加工成熟过程中总体呈下降的趋势,其乳酸菌数量变化与pH值和水分含量变化具有一定的相关性。(3)分离出的115株菌株经初步鉴定,杆菌80株,球菌35株,均为G ;从3个不同时期选出14株有代表性的菌株进行生理生化鉴定,拟确定S1-4、S3-2为清酒乳杆菌(Lactobacillus sakei),G21-10、C50-6、G50-4为戊糖乳杆菌(L.Pentosus),C21-6、C50-8、G50-9为植物乳杆菌(L.plantarum),其他的仅能鉴定到属,有乳杆菌、乳球菌。     

Technological activities of Staphylococcus carnosus and Staphylococcus simulans strains isolated from fermented sausages

The aim of this study was to determine the technological properties of 2 strains of Staphylococcus simulans (Ssm12, Ssm21) and 4 strains of S. carnosus (SC28, SC31, SC54 and SC55) for the selection of a potential starter cultures to employ in the processing of dry fermented sausages. The strains were studied to evaluate nitrate reductase, proteolytic, lipolytic, decarboxylase and antioxidant activities as well as growth ability at different temperatures, pH and NaCl concentrations. Nitrate reductase activity was determined at 15, 20 and 30 °C. By spectrophotometric method all the strains were able to reduce nitrate to nitrite at the different temperatures but these results were not confirmed by the agar plate method. Antioxidant and lipolytic activities were evaluated by spectrophotometric assay. All the strains showed antioxidative enzymes superoxide dismutase (SOD) and catalase whereas all appeared unable to hydrolyse pork fat. Proteolytic activity was determined by agar plate method, spectrophotometric assay (OPA) and sodium dodecyl sulphate gel-electrophoresis (SDS–PAGE) and all strains appeared to be able to hydrolyse sarcoplasmic proteins but not myofibrillar proteins. Finally, all the strains grew at 15 and 20 °C, in presence of 10%, 15% and 20% of NaCl and at pH 5.0 and 5.5 and were unable to produce histamine, cadaverine and putrescine. The results showed that all strains studied possess useful technological activities that would make them eligible as a good starter cultures for fermented sausages.     

Characteristics of lactobacilli isolated from dry fermented sausages

A study of the microflora of Spanish dry fermented sausages showed a similar pattern to that observed in other sausages during ripening. Lactic acid bacteria and organisms growing on Mannitol-salt-agar increased during the first five days, remaining at constant levels afterwards. From MRS agar, 368 strains were isolated and characterized. All Lactobacillus strains (343) could be separated into three groups according to their reactions in the API-50 L system. The biochemical characteristics of the Lactobacillus strains analyzed were those typical of isolates from sausages and other meat products. The extracellular and intracellular lipolytic activities of some strains of the three groups were also studied. It is concluded that lipolytic activity of lactobacilli is mainly directed against mono- and diglycerides and short-chain fatty acid triglycerides.     

Proteolytic and lipolytic activities of mould strains isolated from Spanish dry fermented sausages

Proteolytic and lipolytic activities of ninePenicillium strain and oneMucor strain previously isolated from Spanish dry fermented sausages have been studied.P. camemberti STCC 2267 andAspergillus oryzae ATCC 9362 were also used. Myofibrillar and sarcoplasmic proteins as well as fat extracted from pork meat and -naphthyl acetate, -naphthyl caprilate and -naphthyl laurate were used as substrates. Mould strains were grown in an enrichment medium prepared at pH 5.5 and 7.0 and malt extract broth. Strains were incubated at 18°C and 22°C. Myofibrillar proteins and -naphthyl caprilate were the most hydrolysed substrates. The greater enzymatic activities were observed at a pH 7.0 and 22°C. However, five mould strains showed considerable enzymatic activities under conditions similar to those used for ripening dry fermented sausages. These strains can be assayed as potential starter cultures for industrial sausage production.     

Effect of selected mould strains on the sensory properties of dry fermented sausages

The effect of one Mucor and two Penicillium strains (Penicillium-3 and Penicillium-6) on the development of the sensory properties of dry fermented sausages has been studied. These strains were previously isolated from Spanish fermented sausages and selected for their proteolytic and lipolytic activity. Several experimental batches were prepared: one of them was non-inoculated and considered as control batch, three were inoculated with the selected strains, and the last one was inoculated with a commercial starter culture of P. nalgiovense. The pleasantness of the sensory attributes of the different batches were determined using an unstructured line scale of 10 cm. A triangular test was also carried out. Apart from their external appearance, batches inoculated with Mucor and Penicillium-3 had the highest scores for all the sensory attributes studied. The batch inoculated with P. nalgiovense had the lowest scores and similar to the control batch but its external appearance was considered to be the most pleasant. The batch inoculated with Penicillium-6 presented intermediate characteristics. A relation between these results and the enzymic activity of the moulds was established. The three strains selected for this study are proposed to be incorporated in a commercial starter culture because they improve the sensory properties of these meat products.     

Effect of selected yeast strains on the sensory properties of dry fermented sausages

This study examines the role of yeasts in the sensorial characteristics of dry fermented sausages. A total of 172 yeast strains were isolated from commercially obtained dry fermented sausages and their enzymatic activities studied. Those most active against meat proteins and pork fat were selected. Experimental sausages were manufactured and the yeasts inoculated onto the surface or into the mince. Control batches were manufactured similarly, but without inoculation. After ripening, the composition of the protein and lipid fractions were studied. The sensory properties of the products were evaluated by trained judges. Despite the enzymatic activity of the yeasts, the organoleptic characteristics of the sausages—irrespective of inoculation site—did not differ significantly from those of the controls. The influence of yeasts on the ripening of dry fermented sausages is, therefore, doubtful.     

Selected characteristics of micrococci isolated from Spanish dry fermented sausages

The flora development of two batches of Spanish dry sausages has been studied. Lactic acid bacteria and organisms growing on Mannitol—Salt agar increased during the first five days, remaining at constant levels afterwards. From Mannitol—Salt agar, 629 strains were isolated. The maximum recovery of Gram-positive, catalase-positive cocci was between 5 and 15 days of ripening and after 20 days no micrococci were detected. All isolates of nitrate reducing micrococci (42 strains) showed an acceptable growth at temperatures (19–25°C) and water activities (0.93–0.95) of the sausages during the fermentation step. From the quantitative determination of the nitrate reduction ability, six strains were selected as potential starters for industrial sausage production.