酸芋荷辣椒酱发酵工艺研究

以芋荷梗为主料,新鲜辣椒为辅料,姜、蒜、香油为调味辅料,制作酸芋荷辣椒酱。以感官评分为评价标准,在以发酵时间、发酵温度、辣椒添加量和食盐添加量为单因素试验的基础上进行正交试验,优化酸芋荷辣椒酱的发酵工艺。结果表明,酸芋荷辣椒酱发酵的最佳工艺条件为：发酵时间3 d,发酵温度28℃,辣椒添加量30%,食盐添加量6%,此时,酸芋荷辣椒酱感官评分达89.97分,所得酸芋荷辣椒酱香味浓郁、风味独特、组织脆嫩、色泽搭配适宜、无异味。     

响应面法优化脱乳清风味调料乳的生产工艺

以鲜牛乳和香辛料为主要原料,利用凝乳酶进行脱乳清处理,结合直投式菌种发酵剂进行低温长时发酵,开发出一种风味调料乳。在单因素试验的基础上,通过响应面分析法确定脱乳清风味调料乳最佳的生产工艺参数为香辛料质量比 6 ∶5 ∶4 ∶2 ∶1（花椒油 12 g、辣椒油 10 g、海盐 8 g、黑胡椒粉 4 g、生姜粉 2 g）、凝乳酶添加量 0.4%、白砂糖添加量4%、发酵时间14 h、乳清蛋白粉添加量0.6%。该条件下制成的脱乳清风味调料乳质地均匀、香辛料风味较佳,产品蛋白质含量为7.79%、脂肪含量为5.16%、酸度为90°T、黏度为7 300 mPa·s、活菌数为3.8×107CFU/mL,是一款口味独特、食用方式多样性的新型发酵乳制品。     

圣女果百合搅拌型羊酸奶工艺技术研究

利用鲜羊乳为基料发酵,在传统酸奶发酵剂基础上添加双歧杆菌作为混合发酵剂,添加圣女果、百合混合浆液参与后发酵,通过单因素、正交实验确定搅拌型圣女果百合羊酸奶的优化配方。结果表明:该酸奶最优配方为圣女果和百合的混合浆10%(辅料混合比例为6∶4),蔗糖添加量9%,接种量4%,稳定剂添加量3‰,所得产品富含益生菌,营养丰富,是一种新型羊酸乳制品。     

利用纯种乳酸菌制作泡萝卜的技术研究

研究了不同纯种乳酸菌即肠膜明串珠菌、发酵乳杆菌、嗜热链球菌、嗜酸乳杆菌、保加利亚乳杆菌的组合发酵制作泡菜的变化和风味。结果表明,与传统发酵制作工艺相比,嗜酸乳杆菌+肠膜明串珠菌+发酵乳杆菌组合发酵(添加量为发酵液的5%),发酵速度快、产品风味好、亚硝酸盐含量为0.385×10-6mg/kg低于传统工艺生产的产品(1.55×10-6mg/kg),产品质量稳定。     

无花果风味酸奶的研制

本文以牛乳为主要原料,无花果为辅料,制作无花果风味的凝固型酸奶。以感官评分为评价指标,通过无花果汁添加量、蔗糖添加量、发酵剂接种量和发酵时间4个单因素实验和响应面分析确定最佳工艺。结果表明,8%无花果汁添加量、5%蔗糖添加量、0.03%发酵接种量、4 h发酵时间条件下生产的无花果风味酸奶质地细腻,酸甜可口,具有清新甜香的无花果香味,感官评定评分最高,可达到89.8分。     

米乳发酵饮料的研制

以大米为主要原料,选择黑曲葡萄糖淀粉酶水解、嗜热链球菌和保加利亚乳杆菌的混合菌种作为发酵剂进行乳酸菌发酵,通过正交试验得出最佳配方。这种新型米乳发酵饮料具有独特的风味和良好的营养保健作用,产品中乳酸菌的含量可达３×１０７ｍＬ－１．     

添加大豆分离蛋白对羊乳干酪质构与感官品质的影响

分别以新鲜羊乳为原料、直投式混合干酪发酵剂为主发酵剂、费氏丙酸杆菌为次级发酵剂,添加不同质量比(2%、4%、6%、8%、10%)的大豆分离蛋白(Soy Protein Isolation,SPI)制作混合干酪。在干酪成熟过程中,跟踪测定硬度、咀嚼性、凝聚性、弹性、水分含量等指标,待完全成熟后,结合感官分析以确定SPI添加量对干酪品质的影响。研究结果表明:随SPI添加比例的增大,混合干酪持水性增强,硬度、咀嚼性均下降,而凝聚性、弹性无明显变化趋势。感官分析结果显示,添加4%SPI的混合干酪硬度适中,质地细腻,咀嚼感良好,色泽均,奶香味浓郁,综合评价确定4%SPI为佳添加比例。     

添加桑葚辅料发酵对紫薯酒中花青素含量和风味的影响

为探究添加桑葚辅料发酵对紫薯酒花青素含量和风味的影响,向紫薯汁中添加5%和10%桑葚干进行发酵,检测3种紫薯酒的基本理化指标、花青素含量和挥发性成分含量并进行分析。结果表明:添加桑葚辅料使紫薯酒中花青素含量增加13.5%～39.4%; 3种紫薯酒中共检测到35种挥发性成分,主要是醇类和酯类化合物;紫薯酒中主要有月桂酸乙酯、棕榈酸乙酯、4-萜烯醇等风味物质,添加桑葚发酵后乙酸乙酯、乙酸异戊酯、辛酸乙酯、癸酸乙酯等为主要风味物质,增加紫薯酒风味的丰富性;添加5%桑葚辅料组紫薯酒感官评价得分最高,兼具良好的色泽及果香酒香。     

多菌群发酵红茶菌饮料的研制

以红茶萃取液和葡萄糖为原料,以多种乳酸菌、酵母菌、醋酸菌作为发酵剂,考察采用不同的发酵剂、发酵温度、红茶含量、红茶萃取温度和时间,对发酵饮料风味的影响。结果表明:红茶添加量1.5%,萃取温度85℃,萃取时间5min,葡萄糖添加量10%,添加0.01%植物乳杆菌、0.005%瑞士乳杆菌、0.005%鼠李糖乳杆菌、0.005%酿酒酵母和0.05%醋酸菌为发酵剂的工艺,发酵时间短,饮料风味好。     

复合发酵剂发酵脱脂乳与豆乳的工艺优化

该研究以脱脂乳和豆乳为原料,马克斯克鲁维酵母、嗜热链球菌和保加利亚乳酸杆菌作为发酵剂,以滴定酸度和感官评分作为指标,通过单因素试验及响应面试验,优化脱脂乳豆乳体积比、白砂糖添加量、发酵剂接种量及发酵温度,并对优化后的复配发酵乳在贮藏期间的质构、持水力、滴定酸度、感官评分和活菌数进行测定。结果表明,最佳发酵条件为脱脂乳与豆乳体积比82 ∶18、白砂糖添加量7.25%、发酵剂接种量3.92%,在42 ℃发酵4.5 h,所得复配发酵乳的感官评分最高,为94.85;在该优化条件下制备的发酵乳后熟12 h,硬度为99.39 g,滴定酸度为97.52°T,活菌数为2.7×109 CFU/mL,发酵乳颜色呈乳黄色、组织状态均匀、酸甜适口、口感柔和润滑、具有复配发酵乳独特的豆香味和浓郁的奶香味,在14 d 贮藏期内具有良好的风味、质构及感官接受度。     

肉制品发酵剂木糖葡萄球菌I2的研究

木糖葡萄球菌I 2是通过筛选得到的肉制品优良发酵剂。文中研究了木糖葡萄球菌I 2的发酵条件、5L自控发酵罐的放大试验和不同保护剂对木糖葡萄球菌I 2存活的影响。结果表明,采用2#发酵培养基,培养温度30℃,用2mol/L的NaOH作为中和剂,控制发酵液的pH为7.3,发酵周期16h,发酵液中活菌数最高可达8.7×1010CFU/mL。冷干保护剂以海藻糖最好,冷干后活菌数达1011CFU/g。     

双歧杆菌发酵复合果蔬鲜片的研究

以梨、苹果、山药为原料,经护色、漂烫、接种双歧杆菌、发酵等工序加工成复合果蔬鲜片,研究了不同双歧杆菌的接种量、蔗糖与葡萄糖加入量以及发酵时间等因素对复合果蔬鲜片品质的影响。单因素试验与正交试验结果表明,产品达到较佳口感和外观时,双歧杆菌的接种量为6%,蔗糖加入量为8%,葡萄糖加入量为7%,最佳发酵时间为8h。产品在2℃下,可保藏8 d,双歧杆菌活菌数在1.05×10~7cfu/mL以上。     

微滤膜偶联生物反应器制备泡菜发酵剂

采用自主研发的微滤膜偶联生物反应器制备泡菜用液体发酵剂,直接用于泡菜发酵。研究表明,通过生物反应器可控制乳酸菌培养过程中的pH、温度、溶氧量和追加营养物质的时间,植物乳杆菌在生物反应器内恒定pH培养12 h后活菌数达到5～8×109 CFU/mL;选择中空纤维膜膜滤的操作条件为蠕动泵转速50 r/min,压力0.15 MPa,对菌悬液进行膜滤浓缩1 h可得到4 L活菌数为2～3×1010 CFU/mL的浓缩菌液。浓缩菌液稀释5 000倍作为泡菜用发酵剂,直接用于泡菜发酵。室温条件下发酵3 d得到优质泡菜,比自然发酵短2 d。此微滤膜偶联生物反应器结构简单、使用方便、自动化程度高、适用于工业化大规模连续生产泡菜发酵剂。     

两株乳酸菌的发酵特性及在发酵驴肉肠中的应用

戊糖片球菌(Pediococcus pentosaceus,P.p)与干酪乳杆菌(Lactobacillus casei,L.c)常作为发酵剂应用于发酵香肠的制作,但能否作为驴肉香肠的发酵剂以及发酵剂的配比、菌液浓度等一直没有明确的指标限制。本研究对P.p、L.c的生长曲线、产酸率、耐盐性等特性进行研究分析并进行混菌培养试验,两种乳酸菌均符合发酵肉制品发酵剂的要求并可作为混合发酵剂。将发酵剂不同配比、菌液浓度、添加量等进行单因素试验,pH和感官品评作为评价指标进行四因素三水平的正交试验,得到在当前加工条件下较优的发酵条件:混合乳酸菌发酵剂菌种配比为L.c:P.p=1:1,菌种菌液浓度1×106 CFU/mL,发酵剂添加量1%,发酵温度35℃,发酵时间20 h,此条件下发酵驴肉肠色泽呈枣红色,pH为4.83,符合良好发酵香肠的感官标准。     

Fate of Listeria monocytogenes, Salmonella typhimurium DT104, and Escherichia coli O157:H7 in Labneh as a pre- and postfermentation contaminant

Commercially pasteurized milk (approximately 2% milkfat) was heated at 85 to 87 degrees C/30 min, inoculated to contain 2,000 to 6,000 CFU/ml of Listeria monocytogenes, Salmonella typhimurium DT104, or Escherichia coli O157:H7, cultured at 43 degrees C for 4 h with a 2.0% (wt/wt) commercial yogurt starter culture, stored 12 to 14 h at 6 degrees C, and centrifuged to obtain a Labneh-like product. Alternatively, traditional salted and unsalted Labneh was prepared using a 3.0% (wt/wt) starter culture inoculum, similarly inoculated after manufacture with the aforementioned pathogens, and stored at 6 degrees C and 20 degrees C. Throughout fermentation, Listeria populations remained unchanged, whereas numbers of Salmonella increased 0.33 to 0.47 logs during the first 2 h of fermentation and decreased thereafter. E. coli populations increased 0.46 to 1.19 logs during fermentation and remained that these levels during overnight cold storage. When unsalted and salted Labneh were inoculated after manufacture, Salmonella populations decreased >2 logs in all samples after 2 days, regardless of storage temperature, with the pathogen no longer detected in 4-day-old samples. Numbers of L. monocytogenes decreased from 2.48 to 3.70 to < 1.00 to 1.95 logs after 2 days with the pathogen persisting up to 15 days in one lot of salted/unsalted Labneh stored at 6 degrees C. E. coli O157:H7 populations decreased from 3.39 to 3.7 to < 1.00 to 2.08 logs during the first 2 days, with the pathogen no longer detected in any 4-day-old samples. Inactivation rates for all three pathogens in Labneh were unrelated to storage temperature or salt content. Unlike L. monocytogenes that persisted up to 15 days in Labneh, rapid inactivation of Salmonella typhimurium DT104 and E. coli O157:H7 suggests that these emerging foodborne pathogens are of less public health concern in traditional Labneh.     

乳酸菌组合发酵菌种配方及其增殖培养基的优化

为了将甘肃牧区优良乳酸菌株用于直投式酸奶发酵剂的生产,以从甘肃牧区分离所得的乳酸乳球菌乳脂亚种(HM 598685)、嗜酸乳杆菌(HM 598684)、干酪乳杆菌(HM 598683),按照1:0:0、0:1:0、0:0:1、1:1:0、1:2:0、2:1:0、1:0:1、1:0:2、2:0:1、1:1:1、1:2:1、2:1:1、1:1:2的比例进行混合发酵,通过所制酸奶的感官性状和生化特性确定组合发酵的菌种配方,并对混合发酵的增殖培养基进行优化。结果发现,当3株菌比例为1:1:1时,其混合发酵的凝乳时间最短,为8.5h;所得酸奶的活菌数最大,高达7.90×10~8CFU/mL;而其感官评价中滋味气味及组织形态均显著优于其他组合。根据美蓝实验,当基础培养基中使用胰蛋白酶水解乳蛋白时,培养所得乳酸菌的活性最高,且活菌数可达2.93×10~8CFU/mL。通过L_9(3~4)正交设计,确定最佳增殖因子为酵母粉1%、果糖0.5%、吐温0.2%、乙酸钠0.5%,此时培养所得混合菌活菌数达2.11×10~9CFU/mL;各增殖因子对活菌数影响的主次顺序为:酵母粉>乙酸钠>果糖>吐温。     

Production of benzoic acid as a natural compound in fermented skim milk using commercial cheese starter

In this study, we investigated the production of natural benzoic acid (BA) in skim milk fermentation by 5 kinds of commercial cheese starters. Five kinds of starter were inoculated into 10% reconstituted skim milk, and then the culture was incubated at 2-h intervals for 10 h at 30, 35, and 40°C. In fermentation by MW 046 N+LH 13, the starter for making raclette, BA was highly detected after 8 h at 30 and 35°C. In fermentation by LH 13, the starter for making berg, BA steadily increased and was highly detected at 40°C. In fermentation by TCC-3+TCC-4, the starter for making Caciocavallo and mozzarella, BA was detected after 2 h at 40°C. Also, BA was detected after 4 and 8 h at 35 and 30°C, respectively. In fermentation by Flora-Danica, the starter for making Gouda, BA was increased until 6 h and decreased after 6 h at all temperatures. Among the 5 kinds of fermentation, the level of BA was the highest in fermentation by Flora-Danica at 6 h at 35°C, at 14.55 mg/kg.     

离子交换法解除丁酸梭状芽孢杆菌发酵液中丁酸抑制的研究

采用离子交换法吸附发酵液中的丁酸,从18种树脂中筛选出了1种对丁酸吸交性能较好的树脂A。树脂A对10 g/L的丁酸溶液中丁酸的静态吸附量为243.3 g/kg,对5g/L丁酸梭状芽孢杆菌发酵液中丁酸的静态吸附量则为142.2 g/kg。动态吸附实验表明,树脂A吸附性能良好,洗脱峰高而窄,再生性能优良。5L发酵罐实验表明,发酵残液经陶瓷膜过滤,再经过离子交换树脂脱酸后,补充新鲜培养基打入发酵罐中进行循环使用,大大降低了原发酵液中丁酸对丁酸梭状芽孢杆菌生长的抑制,大幅度提高了菌体浓度,使之由补料分批高浓度培养时的6.1×10~8个/mL提高到1.2×10~9个/mL。     

The use of a starter culture in the fermentation of cassava for the production of "kivunde", a traditional Tanzanian food product

Three cassava fermentation methods (spontaneous fermentation, back-slopping and the use of starter culture) for the production of kivunde, executed in three trials at 30 degrees C, were compared in terms of cyanide level reduction, microbiology and product quality improvement. Among the isolates from spontaneously fermented cassava batches, four strains were selected on the basis of their enzymatic activities and acid production. All were identified as Lactobacillus plantarum and were used as starters in this study. Lowest residual cyanide levels were detected after 120 h fermentation time in samples fermented with the starter culture and were below the maximum value of 10 mg/kg recommended by the Codex/FAO for cassava flour. This finding seems to be related to the alpha-glucosidase activity of the inoculated strains of which API-zyme (Bio-Merieux) tests showed activities of between 20 and > or = 40 nmol/4 h. The total residual cyanide levels of the spontaneous and back-slopping fermentations at 96 h were respectively 43.5 and 47.7 mg/kg dry weight of cassava. Extension of the fermentation period to 5 days, lead to further substantial reduction in the residual cyanide level in both these processes, but not below the recommended maximum value as in the case of starter culture fermented products. The spontaneous and back-slopping fermented cassava showed signs of deterioration after 3 days of fermentation. There was a sharp drop of pH and an increase of titratable acidity for all three batches during the first 48 h followed by a slow rise of pH and drop in titratable acidity towards the end of fermentation. The samples fermented with the starter culture had a smooth texture and pleasant fruity aroma, as opposed to the course and dull appearance and more complex flavour of the samples of spontaneous and back-slopping batches. During fermentation with starter culture, Enterobacteriaceae and yeasts and moulds could not be isolated throughout the period of fermentation (detection limit: 10 colony forming units/g). The present findings indicate the suitability of these Lb. plantarum strains as starter cultures for cassava fermentation in the kivunde process. The paper highlights the potential for the improvement of a traditional African fermented food (kivunde) through the use of a starter culture.