Preparation of lactic acid bacteria compound starter cultures based on pasting properties and its improvement of glutinous rice flour and dough

The effects of 5 lactic acid bacteria(LAB)fermentation on the pasting properties of glutinous rice flour were compared,and suitable fermentation strains were selected based on the changes of viscosity,setback value,and breakdown value to prepare LAB compound starter cultures.The results revealed that Latilactobacillus sakei HSD004 and Lacticaseibacillus rhamnosus HSD005 had apparent advantages in increasing the viscosity and reducing the setback and breakdown values of glutinous rice flour.In particular,the compound starter created using the two abovementioned LAB in the ratio of 3:1 had better performance than that using a single LAB in improving the pasting properties and increasing the water and oil absorption capacity of glutinous rice flour.Moreover,the gelatinization enthalpy of the fermented samples increased significantly.For frozen glutinous rice dough stored for 28 days,the viscoelasticity of frozen dough prepared by compound starter was better than that of control dough,and the freezable water content was lower than that of control dough.These results indicate that compound LAB fermentation is a promising technology in the glutinous rice-based food processing industry,which has significance for its application.

3D printed lactic acid bacteria hydrogel:cell release kinetics and stability

In this study,a new type of 3 D printed living biological hydrogel was developed by integrating lactic acid bacteria(LAB)into biocompatible and non-toxic polymer materials.Interestingly,the living materials loaded with LAB can be freeze-dried and reused for more than 100 times.The bio-hydrogel can be used to co-culture different LAB and keep its fermentation performance stable in long-term use.The release kinetics model and response surface method were used to simulate and optimize the bacteria release mode in the bio-hydrogel.The results show that the release of bacteria from hydrogel is regulated by the coupling of Fickian diffusion and polymer swelling.The stability of LAB hydrogel was evaluated by reuse experiments.The images of confocal microscopy and scanning electron microscope showed that the bacteria with high cell viability were distributed in the hydrogel and intact structure of the living hydrogel was maintained after 100 times of reuse as yoghurt starter.In conclusion,the 3 D printed LAB bio-hydrogel developed in this study has the advantage of reuse and sustainability,which is expected to open up a new way for the preparation of food culture starter.

Selection of Lactic Acid Bacteria Isolated from San Simón da Costa Cheese (PDO) in Order to Develop an Autochthonous Starter Culture

Traditional cheeses are an important reservoir of microbial diversity that can have important biotechnological applications, especially with a view to improving the characteristics unique to each type of cheese, and in this respect, starter cultures consisting of autochthonous lactic acid bacteria strains are of particular interest. In the present study, we investigated lactic acid bacteria population diversity in San Simón da Costa cheese (PDO, Galicia, Spain) and found a predominance of the genus Lactobacillus, which by the end of ripening accounted for 78% of the strains isolated in Rogosa agar, around 40% of those in M17 agar and about 10% of those in MSE agar. The main species of lactic acid bacteria identified were Lactococcus lactis subsp. lactis, Lactobacillus casei subsp. casei, Lb. paracasei subsp. paracasei, Leuconostoc mesenteroides and Enterococcus faecalis. Virtually all the strains studied from a technological point of view yielded more than or equal to 0.24 g 100 mL-1 lactic acid. Lactococcus lactis subsp. lactis (SS 194), Lactobacillus paracasei (SS 1695 and SS 1689) and Enterococcus faecalis (SS 1378 and SS 1449) strains exhibited the greatest proteolytic capacity. Based on the overall technological aptitude of the tested strains, we can propose starter cultures and co-cultures that include different combinations of previous strains with a view to manufacturing San Simón da Costa cheese from pasteurised milk.

Study on the Development of Lactic Acid Bacteria in Bread Dough Enriched with Zinc and Selenium

The incorporation of lyophilized lactic acid bacteria in dough formulation is a current trend in bread making in order toachieve quality improvement and extension of shelf life of bread. Another major aspect for today＇s bread making industry is anincrease of the biological value of bread, by addition of mineral substances that are deficient in bread （such as zinc and selenium）.This is an effective approach to combat the existing mineral deficiency in population nutrition. The aim of the present study is toinvestigate the development of lactic acid bacteria in a medium enriched with zinc and selenium. It was found that the addition ofZnSO4-7H20 in an amount of 0.174 g/kg flour and Na2SeO3.5H20 in an amount of 880.28 μg/kg flour （alone and in combination） didnot inhibit the development of lactic acid bacteria used as starter cultures in bread dough formulation. It was found that the growth ofthe lactococcal component of the applied starters is dominant. The results reveal the possibility of obtaining bread with increasedbiological value and improved quality.

不同乳酸菌接种发酵对泡白菜理化特征及风味的影响

为评估泡白菜中乳酸菌的发酵特性,以植物乳杆菌(Lactobacillus plantarum)PC295、肠膜明串珠菌(Leuconostoc mesenteroides)PC137、柠檬明串珠菌(Leuconostoc citreum)PC222、食窦魏斯氏菌(Weissella cibaria)PC311、清酒乳杆菌(Lactobacillus sakei)PC229、短乳杆菌(Lactobacillus brevis)PC330为发酵菌株,分析不同乳酸菌接种发酵对泡白菜pH、总酸、还原糖、微生物数量、有机酸、游离氨基酸、挥发性风味成分的影响。经6种乳酸菌接种发酵后,泡白菜的pH、还原糖、柠檬酸、苹果酸、游离氨基酸总量以及大肠杆菌数量均下降;不同种乳酸菌表现出不同的发酵性能,植物乳杆菌PC295和短乳杆菌PC330发酵速度快,还原糖消耗量和产酸量高,抑制大肠杆菌效果好;异型发酵菌株产较多的乙酸和乙醇。采用顶空固相微萃取-气相色谱-质谱联用技术共检出挥发性风味物质56种,所有泡菜组均以醇类化合物为主,主要包括乙醇、1-辛烯-3-醇、顺-2-戊烯-1-醇等;清酒乳杆菌PC229和短乳杆菌PC330发酵的泡白菜中,反,反-2,4-庚二烯醛、己醛等醛类化合物和乙酸的相对含量高于其他组;主成分分析结果显示,肠膜明串珠菌PC137和柠檬明串珠菌PC222发酵的泡白菜成熟后其挥发性风味相似。不同种乳酸菌在泡白菜发酵速度、风味类型和底物消耗上存在差异。研究结果为进一步开发白菜类泡菜发酵剂奠定了基础。

传统发酵食品来源乳酸菌在酸奶中的应用研究

本研究以山西地区传统发酵食品来源的70株乳酸菌为研究对象,首先进行单菌株发酵特性的研究,将发酵性能优良菌株同酸奶基础发酵剂嗜热链球菌和保加利亚乳杆菌进行复合发酵,通过测定酸乳滴定酸度、pH、质构性质和感官特性,筛选可用于酸奶发酵的潜在菌株。在对70株乳酸菌进行单菌株发酵特性的研究中发现,菌株M6-2、M8-2、M10-1、M10-2在脱脂乳中培养24 h后,发酵特性较好,酸度分别可达到72.30±2.76°T、60.57±5.53°T、68.39±8.29°T、121.15±11.05°T;pH可达到5.16±0.02、5.19±0.02、4.78±0.01、4.03±0.06,且凝乳状态较好。在进一步通过与基础发酵剂复合发酵脱脂乳中发现,四株菌分别与基础发酵剂发酵酸奶中,M10-2的感官评价得分较高,总分为85.45。滴定酸度和pH分别为90.12±10.16°T、4.37±0.01。硬度、凝胶强度、弹性、内聚性、胶着性等质构特性分别为21.77±2.35 gf、38.62±3.86 gf、0.63±0.05、0.36±0.01、7.88±0.32 gf。经综合评定,菌株M10-2较适用于酸乳发酵剂的开发。

新疆酸驼乳NSLAB的筛选及鉴定

以新疆牧民家庭自然发酵酸驼乳为原料,采用改良的ROGOSA培养基筛选出20株非发酵剂乳酸菌(Non Starter Lactic Acid Bacteria,NSLAB),以产酸、自溶度、氨肽酶活力、蛋白水解能力为指标复筛性能优良的NSLAB,为新疆特色干酪的现代化改造提供新的菌株资源。结果表明:从酸驼乳中复筛得到六株NSLAB(编号X-4、X-5、X-7、X-12、X-13、X-15)。据多元统计分析六株菌综合得分X-5>X-4>X-15>X-13>X-12>X-7。其中X-5Δp H(24h)、自溶度、氨肽酶活力、蛋白水解能力分别为1.08%、28.26%、18.88、3.21U/m L,有较好的应用前景。基于菌株生理生化特性,结合16S r DNA基因序列分析,构建菌株系统发育树明确其分类地位,X-4、X-5、X-13、X-15鉴定为植物乳杆菌(Lactobacillus plantarum),X-7鉴定为发酵乳杆菌(Lactobacillus fermentum),X-12确定为乳酸片球菌(Pediococcus acidilactici)。

Use of Starter Cultures in Olives: A Not-Correct Use Could Cause a Delay of Performances

The role of lactic acid bacteria for a correct course of fermentation of table olives has been extensively reviewed and it is a common idea that the inoculum of selected strains could exert a strong benefit for product quality;however, the basic assumption of this research is that a not-correct preparation of starter could affect its performances in brines and delay the benefit of a starter inoculum. Thus, some selected strains of LAB (lactic acid bacteria) and yeasts were inoculated into brines of Bella di Cerignola olives (Spanish style), as a single starter (LAB or yeasts) or a combined preparation (LAB + yeasts) and compared to a natural fermentation, focusing on the performances of the process (acidification, production of lactic acid) and trying to verify the basic assumption. LAB and yeasts were grown in the opportune lab media and then directly inoculated in brine after the lye treatment. LAB exerts a kind of benefit (increased content of lactic acid) only for 2 - 3 weeks;then, the inoculated samples behave in the same way as not-inoculated ones. Thus, this research underlined that a starter culture, not prepared in the correct way, could not be useful to guide the fermentation.

非热处理技术控制酸奶后酸化研究进展

后酸化是影响酸奶货架期内感官品质、风味特征与稳定性的最主要因素之一。非热处理技术是控制后酸化的新兴手段,可以在有效控制酸奶后酸化的同时最大限度保持食品原有的营养特性及感官品质。文章综述了乳酸菌的后酸化机制,对高静压、超声波、脉冲电场、CO_(2)处理、辐照等非热处理工艺控制后酸化的机理和最新研究进展进行了阐述,并对非热处理技术后酸控制的未来发展方向进行了展望。

乳酸菌发酵剂对杂粮面团及馒头品质的影响

为研究混合乳酸菌发酵对杂粮面团及馒头品质的影响,将黄豌豆粉、莜麦粉、谷朊粉及燕麦β-葡聚糖(oatmealβ-glucan,OBG)复配成杂粮粉基质,利用直投式混合乳酸菌发酵剂发酵面团制作馒头。探究乳酸菌在面团中的酸化能力,分析杂粮面团中OBG、抗性淀粉(resistant starch,RS)和游离氨基酸含量的变化以及面团的微观结构变化,并对发酵前后的杂粮馒头和小麦粉馒头进行品质及营养特性比较。结果表明,在发酵杂粮面团中乳酸菌酸化能力强,发酵24 h后乳酸和乙酸质量浓度分别达到24.85、8.98 mg/mL。与未发酵的杂粮面团相比,乳酸菌发酵杂粮面团中OBG含量下降32.56%,RS含量上升32.88%,游离氨基酸总量提升至1.46倍,氨基酸组成模式更优,部分蛋白质和纤维素发生降解,面筋网络结构更加紧密且连续。在营养方面,乳酸菌发酵前后的杂粮馒头膳食纤维质量分数均高于6%,蛋白质质量分数分别为40.35%和38.38%,属于高纤维高蛋白食品,显著优于小麦粉馒头。乳酸菌发酵杂粮馒头具有更高的体外蛋白消化率和比容,且乳酸菌发酵杂粮馒头感官评价总评分显著高于未发酵杂粮馒头,整体可接受度更高。

基于激光诱导荧光光谱的酸奶乳酸菌数快速检测

以市售搅拌型酸奶为研究对象,利用自行搭建的激光诱导荧光(LIF)采集系统,获取不同乳酸菌数酸奶样品的荧光光谱,探讨酸奶中各种荧光物质的荧光峰强度随乳酸菌数变化的响应关系,结合光散射校正算法建立了酸奶中乳酸菌数定量预测模型.结果显示,不同乳酸菌数酸奶样品均在435、485和520 nm附近出现了荧光特征峰,且均随乳酸菌数的变化呈现规律性变化.利用4种光散射校正方法对酸奶原始荧光光谱进行了校正,其中,OPLEC+SR光散射校正算法能够有效消除与波长相关的基线漂移的影响,所建立的PLSR预测模型结果最优,其校正集、验证集相关系数R_(c)、R_(p)分别为0.9654和0.9533,均方根误差C_(RMSE)、P_(RMSE)分别为0.1525 logCFU/mL和0.2362 logCFU/mL.为验证模型的稳定性与可靠性,利用未参与建模的8个酸奶样品对最优模型进行外部验证,实测值与预测值线性拟合后的相关系数R可达到0.9510,拟合残差模为0.8606,说明所建预测模型可以实现酸奶中乳酸菌数的实时监测.

植物基杏仁酸奶的研制及不同发酵剂对酸奶品质的影响

该研究以杏仁为原料,经乳酸菌发酵制成植物基杏仁酸奶,通过单因素试验结合响应面法优化发酵工艺,并探究不同乳酸菌发酵剂对杏仁酸奶品质的影响。结果表明,最优的发酵工艺为料液比1∶10(g/mL)、发酵剂添加量0.6%、发酵温度40℃、发酵时间10 h,在该条件下,杏仁酸奶质地均匀、口感醇厚、色泽均一,感官评分为89.00,而不同类型发酵剂单发酵杏仁乳均能直接影响植物基杏仁酸奶品质,市售的酸奶发酵剂保加利亚乳杆菌及嗜热链球菌,能稳定有效发酵产酸,发酵制成的植物基杏仁酸奶各项品质指标均优于其他乳酸菌单发酵酸奶。

Recent developments of lactic acid bacteria and their metabolites on foodborne pathogens and spoilage bacteria:Facts and gaps

Lactic acid bacteria(LAB)are common microorganisms found in various ecosystems including in plants,fermented foods,and the human body.Exploring the biodiversity of lactic acid microflora and characterization of LAB is a new approach to form a variety of starter communities to create innovative nutritional food matrices.There has been growing interest in LAB isolated from non-dairy environments as these bacteria exhibit significant metabolic diversity and have unique taste-forming activities.Disease may be prevented,or treated by LAB but the treatment of disease conditions with LAB is highly dependent on the host's microbiome and diet and varies in both effectiveness and side effects from individual to individual.Future perspectives on the study of LAB may be related to the expansion of our knowledge in the fields of genetics and genetic engineering.The application of genetic science may help to improve existing strains and develop new strains with characteristics designed for specific purposes.Therefore,the preservative effects of LAB and their metabolites,as well as their interaction on the growth of food borne pathogens and food spoilage microorganisms were elucidated.In addition,the competitive models for microbial growth between LAB and other microorganisms as well as the role of LAB in the elimination of toxic compounds in food products were discussed.Moreover,the review provided an overview of the risks and benefits of using LAB in the food industry.

浓缩型乳酸菌发酵剂制备中几个技术关键问题的探讨

对浓缩型乳酸菌发酵剂制备中菌株的选择、菌体增殖培养、细胞浓缩分离、生物保藏等技术关键问题进行了探讨,以期为进一步发展浓缩型乳酸菌发酵剂提供依据。

酸奶发酵剂和乳酸菌生物技术育种

由新鲜牛奶制成的酸奶由于其丰富的营养、特殊的风味、爽滑的质构和良好的生理功能 ,倍受人们青睐。对酸奶乳酸菌的微生物种类、功能及其组成的酸奶发酵剂进行了综述 ,并简要介绍了乳酸菌生物工程育种方面的研究进展及酸奶乳酸菌研究领域一些令人感兴趣的课题。

发酵剂菌体自溶对酸乳品质的影响

通过研究发酵剂自溶对菌株产酸、凝乳能力,及对酸乳黏度、持水率、风味物质、后酸化程度等理化指标的影响。结果表明:自溶度较高的乳酸菌菌株在酸乳发酵过程中产酸性能更优,凝乳时间较短;菌株的自溶度对酸乳的黏度、持水率、风味物质成分及含量影响不大,但对酸乳的后酸化程度有着显著影响,高自溶度菌株发酵而成的酸乳在模拟货架期储藏条件下(10～15℃)后酸化程度相对较低。该文为开发新型复合发酵剂提供了理论依据。

浓缩乳酸菌发酵剂的现状

总结了浓缩乳酸菌发酵的应用及研究概况，并对不同的加工方法加以分析。

无腥大豆加工酸豆奶工艺条件的研究

试验利用无腥味大豆为主要原料生产酸豆奶 ,通过正交试验确定了无腥大豆加工酸豆奶的最佳工艺条件。结果表明 ,大豆与水之比为 1∶10 ,乳酸菌数为 16× 10 4 个 /mL ,添加葡萄糖 5 %、蔗糖 4 %、牛奶 30 %和稳定剂 0 .2 % ,在 4 0℃发酵 5h ,可制得色泽洁白 ,组织细腻 ,香味浓郁 ,口感好 ,无豆腥味 。

米发糕的双菌发酵剂工艺研究

以早籼米为原料,利用酵母菌和乳酸菌复配制成米发糕的专用发酵剂,研究两种菌的培养及比例对米发糕品质的影响,确定适宜的工艺配方。结果表明:采用马铃薯培养基对酵母菌进行培养和增菌;采用麦芽浸汁粉培养基对乳杆菌进行培养和增菌;将菌悬液按数量比为酵母菌∶乳酸菌=107∶107进行混合后浓缩至6.5%,加入8.5%米粉,0.3%白糖和0.15%单甘酯,混匀于32℃下热风干燥至含水量为13%。发酵剂贮藏一段时间后制作的米发糕品质略有下降。

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。