酿造发酵剂——纯种发酵的有效途径

该文对酿造发酵剂的研究、开发、生产及应用现状进行了论述,重点介绍了发酵剂菌种的选育、复合酱油曲精的研制、发酵剂的生产工艺及发酵剂应用效果等方面的内容,并将酿造发酵剂与传统工艺进行了比较,获得了可应用于酿造食品生产中的酿造发酵剂.     

DVS乳酸菌发酵剂研究进展

近年来，随着人民生活水平提高和健康意识增强，我国的酸奶、发酵乳产量以每年25％的速度增加。在酸奶和发酵乳制作过程中所必需的微生物制剂即发酵剂直接影响到生产工艺过程及产品质量。目前用于工业生产发酵乳制品的主要发酵剂有两大类，一类为传统的继代式发酵剂，一类为DVS发酵剂。DVS发酵剂又称直投式发酵剂，是指一系列高度浓缩和标准化的冷冻或冷冻干燥发酵剂菌种，可直接加入到热处理的原料乳中进行发酵，因此省略了传统继代式发酵剂使用过程中的菌种活化、母发酵剂、中间发酵剂、生产发酵剂的扩大繁殖过程，减少了菌种车间的投资和空间，防止了菌种的退化和污染。     

肉品发酵剂的研究发展现状

介绍了适合做肉制品发酵剂的微生物,以及这些微生物在肉制品发酵过程中的作用;概述了近几年肉制品发酵剂的研究现状,包括肉制品发酵剂的筛选、发酵剂干燥技术的研究进展和发酵剂活性保护剂的开发状况。同时介绍了国内肉制品发酵剂的研究进展,并对我国肉制品发酵剂未来的发展方向进行了展望。     

干酪成熟过程中发酵剂的作用

介绍干酪成熟过程中乳酸菌发酵剂及二级发酵剂的作用,包括在干酪风味、质地、加速干酪成熟、产生抗菌素及营养和颜色等多方面作用,同时分析成熟期间发酵剂控制不当会引起的负面作用,提出应用具有选择性的发酵剂或经遗传修饰的发酵剂生产干酪具有较强的应用前景。     

冻干保加利亚乳杆菌增菌培养基的筛选

发酵剂是决定酸奶品质的一个关键因素，国内多数酸奶生产企业采用传统的液体发酵剂。液体发酵剂存在菌种扩大培养操作繁琐、周期长、菌种易污染、退化、变异、发酵剂活菌含量低(10^7～10^8／ml)、生产接种量较大等众多弊端。直投式冻干发酵剂是酸奶发酵剂的发展方向，近两年来已有一些有实力、经营意识强的酸奶厂家为了提高产品质量，     

复合发酵剂对羊肉发酵香肠亚硝酸盐残留量和品质的影响

以羊肉为原料不添加发酵剂、添加市售发酵剂和复合发酵剂(植物乳杆菌与肉葡萄球菌混合发酵剂比为1∶3)采用同种工艺生产三组发酵香肠。研究三组羊肉发酵香肠发酵和干燥成熟过程中的p H、Aw、色差、亚硝酸盐(NIT)含量变化以及成品的质构特性。结果显示:发酵过程中,三组发酵香肠的p H、Aw和e值均下降,混合发酵剂组p H迅速降低为4.7,低于对照组和市售发酵剂组,其NIT含量为0.66mg/kg,低于对照组和市售发酵剂组的0.79、0.8mg/kg;成熟结束时,三组的p H和e值开始上升,混合发酵剂组的Aw下降极显著(p0.01)快于市售发酵剂组和对照组,并且三组各项质构指标除黏聚性外均差异极显著(p0.01),最终对照组、市售发酵剂组、混合发酵剂组发酵香肠的NIT含量分别为1.38、1.46、1.26mg/kg。整体上,混合发酵剂香肠品质优于其他两组。     

酸奶发酵剂及酸奶工艺的优化研究

合适的酸奶发酵剂及酸奶工艺的选择对酸奶产品的风味、口感、品质以及货架期有着重要的意义。介绍酸奶发酵剂的发展历史、发酵剂的分类以及发酵剂的性能,通过介绍酸奶工艺的优化,明确影响酸奶品质的因素,最后对酸奶发酵剂及酸奶工艺的优化进行总结与展望。     

肉品发酵剂研究概述

肉品发酵剂可以提高肉制品的营养、风味和卫生安全性,尤其乳酸菌作为保护性发酵剂可以抑制腐败菌的增殖.本文主要论述了肉品发酵剂的微生物组成、生理、遗传学等方面 ,对肉品发酵剂的研究和发展具有重要意义.     

三种益生菌发酵剂固态发酵对豆粕营养品质的影响

采用三种益生菌发酵剂固态发酵豆粕,通过测定发酵豆粕的感官品质、pH值、有益微生物含量、营养指标及卫生指标,比较三种益生菌发酵剂对豆粕品质的影响,以期筛选出适宜豆粕发酵的最优益生菌发酵剂。结果表明,益生菌发酵剂A和C对发酵豆粕的感官性状影响不大,三种益生菌发酵剂均能够显著降低发酵豆粕的pH值、大肠杆菌（Escherichia coli）和霉菌数量（P＜0.05）,显著提高有益微生物数量、粗蛋白、酸溶蛋白、总酸和有机酸含量（P＜0.05）。三种益生菌中以益生菌发酵剂A和益生菌发酵剂C效果即乳酸菌和酵母菌固态发酵豆粕效果较好,结合成本考虑优先选择益生菌发酵剂C。     

开菲尔发酵剂发酵特性研究

以三种开菲尔发酵剂和一种普通酸奶菌种为发酵剂,制作成发酵乳。通过监测四种发酵剂发酵过程的pH值变化趋势,以及在4 ℃冷藏过程中酸度、pH值、黏度、乳酸菌活菌数、酵母菌、口感等指标,分析开菲尔发酵剂与普通酸奶发酵剂的发酵特点及其产品在保质期内特性变化。结果表明,与普通酸奶菌种相比,开菲尔发酵剂凝乳时间较长,发酵时间约为12～20 h,在保质期内,酸度增长较为缓慢,黏度较低,乳酸菌活菌数较高,口感方面优于普通发酵剂酸奶。     

Selection criteria for lactic acid bacteria to be used as functional starter cultures in dry sausage production: An update

Lactic acid bacteria (LAB) have long been used as starter cultures in the production of fermented dry sausages and other meat-derived commodities. These cultures are generally designed to meet food safety, shelf-life, technological effectiveness and economic feasibility criteria. Besides all these traditional properties, novel starter cultures should take into account the risks posed by the formation of biogenic amines in food, and the development and spreading of bacterial resistance to antibiotics. Further, 'functional starters' could protect consumers from harmful bacteria either by a rapid acidification or by the production of antimicrobials (bacteriocins). Specially-selected cultures may also provide probiotic benefits, and, if properly modified, they may even be endorsed with nutraceutical traits. The present review discusses the technological and new selection criteria that should be taken into account when selecting LAB starter cultures for the production of fermented dry sausages.     

Effect of Liquid Smoke on the Growth of Lactic Acid Starter Cultures used to Manufacture Fermented Sausage

Fermented sausage was manufactured using a commercial lactic acid starter culture and varying levels of liquid smoke. Samples were taken during the 24 hr fermentation period and the lactic bacterial count, pH and titratable acidity determined. Final pH values, titratable acidity and lactic bacterial counts were not affected by recommended use levels of liquid smoke, although exponential growth was delayed. Growth studies in a broth medium containing liquid smoke suggest that liquid smoke has the potential for inhibiting the lactic starter cultures used to make fermented sausage.     

Detection and Identification of S. Carnosus in Starter Cultures Using Real Time PCR and Subsequent HRM Analysis of Amplification Products

Nowadays, the necessity to control species composition of commercial starter cultures and their growth during the ripening stage of fermented sausage in order to monitor the technological processes has became topical in Russia. However, there can be some difficulties in identification of an isolated culture when using biochemical methods. Using primers for amplification of bacterial species-specific regions makes it possible to identify starter cultures with a high degree of probability even without using TaqMan probes. Furthermore, using intraspecies polymorphism of the gyrase B subunit gene, we managed to subtype two S. carnosus isolates with the use of HRM analysis.     

The effects of freezing and freeze-drying of Oenococcus oeni upon induction of malolactic fermentation in red wine

Summary The use of Oenococcus oeni starter cultures for the induction of malolactic fermentation (MLF) in wine permits control over the timing of the process and the quality of the wine. Successful inoculation of bacterial starter cultures into wine depends on the selection of suitable strains and on the preparation and conservation of those cultures. Medium for Leuconostoc oenos (MLO) is the best medium for easy and rapid growth of O. oeni cultures under laboratory controlled conditions for isolation and identification. However, this study showed that O. oeni cells inoculated in MLO failed to induce MLF in wine while cells grown in Medium of Preculture (MP) or wine, stored at −20 °C or freeze-dried retained the ability to induce MLF when inoculated in wine. Our results suggest that the use of freeze-dried cultures of O. oeni previously grown in MP is the best choice for industrial application.     

Contribution of starter culture to the sensory characteristics of fermented Almagro eggplants

Trial fermentations were performed using three experimental starter cultures with a view to selecting the most appropriate starter for use in the manufacture of Almagro eggplants. The lactic acid bacterial strains used in the starters had previously been isolated from spontaneous fermentations. The combined action of the obligate heterofermentative species Lactobacillus brevis and the facultative heterofermentative species L. plantarum yielded Almagro eggplants with sensory properties preferred by panelists. Conversely, another obligate heterofermentative species, namely, L. fermentum, present in certain starter formulations tested, appeared to encounter difficulty growing during fermentation and exerted little influence on the sensory characteristics of the eggplants produced.     

Type of starter culture influences on structural and sensorial properties of low protein fermented gels

Organoleptic properties of skimmed milk fermented gels are progressively demanding to produce optimal quality yogurts. Chr‐Hansen trademark registered cultures were used to produce low‐protein (3.4%) gels to assess the ability to redesign the sensorial and textural properties with the choice of starter culture. Resulting gels were assessed for sensorial, textural, rheological, and microstructural properties and compared with a commercial control (4.5% protein). Mouth thickness, syneresis, firmness, elasticity, and consistency values were lower for polysaccharides‐producing cultures. Such cultures contributed to the higher creaminess and tended to give higher ropiness. Observed differences among microstructures of the gel were minute. Microstructural and rheological data corresponded and reflected the instrumental and sensory interpretations. Strong correlations were observed between sensory and instrumental data. Nonprobiotics cultures resulted in promising overall gel properties compared with probiotic cultures according to the principal component analysis. Yet probiotic cultures resulted in lower syneresis than nonprobiotic cultures. Thus, the choice of bacterial culture modifies the sensorial and textural properties of fermented gel with strong correlations, as a result of altered gel network formation with the production of polysaccharides. Inferior textural and sensorial quality aspects, particularly at low protein levels, have negative impact on consumer demand of low protein yogurts. Thus, we attempted to gain required gel textural and sensorial properties with a choice of starter culture with a low protein level. Resulting gel properties at lowered protein content with different starter cultures are not fully known. The present study compares the effect of probiotic and nonprobiotic starter cultures on gel properties, as gel texture and sensory properties are of great interest and thus not willing to be compromised. In addition, we examined the overall texture profile of studied cultures and correlate with sensory properties. Therefore, reducing protein level in milk and achieving required gel properties with the choice of appropriate starter culture is of great commercial interest as a cost‐cutting strategy to produce low‐cost optimum quality yogurt.     

Pulsed electric field pre-treatment for enhanced bacterial survival after drying: Effect of carrier matrix and strain variability

Previous studies suggest that increased intracellular trehalose concentrations can result in increased robustness of probiotics and starter cultures after processing. We evaluated whether pulsed electric field (PEF) pre-treatment, resulting in increased intracellular trehalose concentrations, can lead to enhanced survival during spray drying and subsequent storage and what the effect of the carrier matrix during drying herein is on survival. The applied PEF pre-treatment resulted in increased survival of Lactobacillus plantarum WCFS1 after spray drying and subsequent storage in reconstituted skim milk (RSM), though not in the other evaluated carrier matrices. The same PEF pre-treatment in lactose instead of trehalose electroporation medium resulted also in an increased survival after spray drying in RSM. Further analysis of intracellular trehalose and lactose concentrations revealed that survival after spray drying cannot only be explained by intracellular trehalose and/or lactose concentrations. Experiments with other bacterial strains indicated that strain variability cannot be neglected when designing a process aimed at enhanced bacterial survival after processing. Overall, PEF pre-treatment is promising for enhancing survival of bacteria after drying and storage, though further understanding of the applicability is required for industrial application.Industrial relevance textProbiotics and starter cultures are very common in food industry. Survival of these cultures during drying processes is essential for their application. A pulsed electric field pre-treatment resulting in increased bacterial survival after spray drying and powder storage may contribute to more energy efficient production processes of dried bacterial cultures.     

直投式发酵剂生产四川泡菜的研究

通过分析接入乳酸菌直投式发酵剂和自然发酵四川泡菜发酵过程中亚硝酸盐含量、乳酸菌菌数和产品品质的动态变化,确定直投式菌剂发酵泡菜时的菌粉添加量和食盐用量。结果表明:添加4%食盐,接入0.04%直投式发酵剂,室温25℃,发酵7d后制得的泡菜酸甜适口,色泽好。添加到直投式发酵剂终产品中的亚硝酸盐含量显著低于自然发酵组,仅为2.11μg/mL,且其乳酸菌菌数远高于自然发酵组,肠膜明串珠菌和植物乳杆菌菌数分别达到6.42×107cfu/mL和3.13×107cfu/mL。     

Bacterial community succession and biogenic amine changes during fermentation of fish-chili paste inoculated with different commercial starter cultures

The microbial dynamics, diversity and succession characterisation during the fermentation of fish-chili paste, with and without starter cultures by high-throughput sequencing, were investigated to identify the relationship between microbial composition and the accumulation of biogenic amines. Results showed that Firmicutes was the predominant phylum, and Lactobacillus and Weissella were the main genera during fermentation process, regardless of the inclusion of starter cultures. Compared with naturally fermented samples (NS; no starter cultures), Pediococcus and Staphylococcus flourished in samples inoculated with SBM-52 starter culture (Staphylococcus xylosus + Staphylococcus carnosus + Pediococcus pentosaceus + Pediococcus acidilactici). Staphylococcus also accounted for a larger proportion in samples inoculated with WBX-43 starter culture (Staphylococcus xylosus + Staphylococcus carnosus). Furthermore, Enterobacter was inhibited in inoculated samples. Unweighted pair-group method with arithmetic means and principal component analyses revealed that microbiota structures were different among NS, SBM and WBX samples. In case of biogenic amines, the concentration of putrescine, cadaverine and tyramine increased to higher levels in NS samples compared with inoculated samples. Our work also investigated the relationship between core bacterial communities and biogenic amines. This study provided an improved understanding for the effects of starter cultures on the microbial community and the quality of fish-chili paste.     

Use of autochthonous Pediococcus acidilactici and Staphylococcus vitulus starter cultures in the production of "chorizo" in 2 different traditional industries

The present study determined how the different ripening conditions affected the growth and development of 3 autochthonous starter cultures, and the physico-chemical and sensory characteristics of chorizo. Each of 3 strains of Pediococcus acidilactici (MC184, MS198, and MS200) and one of Staphylococcus vitulus (RS34) were associated to prepare the starter cultures, P184S34, P198S34, and P200S34. Then, chorizo was prepared following 2 manufacturing procedures. The autochthonous starter cultures were able to compete and colonize the sausages in both ripening procedures. The use of the starter cultures showed evident differences by the texture analysis, with the control batches being generally tougher than the starter culture batches. Also, the highest biogenic amine (BA) levels were found in control batches and the lowest in P200S34 batches. While the use of these starter cultures does not change the sensory characteristics of these traditional fermented sausages, it improves their homogeneity and safety, except for P184S34 batch in which more BAs are detected in industry 2. PRACTICAL APPLICATION: The 3 autochthonous starter cultures selected could be used in traditional industries because they are able to compete well and colonize the dry fermented sausages "chorizo." The use of these starter cultures improves the texture and homogeneity of traditional fermented sausages. Biogenic amines decreased in the starter cultures batches improving the safety.