Growth characteristics of meat starter cultures

The Australian Code of Practice for manufacture of dry and semi-dry sausage (salami) states that fermentation temperatures must not exceed 25°C and that a pH of 5·2 must be achieved in the product within 48 h. In order to select the most appropriate starter cultures for fermentation, Lactobacillus plantarum, Pediococcus pentosaceus and Staphylococcus carnosus were characterised with respect to growth and acid production determined at constant pH (4·7, 5·5 and 6·3). L. plantarum and P. pentosaceus showed similar characteristics over the pH range studied while S. carnosus was sensitive to lower pH. Also, P. pentosaceus showed greater psychrotrophic growth without pH control than L. plantarum or S. carnosus. Salami made with P. pentosaceus maintained higher viable numbers in the product over 8 days than did L. plantarum. Growth of S. carnosus in salami could not be detected in the presence of the more pH-tolerant organisms. The growth of L. plantarum and P. pentosaceus did not prevent the development of high levels of non-starter flora, a factor that can be important in determining salami quality. However, the more psychrotrophic P. pentosaceus ensured a greater dominance of starter over non-starter flora.     

Functional meat starter cultures for improved sausage fermentation

Starter cultures that initiate rapid acidification of the raw meat batter and that lead to a desirable sensory quality of the end-product are used for the production of fermented sausages. Recently, the use of new, functional starter cultures with an industrially or nutritionally important functionality is being explored. Functional starter cultures offer an additional functionality compared to classical starter cultures and represent a way of improving and optimising the sausage fermentation process and achieving tastier, safer, and healthier products. Examples include microorganisms that generate aroma compounds, health-promoting molecules, bacteriocins or other antimicrobials, contribute to cured meat colour, possess probiotic qualities, or lack negative properties such as the production of biogenic amines and toxic compounds. The vast quantity of artisan fermented sausages from different origins represents a treasure chest of biodiversity that can be exploited to create such functional starter cultures.     

直投式酸奶发酵剂的商品化生产研究

通过对不同保加利亚乳杆菌与嗜热链球菌菌株的酸化活力、黏度、蛋白水解能力和共生能力等生理学指标的测定,筛选出4对适于发酵生产用的菌株组合,并以菌株Y6+ST1作为进一步研究对象,获得其最佳增殖培养基为番茄汁为2.5%,乳糖为1.0%,酵母膏为0.5%,蛋白胨为1.5%,42℃培养6h后其活菌数达到1.4×109mL-1;Y6+ST1组合的最佳保护剂组成为脱脂奶粉为18.0%,甘油为2.0%,谷氨酸钠为1.0%和吐温-80为0.5%,经冷冻干燥后其活菌数达到3.62×1011g-1。该组合工业化生产的最佳工艺参数是培养温度42.3℃,pH值为6.4,搅拌转速86.8r/min和3%的接种量,1.0%补料(脱脂乳),发酵时间6h;-40℃,15h后,最终冷冻干燥产品活菌数为1011g-1。     

Quality traits of wild boar mould-ripened salami manufactured with different selections of meat and fat tissue, and with and without bacterial starter cultures

Quality traits of wild boar mould-ripened salami were assessed in eight batches produced from two different assortments of meat (hind leg vs. shoulder), fat tissue (backfat from domestic pigs vs. fat tissue from wild boar), and with and without addition of a commercial bacterial starter culture. Chemical composition of finished products (day 35) were in compliance with national food codex. Batches produced with a bacterial starter culture were generally preferred by taste panels, had significantly lower concentrations of TBARS (<1.5 mgmalondialdehyde/kg) and peroxide values (POVs) and lower concentrations of cadaverine (<50 mg/kg), histamine (<10 mg/kg) and putrescine (<60 mg/kg). TBARS and POVs were inversely related to sensory preference scores (r(2)=0.84 and 0.88). Batches produced from shoulder muscles contained significantly higher concentrations of cadaverine, histamine and putrescine. TBARS were highest in batches manufactured with fat tissue from wild boars. These findings should be considered when guides to good practice for the manufacture of game meat products are developed.     

肉品发酵剂及肉品发酵技术优化的研究现状

介绍了发酵肉制品概念、发展史及种类,对常用的肉品发酵微生物的种类及其作用进行了总结;同时从发酵剂、发酵条件的优化2个方面着手,对发酵肉制品未来研究方向进行了推测。     

The effect of processed meat and meat starter cultures on gastrointestinal colonization and virulence of Listeria monocytogenes in mice

Listeria monocytogenes is a foodborne pathogen of major concern to the food industry in general and the meat industry in particular. The aim of this study was firstly to identify a strain of Listeria that was virulent in SPF BALB/c mice. Secondly, to investigate if a traditional meat starter culture (FloraCarn) and nontraditional meat starter (NTMS) cultures of dairy product and human origin (Lactobacillus and bifidobacteria) inhibit this pathogen in vivo. In addition, the inhibition of Listeria was investigated in vitro. In vitro inhibition was investigated using an agar inhibition assay, where soft agar containing the pathogen was laid over colonies of NTMS cultures, and inhibition expressed as the zones of inhibition developing around the colonies. For assessment of virulence, mice were intragastrically challenged with broth cultures of five strains of Listeria. For assessment of anti-listeria effect in vivo, the Listeria strain proven to be most pathogenic (LM3) was given to mice in salami batter containing no other added cultures (control) or batter inoculated with either (1) FloraCarn, (2) a NTMS culture, or (3) a combination of FloraCarn and a NTMS culture. The batter was given to mice after a 3-day fermentation and faecal levels of pathogen and body weight were monitored. Intragastric challenge with LM3, but no other strains, resulted in a significant weight loss (p<0.05) and up to 10(6) colony forming units (cfu) of LM3 per gram faeces. No weight loss was observed in animals fed with salami batter containing LM3. Consumption of salami batter fermented by a combination of NTMS culture (Lactobacillus acidophilus LAFTI(R) L10) and FloraCarn reduced faecal levels of the pathogen by 2.5 log units compared to the control. Consumption of salami batter fermented with FloraCarn and LAFTI(R) L10 (L10) alone reduced faecal levels by 0.5-1 and 1.5 log units, respectively. Of the NTMS cultures investigated here, L10 displayed the greatest inhibition of LM3 in vitro. These results indicate that the ability of pathogenic Listeria to cause listeriosis is dependent on the nature of the food in which the pathogen is present, and that a traditional meat starter culture (FloraCarn) and some NTMS cultures, particularly L10, inhibit growth of the pathogen during passage through the gastrointestinal tract.     

肉制品发酵剂的研究进展

主要讨论了发酵肉制品中所使用的发酵剂及它们的特性和应用,也介绍了优良发酵剂的筛选及构建,并对发酵剂的发展趋势进行了展望。     

Mixed starter cultures to control biogenic amine production in dry fermented sausages

Several combinations of an amine-negative Lactobacillus sakei strain, along with proteolytic Staphylococcus carnosus or Staphylococcus xylosus strains, were used to study the influence of mixed starter cultures on biogenic amine production during the manufacture of dry fermented sausages. Changes in pH, water content, proteolysis, microbial counts, and biogenic amine contents were simultaneously examined in a spontaneously fermented batch and in three mixed starter-mediated batches. A double-controlled microbial charge initially inoculated as mixed starter culture of L. sakei and Staphylococcus spp. (all amine-negative strains) drastically reduced tyramine, cadaverine, and putrescine accumulation. No production of other aromatic amines such as histamine, phenylethylamine, or tryptamine was observed in any batch. The polyamines, spermine and spermidine, were found in raw materials and their levels decreased slightly in the spontaneously fermented batch. No correlation between proteolysis and biogenic amine production was observed. The use of proper technological conditions favoring starter development and the use of the raw materials with good hygienic quality make it possible to produce fermented sausages nearly free of biogenic amines.     

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。     

Stimulation of starter culture for further reduction of foodborne pathogens during salami fermentation

This study was conducted to determine if stimulated meat starter culture (MSC; Pediococcus acidilactici) would further control Escherichia coli O157:H7, Listeria monocytogenes, and Staphylococcus aureus during salami fermentation. Manganese ion (0.005% of MnSO4) was used as a stimulator for the growth and acid production of MSC. After 24-h salami fermentation, nonstimulated MSC and stimulated MSC reduced E. coli O157:H7 levels by 1.3 and 2.3 log10 units, respectively. Nonstimulated MSC reduced L. monocytogenes levels by 1.2 log10 units, whereas the stimulated MSC achieved a 2.2-log10 reduction after 24-h fermentation. In the case of S. aureus, nonstimulated MSC and stimulated MSC reduced S. aureus levels by 1.3 and 2.3 log10 units after 24-h fermentation, respectively. Stimulated MSC by MnSO4 reduced those foodborne pathogens more effectively compared with nonstimulated MSC (P < 0.05).     

The use of commercial starter cultures in the production of Turkish semi-dry fermented sausages

 The effects of three different starter cultures (Pediococcus acidilactici, Staphylococcus xylosus plus P. pentosaceus, S. carnosus plus Lactobacillus pentosus) were evaluated during the production of Turkish semi-dry fermented sausages. Sausages were studied during the fermentation phase, after heat processing and after drying for 24 h and 72 h. Chemical and organoleptical results indicated that in the processing of these semi-dry sausages a starter culture of P. acidilactici should be used. The use of this culture significantly reduced the pH, increased the lactic acid content and percentage of total heme pigments converted to the cured pigment and improved the development of the sausages' characteristics, i.e. color, appearance, flavor and general acceptability. Received: 20 February 1998 / Revised version: 7 May 1998     

HACCP在无公害冷却猪肉生产中的应用

HACCP的全称是Hazard Analysis Critical Control Point，即危害分析关键控制点，它是用来保护食品在整个生产过程中免受可能发生的生物、化学、物理因素的危害，由食品的危害分析和关键控制点两部分组成。其宗旨是将这些可能发生的食品危害消除在生产过程中，而不是靠最终检验来保证产品的可靠性。无公害冷却猪肉是指来自通过无公害认证猪场的生猪，经兽医严格检验检疫合格后，在国家批准并符合国家卫生标准的屠宰厂内进行屠宰，屠宰后的胴体经严格检疫合格后，在-18～-20℃的条件下，进行快速冷却90min，使胴体中心温度由40℃降至28℃，并在表面形成一层“冰衣”，防止肉品水分蒸发和细菌的二次入侵，     

The role of the glassy state in production and storage of freeze-dried starter cultures

The inactivation rates k of the model microorganism F19 (Chr. Hansen A/S, Hørsholm, Denmark) as well as the spin- spin relaxation time, T₂,were determined in the area around the glass transition temperature T_g. By keeping cell-sugar lyophilisates at defined temperatures and water activities, storage above and below T_g could be realized. In order to characterize the temperature dependence of T₂ and k, the results were fitted using the Williams-Landel-Ferry (WLF) and Arrhenius models. T₂ was found to be solely dependent on the temperature interval between T_g and the storage temperature, T_p. In case of inactivation kinetics this temperature interval could not fully explain the results. In contrast to molecular mobility, the microbial inactivation was supposed to be influenced additionally by the absolute storage temperature. This is due to fact that microbial inactivation is a highly complex process which is dependent on a number of physico-chemical reactions with some being more while some are less diffusion limited. In terms of inactivation kinetics and molecular mobility, T_g did not act as an absolute threshold but could divide the results into weakly and strongly temperature-dependent fractions. Within the freeze-drying process the glassy state of the sample matrix did not show a protective effect.     

Characterization of toxin production of coagulase-negative staphylococci isolated from food and starter cultures

In this study a comprehensive analysis of toxin production of food associated coagulase-negative staphylococci (CNS) was investigated. The strains belong to the following staphylococcal species, Staphylococcus carnosus, Staphylococcus condimenti, Staphylococcus equorum, Staphylococcus piscifermentans, Staphylococcus succinus, and Staphylococcus xylosus, which were isolated from fermented food and starter cultures. A collection of 330 strains were analyzed with respect to their hemolytic activity. 59% of the strains exhibited weak to moderate hemolytic activity with human blood and 34% with sheep blood after 48 h incubation. A selection of 35 strains were tested by immunoblot analysis for their ability to produce toxins, such as the most common staphylococcal enterotoxins (SEs), the toxic shock syndrome toxin 1 (TSST-1), and the exfoliative toxin A (ETA). 18 of the 35 strains produced at least one of the toxins with the SED and SEH being the most common. These indicate that the use of CNS in food production demands a safety evaluation.     

姜蒜在肉制品生产中的作用

众所周知,鲜肉在室温下,时间一久就易变质,特别是夏天,而脂肪氧化是鲜肉变质的根本原因。因此,人们常将鲜肉经过一定工艺制成腊肉、火腿、香肠及午餐肉等多种肉制品。为保持肉的颜色红润、防止因脂肪氧化而使肉变质,在传统的肉制品生产工艺中常通过加入硝酸盐和亚硝酸盐来维持肉的色泽,抑制细菌的生长和防止因脂肪氧化而造成的变质。     

栅栏技术在传统肉制品生产中的应用

介绍了栅栏技术的基本原理。针对中国的传统肉制品特性,利用栅栏技术,在不影响其货架寿命条件下改善风味、提高营养价值。在栅栏技术的基础上结合微生物预测技术和HACCP技术使传统肉制品更易于保藏。     

Selection of starter cultures for the production of ugba,a fermented soup condiment

Ugba is a traditional fermented African oil bean condiment that serves as flavouring in soups or as low-cost protein snack in Nigeria. A total of 56 strains of spore-forming bacteria were isolated from 21 ugba samples purchased from retail markets in southwestern Nigeria. Bacillus subtilis (26 strains) was identified as the dominant microorganism of the fermented samples. The total viable count for the ugba samples obtained from the retail outlets was in the range of 1.4᎒⁷-2.8᎒⁹ cfu/g, while the spore-forming bacteria had a count of 1.8᎒¹⁰ cfu/g. Strains of B. subtilis were selected as potential starter cultures based on their enzymatic activities and ability to produce stickiness. The nine selected strains had a range of scores of proteolytic activity (5.2-7.4 mm), amylolytic activity (4.4-5.6 mm) and stickiness (15.1-17.3 cm). Relative viscosity was in the range of 2.3-5.3 U/ml, while protease activity was from 30.1-51.4 U/ml. However, B. subtilis MM-4:B12 that had the highest scores was chosen as starter culture for the laboratory preparation of ugba, and a viable count of 1.4᎒¹⁰, pH of 8.1 and 46.5% moisture content were obtained at the end of 72 h fermentation period. The fermented product had the peculiar characteristics of the traditionally prepared sample which is usually fermented for about 5 days. There were no significant differences in the protein (17.8-18.1%), fat (40.9-41.2) and titratable acidity (0.11-0.13%) of both starter culture fermented ugba and those obtained from the retail markets. However, organoleptic evaluation scores showed the starter-inoculated samples being rated higher by the consumers with regard to consistency, aroma and taste.     

Survival of foot-and-mouth disease virus in sausage meat products (Italian salami)

Determination of the survival of foot- and-mouth disease virus (FMDV) in fresh meat from experimentally infected swine and in several types of sausage meat (Italian salami) produced according to the technology widely applied by the principal Italian producers has been carried out. The purpose of the experiment was to assess if typical Italian salami can be considered safe with regard to the spread of FMD through international trade. The results obtained showed: (a) high titers of FMDV were detected in both muscle and fat tissues from animals slaughtered at the peak of the experimental disease; and (b) FMDV was not detectable in the above tissues 72 h after slaughtering and the same applies to the different types of salami tested 7 days after production. The above results were obtained in tissue cultures and confirmed through piglet inoculation.     

Screening of commercial meat starter cultures at low pH and in the presence of bile salts for potential probiotic use

The survival of lactic acid bacterial strains from eight meat starter cultures under conditions similar to those in the gastrointestinal tract was determined. The conditions in stomach were simulated by using pH 1-5 phosphate-buffered saline. The conditions in small intestine were simulated by using MRS broth over a pH range 4-7 and two bile salt concentrations (0.15% and 0.30%). The survival capacity at pH 3 was strain dependent. 0.30% bile salts were critical for screening bile salt tolerant strains at pH 6. Strains of Lactobacillus sake (RM10) and Pediococcus acidilactici (P2) had the best survival capacities under acidic conditions and at the higher concentration of bile salts.     

A novel approach of direct formulation of defined starter cultures for different kefir-like beverage production

Six pure microbial strains, Kluyveromyces marxianus BD01004, Lactobacillus delbruekii ssp. bulgaricus BD00014, Lactobacillus kefiri BD00002, Streptococcus thermophilus BD00089, Lactococcus lactis BD00736 and Leuconostoc mesenteroides BD01701, previously isolated in our laboratory from diverse sources, were combined in different proportions for the formulation of defined starter cultures for the production of kefir-like beverages in 10% (w/w) reconstituted skim milk. The physicochemical properties of products obtained were analysed by high performance liquid chromatography for ethanol, lactose and lactic acid contents, and by gas chromatography–mass spectrometry for determination of volatile compounds. A comparative study of these products with kefir was further undertaken with the purpose of determining suitable starter culture combinations for production of kefir-like beverages. The results indicated that some of the starter cultures devised were consistent with the production of beverages with characteristics approximating to those of traditional kefir as reported in the literature.