Comparison of the effects of a commercial and an autochthonous Pediococcus acidilactici and Staphylococcus vitulus starter culture on the sensory and safety properties of a traditional Iberian dry‐fermented sausage “salchichón”

The effect of the addition of an autochthonous starter culture and commercial starter culture on the physico‐chemical and sensory characteristics of the dry‐fermented sausage ‘salchichon’ was investigated. Sausages were prepared with a mixture of Pediococcus acidilactici MC184 and Staphylococcus vitulus RS34 as the autochthonous starter culture (P184S34), ripened for 86 days, and compared with a commercial starter batch (CS1). Strains of acid lactic bacteria and Staphylococcus were identified in the samples along the ripening process which demonstrated that the inoculation of sausages assures their implantation during the ripening process. However, P184S34 starter culture showed a higher inhibitory effect on enterobacteria and coliform flora than the CS1 batches, guaranteeing a better quality hygienic sausages. Dry‐fermented sausages ripened with P184S34 showed higher amounts of NPN and volatile compounds derived from amino acid catabolism than the CS1 batches. Especially important was the result found in biogenic amines, since the P184S34 reduced their accumulation compared to the commercial starter batch. The inoculation of a decarboxylase‐negative autochthonous starter culture P184S34 reduced the biogenic amine accumulation guaranteeing safety and homogeneity of the products without producing a negative effect on the sensory characteristics of the traditional fermented sausages.     

Direct Application of Rep‐PCR on Type I Sourdough Matrix to Monitor the Dominance and Persistence of a Lactobacillus plantarum Starter Throughout Back‐Slopping

This study describes the optimization and application of repetitive element‐PCR (rep‐PCR) technique directly on microbial DNA extracted from type I sourdoughs for fast monitoring of a Lb. plantarum starter strain (P1FMC) throughout daily back‐slopping. The challenge was to follow and study the performance of a starter culture directly in sourdoughs without cultivation on selective media. The extraction of good quality microbial DNA suitable for amplification from a complex matrix such as dough was the first target. In addition, the objective to obtain a clear rep‐PCR profile referable to a specific starter strain among a microbial community was pursued. Co‐inoculum trials, in flour matrix, with Lb. plantarum P1FMC and L. lactis LC71 strains and, subsequently, type I sourdough back‐slopping trials were performed. The rep‐PCR amplification profiles obtained were clearly referable to that of Lb. plantarum P1FMC starter in both co‐inoculum trials (also when it was present with one order of magnitude less with respect to L. lactis LC71) and back‐slopping trials where it dominated the fermentation process with loads of 10⁸ cfu g^?1 and prevailed on the autochthonous microbiota. Thus, the approach proposed in this paper could be considered a methodological advancement, based on a culture‐independent one‐step rep‐PCR, suitable for fast monitoring of starter performance.     

油腐乳发酵过程中的品质分析

采用不同毛霉发酵油腐乳,对其发酵过程中的蛋白酶活性、成熟度、微观结构、流变和感官性质进行分析,探究不同毛霉菌种对油腐乳品质的影响。结果表明：在发酵过程中雅致放射毛霉和五通桥毛霉的蛋白酶活性最高;筛选菌种发酵的油腐乳水溶性蛋白、氨基态氮和总酸含量高于其他3 组,而菌种对油腐乳的水分和盐含量的影响不显著;筛选菌种发酵油腐乳的微观结构最致密;雅致放射毛霉发酵油腐乳涂抹性优于其他3 组;总状毛霉和雅致放射毛霉感官评价相对较优。4 种毛霉菌种各有优势,为毛霉混合发酵油腐乳提供了一定的理论依据。     

Selection and use of autochthonous mixed starter for lactic acid fermentation of carrots, French beans or marrows

Strains of Leuconostoc mesenteroides, Lactobacillus plantarum, Weissella soli/Weissella koreensis, Enterococcus faecalis, Pediococcus pentosaceus and Lactobacillus fermentum were identified from raw carrots, French beans and marrows by partial 16S rRNA gene sequence. L. plantarum M1, Leuc. mesenteroides C1 and P. pentosaceus F4 were selected based on the rates of growth and acidification in vegetable juice media, and used as the autochthonous mixed starter for the fermentation of carrots, French beans or marrows. An allochthonous starter, consisting of the same species, was also used for fermentation. A two-step fermentation process (1 day at 25 degrees C and 7 days at 15 degrees C) in brine (1% w/v) followed by storage at room temperature in olive oil until 40 days was set up. Unstarted vegetables subjected to the same treatments were used as the controls. Cell numbers of lactic acid bacteria in the started vegetables were ca. 10,000 (autochthonous starter) and 1000 (allochthonous starter) times higher than unstarted samples throughout the process. When fermented with the autochthonous starter, carrots, French beans or marrows were characterized by the rapid decrease of pH (<4.5), marked consumption of fermentable carbohydrates, and inhibition of Enterobacteriaceae and yeasts. Fermentation with the allochthonous starter did not acidify and inhibit bacteria and yeasts so rapidly. After 40 days, carrots, French beans and marrows fermented with the autochthonous starter had significantly (P<0.05) higher total concentration of vitamin C (ascorbate+dehydroascorbate) with respect to those fermented with the allochthonous starter and, especially unstarted vegetables. The same was found for the indexes of color. Firmness of both started vegetables was higher than unstarted vegetables. Sensory analysis differentiated started vegetables. Carrots and French beans fermented with the autochthonous starter were, especially, appreciated for fragrance. Appearance was the sensory attribute that mainly distinguished marrows fermented with the autochthonous starter.     

发酵菌种对低盐白腐乳感官品质的影响

腐乳是一种营养丰富的中国传统大豆发酵食品,并具有多种生理活性。但腐乳中较高的盐含量严重阻碍其摄入量及功能性的发挥。降低盐度后,不同发酵菌种对腐乳的感官品质影响不可忽略,对此内容的研究将为开发既美味可口又具备良好保藏性的低盐腐乳产品提供选择合适发酵菌种的科学依据。研究中选取雅致放射毛霉、少根根霉和纳豆菌为发酵菌种制备低盐腐乳,以雅致放射毛霉发酵的高盐腐乳(传统腐乳)为对照,对4种腐乳样品进行感官评价,并对整个生产阶段中蛋白质的分解和菌相变化做跟踪监测。结果显示,雅致放射毛霉发酵的腐乳样品有较好的感官品质,在实验所选用的3株菌中最适宜作低盐腐乳发酵菌种;低盐白腐乳中乳酸菌数与其感官品质有显著相关性。     

Effect of starter cultures on the quality of Suan yu,a Chinese traditional fermented freshwater fish

The generation of volatile compounds of four starter cultures composed of isolated microorganisms from traditional Suan yu was investigated. The cultures included two pure starters (PS1: Lactobacillus plantarum 120 and PS2: Pediococcus pentosaceus 220) and two mixed starters (MS1: L. plantarum 120, Staphylococcus xylosus 135 and Saccharomyces cerevisiae 31 at 1:1:1; MS2: P. pentosaceus 220, S. xylosus 135 and S. cerevisiae 31 at 1:1:1). Naturally fermented Suan yu was used as control. The volatile compounds were collected from the headspace of the samples by Solid‐phase microextraction and analysed by gas chromatography–mass spectrometry. The type and total content of volatile compounds in the mixed‐starter‐fermented fish were higher than those of the pure‐starter‐fermented samples and control. A total of seventy nine and eighty volatile compounds were detected in Suan yu fermented with MS1 and MS2, respectively, with ethanol as the predominant compound and hexanal, ethyl acetate, 3‐methylbutanol, 3‐hydroxy‐2‐butanone, hexanoic acid ethyl ester and 2,3‐butanedione as the other compounds. Furthermore, the sensorial acceptance of the different products with mixed starter cultures seemed to improve the quality of Suan yu products.     

Safety improvement and preservation of typical sensory qualities of traditional dry fermented sausages using autochthonous starter cultures

Traditional dry fermented sausages are manufactured without addition of starter cultures in small-scale processing units, their fermentation relying on indigenous microflora. Characterisation and control of these specific bacteria are essential for the sensory quality and the safety of the sausages. The aim of this study was to develop an autochthonous starter culture that improves safety while preserving the typical sensory characteristics of traditional sausages. An autochthonous starter composed of Lactobacillus sakei, Staphylococcus equorum and Staphylococcus succinus isolated from a traditional fermented sausage was developed. These strains were tested for their susceptibility to antibiotics and their production of biogenic amines. This starter was evaluated in situ at the French traditional processing unit where the strains had been isolated. Effects of the autochthonous starter were assessed by analysing the microbial, physico-chemical, biochemical and sensory characteristics of the sausages. Inoculation with the chosen species was confirmed using known species-specific PCR assays for L. sakei and S. equorum and a species-specific PCR assay developed in this study for S. succinus. Strains were monitored by pulse-field gel electrophoresis typing. Addition of autochthonous microbial starter cultures improved safety compared with the traditional natural fermentation of sausages, by inhibiting the pathogen Listeria monocytogenes, decreasing the level of biogenic amines and by limiting fatty acid and cholesterol oxidation. Moreover, autochthonous starter did not affect the typical sensory quality of the traditional sausages. This is the first time to our knowledge that selection, development and validation in situ of autochthonous starter cultures have been carried out, and also the first time that S. equorum together with S. succinus have been used as starter cultures for meat fermentation. Use of autochthonous starter cultures is an effective tool for limiting the formation of unsafe compounds in traditional sausage while preserving their original and specific sensory quality.     

Effect of fermentation with mixed starter cultures on biogenic amines in bighead carp surimi

The effects of one group mixed starter cultures, combined with Lactobacillus casei, Streptococcus lactis, Saccharomyces cerevisiae Hansen, and Monascus anka, and a batch without starter as control on biogenic amines accumulation in the bighead carp surimi during fermentation were investigated. Determination of five different biogenic amines was carried out by reverse‐phase high‐performance liquid chromatography with UV detection. Results showed that mixed starter cultures decreased the pH quickly from initial pH value of 6.4 to 5.2, inhibited the growth of contaminant microorganisms, such as Enterobacteriaceae and Pseudomonas, present in the raw materials, and suppressed the accumulation of histamine, tyramines, spermine and spermidine. Fermentation inoculated with combination of Lactobacillus casei, Streptococcus lactis, Saccharomyces cerevisiae Hansen, and Monascus anka with negative‐decarboxylase activity may prevent biogenic amine formation in the fermented ssurimi and improve hygienic quality of fermented surimi.     

Role of an autochthonous starter culture and the protease EPg222 on the sensory and safety properties of a traditional Iberian dry-fermented sausage "salchichón"

The effect of the addition of an autochthonous starter culture and the protease EPg222 on the physico-chemical and sensory characteristics of dry-fermented sausage ‘‘salchichon” was investigated. Sausages were prepared with purified EPg222 and Pediococcus acidilactici MS200 and Staphylococcus vitulus RS34 as starter culture (P200S34), separately and together, ripened for 90 days, and compared with a control batch. Dry-fermented sausages ripened with EPg222 and starter culture showed higher amounts of AN and volatile compounds derived from amino acid catabolism than the control, especially in samples in which was added the association of enzyme and starter culture (P200S34 + EPg222). There were clear differences shown by the texture analysis, with the P200S34 + EPg222 batch being less hard. Especially important was the result found in biogenic amines, since the association P200S34 + EPg222 reduced their accumulation compared to the EPg222 batch. The use of EPg222 may be of great interest to improve the sensory characteristics of dry-fermented sausages, but its association with the selected starter culture with low decarboxylase activity is necessary to guarantee healthiness and homogeneity.     

Fermentation of soybean (Glycine max) for soy- daddawa production by starter cultures ofBacillus

Bacillus species (Bacillus subtilis, B. licheniformis and B. pumilus) previously isolated from samples of soy- daddawa prepared traditionally were tested singly and in combinations (as starters) for their ability to ferment sterile dehusked cooked soybean for the production of organoleptically acceptable soy- daddawa. The total viable count pattern of organisms in fermenting soybean samples inoculated with single and mixed starter cultures of the Bacillus species were similar. Of the three Bacillus species, only B. subtilis as single or member of a mixed starter produced soy- daddawa which do not differ significantly (P>0·05) from the naturally fermented soy- daddawa in their sensory attributes. This organism also gave the highest level of proteolytic enzyme activity and free amino acid.     

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.     

Improvement of Fermented Chinese Cabbage Characteristics by Selected Starter Cultures

Traditional fermented vegetables have inconsistent quality and high nitrite content, whereas a commercial starter culture could overcome these problems. A total of 34 lactic acid bacteria strains were screened from 2 homemade naturally fermented Chinese cabbages. Fermented characters of single starter or mixed cultures were examined, including acidification, growth rate, and nitrite depletion ability in the fermented culture. As a result, the combined starter culture (Lactobacillus delbrueckii IWQ and Lactobacillus paracasei J21) was selected. The fermented Chinese cabbage resulted from this mixed starter culture had higher sugar content residue (30.5 mg/mL for mixed culture and 22 mg/mL for control). And the titratable acid of the cabbage fermented by the mixed starter was 110°T, which was twice higher than that of control sample. The selected starter culture also had a better texture and sensory qualities than that the starter cultures from a local fermented Chinese cabbage plant, especially for its significantly lower nitrite content (3.00 mg/kg for mixed culture and 4.49 mg/kg for control). The findings of this study form a database for further studies on the development of starter cultures for fermented cabbage production and could replaced the local plant starter culture.     

Effect of Novel Starter Culture on Reduction of Biogenic Amines,Quality Improvement,and Sensory Properties of Doenjang,a Traditional Korean Soybean Fermented Sauce Variety

To select appropriate microorganisms as starter cultures for the reliable and reproducible fermentation of soybean fermented products of Korean Doenjang, various ratios of fungi (Aspergillus oryzae J, Mucor racemosus 15, M. racemosus 42) combined with Bacillus subtilis TKSP 24 were selected as either single, double, or multiple Meju strains for commercial mass production of Doenjang, followed by analysis of sensory characteristics. In the sensory evaluation, Doenjang BAM15‐1 and BAM42‐1, which were fermented with multiple strains (1:1:1), showed the highest sensory scores as compared to control. Based on sensory characteristics, 6 Doenjang samples were subjected to quantitative determination of amino acids, free sugars, and organic acids (volatile and nonvolatile) contents, followed by determination of biogenic amines. Total sweet taste amino acid contents were highest in BAM15‐1 and BAM42‐1 samples (333.7 and 295.8 mg/100 g, respectively) and similar that of control (391.1 mg/100 g). Samples BAM15‐1 and BAM42‐1 showed the relatively high volatile and nonvolatile organic acid contents (154.24, 192.26, and 71.31, 82.42 mg/100 g, respectively). In addition, BAM15‐1 and BAM42‐1 showed negligible biogenic amine formation, ranging from 0.00 to 1.02 and 0.00 to 3.92 mg/100 g, respectively. These findings indicate that determination of food components along with sensory and quality attributes using multiple microbial Meju strains as a starter culture may provide substantial results on improved quality fermented Doenjang products.     

Survival of Escherichia coli O157:H7, nitrite content and sensory acceptance of low‐salt Chinese paocai fermented by screened lactic acid bacteria

Starter cultures of low‐salt Chinese paocai were screened from 135 lactic acid bacteria (LAB) by evaluating their antimicrobial activity and growth characteristics. Furthermore, the survival of Escherichia coli O157:H7, nitrite contents and sensory acceptability of the starter‐fermented paocai were evaluated. LAB BC92, which was identified as Lactobacillus pentosus, was used as a starter culture to produce paocai. In comparison with naturally fermented paocai, the disappearance time of E. coli O157:H7 in starter‐fermented paocai decreased from 5.29 to 3.82 days, and the maximum nitrite content decreased from 11.73 to 8.64 mg kg^?1, and the nitrite reduction time decreased from 4 to 3 days. In addition, starter fermentations were able to accelerate the flavour formation and shorten the paocai ripening period. The paocai that was fermented naturally and fermented by BC92 all had good sensory acceptance, and no significant difference (P > 0.05) was observed.     

Physicochemical and sensory characteristics of soy yogurt fermented with Bifidobacterium breve K-110, Streptococcus thermophilus 3781, or Lactobacillus acidophilus Q509011

The physicochemical and sensory characteristics of soy yogurt fermented with Bifidobacterium breve K-110, Streptococcus thermophilus 3781, or Lactobacillus acidophilus Q509011 for 36 hr at 37°C were investigated and the soyasaponin metabolites of soy yogurt were measured. L. acidophilus reduced the pH of soy yogurt on day 0 to optimum level. After 36 hr, the Brix dropped to 8.48–9.12°Bx. The viable cell counts of soy yogurts on day 0 were 8.43 to 9.01 log CFU/mL. Among starters, B. breve alone produced soyasapogenol B, although it was not detected in non-fermented soybean. B. breve produced poor sensory scores in all sensory aspects. By mixing B. breve with S. thermophilus and L. acidophilus, the sensory scores of B. breve could be improved. These findings suggest that the mixed culture of S. thermopilus or L. acidophilus with B. breve may be an ideal starter for the preparation of soy yogurt.     

Biogenic amine content and proteolysis in Manchego cheese manufactured with Lactobacillus paracasei subsp. paracasei as adjunct and other autochthonous strains as starters

Two different autochthonous strain starter cultures, in which the acidifying starter was composed of strains of Lactococcus lactis, were used for the manufacture of pasteurised milk Manchego cheese. Proteolysis parameters, biogenic amines and sensory characteristics were evaluated and compared with those of commercial starter Manchego cheese and raw milk Manchego cheese manufactured without starter. Autochthonous starter cheeses, and especially those including Lactobacillus paracasei subsp. paracasei as adjunct, presented higher levels of proteolysis than in commercial starter cheese. The concentrations of total biogenic amines in autochthonous starter cheeses were much lower than in raw milk cheese and even lower than in commercial starter cheese. Cheese manufactured with the adjunct strain gave the best results for both flavour intensity and flavour quality, and was the most preferred by panellists. The results suggest that the culture containing Lb. paracasei subsp. paracasei as adjunct could be used for the manufacture of industrial Manchego cheese.     

Utilisation possibility of Enterococcus faecalis isolates from neonate's faeces for production of fermented sausages as starter cultures

This study aimed at assessing the utilisation possibility of Enterococcus faecalis as starter cultures for production of fermented sausages. The E. faecalis isolates isolated from faeces samples of 5‐day‐old healthy newborn babies, identified by 16SrDNA sequencing and free from virulence determinants as proven by genomic sequencing, were used for fermented sausages production as starter culture. Six treatments (four inoculated with four different E. faecalis isolates, one with commercial starter culture and one control) were prepared. The inoculation with E. faecalis showed a stronger acidification compared with the control. The treatments with E. faecalis showed significantly higher flavour and acceptability scores in comparison with the control or commercial starter culture. Both of commercial starter culture and E. faecalis were positive with tyramine. Apart from the amine production, the inoculation with E. faecalis generally improved the acidifying activity and flavour of the products, suggesting their application potentials in fermented sausages production as starter cultures.     

羊肉发酵干香肠在成熟和贮藏过程中感官指标的变化及其相关性

试验通过接种复合发酵剂和添加天然香辛料,采用相同的工艺条件生产4组羊肉发酵香肠,1组为对照组(CO),2组为接种发酵剂组(SC),3组为发酵剂+黑胡椒组(SC+BP),4组为发酵剂+黑胡椒+孜然组(SC+BP+C)。采集成熟后(第7天)及贮藏过程(第14天、第21天和第35天)各组发酵香肠进行感官评价,结果建立了色泽、风味、组织状态和滋味与整体可接受性之间的线性模型公式为Y=0.08X1+0.147X2+0.222X3+0.836X4(R2=0.999),感官特性权重依次为滋味>组织状态>风味>色泽,说明滋味对产品的品质具有决定性作用。发酵剂+黑胡椒(SC+BP)组和发酵剂+黑胡椒+孜然(SC+BP+C)组的色泽评分由于添加黑胡椒的原因,其色泽评分在成熟和贮藏期间一直低于对照组。试验发酵剂组(SC)的羊肉发酵香肠在贮藏2周(第21天)时,各项感官评分均明显高于对照组,而且试验组的膻味评分在贮藏过程中明显低于对照组,说明接种复合发酵剂对羊肉发酵香肠感官品质的提高有一定的作用。     

Influence of a defined-strain starter and Lactobacillus plantarum as adjunct culture on volatile compounds and sensory characteristics of Manchego cheese

Three batches of Manchego cheese were manufactured using one of the following starter culture systems: (1) a defined strain starter culture comprising Lactococcus lactis subsp. lactis and Leuconostoc mesenteroides subsp. dextranicum; (2) the above-defined strain starter culture and an adjunct culture (Lactobacillus plantarum), all these strains being isolated from high-quality Manchego cheeses and (3) a commercial starter consisting of two strains of Lactococcus lactis. Differences in volatile profile and the sensory characteristics of these cheeses were studied. After 4 months of ripening, the two batches of cheese made with the defined strain starter cultures obtained the highest scores for sensory attributes and for the overall impression. Additionally, Purge & Trap and SDE analysis showed a more complex volatile profile in these cheeses than in those made with the commercial starter. Extending the maturation time to 8 months for cheeses made with the defined starter cultures led to significant higher levels of free fatty acids and ethyl esters in those cheeses made without adjunct culture. However, panelists did not find significant differences among the sensory characteristics of the two cheeses.     

Effect of Lactobacillus plantarum on the survival of acid‐tolerant non‐O157 Shiga toxin‐producing E. coli (STEC) strains in fermented goat's milk

The ability of goat's milk fermented with a Lactobacillus plantarum strain B411, and in combination with commercial starter culture, to inhibit acid‐adapted (AA) and non‐acid‐adapted (NAA) environmental non‐O157 STEC strains was investigated. Acid‐adapted and NAA non‐O157 STEC strains were not inhibited in the L. plantarum‐fermented goat's milk, while the goat's milk fermented with the combination of L. plantarum and starter culture inhibited AA more than NAA non‐O157 STEC strains. Environmental acid‐tolerant non‐O157 STEC strains were not inhibited by L. plantarum, starter culture or combination of starter culture with L. plantarum unless they were subjected to prior acid adaptation such as backslopping.