RESUMEN
The objectives of this study were to evaluate the growth and survival of the model probiotic strain Lactobacillus plantarum WCFS1 in co-culture with traditional yoghurt starters and to investigate the impact of preculturing on their survival and metabolite formation in set-yoghurt. L. plantarum WCFS1 was precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor before inoculation in milk. Adaptive responses of L. plantarum WCFS1 were evaluated by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt. The results demonstrated that sublethal preculturing did not significantly affect survival of L. plantarum WCFS1. On the other hand, incorporation of sublethally precultured L. plantarum WCFS1 significantly impaired the survival of Lactobacillus delbrueckii subsp. bulgaricus which consequently reduced the post-acidification of yoghurt during refrigerated storage. A complementary metabolomics approach using headspace SPME-GC/MS and (1)H NMR combined with multivariate statistical analysis revealed substantial impact of sublethally precultured L. plantarum WCFS1 on the metabolite profiles of set-yoghurt. This study provides insight in the technological implications of non-dairy model probiotic strain L. plantarum WCFS1, such as its good stability in fermented milk and the inhibitory effect on post-acidification.
Asunto(s)
Microbiología de Alimentos , Lactobacillus plantarum/crecimiento & desarrollo , Lactobacillus plantarum/metabolismo , Estrés Fisiológico , Yogur/microbiología , Fermentación , Concentración de Iones de Hidrógeno , Lactobacillus delbrueckii/metabolismo , Lactobacillus plantarum/efectos de los fármacos , Metabolómica , Probióticos , Cloruro de Sodio/farmacología , Yogur/análisisRESUMEN
Lupinus mutabilis has protein (32.0-52.6 g/100 g dry weight) and lipid (13.0-24.6 g/100 g dry weight) contents similar to soya bean (Glycine max). The Ω3, Ω6, and Ω9 contents are 1.9-3.0, 26.5-39.6, and 41.2-56.2 g/100 g lipid, respectively. Lupins can be used to fortify the protein content of pasta, bread, biscuits, salads, hamburgers, sausages, and can substitute milk and soya bean. Specific lupin protein concentrates or isolates display protein solubility (>90%), water-absorption capacity (4.5 g/g dry weight), oil-absorption capacity (3.98 g/g), emulsifying capacity (2000 mL of oil/g), emulsifying stability (100%, 60 hours), foaming capacity (2083%), foaming stability (78.8%, 36 hours), and least gelation concentration (6%), which are of industrial interest. Lupins contain bitter alkaloids. Preliminary studies on their toxicity suggest as lethal acute dose for infants and children 10 mg/kg bw and for adults 25 mg/kg bw. However, alkaloids can also have medical use for their hypocholesterolemic, antiarrhythmic, and immunosuppressive activity. Bitter lupins can be detoxified by biological, chemical, or aqueous processes. The shortest debittering process requires one hour. This review presents the nutritional composition of lupins, their uses (as food, medicine, and functional protein isolates), toxicology, and debittering process scenarios. It critically evaluates the data, infers conclusions, and makes suggestions for future research.
Asunto(s)
Lupinus/química , Lupinus/toxicidad , Semillas/química , Alcaloides/análisis , Proteínas en la Dieta/administración & dosificación , Manipulación de Alimentos/métodos , Alimentos Fortificados , Humanos , Lípidos/análisis , Micronutrientes/análisis , Valor Nutritivo , Proteínas de Plantas/análisis , Proteínas de Plantas/química , GustoRESUMEN
This study aimed at determining bacterial concentration and diversity in fresh tropical shrimps (Penaeus notialis) and their surrounding brackish waters and sediment. Freshly caught shrimp, water and sediment samples were collected in Lakes Nokoue and Aheme in Benin (West Africa) during two periods with different water salinity and temperature. We used complementary culture-dependent and culture-independent methods for microbiota analysis. During both sampling periods, total mesophilic aerobic counts in shrimp samples ranged between 4.4 and 5.9 log CFU/g and were significantly higher than in water or sediment samples. In contrast, bacterial diversity was higher in sediment or water than in shrimps. The dominant phyla were Firmicutes and Proteobacteria in shrimps, Firmicutes, Proteobacteria, and Actinobacteria in water, and Proteobacteria and Chloroflexi in sediment. At species level, distinct bacterial communities were associated with sediment, water and shrimps sampled at the same site the same day. The study suggests that the bacterial community of tropical brackish water shrimps cannot be predicted from the microbiota of their aquatic environment. Thus, monitoring of microbiological quality of aquatic environments might not reflect shrimp microbiological quality.
Asunto(s)
Sedimentos Geológicos/microbiología , Microbiota/genética , Penaeidae/microbiología , Mariscos/microbiología , Actinobacteria/genética , Actinobacteria/aislamiento & purificación , África Occidental , Animales , Técnicas de Tipificación Bacteriana , Benin , Chloroflexi/genética , Chloroflexi/aislamiento & purificación , Firmicutes/genética , Firmicutes/aislamiento & purificación , Datos de Secuencia Molecular , Proteobacteria/genética , Proteobacteria/aislamiento & purificación , ARN Ribosómico 16S , Aguas Salinas , Microbiología del Suelo , Microbiología del AguaRESUMEN
The spoilage activity of Pseudomonas psychrophila and Carnobacterium maltaromaticum, two tropical shrimp (Penaeus notialis) spoilage organisms, was assessed in cooked shrimps stored at 0 to 28 °C. Microbiological, chemical and sensory analyses were performed during storage. P. psychrophila had a higher growth rate and showed a higher spoilage activity at temperatures from 0 to 15 °C, while at 28 °C, C. maltaromaticum had a higher growth rate. The spoilage activity of P. psychrophila was found to be higher in cooked shrimp than in fresh shrimp. Observed shelf-life data of shrimps stored at constant temperatures were used to validate a previously developed model that predicts tropical shrimp shelf-life at constant storage temperatures. Models predicting the growth of the spoilage organisms as a function of temperature were constructed. The validation of these models under dynamic storage temperatures simulating temperature fluctuation in the shrimp supply chain showed that they can be used to predict the shelf-life of cooked and fresh tropical shrimps.
Asunto(s)
Carnobacterium/fisiología , Manipulación de Alimentos/normas , Microbiología de Alimentos/métodos , Modelos Teóricos , Penaeidae/microbiología , Pseudomonas/fisiología , Mariscos , Temperatura , Animales , Culinaria , Pseudomonas/crecimiento & desarrollo , Mariscos/microbiología , Mariscos/normasRESUMEN
The objective of this study was to investigate the effect of preculturing of Lactobacillus rhamnosus GG and Bifidobacterium animalis subsp. lactis BB12 under sublethal stress conditions on their survival and metabolite formation in set-yoghurt. Prior to co-cultivation with yoghurt starters in milk, the two probiotic strains were precultured under sublethal stress conditions (combinations of elevated NaCl and low pH) in a batch fermentor. The activity of sublethally precultured probiotics was evaluated during fermentation and refrigerated storage by monitoring bacterial population dynamics, milk acidification and changes in volatile and non-volatile metabolite profiles of set-yoghurt. The results demonstrated adaptive stress responses of the two probiotic strains resulting in their viability improvement without adverse influence on milk acidification. A complementary metabolomic approach using SPME-GC/MS and (1)H-NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Principal component analysis revealed substantial impact of the activity of sublethally precultured probiotics on metabolite formation demonstrated by distinctive volatile and non-volatile metabolite profiles of set-yoghurt. Changes in relative abundance of various aroma compounds suggest that incorporation of stress-adapted probiotics considerably influences the organoleptic quality of product. This study provides new information on the application of stress-adapted probiotics in an actual food-carrier environment.
Asunto(s)
Bifidobacterium/metabolismo , Microbiología de Alimentos/métodos , Lactobacillus/metabolismo , Viabilidad Microbiana , Leche/microbiología , Probióticos/análisis , Yogur/microbiología , Animales , Bifidobacterium/crecimiento & desarrollo , Fermentación , Concentración de Iones de Hidrógeno , Lactobacillus/crecimiento & desarrolloRESUMEN
AIMS: Optimization of traditional processing of soybeans using response surface methodology (RSM) to achieve a minimum level of antinutritional factors (ANFs) in kinema. METHODS AND RESULTS: Central composite rotatable designs were used to optimize the processing stages of kinema preparation. In each stage, the linear or quadratic effects of independent variables were significant in minimizing ANF levels. The predicted optimum condition for soaking was when the raw beans-water ratio was 1 : 10, and the soaking temperature, time and pH were 10°C, 20 h and 8·0 respectively. Here, tannins content (TC), phytic acid content (PAC) and trypsin inhibitor activity (TIA) decreased (P < 0·05). While haemagglutinating activity (HA) level remained unchanged (P < 0·05), total biogenic amines content (TBAC) increased. The optimum condition for cooking was optimally soaked beans-water ratio of 1 : 5, and cooking pressure and time were 1·10 kg cm(-2) and 20 min respectively. Here, TC, PAC, TIA and HA decreased (P < 0·05), but TBAC remained unchanged compared to optimally soaked beans. TC and HA went below the level of detection. The optimum condition for fermentation was obtained when inoculum load was 10(3) total cells g(-1) grits, and fermentation temperature and time were 37°C and 48 h respectively. Fermentation of optimally cooked beans caused a reduction (P < 0·05) of PAC. While TIA remained unchanged (P < 0·05), TBAC increased. In kinema, TC, PAC, TIA and HA decreased (P < 0·05) over raw beans by 100, 61, 71 and 100% respectively. Good agreement was observed between predicted values and experimental values. CONCLUSIONS: The processing treatments significantly minimized the level of ANFs in soybeans. SIGNIFICANCE AND IMPACT OF THE STUDY: RSM was successfully deployed to obtain the optimum condition for kinema-making with a minimum level of ANFs without impairing sensory attributes of the product. The results are useful for commercial production of kinema.
Asunto(s)
Bacillus/metabolismo , Manipulación de Alimentos/métodos , Microbiología de Alimentos/métodos , Glycine max/microbiología , Alimentos de Soja/microbiología , Culinaria , Fermentación , Calor , Ácido Fítico/análisis , Ácido Fítico/metabolismo , Alimentos de Soja/análisis , Glycine max/química , Glycine max/metabolismo , Taninos/análisis , Taninos/metabolismoRESUMEN
Maintaining the freshness of shrimp is a concern to shrimp stakeholders. To improve shrimp quality management, it is of importance to evaluate shrimp spoilage characteristics. Therefore, microbiological, sensory, and chemical changes of naturally contaminated tropical brackish water shrimp (Penaeus notialis) during storage at 28 °C, 7 °C and 0 °C were assessed. H2S-producing bacteria were the dominant group of microorganisms at 28 °C and 7 °C whereas Pseudomonas spp. were dominant at 0 °C. Total volatile basic nitrogen and trimethylamine correlated well (R(2) > 0.90) with the sensory scores. An empirical model to predict the shelf-life of naturally contaminated tropical shrimp as a function of storage temperature was developed. Specific groups of organisms were isolated at the sensory rejection times and assessed for spoilage potential in shrimps of which the endogenous flora was heat inactivated. Isolates capable of producing strong off-odor identified by 16S rRNA sequencing were mainly lactic acid bacteria (LAB) and Enterobacteriaceae at 28 °C or 7 °C and Pseudomonas spp. and LAB at 0 °C. The study contributes to the knowledge about tropical shrimp spoilage and provides a basis for the development of methods and tools to improve shrimp quality management.
Asunto(s)
Bacterias/aislamiento & purificación , Almacenamiento de Alimentos/métodos , Penaeidae/microbiología , Mariscos/microbiología , Animales , Bacterias/clasificación , Bacterias/genética , Bacterias/metabolismo , Humanos , Metilaminas/análisis , Metilaminas/metabolismo , Nitrógeno/análisis , Nitrógeno/metabolismo , Odorantes/análisis , Gusto , TemperaturaRESUMEN
Daqu is a fermentative saccharification agent that is used to initiate fermentation in the production of Chinese liquor and vinegar. Different types of Daqu can be distinguished based on the maximum fermentation temperature, location of production, and raw materials used. We aimed to characterize and distinguish the different types of Daqu using a culture-independent cloning method. The lowest microbial diversity was found in Daqu produced at high-temperature. Principal component analysis (PCA) was used to compare the bacterial composition of Daqu from different regions (i.e., northern Daqu and southern Daqu). Staphylococcus gallinarum and Staphylococcus saprophyticus were found in southern Daqu, and were absent in northern Daqu. The fungi Saccharomycopsis fibuligera and Lichtheimia ramosa dominated in low/medium-temperature Daqu, whereas Thermomyces lanuginosus occurred in high-temperature Daqu. Our study identified potential biomarkers for the different types of Daqu, which can be useful for quality control and technology development of liquor or vinegar production.
Asunto(s)
Bacterias/clasificación , Bacterias/genética , Biota , Microbiología de Alimentos , Hongos/clasificación , Hongos/genética , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , ADN de Hongos/química , ADN de Hongos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Filogenia , ARN Ribosómico/genética , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
Mung bean (Vigna radiata (L.) R. Wilczek) has been intensively researched; scattered data are available on various properties. Data on physical, chemical, food processing, and nutritional properties were collected for whole mung bean grains and reviewed to assess the crop's potential as food and to set research priorities. Results show that mung bean is a rich source of protein (14.6-33.0 g/100 g) and iron (5.9-7.6 mg/100 g). Grain color is correlated with compounds like polyphenols and carotenoids, while grain hardness is associated with fiber content. Physical properties like grain dimensions, sphericity, porosity, bulk, and true density are related to moisture content. Anti-nutrients are phytic acid, tannins, hemagglutinins, and polyphenols. Reported nutrient contents vary greatly, the causes of which are not well understood. Grain size and color have been associated with different regions and were used by plant breeders for selection purposes. Analytical methods require more accuracy and precision to distinguish biological variation from analytical variation. Research on nutrient digestibility, food processing properties, and bioavailability is needed. Furthermore, the effects of storage and processing on nutrients and food processing properties are required to enable optimization of processing steps, for better mung bean food quality and process efficiency.
Asunto(s)
Grano Comestible , Manipulación de Alimentos/métodos , Valor Nutritivo , Disponibilidad Biológica , Carotenoides , Fibras de la Dieta , Proteínas en la Dieta , Hierro de la Dieta , Ácido Fítico , TaninosRESUMEN
In recent years, the Beninese shrimp sector has faced a ban on export to the European Union due to lack of compliance with food safety standards. The present study aimed at obtaining insight into the factors that determine shrimp quality and safety in Benin. A survey was conducted to investigate the relationships between stakeholders, the conditions under which shrimps are handled at fishing areas and processed at shrimp plants, and the stakeholders' perceptions of quality. A total of 325 fishermen, 128 intermediate traders, 12 collectors, and 3 shrimp processing plant managers were interviewed face to face. The results showed that various specific relations existed between the stakeholders. For example, loyalty was ensured by family relationships, or incentives were provided to ensure a supply of shrimps between stakeholders. Shrimp handling practices during the steps prior to shrimp processing at the plants were not in agreement with the requirements of the European regulations. For example, shrimps were kept at ambient temperature (28 ± 1°C) by 94.1% of fishermen and 60.9% of intermediate traders. Shrimps were also stored in inappropriate holding containers and washed with nonpotable water. Fishermen, intermediate traders, and collectors considered shrimp size and texture their priority quality attributes, whereas plant managers considered shrimp appearance (freshness) and texture their priority quality attributes. This survey demonstrated that the steps prior to shrimp processing at the plants are the critical steps for shrimp quality and safety because of temperature abuse and inappropriate hygienic conditions. There is a need to communicate and provide incentives for the stakeholders in the first part of the chain to give priority to shrimp freshness. Moreover, training in Good Fishing Practices and safe food handling practices and evaluation of compliance with the practices through monitoring will contribute to better shrimp quality and safety management.
Asunto(s)
Crustáceos/química , Explotaciones Pesqueras , Manipulación de Alimentos , Mariscos/análisis , Mariscos/normas , Adulto , Animales , Benin , Femenino , Humanos , Masculino , Percepción , Control de Calidad , Temperatura , Recursos HumanosRESUMEN
Chinese Daqu is used as a starter for liquor and vinegar fermentations. It is produced by solid state fermentation of cereal-pulse mixtures. A succession of fungi, lactic acid bacteria and Bacillus spp. was observed during the production of Daqu. Mesophilic bacteria followed by fungi, dominated the first phase of fermentation. Next, lactic acid bacteria increased in relative abundance, resulting in an increase of the acidity of Daqu. At the final stages of fermentation, Bacillus spp. and thermophilic fungi became the dominant groups, possibly due to their tolerance to low water activity and high temperature. Both culture-dependent and culture-independent analyses confirmed that Bacillus spp. were ubiquitous throughout the process. Yeast species such as Wickerhamomyces anomalus, Saccharomycopsis fibuligera and Pichia kudriavzevii were present throughout almost the entire fermentation process, but the zygomycetous fungus Lichtheimia corymbifera proliferated only during the final stages of fermentation. Canonical correspondence analysis (CCA) revealed the significance of acidity, moisture content and temperature in correlation with the composition of the microbial communities at different stages.
Asunto(s)
Fenómenos Fisiológicos Bacterianos , Biodiversidad , Fermentación , Hongos/fisiología , Microbiología Industrial , Microbiota/fisiología , Ácido Acético , Bebidas Alcohólicas , China , Concentración de Iones de Hidrógeno , Temperatura , AguaRESUMEN
A probiotic dairy product was developed on the basis of a traditional dish called mutandabota to enable resource-poor populations in southern Africa to benefit from a functional food. Mutandabota is widely consumed in rural southern Africa, making it an ideal food matrix to carry probiotics. First, a process to produce probiotic mutandabota was designed. Raw cow milk was boiled and subsequently cooled to ambient temperature (25°C). Next, dry pulp from the fruit of the baobab tree (Adansonia digitata L.) was added to the milk at a concentration of 4% (wt/vol). This mixture was inoculated with the probiotic Lactobacillus rhamnosus yoba and left to ferment for 24h, while the growth of the bacterial culture was monitored. Final ingredients were then added to produce probiotic mutandabota that had 14% (wt/vol) baobab fruit pulp and 7% (wt/vol) sugar in cow milk. The pH of probiotic mutandabota was pH 3.5, which ensures that the product is microbiologically safe. The viable plate count of L. rhamnosus yoba increased from 5.8 ± 0.3 log cfu/mL at the point of inoculation to 8.8 ± 0.4 log cfu/mL at the moment of consumption, thereby meeting the criterion to have a viable count of the probiotic bacterium in excess of 6 log cfu/mL of a product. Baobab fruit pulp at 4% promoted growth of L. rhamnosus yoba with a maximal specific growth rate (µmax) of 0.6 ± 0.2/h at 30°C. The developed technology, though specific for this particular product, has potential to be applied for the delivery of probiotics through a variety of indigenous foods in different regions of the world. Upon consumption, probiotic mutandabota is expected to improve the population's intestinal health, which is especially relevant for vulnerable target groups such as children and elderly people.
Asunto(s)
Adansonia/química , Productos Lácteos/análisis , Microbiología de Alimentos , Alimentos Funcionales/análisis , Lacticaseibacillus rhamnosus/química , Probióticos/química , Fermentación , Análisis de los Alimentos , Humanos , ZimbabweRESUMEN
Proto-cooperation between Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus is one of the key factors that determine the fermentation process and final quality of yoghurt. In this study, the interaction between different proteolytic strains of S. thermophilus and L. delbrueckii subsp. bulgaricus was investigated in terms of microbial growth, acidification and changes in the biochemical composition of milk during set-yoghurt fermentation. A complementary metabolomics approach was applied for global characterization of volatile and non-volatile polar metabolite profiles of yoghurt associated with proteolytic activity of the individual strains in the starter cultures. The results demonstrated that only non-proteolytic S. thermophilus (Prt-) strain performed proto-cooperation with L. delbrueckii subsp. bulgaricus. The proto-cooperation resulted in significant higher populations of the two species, faster milk acidification, significant abundance of aroma volatiles and non-volatile metabolites desirable for a good organoleptic quality of yoghurt. Headspace SPME-GC/MS and (1)H NMR resulted in the identification of 35 volatiles and 43 non-volatile polar metabolites, respectively. Furthermore, multivariate statistical analysis allows discriminating set-yoghurts fermented by different types of starter cultures according to their metabolite profiles. Our finding underlines that selection of suitable strain combinations in yoghurt starters is important for achieving the best technological performance regarding the quality of product.
Asunto(s)
Microbiología de Alimentos , Lactobacillus delbrueckii/fisiología , Leche/química , Streptococcus thermophilus/fisiología , Yogur/análisis , Yogur/microbiología , Animales , Fermentación , Cromatografía de Gases y Espectrometría de Masas , Concentración de Iones de Hidrógeno , Lactobacillus delbrueckii/crecimiento & desarrollo , Lactobacillus delbrueckii/metabolismo , Espectroscopía de Resonancia Magnética , Metabolómica , Análisis Multivariante , Streptococcus thermophilus/crecimiento & desarrollo , Streptococcus thermophilus/metabolismo , Compuestos Orgánicos Volátiles/análisis , Yogur/normasRESUMEN
We evaluated processing technology, composition, and socioeconomic significance of mutandabota, a food product made by mixing cow's or goat's milk with dry baobab fruit pulp. Mutandabota production is a gendered activity dominated by women. Nutrient content was (g 100 g(-1) w.b) protein 4.8 ± 1, fat 2.8 ± 0.9, fiber 1.1 ± 0.4, ash 0.9 ± 0.2, carbohydrates 20 ± 1.7, moisture 70.4 ± 3.7, and vitamin C 80 ± 25 mg/100g. Microbiological load (log cfu ml(-1)) was high, 4.7 ± 1.2 mesophilic bacteria, 5.3 ± 2.1 lactic acid bacteria, and 5.0 ± 1.3 yeasts and molds. The pH of milk was 6.7 and the final pH of mutandabota was 3.5 ± 0.1. Mutandabota is a major source of proteins and vitamin C. Its microbiological quality needs evaluation.
Asunto(s)
Adansonia , Dieta , Manipulación de Alimentos , Microbiología de Alimentos , Frutas , Leche , Valor Nutritivo , Animales , Ácido Ascórbico/análisis , Bacterias , Bovinos , Proteínas en la Dieta/análisis , Femenino , Hongos , Cabras , Humanos , Concentración de Iones de Hidrógeno , Factores Socioeconómicos , Levaduras , ZimbabweRESUMEN
PURPOSE: To compare the content of bioaccessible folate, vitamin B12, and isoflavones in tofu and tempe, as influenced by soybean variety and food processing, particularly fermentation. PRINCIPAL RESULTS: Raw soybeans contained 2207-2671 µg/kg (dry matter) folate, cooked tempe 1493-4143, and cooked tofu 968-1273 µg/kg, the difference was attributed to the fermentation in tempe. Vitamin B12 was detected only in tempe (0.16-0.72 µg/kg). Isoflavone aglycones were formed during soaking of soybeans, with only minor differences between the contents in cooked tempe (average 1922-2968 µg/kg) or tofu (1667-2782 µg/kg) but strongly depending on bean variety. CONCLUSIONS: Folate and vitamin B12 contents were mainly influenced by microbial activity during fermentation, whereas isoflavone aglycone content was determined by bean variety. Tofu had lower folate and vitamin B12, but equal isoflavone contents as tempe. Bioaccessibility of folate (80-100%) and isoflavone aglycones (100%) were high.
Asunto(s)
Ácido Fólico/análisis , Manipulación de Alimentos/métodos , Glycine max/química , Isoflavonas/análisis , Alimentos de Soja/análisis , Vitamina B 12/análisis , Bacterias/genética , Bacterias/aislamiento & purificación , Bacterias/metabolismo , Fermentación , Glycine max/microbiologíaRESUMEN
Daqu, a traditional fermentation starter, has been used to produce attractively flavored foods such as vinegar and Chinese liquor for thousands of years. Although Bacillus spp. are one of the dominant microorganisms in Daqu, more precise information is needed to reveal why and how Bacillus became dominant in Daqu, and next, to assess the impact of Bacillus sp. on Daqu and its derived products. We combined culture-dependent and culture-independent methods to study the ecology of Bacillus during Daqu incubation. Throughout the incubation, 67 presumptive Bacillus spp. isolates were obtained, 52 of which were confirmed by 16S rDNA sequencing. The identified organisms belonged to 8 Bacillus species: B. licheniformis, B. subtilis, B. amyloliquefaciens, B. cereus, B. circulans, B. megaterium, B. pumilus, and B. anthracis. A primer set specific for Bacillus and related genera was used in a selective PCR study, followed by a nested DGGE PCR targeting the V9 region of the 16S rDNA. Species identified from the PCR-DGGE fingerprints were related to B. licheniformis, B. subtilis, B. amyloliquefaciens, B. pumilus, B. benzoevorans, and B. foraminis. The predominant species was found to be B. licheniformis. Certain B. licheniformis strains exhibited potent antimicrobial activities. The greatest species diversity occurred at the Liangmei stage of Daqu incubation. To date, we lack sufficient knowledge of Bacillus distribution in Daqu. Elucidating the ecology of Bacillus during Daqu incubation would enable the impact of Bacillus on Daqu to be accessed, and the quality and stabilization of Daqu-derived products to be optimized.
Asunto(s)
Bacillus/metabolismo , Técnicas Bacteriológicas/métodos , Reacción en Cadena de la Polimerasa/métodos , Bacillus/clasificación , Bacillus/genética , Bacillus/aislamiento & purificación , Biodiversidad , Medios de Cultivo/metabolismo , Fermentación , Microbiología de AlimentosRESUMEN
Tempe is a traditional fermented food in Indonesia. The manufacture process is quite complex, which comprises two stages, preparatory soaking of soybeans and fungal solid state fermentation. Daily addition of previous soak water (back-slopping) during the soybean soaking step is considered to be crucial in the manufacture of high quality tempe. The microbial diversity and dynamics of the microbial communities evolving during back-slop soaking of soybeans for tempe making was investigated by culture-independent PCR-DGGE and molecular cloning. Both DNA and total RNA were isolated and included in this study, to obtain a view on the succession of total and viable bacteria in the complex microbiota. DGGE profiles indicated that Enterobacter sp., Enterococcus sp., Pseudomonas putida, Leuconostoc fallax, Pediococcus pentosaceus, and Weissella cibaria, were the predominant bacteria. Their occurrence shifted dramatically during the back-slop soaking procedure. This study combined with previous culture-dependent studies could gain a better understanding of the complex microbiota of traditional fermented food and give useful information for its quality control.
Asunto(s)
Bacterias/clasificación , Bacterias/genética , Biota , Manipulación de Alimentos/métodos , Glycine max/microbiología , Animales , Clonación Molecular , Electroforesis en Gel de Gradiente Desnaturalizante , Fermentación , Indonesia , Reacción en Cadena de la PolimerasaRESUMEN
Daqu is a traditional fermentation starter that is used for Chinese liquor production. Although partly mechanized, its manufacturing process has remained traditional. We investigated the microbial diversity of Fen-Daqu, a starter for light-flavour liquor, using combined culture-dependent and culture-independent approaches (PCR-DGGE). A total of 190 microbial strains, comprising 109 bacteria and 81 yeasts and moulds, were isolated and identified on the basis of the sequences of their 16S rDNA (bacteria) and 26S rDNA and ITS regions (fungi). DGGE of DNA extracted from Daqu was used to complement the culture-dependent method in order to include non-culturable microbes. Both approaches revealed that Bacillus licheniformis was an abundant bacterial species, and Saccharomycopsis fibuligera, Wickerhamomyces anomalus, and Pichia kudriavzevii were the most common yeasts encountered in Fen-Daqu. Six genera of moulds (Absidia, Aspergillus, Mucor, Rhizopus, Rhizomucor and Penicillium) were found. The potential function of these microorganisms in starters for alcoholic fermentation is discussed. In general the culture-based findings overlapped with those obtained by DGGE by a large extent. However, Weissella cibaria, Weissella confusa, Staphylococcus saprophyticus, Enterobacter aerogenes, Lactobacillus sanfranciscensis, Lactobacillus lactis, and Bacillus megaterium were only revealed by DGGE.
Asunto(s)
Bacterias/aislamiento & purificación , Recuento de Colonia Microbiana/métodos , Electroforesis en Gel de Poliacrilamida/métodos , Metagenoma , Reacción en Cadena de la Polimerasa/métodos , Vino/microbiología , Levaduras/aislamiento & purificación , Bacterias/clasificación , Bacterias/genética , Bacterias/crecimiento & desarrollo , Biodiversidad , ADN Bacteriano/genética , ADN de Hongos/genética , Fermentación , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Vino/análisis , Levaduras/clasificación , Levaduras/genética , Levaduras/crecimiento & desarrolloRESUMEN
We sampled a cocoa powder production line to investigate the impact of processing on the microbial community size and diversity at different stages. Classical microbiological methods were combined with 16S rRNA gene PCR-denaturing gradient gel electrophoresis, coupled with clone library construction, to analyze the samples. Aerobic thermoresistant spores (ThrS) (100°C; 10 min) were also isolated and characterized (identity, genetic diversity, and spore heat resistance), in view of their relevance to the quality of downstream heat-treated cocoa-flavored drinks. In the nibs (broken, shelled cocoa beans), average levels of total aerobic microorganisms (TAM) (4.4 to 5.6 log CFU/g) and aerobic total spores (TS) (80°C; 10 min; 4.3 to 5.5 log CFU/g) were significantly reduced (P < 0.05) as a result of alkalizing, while fungi (4.2 to 4.4 log CFU/g) and Enterobacteriaceae (1.7 to 2.8 log CFU/g) were inactivated to levels below the detection limit, remaining undetectable throughout processing. Roasting further decreased the levels of TAM and TS, but they increased slightly during subsequent processing. Molecular characterization of bacterial communities based on enriched cocoa samples revealed a predominance of members of the Bacillaceae, Pseudomonadaceae, and Enterococcaceae. Eleven species of ThrS were found, but Bacillus licheniformis and the Bacillus subtilis complex were prominent and revealed great genetic heterogeneity. We concluded that the microbiota of cocoa powder resulted from microorganisms that could have been initially present in the nibs, as well as microorganisms that originated during processing. B. subtilis complex members, particularly B. subtilis subsp. subtilis, formed the most heat-resistant spores. Their occurrence in cocoa powder needs to be considered to ensure the stability of derived products, such as ultrahigh-temperature-treated chocolate drinks.
Asunto(s)
Bacterias Aerobias/clasificación , Biodiversidad , Biota , Cacao/microbiología , Manipulación de Alimentos , Microbiología Industrial , Bacterias Aerobias/genética , Bacterias Aerobias/aislamiento & purificación , Análisis por Conglomerados , Recuento de Colonia Microbiana , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Electroforesis en Gel de Gradiente Desnaturalizante , Datos de Secuencia Molecular , Filogenia , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADNRESUMEN
AIMS: Enterotoxigenic Escherichia coli is one of the main pathogenic bacteria causing diarrhoea. Earlier studies have shown that tempe-a fungal fermented soya food-has anti-adhesive activity against E. coli in vitro. Our aims were to challenge the anti-adhesive activity under gastro-intestinal conditions and to assess the activity of the nonfermented soya product tofu. METHODS AND RESULTS: In this study, we compared the anti-adhesive activity of two major soya bean products, tempe and tofu, and their ileum efflux after transit through a dynamic gastrointestinal system simulating digestion in the human stomach and small intestine. The results showed that both tempe and tofu have an anti-adhesive activity against E. coli in vitro. Tempe and tofu, after digestion through the stomach and small intestine, have even higher anti-E. coli adhesive activity. CONCLUSIONS: In addition to the proven in-vivo activity of tempe, this confirms the potential antidiarrhoeal effect of both the soya products tempe and tofu. SIGNIFICANCE AND IMPACT OF THE STUDY: As tofu has a much greater circle of consumers, this finding is relevant for the health of a large part of the world's population.