ABSTRACT
Ten probiotic cultures were screened for the ability to hydrolyze soy proteins and bile salt deconjugation (BSD) to select one lactobacilli and one bifidobacteria strain to produce fermented soy beverages (FSBs) containing acerola byproduct (ABP). Next, the effect of the strains and the ABP on the technological and sensory characteristics of these beverages was evaluated during refrigerated storage for up to 28 days. None of the tested strains presented any proteolytic activity against soy proteins. Among the probiotic strains, the best BSD activities were observed for Lactobacillus acidophilus LA-5 and Bifidobacterium longum BB-46, which were further employed, individually or combined, to produce FSB supplemented or not with ABP, using Streptococcus thermophilus TH-4 as a starter, and the effect of these strains and ABP on the technological and sensory acceptability of FSB was evaluated. The probiotic strains did not influence FBS texture parameters, but ABP increased firmness in the ready product. BB-46 increased acidity, therefore decreasing acceptance, whereas the presence of LA-5 and/or ABP increased acceptance, even though the appearance was negatively affected by ABP after 21 days of storage. Thus, the presence of LA-5 and ABP contributed for the sensory acceptance of the FSBs without affecting their technological features. PRACTICAL APPLICATION: Lactobacillus acidophilus LA-5, Bifidobacterium longum BB-46, and/or acerola byproduct (ABP) were applied in the production of fermented soy beverages (FSBs). Principal components analysis was used to evaluate the formulations of the 23 factorial design and the sensory attributes and the effect of storage independently and covariance was the matrix type used for mapping purposes. LA-5 and ABP contributed for the sensory acceptance of FSB, without affecting their technological features, and could be used by food processing companies after scaling up, also reducing the environmental impact by decreasing discarding byproducts, which are sources of bioactive compounds.
Subject(s)
Fermented Foods , Lactobacillus/metabolism , Malpighiaceae/chemistry , Probiotics/metabolism , Soy Foods , Fermentation/physiology , Fermented Foods/analysis , Fermented Foods/microbiology , Food Handling , Soy Foods/analysis , Soy Foods/microbiologyABSTRACT
The ability of different fruit by-products, okara, and amaranth flour, to support the growth of probiotic and non-probiotic strains was evaluated. The tests were conducted with three commercial starter cultures (Streptococcus thermophilus), ten probiotic strains (seven Lactobacillus spp. and three Bifidobacterium spp. strains), and two harmful bacteria representative of the intestinal microbiota (Escherichia coli and Clostridium perfringens). In vitro fermentability assays were performed using a modified MRS broth supplemented with different fruits (acerola, orange, passion fruit, and mango), and soy (okara) by-products or amaranth flour. Orange and passion-fruit by-products were the substrates that most promoted the growth of bacterial populations, including pathogenic strains. On the other hand, the acerola by-product was the substrate that showed the highest selectivity for beneficial bacteria, since the E. coli and Cl. perfringens populations were lower in the presence of this fruit by-product. Although the passion fruit by-product, okara, and amaranth stimulated the probiotic strains, the growth of the pathogenic strains studied was higher compared to other substrates. Different growth profiles were verified for each substrate when the different strains were compared. Although pure culture models do not reflect bacterial interaction in the host, this study reinforces the fact that the ability to metabolize different substrates is strain-dependent, and acerola, mango, and orange by-products are the substrates with the greatest potential to be used as prebiotic ingredients.
Subject(s)
Amaranthus/chemistry , Cell Culture Techniques/methods , Fruit/chemistry , Glycine max/chemistry , Probiotics , Agriculture , Amaranthus/metabolism , Bacteria/chemistry , Bacteria/growth & development , Bacteria/metabolism , Flour , Fruit/metabolism , Industrial Waste , Probiotics/chemistry , Probiotics/metabolism , Glycine max/metabolismABSTRACT
Charqui is a fermented, salted and sun-dried meat product, widely consumed in Brazil and exported to several countries. Growth of microorganisms in this product is unlikely due to reduced Aw, but halophilic and halotolerant bacteria may grow and cause spoilage. Charqui is a good source of lactic acid bacteria able to produce antimicrobial bacteriocins. In this study, an autochthonous bacteriocinogenic strain (Lactococcus lactis subsp. lactis 69), isolated from charqui, was added to the meat used for charqui manufacture and evaluated for its capability to prevent the growth of spoilage bacteria during storage up to 45 days. The influence of L. lactis 69 on the bacterial diversity during the manufacturing of the product was also studied, using denaturing gradient gel electrophoresis (DGGE). L. lactis 69 did not affect the counts and diversity of lactic acid bacteria during manufacturing and storage, but influenced negatively the populations of halotolerant microorganisms, reducing the spoilage potential. The majority of tested virulence genes was absent, evidencing the safety and potential technological application of this strain as an additional hurdle to inhibit undesirable microbial growth in this and similar fermented meat products.
Subject(s)
Bacteria/growth & development , Bacteriocins/metabolism , Biodiversity , Food Preservation/methods , Lactococcus lactis/metabolism , Meat Products/microbiology , Sodium Chloride/metabolism , Animals , Bacteria/isolation & purification , Bacteria/metabolism , Brazil , Fermentation , Lactococcus lactis/genetics , SwineABSTRACT
The aim of this work was to purify and characterize the bacteriocin produced by Lactococcus lactis subsp. lactis KT2W2L previously isolated from mangrove forests in southern Thailand, in order to evaluate its potential as new food protective agent. The active peptide from the cell-free supernatant of this strain was purified in 4 steps: (1) precipitation with 70 % saturated ammonium sulfate, (2) elution on a reversed-phase cartridge using different concentrations of acetonitrile, (3) cation-exchange chromatography and (4) final purification by reversed-phase HPLC on a C8 column. The molecular mass of 3,329.5254 Da of the purified bacteriocin, determined by mass spectrometry, is nearly identical to that of peptide nisin Z. The activity of the purified bacteriocin was unaffected by pH (2.0-10.0), thermostable but was sensitive to proteolytic enzymes. The bacteriocin activity was stable after 8 weeks of storage at -20 °C and 7 weeks of storage at 4 °C, but decreased after 3 weeks of storage at 37 °C. It was stable when incubated for 1 month at 4 °C in 0-30 % NaCl. Inhibitory spectrum of this bacteriocin showed a wide range of activity against similar bacterial strains, food-spoilage and food-borne pathogens. L. lactis subsp. lactis KT2W2L was sensitive to kanamycin, penicillin and tetracycline but resistant to ampicillin, gentamicin and vancomycin. The fragment obtained after amplification of genomic DNA from L. lactis subsp. lactis KT2W2L, with specific primers for bacteriocin genes, presented 99 % homology to the nisin Z gene. PCR amplification demonstrated that L. lactis subsp. lactis KT2W2L does not harbor virulence genes cylA, cylB, efaAfs and esp. The bacteriocin and its producing strain may find application as bio-preservatives for reduction in food-spoilage and food-borne pathogens in food products.
ABSTRACT
This work investigated the effects of irradiation (0, 1 and 2 kGy) on the content of bioactive compounds such as vitamin C and carotenoids with provitamin A activity in arugula during the storage at 571 1C for up to 13 and 16 days, respectively. The vitamin C content decreased in non-irradiated as well as irradiated (1 and 2 kGy) samples during the storage period. On the other hand, no significant change in the content of carotenoids with provitamin...(AU)
Subject(s)
Ascorbic Acid , Refrigeration , FoodABSTRACT
O charque é um produto cárneo tipicamente brasileiro, salgado e seco ao sol, ainda produzido de maneira artesanal. Durante sua produção há uma etapa de fermentação, realizada pela microbiota naturalmente presente na matéria-prima, o que dificulta a padronização do produto, e pode influenciar negativamente em suas características sensoriais e qualidade microbiológica. O controle da etapa de fermentação do charque seria uma alternativa para minimizar este problema e, neste contexto, as bactérias láticas produtoras de bacteriocinas se enquadram de forma interessante. A microbiota autóctone de charque inclui principalmente bactérias láticas e micro-organismos halofílicos e halotolerantes, sendo assim, este produto apresenta potencial como fonte para o isolamento de novas bactérias láticas produtoras de bacteriocinas. Assim, este trabalho teve por objetivo isolar e identificar culturas de bactérias láticas produtoras de bacteriocinas naturalmente presentes no charque, caracterizar parcialmente as bacteriocinas produzidas por essas culturas, avaliar seu potencial de aplicação neste produto para a melhoria de sua qualidade microbiológica e avaliar seu efeito na ecologia microbiana do charque, nas diferentes etapas de sua fabricação. Através da técnica de tripla camada em ágar foi isolada uma cepa de Lactococcus lactis subsp. lactis apresentando o gene codificador para nisina Z e com capacidade de inibir, in vitro, micro-organismos medianamente e altamente halotolerantes isolados de charque, além de outros micro-organismos deteriorantes e patogênicos importantes em alimentos, como Lactobacillus spp., Listeria monocytogenes e Staphylococcus aureus. A bacteriocina produzida pela cepa isolada neste estudo também possui características interessantes para sua aplicação na bioconservação de alimentos, como resistencia ao calor, presença de agente químicos e altos teores de NaCl, além de não ser afetada pelo pH. A aplicação dessa cepa em charque modelo resultou na redução de até 2 ciclos log na população de micro-organismos halotolerantes, indicando apresentar um potencial de aplicação como agente de bioconservação do produto. Os ensaios de avaliação da ecologia microbiana, empregando DGGE, indicaram que a fermentação natural do charque ocorreu com a participação de bactérias láticas dos gêneros Lactobacillus, Streptococcus, Lactococcus e de micro-organismos halotolerantes do gênero Staphylococcus. Além disso, os estudos referentes à dinâmica populacional demonstraram que a adição da cepa bacteriocinogênica ao charque não influenciou, de forma qualitativa, as populações presentes no produto
Charqui is a Brazilian traditional meat product, salted and sun-dried, still manufactured without control of the fermentation step, which is performed by the indigenous microbiota. This fact interferes on the standardization of the product and can negatively affect the sensorial properties and microbiological quality. The application of a known microbiota would be an alternative to minimize this problem and the bacteriocin-producing lactic acid bacteria can can fit in this purpose. The charqui indigenous microbiota mainly includes lactic acid bactéria and halophilic and halotolerant microorganisms, therefore, this product presents a potencial as a source for the isolation of new bacteriocin-producing lactic acid bacteria. The aim of the present work was to isolate and identify bacteriocin-producing lactic acid bacteria from charqui, characterize the bacteriocins produced by the isolated culture, evaluate its potential as biopreservative in charqui and its influence on the microbial populations during the manufacture of the product. A bacteriocinogenic Lactococcus lactis subsp. lactis strain was isolated from charqui through the triple-layer agar technique. This strain produces a nisin-like bacteriocin capable to inhibit in vitro medium and highly halotolerant bacteria isolated from charqui and other food-borne pathogenic and spoilage microorganisms. The application of this strain for charqui manufacturing caused a reduction of up to 2 log in the halotolerant bacteria population, evidencing its potential application for charqui biopreservation. Studies in the populational dynamics using DGGE indicated that the presence of the bacteriocinogenic strain did not affect the microbial populations in the product
