Exploring the Relationships Between Bacterial Community, Taste-Enhancing Peptides and Aroma in Thai Fermented Fish (Pla-ra).

As a traditional Thai condiment, Pla-ra is used to add flavor and richness to dishes. Nine treatment combinations of Pla-ra formulations created from 3 types of fish (Mor fish, Kradee fish, and Mor + Kradee fish) and 4 different carbohydrate sources (none, rice bran, roasted rice, and rice bran─roasted rice mixture) were studied through a 12 month fermentation period (1, 3, 5, 7, 8, 9, 10, 11, and 12 months). 16S rRNA Next Generation Sequencing (NGS) and LC-MS/MS techniques were used to analyze the microbial diversity and identify taste-enhancing peptides. Descriptive sensory analysis was performed on the extracts of the 108 Pla-ra samples mixed in a model broth. Koku perception and saltiness-enhancing attributes were clearly perceived and dominant in all samples, even though glutamyl peptides, including γ-Glu-Val-Gly, were found at subthreshold levels. The samples from mixed fish and Mor fish fermented with roasted ground rice and rice bran for 12 months had the most typical Pla-ra odors and tastes and had high taste-enhancing activities. NGS analysis revealed the presence of bacteria containing a large number of protease and aminopeptidase genes in the samples. Bacillus spp., Gallicola spp., and Proteiniclasticum spp. correlated well with the generation of glutamyl and arginyl peptides and typical odors in the samples. These results confirmed the typical sensory quality of Pla-ra depended on protein sources, carbohydrate sources, and bacteria communities. Further optimization of the microbial composition found could lead to the development of starter cultures to control and promote flavor development in fermented fish products.

Head-space gas chromatography coupled to mass spectrometry for the assessment of the contamination of mayonnaise by yeasts.

Head-space (HS) gas chromatography (GC) coupled to mass spectrometry (MS) is proposed for the assessment of the contamination of mayonnaise as an alternative to plate counting, which is the technique commonly used for evaluating microbial contamination. More specifically, this method was applied in the detection of Candida metapsilosis and Zygosaccharomyces bailii, both of great importance in term of food spoilage since they are resistant to many of the common methods of food preservation. Different chemometric models were investigated using the data obtained by GC-MS (m/z profile, area of the chromatographic peaks and entire chromatographic profile), in order to obtain the highest classification success. The best results were obtained using the chromatographic profile (success rate of 92%). Contaminated samples could also be classified according to the concentration of yeast, obtaining a success rate of 87.5%. Finally, a chemometric model was constructed in an attempt to differentiate between strains.

Ethyl carbamate levels in wine and spirits from markets in Hebei Province, China.

Ethyl carbamate (EC) in wine, grain spirits and wine sauce (145 samples) was analysed using solid-phase extraction and stable isotope dilution GC/MS. Samples were obtained from markets in eight areas (Shijiazhuang, Baoding, Handan, Qinhuangdao, Langfang, Zhangjiakou, Xingtai and Cangzhou) of Hebei Province, China. The method had a limit of detection of 2 µg kg⁻¹, with recoveries varying from 95.7 to 102% and RSD ranging 2.3-5.6%. The average concentrations of ethyl carbamate in wines, grain spirits and wine sauce were 14.7 (<2.0-44.5) µg kg⁻¹, 33.8 (2.9-129) µg kg⁻¹ and 8.7 (<2.0-63.3) µg kg⁻¹, respectively. The results led to the development of limit standards that can be used to predict the concentration of ethyl carbamate in Chinese fermented wines.

Recovery of Salmonella enterica serovars Typhimurium and Tennessee in peanut butter after electron beam exposure.

UNLABELLED: The effect of electron beam (e-beam) radiation on the recovery of Salmonella serotypes Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter over a 14-d storage period at 22 °C was studied. Each Salmonella type was independently inoculated into peanut butter and subjected to e-beam doses that ranged from 0 to 3.1 kGy, confirmed by film dosimetry. After 2-, 4-, 6-, 8-, and 14-d of storage, microbial analyses were conducted. Survivors were recovered on growth and selective media using standard spread-plating methods. Microbial counts (CFU/g) were log-converted and differences were determined by ANOVA and Tukey's Honestly Significant Differences test. When samples were not e-beam-treated, there were no significant changes (P > 0.05) in microbial numbers over time. In e-beamed samples, microbial numbers decreased over time; however, reductions were not always significant. Initial recovery rates (R-rates) 2 d after e-beam treatment were significantly different for the 2 strains of Salmonella and between recovery media (P < 0.05); however, these differences did not persist for the remainder of the storage period (P > 0.05) indicating that injured cells were not able to survive in the high-fat, low-water activity peanut butter environment. R-rates for both strains of Salmonella were maintained until day 14 when there were significant reductions in Salmonella Typhimurium (P < 0.05). These results indicate that Salmonella Tennessee and Salmonella Typhimurium will survive in peanut butter when exposed to nonlethal doses of e-beam irradiation. PRACTICAL APPLICATION: Electron beam (e-beam) irradiation is an alternative to thermal processing; this technique inactivates microorganisms and insects that might be present in a food by generating radiation by accelerated electrons that inactivate organisms directly because of interaction with cell components and indirectly by producing free radicals that disrupt integrity of the cell membrane. E-beam radiation will reduce the number of probable microbiological hazards that could be present while the food remains generally unaffected in texture, taste, and nutritional value. A recent study showed e-beam irradiation to be effective at reducing both Salmonella Tennessee and Typhimurium in peanut butter by one log after exposure to less than 1 kGy, highlighting the need to explore this process further.

Leuconostoc durionis sp. nov., a heterofermenter with no detectable gas production from glucose.

Three lactic acid bacterial (LAB) strains obtained from a Malaysian acid-fermented condiment, tempoyak (made from pulp of the durian fruit), showed analogous but distinct patterns after screening by SDS-PAGE of whole-cell proteins and comparison with profiles of all recognized LAB species. 16S rRNA gene sequencing of one representative strain showed that the taxon belongs phylogenetically to the genus Leuconostoc, with its nearest neighbour being Leuconostoc fructosum (98 % sequence similarity). Biochemical characteristics and DNA-DNA hybridization experiments demonstrated that the strains differ from Leuconostoc fructosum and represent a single, novel Leuconostoc species for which the name Leuconostoc durionis sp. nov. is proposed. The type strain is LMG 22556(T) (= LAB 1679(T) = D-24(T) = CCUG 49949(T)).

Contagem, isolamento e identificaçäo de Bacillus cereus em condimentos preparados, utilizados em embutido cárneo (mortadela) / Counting, isolation and identification of Bacillus cereus in prepared condiments, used in sausage (mortadella)

Os condimentos vegetais têm sido utilizados pelo homem desde a mais remota antigüidade. Säo usados para modificar, de acordo com a vontade do homem, a apetecibilidade e a insipidez dos alimentos, bem como preservar alguns deles. Com o intuito de avaliar as condiçöes higiênico-sanitárias dos condimentos preparados utilizados na elaboraçäo de embutido cárneo (mortadela), analisaram-se 38 amostras de compostos de sal, alho, noz-moscada, cravo, coentro, orégano, pimenta em pó e em pasta, procedentes de estabelecimento industrial submetido à Inspeçäo Federal, quanto a Contagem de Bacillus cereus viáveis em placas. Isso se justifica pela possibilidade dos mesmos participarem da contaminaçäo do produto final, além de fornecer subsídios para uma reflexäo no sentido da criaçäo de padräo microbiológico referente ao Bacillus cereus, tendo em vista a sua importância no processo de toxinfecçöes alimentares.O número de Unidades Formadoras de Colônias por grama do produto (UFC/g) médio foi de 4,60 Log, sendo que 25 por cento das amostras positivas apresentaram resultados iguais ou superiores a este. Das amostras positivas, em 76,6 por cento confirmaram-se bioquimicamente a presença de Bacillus cereus em condimentos preparados, significando risco à saúde do consumidor. Tomando como base a Portaria 451/97 do Ministério da Saúde, os valores obtidos em 25 por cento das amostras positivas caracterizam o produto como ®produto impróprio para consumo¼ e ®potencialmente capaz de causar toxinfecçäo alimentar¼.

Enterobacteriaceae em especiarias utilizadas na elaboraçäo de embutidos cárneos / Enterobacteriaceae in the spices utilized in the elaboration of the sausages products

Os autores promoveram uma avaliaçäo bacteriológica, através da metodología recomendada pelo "Compendium of methods for the microbiological examination of foods", constatando a presença de microorganismos da família enterobacteriaceae em diferentes tipos de especiarias utilizadas na elaboraçäo de embutidos cárneos. Do total de quarenta amostras analisadas 87,5% mostraram a presença de representantes da família Enterobacteriaceae. Entre os diferentes gêneros da família enterobacteriaceae isolados temos a assinalar: Klebsiella; Enterobacter; Providencia; Citrobacter e Proteus