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Grapevine and Horseradish Leaves as Natural, Sustainable Additives for Improvement of the Microbial, Sensory, and Antioxidant Properties of Traditionally Fermented Low-Salt Cucumbers
The agro-food industry produces large amounts of secondary by-products, which can act as a source of bio-active ingredients. These ingredients can be used as valuable additives to support the sustainable circular economy concept. This study aimed to analyze the potential application of horseradish and grapevine leaves in the fermentation process of low-salt pickled cucumbers to improve their sensory and functional properties. The pour plate technique, RT-qPCR, HPLC, and a nine-point hedonic scale test with penalty analysis were used to analyze the traditionally fermented product. The research showed that the addition of both horseradish and grapevine leaves did not negatively affect the kinetics of fermentation and had a positive effect on the overall desirability. Moreover, they contributed to an increase in the concentration of antioxidant compounds, namely gallic acid (grape leaves) and ellagic acid (grapevine and horseradish leaves). Bacterial metabiome analysis showed the positive effect of all analyzed additives on an increase in the relative expression of genes responsible for the synthesis of selected bacteriocins (plantaricin and acidocin). Research results indicated a high potential for sustainable use of by-products (horseradish and grapevine leaves) in the production of traditional low-salt fermented cucumbers with high health-promoting potential.
Effect of Processing Treatment and Modified Atmosphere Packing on Carrot’s Microbial Community Structure by Illumina MiSeq Sequencing
The aim of this study was to analyze the microbiome of carrot (Daucus carota subsp. sativus) subjected to minimal pre-treatment (rinsing in organic acid solution) and packaging in a high-oxygen modified atmosphere, and then stored for 17 days under refrigeration conditions (4 °C). The highest levels of bacteria in the carrot microbiome were characterized, at almost 78%, by bacteria belonging to the Enterobacteriaceae and Pseudomonadaceae families. Rinsing in a solution of ascorbic and citric acids resulted in the improvement of microbiological quality in the first day of storage. However, the use of a high-oxygen modified atmosphere extended the shelf life of the minimally processed product. Compared to carrots stored in air, those stored in high oxygen concentration were characterized by a greater ratio of bacteria belonging to the Serratia and Enterobacter genera, and a lower ratio belonging to the Pseudomonas and Pantoea genera. Moreover, the β-biodiversity analysis confirmed that the oxygen concentration was the main factor influencing the differentiation of the metabiomes of the stored carrots. The bacterial strains isolated from carrots identified by molecular methods were mostly pathogenic or potentially pathogenic microorganisms. Neither the minimal pre-treatment nor packaging in high-oxygen atmosphere was able to eliminate the threat of pathogenic bacteria emerging in the product.
Temperature, Salinity and Garlic Additive Shape the Microbial Community during Traditional Beetroot Fermentation Process
Plant-based traditional fermented products are attracting a lot of interest in global markets. An example of them is beetroot leaven, which is valued for its high bioactive compound content. The variety of production recipes and the spontaneous nature of red beet fermentation favor its high diversity. This study aimed to analyze the impact of external factors—temperature, brine salinity, and garlic dose—on the beetroot fermentation and bacterial metapopulation responsible for this process. The research results confirmed the significant influence of the selected and analyzed factors in shaping the leaven physicochemical profile including organic acid profile and betalain content. Analysis of bacterial populations proved the crucial importance of the first 48 h of the fermentation process in establishing a stable metapopulation structure and confirmed that this is a targeted process driven by the effect of the analyzed factors. Lactobacillaceae, Enterobacteriaceae, and Leuconostocaceae were observed to be the core microbiome families of the fermented red beet. Regardless of the impact of the tested factors, the leaven maintained the status of a promising source of probiotic bacteria. The results of this research may be helpful in the development of the regional food sector and in improving the quality and safety of traditionally fermented products such as beetroot leaven.