SummaryCell immobilization comprises the retention of metabolically active cells inside a polymeric matrix. In this study, the production of jabuticaba (Myrciaria jaboticaba) vinegar using immobilized Acetobacter aceti and Gluconobacter oxydans cells is proposed as a new method to prevent losses of jabuticaba fruit surplus. The pulp of jabuticaba was processed and Saccharomyces cerevisiae CCMA 0200 was used to ferment the must for jabuticaba wine production. Sugars, alcohols (ethanol and glycerol) and organic acids were assayed by high-performance liquid chromatography. Volatile compounds were determined by gas chromatography-fl ame ionization detector. The ethanol content of the produced jabuticaba wine was approx. 74.8 g/L (9.5 % by volume) aft er 168 h of fermentation. Acetic acid fermentation for vinegar production was performed using a mixed culture of immobilized A. aceti CCT 0190 and G. oxydans CCMA 0350 cells. The acetic acid yield was 74.4 % and productivity was 0.29 g/(L·h). The vinegar had particularly high concentrations of citric (6.67 g/L), malic (7.02 g/L) and succinic (5.60 g/L) acids. These organic acids give a suitable taste and fl avour to the vinegar. Seventeen compounds (aldehydes, higher alcohols, terpene, acetate, diether, furans, acids, ketones and ethyl esters) were identifi ed in the jabuticaba vinegar. In conclusion, vinegar was successfully produced from jabuticaba fruits using yeast and immobilized mixed cultures of A. aceti and G. oxydans. To the best of our knowledge, this is the fi rst study to use mixed culture of immobilized cells for the production of jabuticaba vinegar.
A total of 2152 Actinobacteria strains were isolated from native Cerrado (Brazilian Savannah) soils located in Passos, Luminárias, and Arcos municipalities (Minas Gerais State, Brazil). The soils were characterised for chemical and microbiological analysis. The microbial analysis led to the identification of nine genera (Streptomyces, Arthrobacter, Rhodococcus, Amycolatopsis, Microbacterium, Frankia, Leifsonia, Nakamurella, and Kitasatospora) and 92 distinct species in both seasons studied (rainy and dry). The rainy season produced a high microbial population of all the aforementioned genera. The pH values of the soil samples from the Passos, Luminárias, and Arcos regions varied from 4.1 to 5.5. There were no significant differences in the concentrations of phosphorus, magnesium, and organic matter in the soils among the studied areas. Samples from the Arcos area contained large amounts of aluminium in the rainy season and both hydrogen and aluminium in the rainy and dry seasons. The Actinobacteria population seemed to be unaffected by the high levels of aluminium in the soil. Studies are being conducted to produce bioactive compounds from Actinobacteria fermentations on different substrates. The present data suggest that the number and diversity of Actinobacteria spp. in tropical soils represent a vast unexplored resource for the biotechnology of bioactives production.
Mortadella is a widely consumed product due to its sensory characteristics, however, nitrite is used as a preservative and this synthetic additive has been linked to some diseases. In this sense, this study aimed to evaluate the antimicrobial effect of oregano and clove essential oils, besides the major compound carvacrol on Clostridium botulinum endospores inoculated in mortadella and the physicochemical effect of them on the product. The minimum sporicidal concentration of the essential oils and the major compound was determined by the broth microdilution method and the best results used to prepare the mortadellas containing 0 and 150 ppm of nitrite. All the evaluated treatments showed decrease of nitrite levels over time and lower lipid oxidation. The combinations of essential oils and carvacrol did not affect the mortadella color in the final product. In the mortadellas added of combinations of essential oils and of major compound there was reduction in the population of C. botulinum, whereas in mortadella without essential oils the antimicrobial effect was attributed only to the nitrite. The results are promising and suggest the use of clove and oregano essential oils together with carvacrol compound in meat sausages as a natural preservative and action against foodborne pathogens.
The effects of additioning essential oil mixtures and reducing the sodium nitrite content (75 ppm) on Clostridium difficile inoculated in mortadellas and on the product’s technological characteristics were evaluated. 15 essential oils were tested preliminarily, but only four were selected. The minimum bactericidal concentrations found were 1.2 % for Ocimum basilicum, 0.3 % for Origanum vulgare and for Thymus vulgaris and 0.15 % for Litsea cubeba. There wasn`t significant difference in viable cell growth between treatments and the control; however, there was an increase in viable cells of approximately 2.5 log10 MPN/g after the fifth day. Combinations of oils didn`t prevent sporulation, however a synergistic effect was observed in vitro. There was a reduction in pH during storage and a greater amount of residual nitrite for the F1 treatment (Origanum vulgare (0.2 %); Thymus vulgaris (0.05 %) and Litsea cubeba (0.025 %), with 10.23 ppm, and reduction of residual nitrite during the storage period from 18.75 ppm on the first day of storage to 5.11 ppm on the last. No significant changes were observed in the technological characteristics of the product with the analyzed treatments.
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