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Alicyclobacillus spp. they are spore-forming bacteria that deteriorate acidic fruit-based drinks, causing economic losses, with A. acidoterrestris being the most studied, responsible for causing sensory changes, especially in orange juice. The use of natural antimicrobial agents in foods can be an option with great advantages for the industry and the consumer. Therefore, the objective of this work was to investigate the antimicrobial activity of extracts fermented by kefir, from a grape by-product, against A. acidoterrestris. Four extracts were prepared with kefir grains, being 1-grape extract and kefir grains; 2-grape extract, brown sugar and kefir grains; 3-grape extract, ultrasound and kefir grains; and 4-grape extract, ultrasound, brown sugar and kefir grains. The four extracts were fermented at 28 ºC for 7 days. The extracts were centrifuged at 10,000 rpm for 10 min and the supernatant was subjected to membrane filtration (0.22 μm). The minimum inhibitory concentration (MIC) was determined by the serial microdilution technique of extracts of 50 to 0.1% concentration in Bacillus acidoterrestris (BAT) medium. The minimum bactericidal concentration (CBM) was also determined. Structural changes in cells after treatment were evaluated by scanning electron microscopy (SEM). The MIC value capable of inhibiting the visible growth of A. acidoterrestris for all extracts was 1.6%, while the CBM was 50% for extracts 1 and 3, while for extracts 2 and 4 the CBM was 25%. The results show that extracts 2 and 4 obtained better CBM value, possibly because kefir produced more secondary metabolites with the addition of brown sugar, in addition, the use of ultrasound did not interfere. The results of the inhibitory and/or bactericidal concentration indicate that the extracts have activity against A. acidotrrestris.

Ready-to-cook dishes were prepared using the fillet and the belly flap area of hybrid sorubim. The chemical, microbiological and sensorial characteristics of the obtained products were evaluated. Four treatments were elaborated: (T1) fillet, tomato sauce and vegetables; (T2) fillet without tomato sauce or vegetables; (T3) belly flap area with added tomato and vegetables and; (T4) belly flap area without tomato sauce or vegetables. After marinating by immersion using brine, fish cuts with and without sauce/ vegetables were placed in vacuum packages and cooked. Microbiological and proximate analyses showed the products were within the standards required by current legislation. Sensory analysis showed acceptance rates above 70%. The dishes prepared with fillet and belly flap area cuts with added tomato sauce and vegetables were the most acceptable according to the sensory evaluation and purchase intention, with no difference between the types of cut. Therefore, the use of the less commercially desirable meat cut (belly flap area) is feasible in the elaboration of the ready-to-cook moqueca dishes.

Summary This study aimed to evaluate the effect of high‐intensity ultrasound (HIUS) application with different processing times (2.5, 5, 7.5 and 10 min) on the physicochemical, rheological and textural properties, antioxidant activity (AA) and probiotic survival in strawberry‐flavoured fermented probiotic strawberry drink during storage (7°C for 28 days). The application of HIUS resulted in products with lower fermentation times, higher organic acid stability during storage and improved texture (higher firmness and consistency) and functional properties (higher phenolic compounds content and/or AA). Using 2.5 min of processing time would be advisable due to the better probiotic survival to simulated gastrointestinal conditions (probiotic counts higher than 106 CFU mL−1), reduced fermentation times (reduction in 3 h), higher lactic acid content during storage and enhanced AA. The products showed a viable probiotic counts higher than 106 CFU mL−1 during the entire shelf life. HIUS may be considered as an adequate pre‐treatment in the development of probiotic fermented probiotic strawberry drink.

This study aimed to investigate the antimicrobial activity of kefir fermented fruit by-products against strains of Alicyclobacillus spp., and determine their chemical characterization and antioxidant activity. According to the results, extracts fermented for a longer period (72 h) showed greater inhibition, and the extract of acerola by-product fermented for 72 h achieved the best results. For all strains, the Minimal Inhibitory Concentration (MIC) was 0.78%, except for A. acidocaldarius subsp. rittmannii, (1.56%). The same applies to the Minimal Bactericidal Concentration (MBC), in which 1.56% of the extract was capable of inactivating A. cycloheptanicus and A. acidocaldarius. In addition, damages to the structure of the microorganisms caused by the extracts were detected by Scanning Electron Microscopy. Metabolite identification through liquid chromatography (UHPLC-Qtof-MS) showed that the fermented extracts had a greater number of compounds compared to the non-fermented ones, such as glucuronic, succinic and glutaric acids. In conclusion, the extracts of fruit by-products showed to have bioactive properties, such as antibacterial potential and antioxidant activity against the Alicyclobacillus strains tested in this study, not to mention the value added by the use of a food by-product.