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Osmosonication of blackberry juice: Impact on selected pathogens, spoilage microorganisms, and main quality parameters

Wong E., Vaillant F., Pérez A.M.. 2010. Journal of Food Science, 75 (7) : p. 468-474.

DOI: 10.1111/j.1750-3841.2010.01730.x

Osmosonication combines ultrasound with nonthermal concentration. It was applied on tropical highland blackberry (Rubus adenotrichus) juice over different periods of time to assess reductions in microorganism and the impact on main quality parameters. This juice had been inoculated with Salmonella spp., Shigella sp., a lactic acid bacterium, yeasts, and molds. It was then sonicated for 5.9 to 34.1 min at 20 kHz and 0.83 W/mL. Nonthermal concentration was simulated by mixing the juice with a concentrate to obtain 650 g TSS/kg. It was then stored at ?18 ?C for up to 82 h. The lactic acid bacterium, yeasts, and molds were reduced by 1.60 to as much as 5.01 log10 CFU/mL, whereas, for pathogens, reductions were total ?7.1 log10 CFU/mL after 24 h of storage, even for juice not sonicated, because of low pH. Color, antioxidant capacity, anthocyanins, and ellagitannins did not change significantly during sonication treatment up to 32 min. However, an off-flavor was detected after 8 min of sonication. Nonetheless, osmosonication can be considered as an alternative to thermal processes for producing safe and high-quality concentrates.

Mots-clés : jus de fruits; mûre

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