engleski

Influence of high intensity ultrasound on microbial reduction, physico-chemical characteristics and fermentation of sweet whey

The aim of this study was to investigate the influence of high intensity ultrasound on quality of reconstituted sweetwhey in order to substitute thermal treatments i.e. pasteurization. Also, itwas intended to study the influence of ultrasound on fermentation process of pasteurized or thermo-sonicatedwhey with respect to culture activation and sensory properties of the fermented whey. In the first stage, whey was subjected to treatmentswith different power inputs (480 W, 600 W) over 6.5, 8 and 10 min at constant temperature (45 °C, 55 °C). Treated whey samples were analyzed for microbiological quality, particle size distribution, protein content, acidity, electrical conductivity, viscosity and sensory properties. All of the analyzed parameterswere comparedwith the control sample (pasteurized) and freshwhey. Subsequently, influence of high intensity ultrasound on pasteurized or thermo- sonicated whey fermentation with yoghurt culture and with monoculture Lactobacillus acidophilus La-5 was investigated. Ultrasound treatments were applied for culture activation prior to or after the inoculation. Whey thermo- sonication by nominal power of 480Wfor 10 min at 55 °C resulted in bettermicrobiological quality and sensory properties in comparison to whey pasteurization. Ultrasound treatments with nominal input power of 84 W over 150 s resulted in the highest increase of the viable count during the activation process. Whey fermentation by ultrasonicated culture La- 5 lasted 30min shorter and resulted in higher viable cells count.

Whey; Thermo-sonication; Quality; Microbial reduction; Fermentation

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