engleski

Comparison of thermo-sonication, thermal and ultrasound treatments on microbiological quality and sensory properties of fresh sweet whey

In this study the influence of different ultrasound power inputs (400W, 320W, 240W) without and with heat pre-treatment (35ºC, 45ºC, 55ºC) on microbial inactivation and sensory properties of fresh sweet whey in comparison to conventional pasteurization batch process were investigated. In general, ultrasonication and thermo-sonication treatments with pre-heating to 35ºC showed no impact on reducing any group of studied microorganisms. Thermo-sonication treatment performed for 8 minutes at power level 100 (400W) and preheating to 55ºC was the only one that resulted in greater reduction of total viable cell count in comparison to that observed by simulating conventional batch pasteurization process. Reduction of coliform bacteria number and yeasts and moulds number increased with power input, exposure time and temperature of heat pre-treatment. Sensory properties after ultrasonication and thermo-sonication improved in comparison to that after conventional pasteurization batch process. Preheating to 55ºC resulted in occurrence of metallic aftertaste regardless the ultrasound power input, while applying power level 60 and/or preheating to 35 ºC resulted in poorer mouthfeel. Therefore, thermo-sonication treatments when power levels 100 (400 W) and 80 (320 W) were combined with preheating to 45ºC, regardless exposure time, appeared to be the optimal for purpose of improving sensory properties of whey.

whey; thermo-sonication; microbiological analysis; sensory properties

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