Effects of ultrasound on whey quality

Utjecaj ultrazvuka na kakvoću sirutke proučavao se preko mjerenja ukupnog broja mikroorganizama i broja kvasaca i plijesni te senzorskim ispitivanjem sirutke tretirane ultrazvukom. Provedena su tri tretmana nativne sirutke ultrazvukom frekvencije 24 kHz. Kod prvog tretmana koristila se sonda promjera 10 mm i ultrazvuk jakosti 100 W, 75 W, 50 W, u razdoblju od 2,5; 5;0; 7,5 i 10min za svaku snagu. Tijekom drugog tretmana koristila se sonda promjera 7 mm, ultrazvuk snage 400 W, 300 W i 200 W, kroz 2,5; 5,0; 7,5 i 10 min. Također tijekom drugog tretmana koristila se sonda promjera 40mm, ultrazvuk snage 400 W, 300 W i 200 W, kroz 7,5 i 10 min. Tijekom trećeg tretmana koristila se sonda promjera 10 mm i ultrazvuk snage 400 W i 100 W tijekom 10, 15 i 20 min. Paralelno s tretiranjem ultrazvukom tijekom sva tri tretmana uzorci su bili podvrgnuti i pasterizaciji, niskoj i dugotrajnoj (65 °C/30 min) te visokoj i kratkotrajnoj (72 °C/15 s). Rezultati su pokazali da jedino djelovanje ultrazvuka snage 400 i 300 W ultrazvučne sonde promjera 7 mm kroz 2,5; 5,0; 7,5 i 10 min zadovoljavajuće djeluje na smanjenje broja bakterija, kvasaca i plijesni. Utjecaj ultrazvuka svih korištenih snaga ultrazvučnih sondi u zadanom vremenu ne izaziva velike negativne učinke na senzorska svojstva sirutke (izgled, miris, boja, okus).Purpose of this research is to test the effects of ultrasound on whey quality. Effects of ultrasound on whey quality were observed trough measurement of number of microorganisms and number of yeast and moulds and trough measurement of sensory properties. Three treatments were done using ultrasound of 24 kHz. In first treatment probe with diameter of 10 mm and ultrasound of 100 W, 75 W, 50 W was used trough 2,5; 5,0; 7,5 and 10 min for every intensity of ultrasound. In second treatment probe with diameter of 7 mm and ultrasound of 400 W, 300 W and 200 W was used trough 2,5; 5,0; 7,5 and 10 min. Also in second treatment probe with diameter of 40 mm and ultrasound of 300 W and 200 W was used trough 7,5 and 10 min. In third treatment probe with diameter of 10 mm and ultrasound of 400 W and 100 W was used trough 10, 15 and 20 min. Parallel with ultrasound in all three treatments, samples were also treated with pasterization, low temperature, long time (65 °C/30 min) and high temperature, short time (72 °C/15 s). Results have shown that only ultrasound of 400 and 300 W from probe with diameter of 7 mm trough 2,5; 5,0; 7,5 and 10 min have satisfactory results on reduction of bacteria, yeast and moulds. Performance of ultrasound of all intensities, probes and time has no or very little effect on sensory properties of treated whey (looks, smell, color, taste)