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Research background. The application of high power ultrasound combined with a slightly increased temperature on raw cow’s milk, skimmed cow’s milk and skimmed cow’s milk that passed the bactofugation process was analysed. We combined ultrasound with bactofugation of milk to achieve the microbiological accuracy that is equivalent to pasteurization. Experimental approach. The milk samples (200 mL) were treated for 2.5, 5, 7.5 and 10 min with high-power ultrasound (200 and 400 W) with a frequency of 24 kHz. The treatments were conducted with a constant duty cycle of 100 %. Temperatures during the treatments were 20 and 55 °C. The somatic cell count of the aerobic mesophilic bacteria, as well the number of Enterobacteriaceae, Escherichia coli and Staphylococcus aureus cells were analysed. Results and conclusions. From the perspective of the reduction of the total count of bacteria, the best result was achieved by high-power ultrasound at 400 W treated for 10 min. High reduction of Enterobacteriaceae, E. coli and S. aureus cells was achieved with ultrasound treatment of raw, skimmed and skimmed cow’s milk that passed the bactofugation with a power of 200 and 400 W regardless of the treatment time. Novelty and scientific contribution. This work combines bactofugation and high-power ultrasound for the inactivation of microoganisms. This combination was used at a slightly increased temperature (up to 55 °C), which is much more economical than pasteurization, while it preserves the sensory and physicochemical properties of milk.

Research background. Two methods of milk treatment were used, ultrasound (innovative method) and bactofugation, after which the physicochemical and sensory properties of the milk were examined, with the primary aim of achieving the quality and consistency of the pasteurized milk. Experimental approach. Ultrasound power of 200 and 400 W and frequency of 24 kHz with constant wave cycle were used. Milk treatment duration was 2.5, 5, 7.5 and 10 min with sonification at temperature of 20 °C (room temperature) and thermosonification (ultrasound at temperature higher than room temperature) at temperature of 55 °C. The purpose of this study is to investigate the effect of high-power ultrasound combined with a slightly increased temperature on whole, skimmed and skimmed cow's milk pretreated with bactofugation. Results and conclusions. The best sensory grade was achieved when milk was treated with ultrasound power of 200 W at 20 °C for max. 7.5 min. This research shows the potential of the applications of high-power ultrasound in dairy industry combined with bactofugation as a pretreatment of milk at a slightly increased temperature (up to 55 °C). Novelty and scientific contribution. The application of these two treatments requires milder processing conditions than pasteurization, it is economical and more environmentally friendly technological process that preserves better nutritional values of milk, which is preferred by costumers.

Research background. Two methods of milk treatment were used, ultrasound (innovative method) and bactofugation, after which the physicochemical and sensory properties of the milk were examined, with the primary aim of achieving the quality and consistency of the pasteurized milk. Experimental approach. Ultrasound power of 200 and 400 W and frequency of 24 kHz with constant wave cycle were used. Milk was treated for 2.5, 5, 7.5 and 10 min with sonification at 20 °C (room temperature) and thermosonification (ultrasound at temperature higher than room temperature) at 55 °C. The purpose of this study is to investigate the effect of high-power ultrasound combined with a slightly increased temperature on whole, skimmed and skimmed cow’s milk pretreated with bactofugation. Results and conclusions. The best sensory quality was achieved when milk was treated with ultrasound power of 200 W at 20 °C for max. 7.5 min. This research shows the potential of the applications of high-power ultrasound in dairy industry combined with bactofugation as a pre-treatment of milk at a slightly increased temperature (up to 55 °C). Novelty and scientific contribution. The application of these two treatments requires milder processing conditions than pasteurization, it is economical and more environmentally friendly technological process that preserves better nutritional values of milk, which is preferred by consumers., Pozadina istraživanja. Primjenjene su dvije metode obrade mlijeka: ultrazvuk (inovativna metoda) i baktofugiranje, nakon čega su ispitana fizikalno-kemijska i senzorska svojstva mlijeka, s osnovnom svrhom postizanja kakvoće i konzistencije pasteriziranog mlijeka. Eksperimentalni pristup. Korištena je snaga ultrazvuka od 200 i 400 W pri frekvenciji od 24 kHz s konstantnim valnim ciklusom. Mlijeko je tretirano sonifikacijom tijekom 2,5; 5; 7,5 i 10 min na 20 °C (sobnoj temperaturi) i termosonifikacijom (primjenom ultrazvuka na temperaturi višoj od sobne temperature) na 55 °C. Svrha je ove studije bila istražiti učinak ultrazvuka velike snage u kombinaciji s djelomično povišenom temperaturom na sirovo punomasno, obrano i obrano kravlje mlijeko prethodno obrađeno baktofugiranjem. Rezultati i zaključci. Najbolja senzorska kakvoća postignuta je obradom mlijeka ultrazvukom snage od 200 W pri 20 °C, tijekom maksimalno 7,5 min. Ovo istraživanje pokazuje potencijal primjene ultrazvuka velike snage u mljekarskoj industriji u kombinaciji s baktofugiranjem kao postupkom prethodne obrade mlijeka na djelomično povišenoj temperaturi (do 55 °C). Novina i znanstveni doprinos. Tijekom primjene ova dva postupka prerade mlijeka koriste se blaži uvjeti obrade od pasterizacije, pa se mogu smatrati ekonomičnim i ekološki prihvatljivijim tehnološkim postupcima, pomoću kojih se može bolje očuvati hranjiva vrijednost mlijeka, a što preferiraju i potrošači.