Composition properties, physicochemical characteristics and shelf life of whole milk after thermal and thermo-sonication
2009
Bermúdez-Aguirre, Daniela | Mawson, Raymond | Versteeg, Kees | Barbosa-Cánovas, Gustavo V.
Raw whole milk (RM) was pasteurized with heat-pasteurized milk (TT) and thermo-sonication (US) treatments. Batch pasteurization was used for TT and 36, 72, 108 and 120 μm of the ultrasound wave intensity (24 kHz, 400 W); in addition, the heat conditions were applied together for US. Apparent protein content of US milk decreased; butter fat content was increased by US treatment. Proximal analysis showed the presence of added water in US milk and a decrease of nonfat solids, whereas pH was decreased for US milk, lactic acid was increased and density was decreased from RM to US; also, the color of US milk was whiter. The tested parameters for the TT samples were often intermediate between RM and US samples. Statistical analysis showed a significant difference (P < 0.05) among all treatments. After 16 days, US samples (4C) did not show mesophilic growth higher than 2 log; pH, acidity and color remained constant. Thermo-sonication (US) is an available method that can improve some sensorial and quality milk characteristics such as color and appearance, while at the same time, ultrasound pasteurizes the product. Minor changes in nutritional properties of milk (i.e., protein content) have been reported after US, with the advantage of extending the shelf life of the product for more than 16 days at 4C without the use of intensive heat treatments. This is a potential technology for use in research and development of new and current products in the dairy industry.
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