COMPOSITION PROPERTIES, PHYSICOCHEMICAL CHARACTERISTICS AND SHELF LIFE OF WHOLE MILK AFTER THERMAL AND THERMO‐SONICATION TREATMENTS

ABSTRACT 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. PRACTICAL APPLICATIONS 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.

[1]  Margaret C. Neville,et al.  E – The Physical Properties of Human and Bovine Milks , 1995 .

[2]  M. Villamiel,et al.  Influence of high-intensity ultrasound and heat treatment in continuous flow on fat, proteins, and native enzymes of milk. , 2000, Journal of agricultural and food chemistry.

[3]  A. Kelly,et al.  Effect of milk pasteurization temperature and in situ whey protein denaturation on the composition, texture and heat-induced functionality of half-fat Cheddar cheese , 2004 .

[4]  H. Heusinger.  Formation and polymerisation of malonaldehyde during irradiation of aqueous solutions of d-glucose and lactose with ultrasound , 1986 .

[5]  M. Şengül,et al.  Effect of Ultrasound Treatment on Milk Homogenisation and Particle Size Distribution of Fat , 2004 .

[6]  S. L. Owens,et al.  Influence of Bacterial Cell Population and pH on the Color of Nonfat Milk , 2001 .

[7]  U. Pal,et al.  Quality and shelf-life of goat milk Paneer in refrigerated storage , 1996 .

[8]  K. Hasiba,et al.  Inactivation of Escherichia coli by ultrasonic irradiation. , 2004, Ultrasonics sonochemistry.

[9]  B. Miralles,et al.  Changes in flavour and volatile components during storage of whole and skimmed UHT milk , 2001 .

[10]  T. W. Keenan,et al.  CHAPTER 2 – The Structure of Milk: Implications for Sampling and Storage: A. The Milk Lipid Globule Membrane , 1995 .

[11]  D Knorr,et al.  Nutritional improvement of plant foods by non-thermal processing* , 2002, Proceedings of the Nutrition Society.

[12]  T. Moraes-santos,et al.  Effect of heat treatment on the nutritional quality of milk proteins , 1997 .

[13]  R. Mehta.  Milk Processed at Ultra-High-Temperatures - A Review 1. , 1980, Journal of food protection.

[14]  B. Slaghuis,et al.  The freezing point of authentic and original farm bulk tank milk in The Netherlands , 2001 .

[15]  J. O'brien.  Reaction Chemistry of Lactose: Non-Enzymatic Degradation Pathways and Their Significance in Dairy Products , 1997 .

[16]  Supeno,et al.  Sonochemical formation of nitrate and nitrite in water , 2000, Ultrasonics sonochemistry.

[17]  S. Patton.  Browning and Associated Changes in Milk and Its Products: A Review , 1955 .

[18]  D. Mollé,et al.  Effects of storage temperature on physico-chemical characteristics of semi-skimmed UHT milk , 2008 .

[19]  R. Nishimura,et al.  Inactivation effect of sonication and chlorination on Saccharomyces cerevisiae. Calorimetric analysis. , 2004, Ultrasonics sonochemistry.

[20]  S. Patton,et al.  B – Particulate Constituents in Human and Bovine Milks , 1995 .

[21]  Hao Feng,et al.  Inactivation of Escherichia coli with power ultrasound in apple cider , 2006 .

[22]  Farid Chemat,et al.  Hazard analysis and critical control point (HACCP) for an ultrasound food processing operation. , 2004, Ultrasonics sonochemistry.

[23]  W. Horwitz.  Official Methods of Analysis , 1980 .

[24]  K. Hashiba,et al.  Inactivation of Saccharomyces cerevisiae by ultrasonic irradiation. , 2004, Ultrasonics sonochemistry.

[25]  H. Lawless,et al.  The Influence of Fat on the Sensory Properties, Viscosity, and Color of Lowfat Milk , 1995 .

[26]  Dietrich Knorr,et al.  Applications and potential of ultrasonics in food processing , 2004 .

[27]  M. Kontominas,et al.  Shelf life of whole pasteurized milk in Greece: effect of packaging material , 2004 .