Abstract
Using of traditional milk pasteurization methods caused fouling by heat, particularly rapid pasteurization by ohmic heating at 220 volts resulted protein denaturation, when milk holding of 15 sec under ohmic heating at 72°C. So to control these properties a Non-thermal treatment by different electrical fields at 20, 27.5, 55 V/cm (80, 110, 220V, AC) and quickly milk pass between poles in a long narrow tube during less than 0.8 sec. The study focused on applying different electrical fields in milk pasteurization as a non thermal treatment and calculates the electrical conductivity, viscosity of milk, holding time, productivity, performance coefficient and measurement of final output milk temperature at 20, 27.5, 55 V/cm, pH, acidity, chemical composition, microbiological characteristics and storage periods for the pasteurized milk. The obtained results indicated that the final output milk temperature was reached 40°C and electrical conductivity was increased and viscosity was decreased with increasing temperature and productivity and performance coefficient were 1140 L/h, 99.8 respectively. More over pasteurized milk chemical composition and it’s pH were not influenced in electrical field. Resulting of bacteria elimination and alkaline phosphatase was inhibited by the electrical field as well. The results showed that the electrical field 55 V/cm is better than other electrical fields (20, 27.5 V/cm).
Highlights
Manufacture of virtually all milk and dairy products involves heat treatment, which is mainly aimed to kill microorganisms and inactivation of enzymes, or to achieving some other, mainly chemical, changes
The study focused on applying different electrical fields in milk pasteurization as a non thermal treatment and calculates the electrical conductivity, viscosity of milk, holding time, productivity, performance coefficient and measurement of final output milk temperature at 20, 27.5, 55 V/cm, pH, acidity, chemical composition, microbiological characteristics and storage periods for the pasteurized milk
The obtained results indicated that the final output milk temperature was reached 40°C and electrical conductivity was increased and viscosity was decreased with increasing temperature and productivity and performance coefficient were 1140 L/h, 99.8 respectively
Summary
Manufacture of virtually all milk and dairy products involves heat treatment, which is mainly aimed to kill microorganisms and inactivation of enzymes, or to achieving some other, mainly chemical, changes. This depends on the intensity of the treatment, i.e., the combination of temperature and duration of heating. Pasteurization is a mild process, designed to inactivate the major pathogenic and spoilage bacteria found in raw milk It should produce minimal chemical, physical and organoleptic changes in the product (Smit, 2003). As well as microwave pasteurization (Wang and Sastry, 2003; Albert et al, 2009; Al-Hilphy et al, 2010). Virgiliu et al (2007) stated that the methods of pasteurization are used may be slow pasteurization or low pasteurization at the temperature of 62-65°C/30 min, respective 20 min, where as midst pasteurization or shorten pasteurization is performed at the temperature of 72-78°C/15 sec. known as, High pasteurization or instantaneous pasteurization (HTST) is performed between 85-90°C, for a few sec. followed by sudden cooling at 10°C
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