EFFECT OF MICROWAVE AND SOME TREATMENTS ON MICROBIAL INACTIVATION RATE OF MILK

Ghanem, T.H.; Omar, M.A.M

doi:10.21608/mjae.2010.105941

EFFECT OF MICROWAVE AND SOME TREATMENTS ON MICROBIAL INACTIVATION RATE OF MILK

Document Type : Original Article

Authors

T.H. Ghanem ¹
M.A.M Omar ²

¹ Associate Prof., Agric. Eng.. Fac. of Agric., Al-Azhar Univ. (Cairo), Egypt.

² Associate Prof., Dairy Science Dept. Faculty of Agric.,Al-Azhar Univ.(Cairo), Egypt.

10.21608/mjae.2010.105941

Abstract

The aim of the present work is to study the effect of three different microwave power levels of 285, 385 and 470 W and alternating mixed treatments (20 seconds in microwave and 20 seconds sudden cooling) repeated one, two and three times on the total microbial counts (CFU/g) of milk . It was found that as the microwave power increases the total microbial counts decreases from 3.6x10¹⁰ to 2.4x10⁴ CFU/g. Insignificant differences were found between 385 and 470 W for the pure microwave treatments. The decimal reduction time were 10.36 s, 7.87 and 7.49 s for the three power levels respectively. For the mixed alternating treatments the power level of 470 gives the least total bacterial count of 3.3x10³ CFU/g compared to 3.5x10³ for the power level of 385W at 2450 MHz. The decimal reduction times were 39.23 and 38.90 s for 385 and 470 W for the three times treatments respectively. Semi-logarithmic models were satisfied for the pure microwave and alternating mixed treatments with coefficient of determination of 0.98.

Main Subjects

Biosystems Engineering

References

American Public Health Association.1987.Standard methods for the examination of diary products,1970Broadway,. N.Y. USA:19.

Chen, M.W. 2004. Microwave power control strategies on the drying process. M.Sc Th. Biological Eng.Dept. Mc Gill U.Montrial:2.

Disssel,M.M.Bowersox,E.M. and Jeter W.s.1960. Bacteria in electrically cooked foods. J.M.A Diet. Association.37(9)230-233.

Lechowich,R.V.,Benchat L.R. and Webester 1969. A procedure for evaluating the effect of 2450 MHz microwave on Streptococcus Faecalis and Saccharomyces Cerevisiae. Applied Microboology.17(1):106-110.

Mullin,J 1995. New methods of food preservation (microwave processing). Blackie Academic and professional, N.Y.117-121.

PrabhanjanD.G.,Ramaswamy,H.S. and Ragharam,G.S.1995.Microwave assisted convective air drying of thin layer carrots. J. of food Engineering,25:283-293.

Toledo,R.T.1991.Fudamentals of food process engineering. An AVI book Pub. By Van Nostrand Reinhold.N.Y.10003.ISBN. o-442-23988-6:133-136.