The document discusses the irradiation process used to sterilize and preserve food. It describes how irradiation works by damaging microorganisms through direct and indirect effects. Common sources of ionizing radiation used in food irradiation are gamma rays, x-rays, and electron beams. Irradiation is effective at inactivating bacteria, parasites and insects while extending the shelf life of foods like meat, produce and spices. The appropriate radiation dose depends on the target organism and desired effect.
1. LECTURE NOTES 03/08 “IRRADIATION PROCESS” SAIFUL IRWAN ZUBAIRI PMIFT, Grad B.E.M. B. Eng. (Chemical-Bioprocess) (Hons.), UTM M. Eng. (Bioprocess), UTM ROOM NO.: 2166, CHEMISTRY BUILDING, TEL. (OFF.): 03-89215828, FOOD SCIENCE PROGRAMME, CENTRE OF CHEMICAL SCIENCES AND FOOD TECHNOLOGY, UKM BANGI, SELANGOR 28 MAY 2008
25. What Is Food Irradiation? “ Food irradiation is the process of exposing food, either packaged or in bulk to carefully controlled amounts of ionizing radiation for a specific time to achieve certain desirable objectives”
26. Ionizing Radiation Ionizing Radiation: “X-rays, alpha, beta, and gamma rays (short wavelength-high energy) which cause whatever material they strike to produce ions”
52. Examples of irradiation processes Control insects in fruits and vegetables up to 1 kilogray Kill insects and microbes in spices up to 30 kilogray Control Trichinella (a parasite) in pork 0.3-1 kilogray Inhibit sprouting of potatoes 50-150 gray Control insects in wheat and flour 200-500 gray
Hinweis der Redaktion
The policy is to first decide on the outcome you are trying to achieve and then use the minimum amount of radiation that will achieve that result.
I’m sure you’re familiar with the electromagnetic spectrum that includes radio and television waves, microwaves and visible light. But ionizing radiation has shorter wavelengths and consequently higher energy---enough energy to break chemical bonds in molecules resulting in chemical changes in foods and the insects that contaminate those foods.
The two main sources of ionizing radiation are (1) gamma rays from a radioactive source, primarily cobalt 60, and (2) high energy electrons or x-rays produced by an electron beam accelerator.
Extensive research over the past five decades has established the safety of ionizing radiation as a food processing technique.
And today as you can see, most of the developed countries of the world have approved food irradiation of some type. Currently more than 100 million tons of food are being iradiated and used by consumers. SHOW BOOK Here in the United States we have been on the slow side in adopting this technology….it seems clear that he main reason for this is the publics attitude toward a technique that involves radiation treatment. Yet where irradiated foods have been offered along with an informational campaign, the public is willing to pay a higher price for the irradiated foods. Why then do we need ways to detect the irradiated product?
Impedance is th etotal opposition to the flow of current by a circuit…the vector sum of the resistance and reactance.
From Japan where upwards of 20, 000 tons of potatoes a year are irradiated in a facility like this one, came a study from their agriculture department on potato impedance which reported that at low frequencies radiation produced a measurable change in impedance while at higher frequencies the difference disappeared. So by finding the ratio of the low to high impedance of a group of irradiated potatoes and comparing that to a group of unirradiated potatoes, a distinction could be found.