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	NUTRITIONAL EVALUATIONS of IRRADIATED FOODSCenter For Consumer Research - Food Irradiation

	Is Irradiated Food Safe?	How is Safety Tested?
	Does Nutritional Value Change After Irradiation?	Are There Hazards with Food Irradiation?

Updated: May 07, 2000	Does Nutritional Value Change After Irradiation? Nutritional studies have shown that low-dose food irradiation does not cause significant changes in nutritional value. Even at the higher doses of irradiation used to extend shelf-life or control harmful bacteria, nutritional losses are less than, or about the same as cooking and freezing. At lower doses, nutrient losses are either not measurable or insignificant. Any change in nutritional value caused by irradiation depends on a number of factors, including the radiation dose, the type of food, packaging and processing conditions, such as temperature during irradiation and storage time. All forms of food processing--cooking, freezing, canning and even storing foods--lower the amounts of some nutrients. Persons opposed to irradiation may claim high nutrient losses; however they incorrectly refer to studies that expose food to high doses not permitted in the United States or they refer to older studies that failed to accurately measure nutritional value (Diehl, 1990; Thorne, 1991). UCDavis Food Sciences.

Nutritional Value of Irradiated Food

Irradiation of food products is just like any other "cooking" process in that some of the nutritional value of the food is lost. The purpose here is to outline those loses. Above is the symbol for irradiated food.

Why irradiate and approved FDA doses

How irradiation is done

How is the nutritional value effected

Other effects of irradiation of food

Food irradiation Game

Why irradiate and approved FDA doses.

Food irradiation is one way that food can be preserved longer. It does this by destroying insects, fungi or bacterial growth that can make the food inetable. By destroying the bacterial growth you also can delay the time that it take for fruits and vegetables to ripen, thus extending shelf life or the reduction of possible human disease caused by salmonella, botulinum, or Trichinae. The table below outlines some of the purposes for different food products and the approved dose. See [6] for a more detailed summary of approved food irradiation processes.

Foods Permitted to be Irradiated Under FDA's Regulations [7]

Food	Purpose	Dose
Fresh pork	Control Trichinae spiralis	0.3 kGy min to 1 kGy max
Fresh foods	Growth and maturation inhibition	1 kGy max
Foods	Arthropod disinfections	1 kGy max
Dry Enzyme preparations	Microbial disinfections	10 kGy max
Dry spices/seasonings	Microbial disinfections	30 kGy max
Poultry	Pathogen control	3 kGy max
Frozen meats (NASA)	Sterilization	44 kGy min
Refrigerated meat	Pathogen control	4.5 kGy max
Frozen meat	Pathogen control	7 kGy max

How is the nutritional value effected.

Protein:

There are at least three kinds of structures in proteins: Primary: amino acids with peptide bonds

Secondary: arrangement of polypeptide chains Tertiary: spatial configuration in 3D of polypeptide chains

Irradiation can change the structure of a protein, primarily by breaking hydrogen bonds and other linkages in the long chains that make up proteins. A high dose will change the primary structure while moderate doses will affect the secondary and tertiary structures. In the table below you can see that there is not a lot of change to the amino acids from the irradiation. Thus the key components of proteins, amino acids, are primarily unaffected and thus so is protein in general.

Amino Acid Content of Dry Gelatin after Irradiation

		Dose (kGy)
Amino Acid	Control (no irradiation)	10	25	35
Hydroxyproline	11.9	10.6	11.0	13.0
Aspartic acid	5.4	6.0	5.7	5.5
Threonine	1.65	2.12	1.70	1.70
Serine	3.13	3.14	3.15	3.30
Glutamic acid	10.1	10.5	10.3	10.0
Proline	13.55	13.3	13.2	14.4
Glycine	22.3	21.2	21.3	21.5
Alanine	8.6	9.35	9.2	8.6
Methionine	0.53	0.90	0.53	0.40
Isoleucine	1.15	1.23	1.16	1.00
Leucine	2.80	2.80	2.74	2.70
Tyrosine	traces	traces	traces	traces
Phenylalanine	2.04	1.90	1.87	1.90
Hydroxylysine	0.90	0.91	0.77	1.10
Lysine	3.45	3.87	3.48	2.70
Histidine	0.77	0.73	0.64	0.60
NH4	1.12	1.01	0.77	0.90

Carbohydrates:

None of my references cite any actual data for the effects of irradiation on carbohydrates. In [2] the author goes into some detail about how the different bonds are broken and states "generally the radiation-induced changes in carbohydrates are too small to be very important in food irradiation." This statement is agreed upon in the other sources. One note to make is that irradiation breaks the glycosidic bond which is the primary cause of the reduction in firmness and texture.

Lipids:

In general, fats are not carriers of insects or parasites and they do not decay from microbial action. For these reasons there is no real desire to irradiate fats other than the fact that they are a part of foods that contain carbohydrates and/or protein. [3] reports the following test on polyunsaturated fatty acids (PUFAs):

substance	Dose (kGy)	PUFAs lost
herring fillets	59	none observed
whole grains of rye, wheat, and rice	0.1-1	none observed
whole grains of rye, wheat, and rice	63	only small losses

No significant effects on the fatty acid composition of the lipids of chicken meat sterilized by gamma-ray or electron irradiation for the Raltech feeding studies were observed." These results seem to point that the loss of fatty acids is negligible in the FDA approved range of dose (see page Approved Foods ).

Vitamins:

Irradiation of food, like cooking (thermal process), causes a loss of vitamins. The presence of oxygen and temperature greatly effect the amount lost. For example a beet that was electron-irradiated with a dose of 10kGy had a loss of thiamine that "[3] was 65% at room temperature, 24% at -10° C, 12% at -20° C, and 5% at -75° C." Note that the beet was in a sealed can of nitrogen. For an oxygen example beef was irradiated to 30 kGy in Nitrogen and it had no loss of Vitamin E while in the presence of air the loss was 37%. The table below compares non-irradiated, heat sterilized and irradiated chicken meat. From it you see that the thermal and irradiation losses track rather closely with a couple exceptions.

Vitamin content of frozen, thermally processed, gamma-irradiated and electron-irradiated enzyme-inactivated chicken meat [3]

	Process
Vitamin	Frozen Control	Heat-sterilized	Gamma-irradiated (59 kGy at -25° C)	Electron-irradiated (59 kGy at -25° C)
Thiamine hydrochloride (mg/kg)	2.31	1.53a	1.57 a	1.98
Riboflavin (mg/kg)	4.32	4.60	4.46	4.90 b
Pyridoxine (mg/kg)	7.26	7.62	5.32	6.70
Nicontinic acid (niacin) (mg/kg)	212.9	213.9	197.9	208.2
Pantothenic acid (mg/kg)	24.0	21.8	23.5	24.9
Biotin (mg/kg)	0.093	0.097	0.098	0.103
Folic acid (mg/kg)	0.83	1.22	1.26	1.47 b
Vitamin A (IU/kg)	2716	2340	2270	2270
Vitamin D (IU/kg)	375.1	342.8	354.0	466.1
Vitamin K (mg/kg)	1.29	1.01	0.81	0.85
Vitamin B12 (mg/kg)	0.008	0.016 b	0.014 b	0.009

NOTE: Gamma radiation provides results nearly identical to X-radiation.

a significantly lower than frozen control

b significantly higher than frozen control

Minerals:

"[3] Mineral and trace elements are not affected by irradiation, and there is no evidence that the bioavailability of these elements might be adversely affected by irradiation."

Summary of Nutritional value:

Proteins, carbohydrates, fats, and minerals are primarily unaffected by irradiation from a nutritional point of view. Vitamins on the other hand have various levels of loss with thiamin and Vitamin E & C being the most sensitive. See the table below for vitamin sensitivity.

Relative Radiation Sensitivity of Vitamins

Most sensitive Moderately Sensitive least sensitive

Fat-soluble vitamins

Vit. E -> Carotene -> Vit. A -> Vit. D -> Vit. k

Water-soluble vitamins

Vit. B1 (thiamin) -> Vit. C -> Vit. B6 -> Vit. B6 -> Folate, nicontinic acid (niacin) -> Vit B12

Other effects of irradiation of food.

From above it can be seen that the nutritional effects are not that great, unfortunately there are some other undesirable affect that occur. One of them is that the food can develop off flavors. These flavors have "[1] been variously described as 'goaty', 'wet-dog', etc. It resembles a scorched flavor." According to [2] this off flavors are most likely to occur in eggs and dairy products. "[1] Beef is known to be the most prone among the common meats to development of the characteristic irradiation off-flavor." If the doses for meat are kept in the 4Mrad (40 kGy) region there is little or no off-flavor. The loss of texture (softening) is the main draw back from a qualitative point of view relative to fruits and vegetables, though discoloration is also an issue. Overall it seems that with judicious use of the amount of radiation and other techniques (such as irradiating at low temperature, the absence of oxygen and chemical additives) allow most food to be treated with minimal negative effects.

Food irradiation game by Mike Gobster courtesy of Moltar Productions

The purpose of the game is to eliminate the germs before the nutritional value of the food goes to zero. Each time you fire the x-ray gun to kill germs, the nutritional value of the food goes down.

References

1. W.M. Urbain, Food Irradiation: Benefits and Limitations, Factors influencing the economical application of food irradiation. Proceedings of a panel ... organized by the Joint FAO/IAEA Division of Atomic Energy in Food and Agriculture and held in Vienna, Austria, 14-18 June 1971, pp. 101-115.

2. Walter M. Urbain, Food Irradiation, Academic Press, 1986.

3. Joint FAO/IAEA/WHO Study Group, High-Dose Irradiation: (Wholesomeness of Food irradiated with Doses Above 10kGy), 1997, Geneva, Switzerland.

4.T.K. Murray, Nutritional aspects of Food Irradiation, Recent advances in Food Irradiation, edited by P.S. Elias, A.J. Cohen, Elsevier Biomedical, 1983, pp.203-216.

5. Charlotte P. Brennand, Food Irradiation, http://www.physics.isu.edu/radinf/food.htm, Idaho State University, 1995.

6. Elizabeth L. Andress, Keith Delaplane, George Schuler, Food Irradiation, http://www.fcs.uga.edu/pubs/current/FDNS-E-3.html, University of Georgia, 1998.

7. Kim M. Morehouse, Food Irradiation: The treatment of foods with ionizing radiation, ~dms/opa-fdir.html"http://vm.cfsan.fda.gov/~dms/opa-fdir.html, US Food and Drug administration, updated 1999.

8. JF Diehl, Food irradiation: is it an alternative to chemical preservatives? Food additives and contaminants, 1992, 9:409-416.

9. S Bachman, H. Zegota, Physicochemical changes in irradiated (gamma 60Co) inulin. Improvement of Food Quality by Irradiation. Intl. Atomic Energy Agency, Vienna, 1974.

by J.D. Glaess for EEE591/460

Arizona State University

Last Updated: April 30, 2002

Cell Structure & DNA

When reading the Carbohydrate Deficient Glycoprotein Syndrome research material it is helpful to have a refresher of some basic science concepts. That is what I hope this page provides. Please let me know if any information is incorrect or outdated. The following information is taken from FOCUS ON LIFE SCIENCE, author Charles H. Heimler.

Cells

The human body contains millions of cells. A cell is the basic unit of structure and function in an organism. Cells are like bricks that make a building. Cells are the basic building blocks of organisms. Every organism is made of cells and every cell comes from another cell. This idea is called cell theory.

All cells are alike in some way. A cell membrane is a thin layer that surrounds and holds that parts of a cell together. It is made of proteins and fats. The cell membrane controls the movement of material into and out of a cell. In the cells of most organisms, there is a ball-shaped nucleus (NEW klee us). The nucleus contains a nucleolus and nucleoplasm. This material inside the nucleus controls the cell. Not every cell has a nucleus inside it. For example, a red blood cell loses its nucleus as it matures.

Cell Parts

Cytoplasm is the watery material of the cell and contains many cell materials such as proteins, enzymes, waste products, and salts. Photographs of cells magnified 40,000 to 50,000 times show tubelike structures in the cytoplasm. The tubes form a network called the endoplasmic reticulum (en duh PLAZ mihk.rih TIHK yuh lum), or ER. The ER at times connects with the cell membrane or with the nuclear membrane. The ER changes constantly and is a place where many cells substances are made.

Ribosomes (RI buh sohmz) are tiny grainlike particles. They are so small they can be seen only with an electron microscope. Ribosomes are the sites in cells where proteins are made. Proteins are large, complex substances that are building blocks of living substances. Robosomes are made within the nucleolus in the nucleus of a cell. The ribosomes pass out of the nuclear membrane into the cytoplasm. Some ribosomes are found along the edges of the ER. Some form long strings in the cytoplasm. They both produce proteins.

Golgi (GAUL jee) bodies are found in cytoplasm, also. They are made by ER. Golgi bodies store and release chemicals in the cell. The chemicals effect other processes occurring in the cell.

Mitochondria (mite uh KAHN dree uh) are rod-shaped bodies in the cytoplasm. They are involved in the chemical reactions that release energy for use in the cell.

DNA

DNA is deoxyribonucleic (dee AHK sih ri boh noo klay ihk) acid. DNA is the genetic material in the nuclei of cells. The chromosomes that appear in the nucleus of a cell during mitosis are made of DNA. Mitosis is the name given to the process in which the nucleus divides so that two new cells can form. DNA molecules can be very large. DNA contains a code with information that regulates the activities of a cell. The DNA code controls the chemical changes that make up a cell's life activities. Genes responsible for different inherited traits are short sections of DNA molecules.

DNA regulates a cell by controlling the production of cell enzymes and other proteins. Enzymes regulate the chemical changes involved in cell activities such as respiration. DNA also has the ability to replicate or make more DNA just like itself.

DNA is a long, threadlike molecule with the shape of a double helix. The shape of a helix is like a corkscrew. The two helixes in the module wind around each other and are connected by bonds that form a spiral ladder.

RNA

RNA is ribonucleic (ri boh noo KLAY ihk) acid and is similar to DNA in structure, but is single- stranded. RNA works together with DNA to regulate a cell. Like DNA, RNA controls cells through the making of proteins. Inside the nucleus, a copy of the DNA code is made like a blueprint in the form of RNA mulecules. The RNA molecules leave the nucleus and enter the cytoplasm. They are messengers that carry information from the DNA to the ribosomes. Ribosomes work like assembly lines that make enzymes and other cell proteins.

Gene

A gene is the unit of inheritance that is passed from parents to offspring. For each trait, there are at least two genes that control its inheritance. Genes occur in pairs on chromosomes inside the nucleus of a cell. There are dominant genes for dominant traits and recessive genes for recessive traits. A dominant gene may mask a recessive gene when the genes are paired.

Genes are located on the chromosomes. A pair of chromosomes contains pairs of genes. One gene of each pair is on one chromosome and the other gene is on the matching chromosome. A human body cell normally has 46 chromosomes.

A string of pearls may be used as a simple model of a chromosome. Each pearl represents a gene. The row of pearls is like a chromosome with its genes.

Carbohydrates

A carbohydrate is a compound composed of carbon, hydrogen, and oxygen, The ratio of hydrogen to oxygen is a carbohydrate is 2:1. Sugar and starch are two carbohydrates.

Carbohydrates are important sources of energy. During digestion, most carbohydrates are changed to a simple sugar called glucose. Glucose is carried to the body's cells by the circulatory system. In the cells, glucose is broken down with the help of oxygen in the chemical change that releases energy. The energy is used for the growth and repair of cell parts and for other cell activieies.

Glycogen (GLI kuh jun) is another carbohydrate present in the human body. It is formed from glucose and stored in the liver and muscle cells. Glycogen contains stored energy. Glycogen is converted back to glucose as it is needed by the body's cells.

Proteins

Protein

is a nutrient made of amino acids. All amino acids are organic compounds that contain carbon, hydrogen, oxygen, and nitrogen. Two amino acids contain sulfur. Amino acids are building blocks of larger protein molecules. More than 20 different amino acids are required to keep your body healthy. The 20 amino acids can form an almost endless number of proteins.

Amino acids are used for the growth and repair of body tissue and to make hormones, enzymes, and antibodies. They are also a source of energy.

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