Bacterial Toxins

Of the many different causes of foodborne diseases, bacteria are by far the most common. About half of all cases of diarrhea in the U.S. are of foodborne origin, and, according to the CDC, microbial diseases are on the rise. The reasons for the increase in foodborne illnesses are as follows. (1) There are better epidemiological capacities and better means to report cases, as well as better means to detect and identify foodborne illnesses. (2) Over the last few decades, people have made...

Study questions and exercises

Distinguish between intentional and incidental food additives. Provide a few examples of each and describe how incidental additives get into foods and why intentional additives (function of additives) are added to foods. 2. Discuss how the Delaney Clause has impacted on the use of food additives in foods and the implication this clause has on safety evaluation of additives. Put into perspective the benefits and risks of additives in foods. 3. List the common food-preservation techniques and...

Recommended readings

Albert, A., Selective Toxicity The Physio-Chemical Basis of Therapy, 6th ed., Chapman & Hall, London, 1979. Combs, G.F, Jr., The Vitamins Fundamental Aspects in Nutrition and Health, 2nd ed., Academic Press, New York, 1998. Meydani, M., Impact of aging on detoxification mechanisms, in Nutritional Toxicology, Kotsonis, F.N., Mackey, M., and Hjelle, J., Eds., Raven Press, New York, 1994, pp. 49-66. Netter, K.J., Toxicodietetics dietary alterations of toxic action, in New Concepts and...

Food Intolerance and Allergy

According to some surveys, 20 to 25 of people in the U.S. are allergic to certain foods. Self-reported information based on changes in dietary habits to accommodate a food problem is likely to be mostly erroneous. Often, patients who say they have a food allergy avoid a food and never seek medical advice. Diagnosis of food allergies is overworked, poorly defined, and misused. There are many misconceptions about food allergies, such as understanding of the causes of food allergies and their...

History of food irradiation

As noted in Table 18.1, the benefits of ionizing radiation have been known since 1905. In addition to its potential to irradiation can be used to eliminate pests such as the screw worm fly, which preys on cattle, the Mediterranean fruit fly, and the tsetse fly, by the release of sterile insects. Worries about nuclear weapons, combinedwithanantiprogressideology, began to hinder food irradiation research afterthe war. Althoughthere wasatthat time an adequate supply of gamma rays, the high-energy,...

Nitrates nitrites and nitrosamines

Nitrates and nitrites in preserved meats (bacon, cold cuts) can prevent growth of Clostridium botulinum, the organism that can produce the potent botulinum toxin. However, nitrates and nitrites have been shown to have adverse effects, such as methemoglobinemia and carcinogenesis, the latter resulting from the formation of nitrosamines. Coincidentally, reduction of nitrate to nitrite is a common reaction for bacteria in the GI tract. Usually, the GI effect on nitrite is preceded by nitrate being...

Metabolism and Excretion of Toxicants

Leupeptin Plant

The amount of free plasma toxicant is a function of the toxicant's absorption, distribution, and elimination (Figure 9.1). In Chapter 8, a variety of factors that govern the absorption of toxicants in the gastrointestinal (GI) tract were discussed. This chapter focuses on factors that influence distribution and elimination of toxicants. Toxicants and other foreign compounds (xenobiotics) undergo metabolic transformation in the body. In many situations, the rate of metabolism is the primary...

Products of the maillard reaction

In the Maillard reaction, reducing sugars pentoses gt hexoses condensate with amino acids, producing a mixture of insoluble dark-brown polymeric pigments, termed melanoidins. Aldoses and ketoses react with aliphatic primary and secondary amines of amino acids and proteins to form -glycosides, which readily dehydrate to Schiff's base by the Maillard reaction Figure 19.4 . This is the basis for the well-known nonenzymatic browning reaction. In the early stages of the reaction, premel-anoidins are...

Risk characterization

With information about the dose-response and exposure features of the substance, the risk can be characterized. Risk characterization is the process of estimating the probable incidence of an adverse health effect to humans who are under the circumstances of exposure. When every data is available, risk characterization should be based on human data. However, frequently human data is fragmented, incomplete, or even lacking. Thus, extrapolations are made from dose-response relationships...