A. Edwin Woods

MECHANISM OF THE CHLOROPEROXIDASE-CATALYZED BROMINATION OF TYROSINE

Abstract Free molecular Br2 was the intermediate formed in the bromide-dependent chloroperoxidase reaction. CPO was deactivated by free Br2 molecules associated with the destruction of its heme structure. The tyrosine bromination reaction was a nonenzymic chemical reaction between free molecular Br2 and tyrosine.

Food Laws and Regulations

A paramount objective of the food industry is to provide a continuing supply of safe, wholesome foods for the public. To achieve this goal, food producers must be concerned about possible deterioration of foods, their contamination with microorganisms or potentially hazardous chemicals (e.g., residues of pesticides used in agriculture), and the safety of additives or other materials used in food processing.

Purification, physical properties and kinetics of peroxidases from freshwater crayfish (genus Orconectes)

Abstract 1. 1. Soluble peroxidases were purified from freshwater crayfish hepatopancreas, 593-fold purification was achieved. 2. 2. Molecular weights of 33,000, 76,000 and 147,000 were determined for the peroxidases by SDS polyacrylamide gel electrophoresis and Sephacryl S-200 gel filtration. 3. 3. Isoelectric points between 3.5 and 8.5 were determined for six isoperoxidases. 4. 4. Halogenation of tyrosine was observed, mechanism for guaiacol oxidation and iodide peroxidation is discussed.

Meat, Poultry, and Fish

In this discussion, meat is defined as the flesh of cattle, swine, sheep or goats that is consumed for food. It consists of muscle fibers held together by connective tissue and interspersed with nerves and blood vessels, which normally accompany the tissue. A single muscle contains a number of fiber bundles, held together by a sheath of connective tissue, the epimysium. Groups of fibers are associated into fiber bundles which, in turn, are surrounded by a sheath of connective tissue, the perimysium. The basic unit of muscle is the fiber, and it is bounded by the endomysium and sarcolemma.

Milk and Milk Products

Milk and milk products , Milk and milk products , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزیMilk is the normal secretion of the mammary glands for the feeding of the young of mammals. In the United States, the primary milk in commerce is cow’s milk. The responsibility for insuring the quality of this food product rests primarily with the individual states rather than with the federal government. Consequently, legal definitions of milk are not uniform within the United States. The U.S. Public Health Service (USPHS) has encouraged the adoption of adequate and uniform state and local control legislation. The following definition from its Grade A Pasteurized Milk Ordinance (1965) has been adopted by a majority of the states: “Milk is hereby defined to be the lacteal secretion, practically free from colostrum, obtained by the complete milking of one or more healthy cows, which contains not less than 8 1/4;% milk solidsnot-fat and not less than 3 1/4% milk fat.”

Coloring Agents and Color of Foods

Color is unconsciously incorporated into our impressions of foods because our eyes are constantly supplying the brain with color information that is instinctively associated with all other information about any given food. Radishes are “red,” bananas are “yellow,” and lettuce is “green.” In fact, we associate a particular color with almost every food we come in contact with in our daily lives. Thus, color is a significant factor in consumer acceptance of foods, and consumers automatically associate certain color characteristics with fresh and wholesome quality. This evident characteristic of foods is included in the quality standards for fresh and processed fruits and vegetables, fats and oils, meats, dairy products, poultry, and eggs. In the processing, preservation, and storage of some food products, the “natural color” may be destroyed. This fact has spurred food processors to develop methods for retaining the best possible color in foods.

Instrumental Methods Used in Food Analysis

The development of solid state electronics, grating optics, microprocessors, and minicomputers represents but a few of the outstanding changes that have occurred in analytical instruments over the past decade. Instruments are, as a result of these developments, more stable and reliable, and afford the food chemist more convenient techniques of data acquisition.

Food Deterioration, Preservation, and Contamination

Since prehistorical times, humans have sought to keep excess food obtained in times of plenty for use during periods when obtaining food was difficult. However, because of its chemical composition, food is subject to various deteriorative processes. Thus, of necessity, man learned early to preserve food, i.e., treat it so as to prevent or retard its natural deterioration. During the past few hundred years, the development of increasingly effective preservation methods, coupled with the advent of efficient means of transportation, has permitted the growth of towns and cities. The food supply for today’s towns and cities is no longer dependent on production from the immediate surrounding area but rather is drawn from all regions of a country, and to some extent even from foreign countries. Without effective food preservation methods and adequate transportation modern urban life would be impossible.

Sampling and proximate analysis

Considerable information about a food sample can be gained through a general analysis of its main components—moisture, crude fat, crude protein, ash, and crude fiber. The determination of the percentages of these components is termed a proximate analysis. In some cases, a proximate analysis may be all that is required and the more sophisticated instrumental methods discussed in Chapter 3 may be unnecessary. For example, a proximate analysis is usually sufficient to establish the general category of foodstuff to which a particular sample belongs and the similarity of a particular food sample to materials previously reported in the literature.

Wheat and Wheat Products

Cereals are the dried seeds of the cultivated grasses, which belong to the family Gramineae. They include wheat, rye, barley, corn, oats, grain sorghum, and millet. Buckwheat, although not a true cereal, is usually included with them.