Principal foods

Every continent, except Antarctica, grows com 40% of the present world crop is produced in the United States. In the 1987—1988 crop year, 12 states (Iowa, HI., Nebr., Minn., Ind., Ohio, Wis., Mo., S. Dak., Mich., Kans., and Tex. in order of production) produced 157.5 million metric tons (6.2 biUion bushels) that was 88% of the United States and 36% of the world s crop (66). Yield is influenced by many factors, including climate, pest control, planting density, and fertilization. Yield in the United States has increased from about 1.5 metric tons /hectare in the 1930s to about 7.5 metric tons /hectare. In 1985, a test plot produced 23.2 metric tons /hectare and yields approaching 40 metric tons /hectare are considered possible com is the most productive of the principal food crops. 

The food producing industry has responded to consumer demand for foods with lower fat content (Table 1). Foods with low or no cholesterol claims leaped 78% from 1980 to 1990, in spite of the fact that many of the principal food producers reduced the amount of new product introductions during 1989 and 1990 (7). Table 2 indicates the change in the market for various food industry segments, especially those suspected as fat problem generators, including dairy and meat foods. Many low fat and low cholesterol foods were created by a dding claims to food that have always been low in fat and/or cholesterol. 

Although most seeds contain starch as the principal food reserve, many contain other polysaccharides and some have industrial utility. The first seed gums used commercially were quince, psyUium, flax, and locust bean gum. However, only locust bean gum is stiU used, particularly in food appHcations quince and psyllium gums are only used in specialized appHcations. 

It is fortuitous that indigenous concentrations of vitamin E in the principal food sources are on the order of mg rather than yug/100 g, for the tocopherols and tocotrienols exhibit relatively low intensities of UV absorption. Individual vitamers are characterized by a slightly different absorption maximum within the wavelength range of 292-298 nm in ethanol. Published A] m values for the tocopherols at their Amax in ethanol are a-T 70-73.7 at 292 nm, (3-T 86-87 at 297 nm, y-T 90-93 at 298 nm, and <5-T 91.2 at 298 nm (126). The different absorption characteristics among the vitamers necessitates the running of individual standards for accurate quantitation of each vitamer. The absorption intensity of a-tocopheryl acetate is lower still with an A j m value of only 40-44 at the Amax of 285.5 nm (44). Reported minimum detectable quantities of a-, / -, y-, and (5-tocopherols at 295 nm are, respectively, 50 ng, 70 ng, 90 ng, and 130 ng (127). 

Animal products are the principal food sources of vitamin B 2 (19,167). Organ meats, such as liver, kidney, brain, and heart, are the best sources. Plant products contain very little vitamin B,2, which is an important consideration for strict vegetarians. 

Domestication of plants an artificial selection process carried out by humans to produce plants that have fewer undesirable traits of wild plants, and which renders them more dependent on artificial (usually enhanced) environments for their continued existence. The practice is estimated to date back 9,000—11,000 years. Today, all of our principal food crops come from domesticated varieties. Over the millennia many domesticated species have become utterly unlike their natural ancestors. Corn cobs are now dozens of times the size of their wild ancestors, producing seeds that are more digestible (figure 4.2). 

The development of the M. leidyi population in the Black Sea ecosystem led to a decrease in the biomass, abundance, and species diversity of edible zooplankton, fish larvae, and eggs, which are the principal food objects of M. leidyi (Figs. 3, 4) [38-41]. 

Approximate amino acid composition of wild and hatchery trout (Salvelinus fontinalis) and some of their principal foods (Grammarus and Hexagenia bi-lineata). Contribs. Boyce Thompson Inst., 20, 103 (1959). 

Organism Time to Symptoms (h) Principal Foods Peak Incidence (U.S.A) Principal Mechanism of Pathophysiology Duration Treatment... 

The principal food products providing phenolic antioxidants to the diet of European countries are onions, apples, citms fruits, tea, grapes and red wine. However, many other fruits and vegetables rich in phenolic antioxidants could be also included in this list. For example, berry fruits, cherry tomatoes, some red lettuce cultivars, artichokes, green asparagus, spinach, olives, broccoli and eggplant, are very rieh in antioxidant phenolics. 

FUNCTIONS Biological function restricted to source of energy. Principal food-reserve materials in animals. Found in cells of vertebrates and invertebrates. No commercial... 

Cereals have low confenfs of essential amino acids, particularly lysine and tryptophan. In developing countries especially, this creates nutritional deficiencies for a large proportion of the population because a single cereal may account for a major part of the protein intake. In some countries (Central and South America and sub-Saharan Africa), people rely on maize as their principal food. In order to counter the problem, high-lysine mutants of maize have been identified. However, these mutants are associated with negative effects on yield and they have soft, chalky kernels that are susceptible to disease and insect damage. 

The chemical characteristics of water are most commonly described by the concentrations of a limited number of dissolved inoiganic ions, lumped parameters such as alka-Unity, acidity, hardness, conductivity, the aqueous caibon dioxide concentration, the radioactivity, and lumped mea-suies of the organic content such as biochemical oxygen demand, as indicated in Table VI. Concentrations of other inorganic ions and spedlic or nic compounds are important in relation to particular rrses. The most common issues with respect to concentrations of particular ions and compounds are related to toxicity. For example, the maximum concentration limit (MCL) for arsenic in drinking water of 50 /tg/L is based on the average ability to excrete approximately 900 of arsenic per day, the probable intake of arsenic from other soirrces (principally food), and the assumption that we will follow recommendations to... 

Starch is the principal food reserve of plants, glycogen functions as a carbohydrate reserve for animals, and cellulose serves as structural material in plants. 

Besides water, plants and animals constitute man s principal food. Plants and animals need organic carbon compounds in order to develop their body substance and to meet their energy requirements. In contrast to the animals, plants can build these carbon compounds from the basic substances water and carbon dioxide (assimilation). For this purpose, suf-hcient energy must be made available, e.g., by sunlight and its utilization via chlorophyl (green leaf). 

The chromatography of the principal food components is treated in various chapters triglycerides, fatty acids etc. in Chapter M sugars and derivatives in Chapter X amino acids and peptides in Chapter V and naturally occurring colouring materials and vitamins in Chapter K. 

---