Publisher Summary This chapter discusses four species of grain legumes of the lowland tropics—that is, peanuts, pigeon peas, cowpeas, and mung beans. Various aspects of these species, such as plant improvement, plant protection, growth processes, and management are described. These four species made up 87% of both the cultivated area and total production on a worldwide basis. Some botanical and adaptive characters of tropical lowland grain legumes are summarized to facilitate direct comparisons of their potential for specific situations. Although species are grouped according to their presumed ecological use patterns, considerable overlap occurs in adaptation and in microclimates of particular locales within regions. The chapter describes various comparative features of tropical species, such as (1) plant types, (2) soil and climate preference, (3) susceptibility to pests and diseases, and (4) yielding ability. To emphasize the positive aspects of growing tropical legumes, a broad array of uses for these crops and their beneficial effects on soil and crops are summarized.

Grain legumes of the lowland tropics

Groundnuts were originally considered to be food for animals; then they were used as food for slaves. They have now become an important source of protein in many developing countries. A summary of the important food uses of groundnuts and the fortified foods that use groundnuts or groundnut protein has been given by Singh and Singh (1991).

The composition and nutritive value of groundnut kernels

The effect of an early-, mid-, or late-season planting date on the fatty acid chemistry of four high oleic acid, one mid oleic acid, and five normal oleic acid peanut (Arachis hypogaea L.) genotypes was evaluated over a three year period. Oleic acid was also compared to other fatty acids and to indices of oil quality. High-oleic genotypes included SunOleic 97R, UF98326, UF99621, and 88x1B-OLBC1-6-1-3-1-b2-B with a mean oleic acid content between 77.8 and 82.5%. Florida MDR98, a mid-oleic cultivar, was intermediate in oleic acid chemistry (59.8-68.0%). The normal oil chemistry lines (Georgia Greene, Andru93, Florunner, 86x13A-4-2-3-2-b3-B, and UF97102) had an oleic acid content between 50.0 and 59.0%. The ratio of oleic to linoleic (O/L) was 18:1 to 51:1 for high-oleic lines and 1.7:1 to 3.5:1 for normal genotypes. When analyzed as a split-split plot in time, year had a highly significant effect (P < 0.001) on the eight main fatty acids, iodine value, ratio of unsaturated to saturated fatty acids (U/S), and percentage of saturated fatty acids. Thus, data were analyzed separately by year. Although genotypic effects were highly significant each year, planting date influenced oil chemistry in two of three years. During both 1999 and 2000, 11 of 12 variables were influenced by planting date and by genotype x planting date interactions. Iodine values were approximately 75 for high-oleic lines compared to 90-95 for normal genotypes. The highest correlations occurred for oleic acid (18:1) and linoleic acid (18:2) (r = -0.996) and for oleic and palmitic (16:0) acids (r = -0.959). Oleic acid was also inversely related to iodine value (r = -0.978) and to percentage saturation (r = -0.841).

Influence of year and planting date on fatty acid chemistry of high oleic acid and normal peanut genotypes.

Effect of drought on oil, fatty acids and protein contents of groundnut (Arachis hypogaea L.) seeds

Summary
The effects of temperature and moisture content on fat oxidation (peroxide value) during storage of commercial unblanched salted roasted peanuts were investigated by storing 1.4 ±0.02% moisture samples at 15°C, 25°C, 35°C and 1.4 ± 0.02%, 2.2 ± 0.04%, 2.86 ± 0.03%, 3.9 ± 0.06% moisture samples at 35°C. Oxidation took place even at low temperatures and the rate of oxidation was especially accelerated at high temperatures. the Q10 value for peroxidation was calculated as 1.60 from the shelf-life plot (r= 0.821).

The accelerated shelf life test at various moisture contents showed rate of peroxide formation is decreasing near or above BET monolayer value, 2.13%, calculated from the BET equation (r= 0.997) and then increasing with further increase in moisture content. In order to prevent the loss of desirable crispness of the product BET monolayer value is proved to be the most suitable for extending shelf life.

The effects of temperature and moisture content on lipid peroxidation during storage of unblanched salted roasted peanuts: shelf life studies for unblanched salted roasted peanuts

Eight varieties of peanuts were grown under measured field conditions. Seed obtained at five successive harvest dates and separated into three maturity levels were analyzed for fatty acid composition of oil. Mature peanuts were mostly higher in stearic (18:0) and oleic (18:1) acids, and lower in linoleic (18:2), arachidic (20:0) and behenic (22:0) acids. Oleic-linoleic ratios, which are correlated with oil stability, were higher in mature peanuts.

Effect of maturity on the fatty acid composition of eight varieties of peanuts grown at perkins, Oklahoma in 1968

An improved method for the extraction of free amino acids and a peptide of unknown composition with a methanol:chloroform:water mixture (60:25:15; v:v:v) was described. The largest variations were related to maturity. If the amino acids were ranked in descending order, glutamic acid, followed by asparagine (including asparagine, glutamine, threonine, and serine), topped the list in the mature and low intermediate groups, except in Valencia at 141 days. The peptide and phenylalanine were usually in the top six, while aspartic acid occurred there fairly often. Arginine was the highest in immature peanuts. Proline was found in higher concentrations in immature peanuts than previously reported. The presence of two nonprotein amino acids (γ-methyleneglutamine and γ-methyleneglutamic acid) in mature kernels was confirmed.

M. E. Mason

Papers

Effect of maturity on the fatty acid composition of eight varieties of peanuts grown at perkins, Oklahoma in 1968

Effect of harvest date and maturity upon free amino acid levels in three varieties of peanuts