B-vitamin content of corn meal during natural lactic acid fermentation
Authors:   , Murdock Fred 
Published: December 2024

Cereal grains and food legumes provide 70 percent of the calories and protein for the people of Asia, Africa, and Latin America (Johnson et al., 1978). Corn is a main dietary staple of Latin America and Africa. In Africa essentially all of the corn grown is for food (Inglett, 1970a). In the United States, about 75 percent of the comproduced is for feed and about 20 percent is for export (Johnson et al., 1978). The production of corn is larger than that of any other crop in the United States. Corn is the major feed used in hog production in the United States. About 40 percent of the corn grain fed to livestock during the period 1965-1968 was fed to hogs (Moore and Dwoskin, 1970). A major portion of some human diets is corn. However, present day varieties of corn cannot qualify as a complete food source for humans or animals such as swine which are similar in nutritional requirements to man. The quality of the endosperm protein is low, and there are deficiencies of several vitamins and minerals (Mertz, 1970). In particular, pellegra is associated with corn staple diets (Dyke, 1965). Fortification, blending with legumes, and genetic experimentation, are among the methods that are used to improve corn and corn products nutritionally. Opaque-2-corn, a genetic variant with improved protein quality, is used to only a limited extent because its agronomic characters are inferior to those of normal corn (Johnson et al., 1978). Another method that is being explored for nutritional improvement is fermentation, either by pure cultures or by the natural flora. According to Frazier (1967), a wet mash of grains or of the meals undergoes a lactic acid fermentation, chiefly by the lactic acid bacteria and coliforms normally present on plant surfaces. Hesseltine (1979) reported that many traditional main course dishes of Mid-Asia, Africa, and the Mideast are produced by natural lactic acid fermentations of the grains, legumes, and milk, either singly or in various combinations. Hesseltine (1979) stated that many of these fermented foods, as compared to the nonfermented ingredients, had enhanced digestability, higher amounts of some vitamins, and longer shelf life due to the acid produced and the lowered pH. Concerning both traditional lactic acid fermented foods and fungal fermented foods, such as tempeh, Van Veen and Steinkraus (1970) stated that digestability was increased, but the nutritive quality of the protein was not increased by the process. The riboflavin content of these foods was generally increased or remained constant, but the contents of other vitamins were variable. Increases in riboflavin in these foods were significant because, according to Platt (1964), the lack of riboflavin is the most common vitamin deficiency among the people of the world. Hamad and Fields (1979) reported that a natural lactic acid fermentation of cereal grains improved the protein quality. Using the method of Tetrahymena pyriformis to determine the percent Relative Nutritive Value ( percent RNV) as the index of protein quality, Hamad and Fields (1979) found significant (P[less than]0.05) increases in barley, wheat, and rice. The improvements in percent RNV of corn and millet were significant (P[degrees]0.01). They also evaluated available lysine in these products and found a significant (P[less than]0.05) increase. Available lysine, and tryptophan, and percent RNV increased significantly (P[less than]0.05) in natural lactic acid fermented corn meal (Tongnual et al., 1981). Zamora and Fields (1979a) found similar increases in percent RNV and in limiting amino acids in fermented cowpeas and chickpeas. The conditions of fermentation found to increase percent RNV varied, but generally a 1:4 w/v mixture of meal and tapwater was incubated at temperatures between 25 [degrees] and 37 [degrees] C for four to six days. The amounts of riboflavin, niacin, and thiamin in these fermented products were also evaluated after four or five days of fermentation. Riboflavin usually increased or remained constant, while niacin and thiamin usually decreased or remained constant. Tongnual et al. (1981) evaluated the changes in percent RNV during a seven day natural lactic acid fermentation of corn meal and found that the percent RNV increased most during the first 48 hr of fermentation and continued to increase until the fourth day but was unchanged afterward. Lopez (1982) also found that the greatest decrease in phytate occurred during the early stages of the fermentation. Similarly, it was the purpose of this research to evaluate the effect of natural lactic acid fermentation of corn on vitamins of the B-complex. Thiamin, niacin, riboflavin, folacin, vitamin B12, pantothenic acid, pyridoxine, biotin, and choline contents of whole nonfermented corn meal and samples fermented either one, two, three, or four days were assayed in order to determine the time of fermentation required to give maximum levels of all of these vitamins.