Effect of nixtamalization (Alkaline cooking) on fumonisin-contaminated corn for production of masa and tortillas.

Studies were undertaken to determine the fate of the mycotoxins, fumonisins, during the process of alkaline cooking (nixtamalization), using normal-appearing corn that was naturally contaminated with fumonisin B(1) (FB(1)) at 8.79 ppm. Corn was processed into tortillas, starting with raw corn that was cooked with lime and allowed to steep overnight; the steeped corn (nixtamal) was washed and ground into masa, which was used to make tortillas. Calculations to determine how much of the original fumonisin remained in the finished products took into consideration that FB(1) will be converted to hydrolyzed fumonisin B(1) (HFB(1)) by the process of alkaline cooking. All fractions, including steeping and washing water, were weighed, and percent moisture and fumonisin content were determined. Tortillas contained approximately 0.50 ppm of FB(1), plus 0.36 ppm of HFB(1), which represented 18.5% of the initial FB(1) concentration. Three-fourths of the original amount of fumonisin was present in the liquid fractions, primarily as HFB(1). Nixtamalization significantly reduced the amount of fumonisin in maize.

[Properties of white sorghum diastatic malt]. / Propiedades de malta diastásica de sorgo blanco.

Diastatic malt enzymes have potential to hydrolize pregelatinized starches releasing soluble sugars, lowering viscosity of slurries and allowing the use of high nutrient densities for preparation of cereal-based creams, baby food and drinks. Determination of the extent in which sorghum malt is able to develop desirable functional properties such as viscoty, water solubility and nutritional quality is fundamental. In this work the characteristics of a white sorghum during germination and the resulting malt were evaluated. "Dorado" white sorghum was germinated at 28 degrees C and 95% RH during 6 days in complete darkness, dried at 55 degrees C and ground to produce diastatic malt flour. Physicochemical, chemical, diastatic and nutritional characteristics of malt and its ability to liquify precooked flour slurries were determined. Maximum diastatic activity occurred at 3-4 days germination. Dry matter loss increased during germination at a rate of 2.7 percent units per day. Longer germination resulted in increased dry matter loss and decreased diastatic activity. Water solubility index of sorghum increased linearly during the first 5 days of germination probably caused by the production of soluble sugars and free amino acids. In vitro protein digestibility, lysine content and C-PER increased during germination. Sorghum malt was able to liquify precooked rice, wheat, oats or millet pastes (20% solids) in 5 min mixing at 30 degrees C. Utilization of malts with maximum diastatic activity are useful to liquify precooked cereal pastes or drinks and to increase the total solid contents and nutrient density while keeping the liquid properties of the product.(ABSTRACT TRUNCATED AT 250 WORDS)

The tortilla making properties of two improved maicillo cultivars from Honduras.

Grains of two improved maicillo hybrids (Sorghum bicolor (L) Moench) and their criollo (Landrace) counterparts grown at two farmsites in Honduras were lime-cooked and processed into table tortillas. Kernels from the criollos were less dense and softer than kernels from the improved cultivars. The improved maicillos had straw or red plant and glume colors while the criollos were less dense and softer than kernels from the improved cultivars. The improved maicillos had straw or red plant and glume colors while the criollos had purple colored plants with black or purple glumes. The soft textured criollo kernels required less cooking than their harder improved counterparts. Nixtamals cooked to contain 53-55% moisture were the most suitable for processing into tortillas. Both improved maicillos compared favorably with Sureño (used as positive control during processing). The criollos produced darker, less acceptable tortillas. Masa and tortillas from criollos darkened during lime-cooking especially during baking. All sorghums and their respective tortillas had similar chemical composition. The improved maicillos bred in Honduras have a significantly improved plant and glume color with white pericarp. The sorghum improvement was also observed in the overall tortilla quality.

The tortilla making properties of two improved maicillo cultivars from Honduras

Grains of two improved maicillo hybrids (Sorghum bicolor (L) Moench) and their criollo (Landrace) counterparts grown at two farmsites in Honduras were lime-cooked and processed into table tortillas. Kernels from the criollos were less dense and softer than kernels from the improved cultivars. The improved maicillos had straw or red plant and glume colors while the criollos were less dense and softer than kernels from the improved cultivars. The improved maicillos had straw or red plant and glume colors while the criollos had purple colored plants with black or purple glumes. The soft textured criollo kernels required less cooking than their harder improved counterparts. Nixtamals cooked to contain 53-55 moisture were the most suitable for processing into tortillas. Both improved maicillos compared favorably with Sureño (used as positive control during processing). The criollos produced darker, less acceptable tortillas. Masa and tortillas from criollos darkened during lime-cooking especially during baking. All sorghums and their respective tortillas had similar chemical composition. The improved maicillos bred in Honduras have a significantly improved plant and glume color with white pericarp. The sorghum improvement was also observed in the overall tortilla quality.

Microbiological Characteristics and Shelf Life of Corn Tortillas with and without Antimicrobial Agents.

Commercial corn tortillas were assayed for pH, moisture, aw, aerobic plate count (APC) and mold and yeast count (MYC). The shelf life of commercial tortillas ranged from 3 to 60 days, depending on the amount and type of preservative added. High initial APCs of commercial tortillas were associated with poor sanitary conditions at the plants, airborne contamination and improper storage practices. Shelf life of tortillas was greatly enhanced by refrigerated storage with or without the use of antimicrobials. For tortillas stored at 25°C, substantial increases in shelf life were attained by acidification (0.45% fumaric acid) plus addition of K-sorbate or Ca-propionate, but particularly by combination of these two antimicrobials. For tortillas stored at 4°C, shelf life of non-acidified samples was somewhat enhanced by addition of parabens and combinations of K-sorbate and Ca-propionate. Shelf life of acidified tortillas at 4°C was somewhat enhanced by addition of parabens and K-sorbate but increased substantially by addition of Ca-propionate and combinations of K-sorbate and Ca-propionate.

Factors affecting starch digestibility with special emphasis on sorghum and corn.

Starch exists inside the endosperm of cereals enmeshed in a protein matrix, which is particularly strong in sorghum and corn. Starch digestibility is affected by the plant species, the extent of starch-protein interaction, the physical form of the granule, inhibitors such as tannins, and the type of starch. Among the cereals, sorghum generally has the lowest starch digestibility. The resistance to digestive action of the hard peripheral endosperm layer is largely responsible for this effect. Processing methods such as steam-flaking and reconstitution are effective in raising sorghum digestibility to near that of corn. Waxy sorghum shows consistently higher feeding value than normal sorghum. Both the starch granules and the protein matrix around them are more digestible in waxy grain. The development of new heterowaxy or waxy sorghum hybrids may further increase sorghum feed efficiency.