Influence of kernel damage on corn nutrient composition, dry matter losses, and processability during alkaline cooking
1998
Almeida-Dominguez, H.D. | Ordonez-Duran, G.G. | Almeida, N.G.
The nutrient losses of corn containing 0-30% damaged kernels that occurred durin g alkaline cooking into tortillas were examined. Samples from different stages d uring processing were tested for chemical composition and protein fractionation. The most prevalent type of kernel damage was mechanical, followed in decreasing order by molds, insects, heat, and rodent damage. Corn with higher content of d amaged kernels was susceptible to overcooking, resulting in cracked or fully ope n nixtamal kernels and sticky masa that were difficult to handle during processi ng. Nutrient losses increased with increasing levels of kernel damage. Most nutr ient losses from sound corn kernels occurred during washing as the pericarp and attached solids were removed. During simmering, damaged corn kernels were fully cooked into physically opened kernels with more nutrients being extracted into t he water. About 15% of total solids and 50% of both crude fiber and fat were los t during cooking of corn with 30% kernel damage. The greatest losses were consis tently observed for albumins and globulins from both sound and damaged kernels a t all stages of cooking. Appropriate control of kernel damage level is required to improve yield of product with consistent quality. The susceptibility to overc ooking of excessively damaged corn increases the complexity to consistently meet product quality specifications. Excess dry matter losses in the cooking liquor can significantly increase the risk of environmental contamination and cost of s ewage water treatment.
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