Nutritional evaluation of sorghum as affected by germination with main reference to dietary bulk and protein quality
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Date
1984
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Publisher
Sokoine University of Agriculture
Abstract
The nutritional value of sorghum as affected by germination and
different dehulling techniques was studied with emphasis on protein
quality, dietary bulk and food intake.
Two low-tannin and two high-tannin
varieties were investigated.
Nutrient content was affected by germination:
minor changes
occurred in proximate composition, except for a significant decrease in oil
in all varieties.
Thiamine, riboflavin and niacin content increased.
Lysine increased in all varieties and the other essential amino acids inĀ
creased marginally.
Dietary fibre was unaffected. Tannin content decreased
significantly.
Traditional and abrasive dehulling decreased the amount of protein,
oil, dietary fibre, minerals, tannins and phytic-phosphorous.
protein digestibility was
Nutrient availability measured in vitro:
significantly higher in the low-tannin varieties.
Germination and dehulling increased digestibility in all varieties.
Cooking reduced protein
digestibility in the high-tannin varieties and significantly more than in
the low-tannin cultivars.
Iron availability was low in all varieties and
increased only in one high-tannin variety after germination.
Nutrient availability measured in vivo by rat-bio-assay:
protein
digestibility was high in low-tannin cultivars but low in high-tannin
varieties.
Germination increased digestibility only in one high-tannin variety.
Biological values were higher in the high-tannin varieties.
BV and NPU were not affected by germination.
In vivo iron availability was
higher in the low-tannin varieties and was increased by germination in only
one of the high-tannin varieties. Zinc availability was low and was unaffected by germination and
tannin content.
Dietary bulk and food intake:
When preparing weaning gruels, three
times as much germinated flour of the low-tannin varieties, as compared to
ungerminated, could be mixed into the same volume, while maintaining the
same consistency of the gruel.
Germinated flour of high-tannin varieties did not have this effect.
Addition of 5% germinated low-tannin sorghum
flour (enzyme-rich) to thick ungerminated gruels reduced the viscosity to
acceptable weaning food consistency.
This method of reducing dietary bulk
of weaning food was accepted and used by mothers at village level.
Food
intake by 12-48 months old preschool children was significantly higher for
bulk-reduced low viscosity gruel with 20% solids, compared to untreated
gruel.
It was concluded that sorghum nutrient content is comparable to
other cereals except for the high tannin content.
Germination generally
improves nutritional value through increased lysine, better protein
digestibility and reduction of anti nutritional factors, mainly tannins.
The use of bulk-reduced high nutrient density weaning foods could eventually improve the nutritional status of young children.
Description
Thesis
Keywords
Sorghum-germination, Milling, Nutrient content and availability, Dietary bulk, Weaning food intake