Archivos Latinoamericanos de Nutrición (Sep 2004)
Caracterización nutricional de los carbohidratos y composición centesimal de raíces y tubérculos tropicales cocidos, cultivados en Costa Rica
Abstract
RESUMEN Las raíces y tubérculos tropicales (RTT) son alimentos básicos de la dieta de los pobladores de estas zonas; son producidos por pequeños y medianos agricultores y se les ha prestado poca atención. En el presente estudio se caracterizó nutricionalmente los carbohidratos y se determinó la composición centesimal de yuca (Manihot esculenta), tiquisque (Xantosoma sp ) y ñame (Dioscorea alata) cocidos. La composición proximal se determinó, en 20 muestras de cada producto, mediante la metodología del AOAC y se caracterizaron los carbohidratos (fibra dietética, almidón disponible, almidón resistente y tasa de amilólisis) por medio de métodos enzimáticos. Las tres RTT cocidas están compuestas fundamentalmente por agua y carbohidratos. Son fuentes moderadas de energía y fibra dietética, bajas en proteína y libres de grasa. Los contenidos de humedad, proteína, cenizas y fibra dietética difieren significativamente (p Nutritional characterization of carbohydrates and proximal composition of cooked tropical roots and tubers produced in Costa Rica. Tropical roots and tubers (TRT) are important staple foods in the tropics. TRT are produced by small farmers and have received only limited attention. The objective of this paper was to evaluate nutritionally important carbohydrate fractions and proximal composition of cooked cassava (Manihot esculenta), cocoyam -or tannia- (Xantosoma sp) and yam (Dioscorea alata) grown in Costa Rica. Twenty boiled samples of each TRT were analyzed for proximal composition, following AOAC protocols. Carbohydrate fractions (dietary fiber, available and resistant starch) and alpha -amylolysis rate were assessed by enzymatic methods. All TRT analyzed consisted mainly of water and carbohydrates, representing moderate dietary fiber and energy sources. They show a low protein level and contain no fat. Moisture, protein, ashes and dietary fiber contents vary significantly (p<0.01) among the three species. In terms of their proximal composition, these locally grown TRT differ from TRTs cultivated in the South Pacific area, but appear similar to other Latin American varieties. In all samples most of the dietary fiber (84-88%) is insoluble; available starch ranges between 74 and 84% of the dry matter, whereas resistant starch content varied between 0.7 and 1.7%. Amylolysis rate was similar for cassava and cocoyam, whereas a significantly slower digestion (p<0.01) was recorded for yam. Compared to values reported in the literature for other starchy foods and to gelatinized potato starch, used as reference sample, the studied TRT showed intermediate amylolysis rates. It is concluded that consumption of these TRT may be promoted in Costa Rica and other countries with a similar nutritional situation.
