IN-VITRO PROTEIN DIGESTIBILITY AND MINERAL AVAILABILITY OF GREEN BEANS (PHASEOLUS-VULGARIS L) AS INFLUENCED BY VARIETY AND POD SIZE

Three varieties of green beans (Cleo, Strike and Sentry) were harveste d and sorted into four fractions according to pod size (diameter <7 mm ; 7-8.5 mm; 8.6-10 mm and > 10 mm). Ash content and dietary fibre incr eased significantly as pod size increased mainly in Cleo and Strike be ans. Strike showed the highest fibre content (378.0 g kg(-1)) but the lowest carbohydrate (364.6 g kg(-1)) and ash (68.4 g kg(-1)) values. M ean values for Fe and ME content were higher in Cleo beans (70.9 and 2 7.1 mg kg(-1), respectively), Zn, Cu and Mg were higher in Strike bean s (48.7 mg kg(-1), 22.4 mg kg(-1) and 3.15 g kg(-1), respectively) whi le Na and Ca values were maximum in Sentry (459.1 mg kg(-1) and 7.11 g kg(-1), respectively), Trypsin inhibitor was negatively related to in vitro protein digestibility but no relationship was found between thi s last parameter and phytic acid content. This antinutrient, together with dietary fibre, and a negative influence on in vitro mineral dialy sability of green beans. (C) 1998 SCI.