Heterosis and Heritability of Chemical Quality of Butter Derived from Some Cocoa (Theobroma Cacao L.) Clones

Abstract

Butter from dry cocoa beans of five cocoa (Theobroma cacao L.) clones and their intercrossed hybrids were analyzed for chemical quality (acid, peroxide and iodine) in order to gain insight on the heterosis and broad-sense heritability values for these traits. Standard procedures were used for estimation of the lipid content and the indices. Hybrid F20 had the highest lipid content (59.7%) while the parent SCA12 and hybrid F12 had the lowest with 44.5 and 45% respectively. The acid index varied between 19.4 and 28.8 mg KOH/g, iodine index from 10.2 to 30.5 g/100g and peroxide index from 0.3 to 7.3 meq.g O2/kg. The acid index was higher than recommended limits for edible oils, iodine index lower and peroxide index within the international norms for conventional oils. Hybrids F12, F40 and F79 presented a positive mid-parent heterosis for acid index while F14, F13, F20 and F79 showed it for peroxide index. With regards to best-parent heterosis, only F40, F13 and F79 for acid index and F14 and F13 for peroxide index showed positive heterosis effect. For iodine index, about 71 % of hybrids showed a positive mid-parent heterosis. The acid and peroxide indices showed high heritability (while the iodine index had moderate heritability) estimates and this heritability could be said to be cytoplasmic except for the reciprocal hybrids F13 and F79 (acid index). The Principal component analysis categorized two distinct groups of six individuals each. Quality characteristics were moderate for butter obtained from the first cluster and lower for the second one. When all these quality parameters are taken into account, F79 and its reciprocal hybrid F13 showed the highest hybrid vigour. Their parents can be therefore considered as the best combination for producing hybrids with high nutritional oil quality vigour.