Studies On The Degradation Of Testa Of Cocoa (Theobroma Cacao L .) By Aspergillus, Species Isolated From Mouldy Cocoa Beans

ABSTRACT Cocoa beans at the Toma Warehouses were found to be contaw minated with a tota l number o f 21 fungus sp ecies, the predominant species belonging to the genus A spergillus. The annual average contamination was 4,9 per centi Infection in the main crop was lower (3»9 per cent) than in the minor crop (6 ,4 per ce n t). The higher the bean moisture content the greater the fungal in fe ctio n . Extracts o f testa of fermenting cocoa beans depressed vegetative growth in Aspergillu s f la vus» A spergillus fumjgatus, A spergillus niger, Aspergillu s t amari i and Sclerotium r o lfs ii* iS, r o l f s i i was more inhibited than the AspergiTlua species* Extracts of testa o f beans already fermented and being dried had no e ffe c t on growth o f mycelium of the Aspergillus species but stimulated that o f S. r o l f s i i . A. fumjgatus grew best in Sabouraud's broth medium while A. tamarii grew best in Czapek Dox broth medium* Cotyledons and testa o f cocoa beans possessed phenolic compounds; free phenols, orthodihydric phenols, flavon ols and anthooyanins, The quantities of these compounds changed in d ifferen t ways during curing of the beansc Free phenols content in both cotyledons and testa decreased during fermentation and drying of the beans, Orthodihydric phenol levels in both cotyledons and testa , on the other hand, increased during fermentation and decreased during drying of the beans„ Flavonol content in the cotyledons increased during fermentation and decreased during drying, while it decreased in the testa during both fermentation and drying. The anthocyanin content o f the cotyledons decreased with curing but increased sig n ifica n tly in the testa . Some of the phenolic compounds inhibited germination of conidia and germ tube growth in A. fla v u s. li. fumigairus. and A« tamarii and germination o f scle ro tia o f _§» r o l f s i i to varying degrees. Others, however, stimulated germination,. The compounds in either case were not iden tified * Fungal contamination of cocoa beans was observed in unfermented fresh cocoa beans and in beans at various stages o f fermentation and dryingt Invsuling fungi occupied mainly the micropylar and stylar regions o f the beans, The composition o f the flora- changed as fermentation and drying of the beans progressed.