Styro-cooler Fermentation

Styrofoam coolers of dimensions 27 cm (L) x 26 cm (W) x 17 cm (D) or 44 cm (L) x 28 cm(W) x 29 cm (D) respectively are a convenient way to ferment small (between 15 – 30 kg) bean quantities from the same variety or a defined mixture of varieties. 

Styrofoam coolers are relatively cheap and easily available in most countries. Six to eight holes evenly spaced at 4 cm and of diameter 1.5 cm are made on the underside to facilitate the drainage and aeration of the fermenting mass. 

It is recommended that the coolers (regardless of size) are placed off the ground (on small blocks of wood) to allow for optimal drainage and aeration.

New coolers can be inoculated artificially with a defined micro-floral matrix at particular time intervals, scrapings from a used fermentation box (preferred) or left to be naturally inoculated by fruit flies. 

Inoculation from a used fermentation box is achieved by taking scrapings from the inside top and bottom surfaces and mixing in double the volume of water (distilled water is best) to create a paste. 

This paste is thoroughly mixed into the wet beans when they are filled into the cooler at the start of fermentation to evenly distribute the inoculum from the used fermentation box throughout the fresh wet bean matrix. 

This is then covered with banana leaves and the matching Styrofoam lid to retain the heat given off during fermentation. 

The beans are generally turned by mixing well after 48 hours and 96 hours and the optimal end point is determined by visual inspection.