DEVELOPMENT OF TREATMENT POCEDURE FOR BREWERY SPENT YEAST SLURRY (Saccharomyces cerevisiae) AS CHEAP PROTEIN SOURCE FOR CATTLE NOURISHMENT

Abstract

Brewery spent yeast slurry is a nutritionally reach by product generating from brewing process and have the potential to use in animal nourishment as a cheap source of protein compare to commercial feed formulations with further treatments to reduce the bitterness character by reducing iso - alpha acid concentration and dissolved alcohol content. Different concentrations of alkaline - sodium hydroxide (NaOH) 0.1N, 1N, 2N, 3N, were used to treat the brewery spent yeast collected from Heineken Lanka Limited at room temperature (28 'C) with compare to fresh water as control to identify the effectiveness with the best removal of bitterness character (iso- alpha acid), best removal of alcohol with well-preserved yeast cell count. For analysis those parameters anton paar alcolizer method, spectrophotometer method and neucleo cell counter method were used respectively. It is evident that the bitterness character of brewery spent yeast must reduce to 2 BU for usage in edible purpose. According to the final data analysis better reduction of bitterness evident with alkaline treatment compare to the fresh water treatment and 2N concentration of sodium hydroxide (NaOH) was proved as the best treatment to reduce the bitterness of brewery spent yeast at the room temperature (28 'C). The resulted bitterness. alcohol and total cell counts were 0.32500 BU, 0.02000 v/v and 1.06 x 105 respectively. To preserve the treated spent yeast centrifugal drying method was used and powder recovering capacity was 49.7%. The sieve analysis proved majority of powder portion (80.40%) is 0.50 mm - 0.125 mm diameter range. Active dry yeast powder for crude protein analysis by semi-micro keldahal method as modified by Bremner, (1965) proved it contain 46.4 % crude protein which can cheaply use in cattle nourishment comparatively with commercially formulated feed.