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.
