It is stated that barley used in beer production contains approximately 60-65% starch, almost all of this starch is fermented into alcohol and carbon dioxide during beer production, and other nutrients and minerals remain in the pulp, condensing three times more.
Allen and Stewenson report that since almost all of the soluble or fermentable carbohydrates are removed during beer production, most of the remaining carbohydrates consist of raw cellulose, 25% of the raw cellulose in barley pulp is converted into simple sugars, and the water-soluble carbohydrate content remains around 6.92% - 8.95% in dry matter. Smith states that this amount of soluble carbohydrate is sufficient to obtain good, high-quality silage.
It is stated that barley pulp contains around 28% crude protein and 23% digestible protein in its dry matter, and this amount is equal to much more corn gluten than wheat bran. It is stated that barley pulp is a source of selenium. It is reported that the calcium and phosphorus content of barley pulp is three times that of the barley used in beer production.
The nutrients and energy content of fresh barley pulp are shown in Table 1.
H. PROTEIN (%).................................................: 27.84
H. FAT (%)............................................................: 9.92
STARCH (%)........................................................: 6.96
M. ENERGY (Kcal/kg).......................................: 2310.54
CELLULOSE (%).................................................: 30.21
ASH (%)...............................................................: 4.27
MOISTURE (%)...................................................: 74.45
NITROGEN-FREE EXTRACT MATTER (%).: 6.21
NOTE: M. ENERGY IS CALCULATED ON DRY MATTER.
If the process of reducing the water content of barley pulp is done by heating, the digestibility of proteins and carbohydrates is negatively affected. Removing water from the pulp by mechanical processes causes the loss of water-soluble nutrients.