CARBOHYDRATES IN MALTING AND BREWING VI. CHANGES IN THE CARBOHYDRATE COMPOSITION OF BARLEY ON RIPENING AND CORRESPONDING VARIATIONS IN NITROGENOUS CONSTITUENTS

Open Access
Publisher Website
Google Scholar
Abstract
Examination of the carbohydrates of Carlsberg and Spratt-Archer barleys from the time of ear emergence to the period of full maturity of the grain revealed very similar patterns of behaviour during ripening. Thus, increases in the amounts of glucose and fructose present in individual corns just after ear-formation preceded large temporary rises in the quantities of sucrose and fructosans. On the other hand, raffinose was not observed In the grain until the bulk of the synthesis of other carbohydrates was complete. The amounts of sucrose and fructosans later diminished as starch was synthesized, although the two processes were not necessarily interdependent. It is particularly noteworthy that, during the early phases of starch formation, the ratio of amylose to amylopectin in the total starch was lower than in the mature grain. The major part of the starch was synthesized during a period of 4–6 weeks after ear emergence. Among other changes, the total nitrogen content increased steadily over the 7 weeks after ear emergence, after which protein synthesis ceased. Simpler nitrogen compounds, soluble in aqueous ethanol, reached a maximum value after 5–6 weeks while the amino acids attained a transient peak value after 2–4 weeks, thereafter declining as more complex materials were synthesized.