ADVANCEMENTS IN UNDERSTANDING AND MANIPULATING ALLIUM FLAVOR: CALCIUM AND CHLORIDE

Sulfur metabolism and accumulation in Allium directly affect consumer preference and consumption by modifying their flavor attributes. When growing onions, we have frequently observed that flavor intensity can not be fully predicted from the sulfur level indigenous to the production area. Drawing off of empirical observations and analyses, calcium and chloride levels were possibly associated with lower than expected flavor intensity. The positive effects of calcium are well known to onion. However, it is not widely known that onions require high levels of chloride. Further, the two ion’s effects on sulfur metabolism in plants are loosely understood. Studies were conducted in the field and in greenhouse experiments which tested the effects of calcium chloride on onion growth and sulfur uptake and metabolism. Calcium chloride was found to decrease sulfur accumulation in the bulb, lower bulb pungency, and affect the cysteine sulfoxide flavor precursors. Additionally, calcium chloride improved post-harvest shelf life and bulb weight. Results indicate calcium chloride may be a new and exciting tool to assist growers of mild onions in mitigating high sulfur environments.