Effect of drying, freezing and storage of dried and frozen onion (Allium cepa L.) on its pungency

The paper contains results of studies of drying and freezing effects, as well as storage of dried and frozen onion on its pungency. The effect of onion bulbs preparation on pungency was estimated as well. The pungency measurements were based on determination of pyruvate produced enzymatically by alliinase. Storage at 20°C of skinned onion decreases sligthly pungency, however three weeks storage at 0-2°C did not change it. Other results indicate that freezing at -25°C, and followed thawing led to large losses - reaching 75% of pungency found in the onion taken to the process. Storage of the frozen onion caused further decrease its pungency. Decrease of pungency during drying was depended on temperature of the process. Low drying temperature (40 and 50°C, 20 hours) caused only 15-20% decline of pungency. Higher temperature drying (60°C) resulted in 50% losses of onion pungency.