Studies on Respiration Rate of Small Onions at Different Temperature Conditions

Small onions (Allium cepa aggregatum) is one of the world's oldest cultivated vegetable. These onions are stored for longer periods till demand in domestic and export markets increases. To suggest the best storage practice the crop's respiration rate needs to be found. Closed system type experimentation was conducted for CO-3 variety of small onions to predict the change in concentration of gases inside the bottles during storage. The change in concentration of gas is found to follow the exponential decay function for O₂ consumption and exponential growth function for CO₂ evolution. The predictive modelling is done using the software Origin Pro V 8.0724. The respiration rate of O₂ are 0.052±0.03, 0.196±0.07, 0.416±0.03, 4.862±0.31 and 5.691±0.41 ml kg⁻¹ h⁻¹ at 0, 10, 20, 30 and 40ºC respectively. The respiration rate of CO₂ are 0.042±0.38, 0.165±0.05, 0.3814±0.07, 4.759±0.24, 5.62±0.47 ml kg⁻¹ h⁻¹ at 0, 10, 20, 30 and 40ºC, respectively. The respiration quotient of the CO-3 small onions ranges between 0.81 ± 0.06 to 0.99 ± 0.12 and it increases with increase in temperature. A simple program was developed for calculating the respiration rate by SAS 9.1.3 which will calculate the respiration rate in fraction of seconds.