Influence of moisture content, temperature and heating rate on germination rate of watermelon seeds

Abstract

Thermal treatments are widely used to control bacterial fruit blotch on watermelon seeds contaminated by pathogens. It is necessary for developing effective heat treatments for seed pasteurization, which will not adversely affect their germination properties. The purpose of this study was to determine the effect of moisture content, temperature and heating rate on the germination rate of watermelon seeds by using a special heating block system. The results showed that the heating rate during the come-up time had no significant effect (P > 0.05) on the germination rate of watermelon seeds, however, the holding time had a significant effect (P < 0.05). The germination rate of watermelon seeds heated at a fixed heating rate of 5 °C/min satisfied the national standard when the treatment temperature was below 75 °C. The curves for germination rate under different moisture contents and temperatures with holding time were fitted by Weibull model. The germination rate of watermelon seeds decreased with increasing temperature but increased with decreasing moisture content. An artificial neural network model was established under the fixed heating rate of 5 °C/min for predicting treatment conditions within the range of experiments. The mean square error and correlation coefficient for predicted and actual values on germination rate in this model were 0.013 and 0.950, respectively. Results of this study could be used to develop a rapid and effective watermelon seed treatment process based on watermelon seed germination and microbial / insect inactivation.