Comparison of the Effect of Mint Extract and Chlorpropham on Preventing Potato Sprouting in the Storage

  Sprouting is one of the main reasons of wasting about one half of potatoes during the storage. The existing methods to control sprouting in long term storage (for example postharvest applications of chlorpropham) can do the job as well, but the incidence of quality problems and undesirable side effects in such potatoes, and more importantly, the growing interest in organic food products, have challenged the application of these methods. The peppermint extracts used in the experiment were obtained from dried peppermint leaves in 48 hours, at room temperature using 1:1 distilled water-alcohol solution, and with the normal air pressure. The peppermint extracts were dried for 10 days and then transferred to a dark glass bottle by means of petroleum ether (as solvent) and were kept at 2°C until being used for later use. Herbal extracts of peppermint were used at concentrations of 0, 0.5, 1, 2 and 4 g/l, with regular intervals of 2, 4 or 6 weeks during the 5 months of potato (Agria cultivar) storage while sprouting was monitored. Direct contact between tubers and the peppermint extracts was not allowed. To provide the needed oxygen for the tubers respiration, the containers apertures were opened for 15-20 minutes every four weeks and were sealed again. A group of tubers was only treated by 37g chlorpropham (5% purity). To do this, the powder was poured into the container, completely sealed and slowly shaken for 10 minutes. The sealed container was kept at room temperature for 48 hours. All experiments were repeated 3 times. Data was analyzed by a completely randomized design (CRD) with a factorial experiment. According to the results, by increasing the concentration of mint from 0.5 to 2 g/l, sprouting potato was controlled more effectively and meaningfully. More concentration in the control of potato sprouting was not significant. Use of this extract at a concentration of 0.5 g/l stimulates the germination of tubers compared to the control. Extensive sprouting of tubers was delayed for up to 4 months compared to the control treatment too. Application of peppermint extract caused %92 and %96 decrease in potato germination and total weight sprouting respectively. Organoleptic evaluation of the boiled and fried potato samples, treated with the mint extract and chlorpropham, did not show significant differences. Use of 2 g/l mint extract will be able to decrease waste potato tubers in storage up to 6 percent. Replication of every 4 weeks extracts application is absolutely essential for the best result. Organoleptic evaluation of the boiled and fried potato samples, treated with the mint extract and chlorpropham, received more points compared to contro