Study On Post-harvest Peel Browning Inhibition Technique And Mechanism Of Huangguan Pear

Huangguan pear is bred by our county, which ripes early and is popular in consumer, butrapid postharvest browning appearing in fruit peel during maturation and early postharveststorage time, and with the extension of the storage time, the quality of the pear is reduced,those affect the pear commodity value seriously. In this paper, slow-cooling plus1-MCP,glutathione, methyl jasmonic acid, citric acid and ethylenetreatments were studied on itsimpact of inhibiting peel browning and improving fruit quality, this paper also explored thepeel browning mechanism, aimed to not only find an simple and effective method whichcould be effectively on controlling peel browning and keeping the fruit quality, but alsoprovide theory basis on controlling peel browning. The results showed that:(1) Compared to slow-cooling alone and rapied cooling treatment, Slow-cooling plus1-MCP treatments decreased the occurrence of the peel and core browning of Huangguan pearsignificantly, inhibited the reducing of the VC content and kept better subjective evaluation;Compared to rapied cooling treatment, they were better on inhibiting flesh browning during,the decreasing of titratable acid and the increasing of malondialdehyde and ethanol content.Comprehensive evaluation, we selected11~12°C, decreasing1°C/d plus1-MCP for the bestproductive treatment.(2) Glutathione and methyl jasmonate treatments inhibited the peel browning ofpostharvest Huangguan pear effectivly, kept good appearance, taste and higher shelf life’s VCcontent, but it had no significant effect on hardness and soluble solids content. Glutathionetreatment could effectively restrain the browning of flesh and core and the increasing ofmalondialdehyde and ethanol content caused by rapid cooling, but compared with8~9°C,dreasing2°C/d, its browning degree of flesh and core during shelf life increased slightly;Methyl jasmonate treatment had higher flesh, core browning and malondialdehyde, ethanolcontent, and stalk dryness increased also.(3) Citric acid treatment could effectively inhibit the peel browning of postharvestHuangguan pear and the decrease of VC content during shelf life, it was also effectively oninhibiting the core browning and the increasing content of MDA and ethanol caused by rapidcooling. But compared with8~9°C, dreasing2°C/d, the pulp and core browning and thecontent of malondialdehyde and ethanol were increased. Citric acid treatment had nosignificant effect on fruit firmness and soluble solids, and it could not slow down the decrease of the titratable acidity and soluble sugar content did effectively, the fruit flavor was also poor.(4) The experiments showed that the peel browning of postharvest Huangguan pear had arelation to the activity of PPO, POD, SOD and the content of phenolic compounds of peel, butthe mechanisms for inhibiting the peel browning were different in these treadments. Ethylene,glutathione and methyl jasmonate treatments controlled the peel browning of postharvestHuangguan pear effectively, the electric conductivity of the treated peel and the respiratoryrate of the treated fruits were lower than control. In the treadments of ethylene and glutathione,the PPO and POD activities were lower than control, while the PPO and POD (except in the12th days of storage time) activities of methyl jasmonate treadment were higher than control;the total phenolic content of ethylene treatment was lower than one day at room temperaturetreatment and control, while the glutathione and methyl jasmonate treatments’ was higher thanwater treatment and control; the SOD activity of ethylene treatment was higher than control,while the glutathione treatment’ was lower than control.