Pengaruh Penambahan Asam Sitrat Terhadap Proses Non-Enzimatik Browning Jus Buah Pir Yali (Pyrus bretschneideri Rehd.)

The purpose of this study was to find out how effective citric acid is against the nonenzymaticprocess of browning Yali Pear fruit juice (Pyrus bretschneideri Rehd. Theresearch was conducted in a complete randomized design consisting of 5 replications. Thenon-enzymatic browning inhibition process was tested with citric acid treatment as the mainfactor with five concentrations ie 0% w/v, 2,5% w/v, 5% w/v, 7,5% w/v and 10% w/v.Qualitative parameters were dehydrogenase enzyme activity and reducing sugar level.Quantitative parameters were browning index and total soluble carbohydrate content.Levene test, analysis of variance, and Tukey test were performed at 5% significant level. Theresults showed that decrease in dehydrogenase enzyme activity occurs along with increasingthe concentration of citric acid. The level of reducing sugar has increased along with theincrease of citric acid concentration. The 7,5% w/v citric acid concentration effectivelyinhibited non-enzymatic browning of Yali Pear juice with a 21% reduction in the browningindex. Total soluble carbohydrate content increased 7% at 7.5% w/v citric acidconcentration. From the results of the study it was concluded that citric acid at 7,5% w / vconcentration was the inhibitor of non-enzymatic browning and dehydrogenase enzymeactivity, but stimulator of total soluble carbohydrate and reducing sugar level.

Effects of 1-MCP Treatment on the Ethylene Synthesis of Postharvest Yali Pear Seeds

The effects of 1-MCP treatment on the ethylene synthesis of Yali pear seeds of different harvest maturity were evaluated during storage. Yali pear fruit (early harvested and late harvested) were treated with 1.0 μL.L-11-MCP for 20 h at room temperature, packaged in PE plastic film and then stored at 0±1°C for 180 days. The results show that the respiration, ethylene production, ACC content, ACO and ACS activities of the seeds of early harvested Yali pear fruit with 1-MCP treatment decrease significantly during storage, the peaks decrease and are delayed for 60 days. But 1-MCP treatment has no significant effects on the indexes related with ethylene synthesis to the seeds of late harvested fruit. 1-MCP can be used to inhibit the synthesis of ethylene in the seeds effectively and keep the quality and extend the shelf life of early harvested Yali pear fruit.