Studies On Juicy Sac Granulation During Postharvest Storage Of Guanxi Pomelo And Techniques Of The Freshness Preservation Of Peeled Pomelo Sections

Produced in pinghe County, Zhangzhou city, Fujian province of Guanxi pomelo, gains high popularity from consumers because of its good flavor and quality. There are some adverse changes in Guanxi pomelo during postharvest storage, such as water loss greatly, juicy sac granulation seriously and bitterness accumulation, which is greatly affect the quality. This paper started with the mechanism of juicy sac granulation of Guanxi pomelo during postharvest storage, studied on the effects of vacuum pre-cooling treatment and ozone treatment on the quality of Guanxi pomelo.The results were as follows:1. The Preliminary theory research on mechanism of juicy sac granulation of post-harvest Guanxi pomeloAt room temperature, by observing changes of moisture and other physical- chemical indices of shaddock, explored the mechanism of juicy sac granulation during postharvest. The results showed that during postharvest storage, some of moisture transferred from the flesh to fruit peel, and the peel turned thickened. The time of peroxidas (POD) activity peak appeared after the juicy sac granulation, from then on, the progress of pulp granulation speeded up, and this conclusion was different from previous researchers. Our researches considered that POD activity peak was not the sign of juicy sac granulation, but it could promote this progress, and the reason of pulp granulation during postharvest storage is maybe moisture transferring and peel's re-growthing.2. Effects of vacuum pre-cooling treatment on storage quality of Guanxi pomelo sectionsThe effects of different vacuum pre-cooling temperature treatment on juicy sac granulation and storage quality of Guanxi pomelo sections was investigated by comparison the quality of blank sample. The results showed that the progress of juicy sac granulation was slow down and the quality was better by vacuum pre-cooling treatment. The researches indicated that vacuum pre-cooling treatment could effectively maintain the quality of Guanxi pomelo sections.3. Effects of ozone treatment on storage quality of peeled pomelo sectionsOzone strong oxidizing can effectively decomposing the ethylene produced by peeled pomelo sections during storage, thus achieved the purpose of delaying after-ripening and extending the storage period. By choosing different ozone processing time for pomelo, separately inspected the influence of storage quality. The results showed that the physico-chemical indexes of treated 10min group such as moisture content, total sugar, soluble solids content and cellulose content superior to that of the control, and the POD activity peak appeared latest by treating 10min with ozone. Through the research, we could find that the process of juicy sac granulation was delayed and the original quality of pomelo was well kept by treating with ozone.4. Optimization of vacuum pre-cooling treatment combined with ozone treatmentSelecting vacuum pre-cooling treatment terminal temperature, ozone processing time and ozone processing frequency for the test taker factors, researching the effect of vacuum pre-cooling treatment combined with ozone treatment on preservation of peeled pomelo sections with L9(34) orthogonal test. Conclusions are as follows: the relatively optimal combination was 5℃pre-cooling treatment terminal temperature, 10min ozone processing time and every 10d processing again. In such conditions, moisture content, total acid content, Vc content and total soluble solids content detected after 35d storage period were not changed much compared with the fresh under the same storage conditions -- Temperature for (5±0.5)℃, relative humidity for (90±5) %. This study indicated that the quality of peeled pomelo sections could be kept well with the method of vacuum pre-cooling treatment combined with ozone treatment.