Studies On Postharvest Quality, Biochem-Physiology And Enzymatic Browning Of Trapa Ssp.

Trapa spp. is easy to be brown, senescent and decay, and just be stored for 3-6days at room temperature, which shortens the period of selling and processing, and restricts the development of Trapa spp production. This thesis studied the quality, physiology and enzymactic browning changes of Trapa spp. to offer the bases of the postharvest technique. The results were as following:1. The data of Trapa spp.'s physiological and qualitive determination at different storage temperature indicate that 3 ℃ could extend the storage time of Trapa spp.. 3℃ was more effective than room temperature to slow down the respiratory rate (the maximum difference could be as great as 60mgCO₂ kg^-1·h^-1), to decrease the water loss, to inhibit LOX and POD activities, to reduce the output of superoxide anion, to stabilify AsA content, to maintain SOD, CAT, APX and PAL activities, to reduce MDA content, to have low contents of free phenol and total phenols, and therefore, to delay the tissue senescence of Trapa spp..2. Maturity plays an important role on the storage of Trapa spp.. Trapa spp. which is less mature stored at low temperature maintained better taste, had higher reducing sugar, less starch and dry substance just like at harvest. During storage, the less mature Trapa spp. had significantly higher SOD and respiratory rate than more mature Trapa spp., and had lower activities of CAT and APX, higher activities of PAL and POD. The contents and change patterns of less mature and more mature Trapa spp. showed different.3. The phenols extracted from fresh Trapa spp. were investigated by TLC, ultraviolet scanning and HPLC. The results showed that there are gallic acid, chlorogenic acid, catechin, caffeic acid in both sarcocarp and pericarp of Trapa spp.. Caffeic acid is the main phenol in pericarp, while Gallic acid is in chief in sarcocarp. The contents of catechin are plentiful in both pericarp and sarcocarp .4. The optimal pH of POD from Trapa spp. sarcocarp was 5.0 and 7.5, while the optimal pH of POD from Trapa spp. pericarp was 6.0. The optimal temperature of POD from sarcocarp was 25-30℃, while 40℃ from pericarp. The Trapa spp.POD from pericarp had better heat resistance, to inactivate the POD needed more than 15s in boiling water.