Study On The Storage Properties And Fresh Keeping Technologies Of Strawberry (FengXiang Variety) At Room Temperature

A strawberry variety, "feng xiang" was taken as experimental material, sprayed with calcium chloride solution before harvesting and treated with different O₃ dosages, heat air at different temperatures and calcium chloride solution with diffeent concentration after harvesting, and then were stored at normal temperature. The storage quality indices such as respiration, firmness, weight loss, rot index, polygalacturonase (PG) and endo-l,4-β-D-glucanase (Cx) activities and relative electric conductance(Rec) of strawberry were investigated and main compositions such as soluble solids, reducing sugar , ascorbic acid, organic acid and anthocyanin in strawberry were analyzed during storage. Those research were aimed to provide theoretical guidance for postharvest fresh keeping of strawberry at normal temperature. The main research contents and corresponding results were summarized as follows:PG and Cx enzymatic properties in "feng xiang" strawberry were studied. The results indicated that the activities of PG and Cx were at a range of 4 U.ml^-1 to 7 U.ml^-1 and optimum pH and temperature of PG and Cx were 5.0, 30℃and 5.5, 37℃ , respectively in mature strawberry fruit.The correlation of PG and Cx activities with firmness and Rec. of strawberry during growth period was studied. The results indicated that the PG and Cx activities were determined at early growth stage of fruit and then increased with growth period. The correlation coefficients of PG and Cx activities with firmness and Rec. were -0.776, -0.887, 0.923 and 0.980, respectively , which indicated that PG and Cx were important to consenescence of strawberry."feng xiang" strawberry was treated with O3 for 0 min, 3 min and 6 min, and then stored at (20±2℃). The physiological indices and nutritive quality of strawberry were investigated. The results indicated that with O3 treatment for 3 min, the respiration, rot indexes, enzyme activity and Rec.of strawberry were significantly inhibited and the loss of soluble solids, organic acid and Vc content were reduced. However, with treatment O3 for 6 min, strawberry respiration was promoted, rot indexes increased and nutritive quality of strawberry decreased due to the damage of O2 from O3 decomposing to cell membrane of strawberry.In this experiment, strawberry fruits were heated with 40℃ air for 0 min, 10 min, 20min, 30 min to 40 min respectively and then stored at normal temperature (20±2℃ ). The main physiological and nutritive value indexes of strawberry were determined. The results indicated that 40℃ air treatment could decrease rot indexes, Rec, inhibit PG and Cx enzymatic activities and low the loss of several nutrition substances. Of which, the effect of treatment with 40℃ air for 30 min was obvious.The strawberry fruits were dipped into CaCl₂solution with concentration 0, 0.5%, 1.0%, 1.5% and 2.0% at 30℃ for 2 min and surface water of strawberry was dried out and stored at normal temperature (20±2℃). The changes of physiology and senescence of strawberry was studied during storage. The results indicated that the effect of 1.0% CaCl₂ treatment on senescence indexes was the most distinct. The respiration and rot indexes of strawberry were aggravated with treatment of overhigh concentration of CaCl₂ solution.Strawberry was sprayed with 0-1.5% CaCl₂ solution at the early , middle and mature growth stages. The effect of CaCl₂ concentration and spray time on the quality of strawberry fruits was observed at harvesting and during storage period. The result indicated that the optimum combination was spraying at early stage of strawberry fruit growth for 3 times every 3 days with 0.5% CaCl₂ concentration. At strawberry expanding stage and color transition stage, strawberry could not absorb Ca efficiently. Overhigh Ca concentration could damage the cell membrane of strawberry and promote its senescence.