Effect Of Film Packaging And Hypobaric Storage On Postharvest Physiology, Quality And Disease Resistance In Strawberries

Strawberry (Fragaria ananassa Duch.) belongs to Rosaceae and is a perennial herbaceous plant. It is very popular for its tender, delicious and nutritious. The postharvest strawberries carry on high metabolic and physiological activities such as respiration, therefore, the reserved energy and nutrients of strawberries are rapidly consumed by these activities. It leads to softening, decay and flavor loss of the fruit. Strawberries are very suggestible to mechanical injury and microbial infection during harvest, storage and transportation. The berries lose quality easily and are very perishable because of the reasons above.The’Hongjia’strawberries were used as experimental material in this study. The pathogenic microbes of postharvest strawberry were isolated and identified. The effects of film packaging and hypobaric storage on postharvest qualities, antioxidation and peroxidation of cytomembrane were investigated in strawberry fruits. The Botrytis cinerea and Aspergillus niger were inoculated to healthy strawberries and the effects of film packaging MAP and hypobaric storage on disease resistance in these strawberries were studied. There were the results below:(1)The tissue isolation was used to get postharvest pathogenic microbes, and four kinds of fungal strains were obtained after isolation and purification. The fungal strains’ colonial morphology and micromorphology were observed. The observation results and fungal identification manuals were combined to confirm the species of four fungal strains. These four fungi belong to Botrytis cinerea, Aspergillus niger, Mucor sp. and Penicillium sp.(2)Film packaging MAP reduced the decay index, weight loss rate, slowed down respiratory rates, maintained strawberry color andfirmness, inhibited the decrease of TSS, TA and Vc contents. It also can delay the decline of anthocyanin and flavonoid contents, but didn’t have a significant effect quantitatively. The activities of POD, CAT, SOD and APX gradually increased, the decline of CAT, SOD and APX activities was delayed, the activity of LOX and the increase of MDA content were inhibited during the storage. The result showed that film packaging MAP maintained the quality of strawberries and delayed senescence by keeping the content of nutritional ingredients, scavenging the ROS in time and restraining from peroxidation of cytomembrane. Comparison among the four PE films of different thicknesses and CK showed that 0.04 mm thickness PE film was the best choice for maintaining the quality and physiological activities in strawberry fruits during storage.(3) Hypobaric storage reduced the decay index and slowed down respiratory rate, while increased the weight loss rate, maintained strawberry fruit color and firmness, inhibited the decrease of TSS, TA, Vc and anthocyanin. It also delayed the decrease of flavonoid content, but didn’t have a significant effect quantitatively. The activities of POD, CAT, SOD and APX gradually increased, the decline of APX activities was delayed, the activity of LOX and the increase of MDA content were inhibited during the storage. The results showed that hypobaric storage maintained the quality of strawberries and delay senescence by keeping the content of nutritional ingredients, scavenging the ROS in time and restraining from peroxidation of cytomembrane. Comparison among the three pressures (20 ± 5kPa,50± 5kPa and 80±5kPa) and CK showed that 50±5kPa was the best choice for maintaining the quality and physiological indexes in strawberry fruits during storage.(4)Film packaging MAP slowed down the decay index in strawberries which were inoculated with Botrytis cinerea and Aspergillus niger. The storage of these strawberries packed with 0.04 mm film maintained the lowest decay rate, significantly increased the content of total phenolics and activities of PPO, PAL, CHI and GLU. It also delayed the decrease of total phenolics content and PPO activity. The results showed that film packaging MAP can increase the disease resistance by improving the activities of defensive enzymes and content of noenzyme components to reduce the fruitdecay.(5)Hypobaric storage slowed down the decay index in strawberries which were inoculated with Botrytis cinerea and Aspergillus niger. The storage of these strawberries under 50 ± 5kPa maintained the lowest decay rate, significantly increased the content of total phenolics and activities of PPO, PAL, CHI and GLU. It also increased the total phenolics content in strawberries previously inoculated with Botrytis cinerea. The results showed that hypobaric storage can increase the disease resistance by improving the activities of defensive enzymes and content of noenzyme components to reduce the fruitdecay.