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Study On Extending The Shelf-life Of Green Asparagus And Peach Fruit

Posted on:2007-10-08Degree:DoctorType:Dissertation
Country:ChinaCandidate:J S AnFull Text:PDF
GTID:1101360185495851Subject:Agricultural Products Processing and Storage Engineering
Abstract/Summary:PDF Full Text Request
The research was to combine the modifid atmosphere packaging (MAP) with other strorage methods on the green asparagus and the peach fruit. The physical, chemical and physiology changes of green asparagus and peach fruit during storage were investigated. Through discussing the mechanism of MAP, It can provide the base of application and the guide for the industrialization of this strorage method.Firstly, Fresh green asparagus (Asparagus officinalis L.) spears were subjected to a prestorage treatment by dipping in 20ppm 6-benzylaminopurine (6-BA) for 10 min. Treated and untreated spears were placed into low-density polyethylene (LDPE) bags with a thickness of 15μm, in which a passive modification of the atmosphere was developed, or 25μm, in which a gas mixture of 10 kPa O2 + 5 kPa CO2 was flushed and then the bags were stored for 24 days at 2°C. Atmosphere composition, chlorophyll, ascorbic acid, fiber, color and sensory attributes were determined every 4 days. Throughout the storage period, O2 level decreased from the initial values (21kPa, 10kPa) to 2.1–4.2 kPa in package without 6-BA treatment and to 4.9–6.8 kPa in package with 6-BA treatment. CO2 level increased from the initial value (0kPa, 5kPa) to 5.5–7.2 kPa in packages without 6-BA treatment and to 4.1–6.1 kPa in packages with 6-BA treatment. In both packaging treatments, at the end of the 24-day storage period, the spears treated with 6-BA had a better color, firmness and overall appearance; moreover they retained more chlorophyll and ascorbic acid and they had less fiber.The changes in lignifying, antioxidant enzyme activities and cell wall compositions of green asparagus (Asparagus officinalis L.) in 1 mg/l aqueous ozone pretreated, and subsequent modified atmosphere packaging (MAP) during storage at 3°C for 25 days was investigated. The enzyme activities in asparagus including phenylalanine ammonia lyase (PAL), superoxide dismutase (SOD), ascorbate peroxidase (APX,), and glutathione reductase (GR) were inhibited by aqueous ozone treatment and subsequent modified atmosphere packaging. Changes in lignin, cellulose and hemicellulose contents were also monitored during storage. Similarly, the increasing of the cell wall compositions under the aqueous ozone treatment and MAP were significantly reduced (P<0.05). The possible mechanism in which changes in enzymatic activities and cell wall compositions in green asparagus under aqueous ozone pretreated and subsequently MAP were discussed.Silver nanoparticles have recently gained increased interests due to their extended applications in food processing for antimicrobial purposes. The aim of this study was to evaluate the effect of a silver nanoparticles-PVP coating on the weight loss, ascorbic acid, total chlorophyll, crude fiber, color, firmness and microbial quality of asparagus stored at 2°C and 10°C. Asparagus were first disinfected by 100 mgl-1 sodium hypochloride solution for 15 minutes. They were then immersed in the coating solution with silver nanoparticles for 3...
Keywords/Search Tags:Asparagus officinalis L., Peach, Storage, Postharvest physiology, Modified atmosphere packaging, 6-Benzylaminopurine, Silver nanoparticles, Aqueous ozone, modeling
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