The improvement of the shelf life of vegetables through pre- and postharvest treatments

[摘要] English: The improvement of the shelf life of carrots and tomatoes through integrated pre- andpostharvest treatments was investigated. Preharvest ComCat® treatment of carrot andtomato plants was combined with postharvest disinfecting using chlorinated or anolytewater, modified atmosphere packaging in Xtend® film, and different storage temperatures.The physiological, chemical, biochemical and microbiological quality of carrots andtomatoes were effectively improved by the combined effect of modified atmospherepackaging in Xtend® film and the optimum storage temperatures of carrots, at 1°C, andtomatoes, at 13°C. The shelf life of carrots and tomatoes was effectively improved, whilethe quality characteristics were maintained.Disinfecting vegetables with anolyte water gave better results than chlorinated water.Chlorinated water treatment decreased ascorbic acid content, and increased physiologicalweight loss and peroxidase activity. The surface tissue of carrots was etched by chlorine,which created penetration zones for microorganism, and disadvantaged the shelf life.Disinfecting with anolyte water, in combination with modified atmosphere packaging andoptimum storage temperatures, supported quality characteristics, and therefore contributedto improving shelf life of carrots and tomatoes.Preharvest spraying of plants with ComCat®, improved the quality of carrots. At harvesta slightly higher ascorbic acid, total soluble solids, total available carbohydrates andsucrose content was noted. The sucrose to hexose ratio at harvest was also slightly higher,and the microbial populations were slightly lower. Preharvest ComCat® treated tomatoeshad a lower pH, fructose and glucose content, and higher titratabie acidity and peroxidaseactivity at harvest, which resulted in lower populations of natural microorganisms.During storage at 13°C and room temperature, ComCat® treated tomatoes displayedbetter maintenance of total soluble solids and ascorbic acid, and lower peroxidase activity.These tomatoes also maintained better microbiological and marketable quality. The freesugar content remained lower in ComCat® treated tomatoes as well as carrots duringstorage. It seems as if the fruit part of a plant is more affected by the ComCat® treatment,e.g. tomato, than the root part, e.g. carrots.The interactive effect of preharvest ComCat® spraying, disinfecting with chlorinated oranolyte water, modified atmosphere packaging in Xtend® film and different storagetemperatures was significant on several postharvest quality parameters of carrots andtomatoes. The postharvest quality of ComCat® treated carrots and tomatoes in the storageatmosphere, created by forced ventilation evaporative cooling, was also better than that ofthe controls.

[发布机构] University of the Free State