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dc.contributor.advisorOsthoff, G.
dc.contributor.advisorSteyn, M. S.
dc.contributor.authorWorkneh, Tilahun Seyoum
dc.date.accessioned2018-05-07T10:36:54Z
dc.date.available2018-05-07T10:36:54Z
dc.date.issued2002-11
dc.identifier.urihttp://hdl.handle.net/11660/8239
dc.description.abstractEnglish: The improvement of the shelf life of carrots and tomatoes through integrated pre- and postharvest treatments was investigated. Preharvest ComCat® treatment of carrot and tomato plants was combined with postharvest disinfecting using chlorinated or anolyte water, modified atmosphere packaging in Xtend® film, and different storage temperatures. The physiological, chemical, biochemical and microbiological quality of carrots and tomatoes were effectively improved by the combined effect of modified atmosphere packaging in Xtend® film and the optimum storage temperatures of carrots, at 1°C, and tomatoes, at 13°C. The shelf life of carrots and tomatoes was effectively improved, while the quality characteristics were maintained. Disinfecting vegetables with anolyte water gave better results than chlorinated water. Chlorinated water treatment decreased ascorbic acid content, and increased physiological weight 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 and optimum storage temperatures, supported quality characteristics, and therefore contributed to improving shelf life of carrots and tomatoes. Preharvest spraying of plants with ComCat®, improved the quality of carrots. At harvest a slightly higher ascorbic acid, total soluble solids, total available carbohydrates and sucrose content was noted. The sucrose to hexose ratio at harvest was also slightly higher, and the microbial populations were slightly lower. Preharvest ComCat® treated tomatoes had a lower pH, fructose and glucose content, and higher titratabie acidity and peroxidase activity at harvest, which resulted in lower populations of natural microorganisms. During storage at 13°C and room temperature, ComCat® treated tomatoes displayed better maintenance of total soluble solids and ascorbic acid, and lower peroxidase activity. These tomatoes also maintained better microbiological and marketable quality. The free sugar content remained lower in ComCat® treated tomatoes as well as carrots during storage. 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 or anolyte water, modified atmosphere packaging in Xtend® film and different storage temperatures was significant on several postharvest quality parameters of carrots and tomatoes. The postharvest quality of ComCat® treated carrots and tomatoes in the storage atmosphere, created by forced ventilation evaporative cooling, was also better than that of the controls.en_ZA
dc.description.abstractAfrikaans: Die verebetering van rakleeftyd van geelwortels en tamaties gedurende ge-ïntegreerde voor- en na-oes behandelings is ondersoek. Voor-oes ComCat® behandeling van geelwortel- en tamatieplantjies is gekombineer met na-oes ontsmetting met gechlorineerde of anolyte water, gemodifieerde atmosfeer verpakking met Xtend" film en verskillende bergi ngstemperature . Die fisiologiese, chemiese, biochemiese en mikrobiologiese gehalte van geelwortels en tamaties is effektief verbeter deur die gekombineerde effek van gemodifieerde atmosfeer verpakking in Xtend® film en optimum bergingstemperature van geelwortels, by 1°C, en tamaties, by 13°C. Die rakleeftyd van geelwortels en tamaties is effektief verbeter terwyl die gehalte-eienskappe behou is. Ontsmetting van groente met anolyte water het beter resultate gelewer as met gechlorineerde water. Gechlorineerde water behandeling het askorbiensuurinhoud verlaag, en fisiologiese massaverlies en peroksidase aktiwiteit verhoog. Die oppervlakweefsel van geelwortels is deur chloor geëts, wat indringingsones vir mikroorganismes geskep het, en die rakleeftyd benadeel het. Ontsmetting met anolyte water, in kombinasie met gemodifieerde atmosfeer verpakking en optimum bergingstemperature, het gehalteeienskappe ondersteun, en so bygedra tot verbetering van rakleeftyd van geelwortels en tamaties. Voor-oes bespuiting van plantjies met ComCat®, het die gehalte van geelwortels verbeter. Tydens oes is 'n effens hoër askorbiensuur-, totale oplosbare soliede-, totale beskikbare koolhidrate- en sukrose inhoud waargeneem. Die sukrose tot heksose verhouding was ook effens hoër, en die mikrobiese populasies was effens laer. Voor-oes ComCat® behandelde tamaties het by oes 'n laer pH, fructose- en glukose inhoud, en hoër titreerbare suur en peroksidase aktiwiteit gehad, wat tot laer populasies mikroorganismes gelei het. Gedumede berging by l3°C en kamertemperatuur, het ComCat® behandelde tamaties 'n beter behoud van totale oplosbare soliede en askorbiensuur, en laer peroksidase aktiwiteit getoon. Hierdie tamaties het ook beter mikrobiologiese- en bemarkbare kwaliteit behou. Die vrye suikerinhoud het laer gebly in ComCat® behandelde geelwortels sowel as tamaties gedurende berging. Dit blyk dat die vruggedeelte van 'n plant, bv tamatie, meer deur die ComCat® behandeling beïnvloed word as die wortelgedeelte, bv geelwortel. Die interaktiewe effek van voor-oes ComCat® bespuiting, na-oes ontsmetting met gechlorineerde- of anolyte water, gemodifieerde atmosfeer verpakking met Xtend® film en verskillende bergingstemperature was beduidend op verskeie na-oes gehalteparameters van geelwortels en tamaties. Die na-oes gehalte van ComCat® behandelde geelwortels en tamaties in die bergingsatmosfeer, geskep deur forseerde ventilasie verdampingsverkoeling, was ook beter as die van die kontroles.en_ZA
dc.description.sponsorshipAgricultural Research Training Project (ARTP)en_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectVegetables -- Postharvest technologyen_ZA
dc.subjectVegetables -- Preharvest technologyen_ZA
dc.subjectVegetables -- Storageen_ZA
dc.subjectThesis (Ph.D. (Microbial, Biochemical and Food Biotechnology))--University of the Free State, 2002en_ZA
dc.titleThe improvement of the shelf life of vegetables through pre- and postharvest treatmentsen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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