Avocados are becoming an increasingly important crop in South Africa, where the main producing areas include Limpopo, Mpumalanga and KwaZulu-Natal provinces. The South African avocado industry faces considerable challenges including increasing competition exporting avocados, particularly to the European market. The processes involved to export avocados has markedly improved over the past two decades, however there is always room for improvement and it is necessary to remain competitive on a global scale. Issues such as fruit being partially soft on arrival, quality defects and cold chain management breakdown are still present. It is necessary to investigate new aspects of cold storage such as extending the storage period and understanding the physiological aspects involved. To improvement such issues, an investigation was conducted on ultra-low temperature shipping (1°C) as well as the use of 1-MCP; the implementation of deliberate cold chain breaks to achieve a better understanding as to the quality influences involved; an extended storage period of 56 days to assess the quality issues and benefits involved; as well as investigating the physiological aspects involved with all above treatments on 'Hass' avocados. An initial study saw early-, mid- and late-season 'Hass' avocados stored at 1°C or 5.5°C for 28 days. Additional treatments included fruit treated and not treated with 1-MCP as well as waxed and unwaxed fruit. Storage at 1°C was comparable with 1-MCP treatment for both fruit softening in storage and extending the ripening period. Storage at 5.5°C resulted in partial in-transit ripening, if 1-MCP was not used. Early-season fruit incurred the most external chilling injury but overall levels were minimal and not concerning. Mid-season fruit were the most sound in terms of quality. It is suggested that 1°C can be used as a viable economic alternative to 1-MCP for long distance shipping of 'Hass' up to 28 days. The cold chain break trial included a 24 hour delay before cold storage, a deliberate 8 hour break at day 14 of cold storage where fruit were removed from cold storage and a control of 28 days cold storage where no break was involved. Early-, mid- and late-season 'Hass' avocados were stored at 1°C or 5.5°C for 28 days. Additional treatments included fruit treated and not treated with 1-MCP as well as waxed and unwaxed fruit. It was found that cold chain breaks do influence the amount of water loss, fruit softening and days taken to ripen. Storage at 1°C did not entirely negate the effects of cold chain breaks compared with 5.5°C, but did result in fruit which were harder at the end of storage and took longer to ripen. The use of 1-MCP also had advantageous effects with respect to significantly lengthening the ripening period, even when a cold chain break occurred, compared with fruit not treated with 1-MCP. As results of the study differed in some respects to those of previous studies, it is recommended that further work be conducted to determine what fruit or pre-harvest factors affect the fruit physiological changes which take place when cold chain breaks occur. Having the option to make use of an extended storage period would be of benefit to the industry if delays occur and fruit have to be maintained under cold storage. Extended storage of South African avocados, especially at the end of the season would also allow for the option of strategically holding back fruit from the export market in order to extend the supply period. It would not only benefit export options, but would also be highly beneficial to local pre-packers, as it would reduce the need to import fruit from the Northern hemisphere production areas during the South African off-season. Early-, mid- and late-season 'Hass' avocados were stored at 1°C or 5.5°C for 56 days. Additional treatments included fruit treated and not treated with 1-MCP as well as waxed and unwaxed fruit. The combination of 1°C with the use of 1-MCP resulted in a good shelf life as well as maintenance of internal quality and integrity. External chilling injury is of concern for early-season fruit, however, mid- and late-season fruit did not incur extensive damage. It is, therefore, advised that fruit placed in extended storage are marketed through the 'Ready ripe' program to mask any chilling injury on the 'Hass' fruit. Avocados are renown as a "healthy food" due to their nutritional value as well as containing relatively high concentrations of antioxidants. The fruit also contain high amounts of C7 sugars which can act as antioxidants. Additionally, C7 sugars and other antioxidants play important roles in fruit quality. Therefore, it is important to understand how varying storage conditions and treatments affect the levels of these physiological parameters. Treatments of cold chain break/delay included a deliberate 8 hour break at day 14 of cold storage where fruit were removed from cold storage, a 24 hour delay before cold storage and a control of 28 days where no break was involved. A 56 day extended storage period was also used. Early-, mid- and late-season 'Hass' avocados were stored at 1°C or 5.5°C for 28 days. Additional treatments included fruit treated and not treated with 1-MCP as well as waxed and unwaxed fruit. The use of 1-MCP maintained higher levels of antioxidants, ascorbic acid and C7 sugars for both the 28 day and the 56 day storage periods. The 24 hour delay had a tendency to increase consumption of anti-oxidant and sugar reserves. The use of 1°C resulted in antioxidant and ascorbic acid levels decreasing while maintaining higher sugar levels. Overall, high stress imposed on fruit decreased reserves resulting in poor quality fruit. The use of 1°C and 1-MCP treatments maintained fruit quality. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

No description available.

Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: By world standards South Africa’s contribution to fresh blueberry production is very small, a mere 0.25 %. This seemingly insignificant and unimpressive statistic is, however, by no means indicative of the impending impressive potential the South African blueberry industry holds. South Africa is encountering a rapid growth phase off a very small base and the current 100-150 ton export crop is expected to increase to a range of 500 to 600 tons or more in the next five years. Consequently, export by sea must be considered as a logistic alternative. Seafreight success relies on controlled atmosphere storage which in turn relies on berries of exceptional quality. To achieve this, fundamental differences between blueberry cultivars must be examined and blueberry handling and storage regimes must be assessed and optimised. This study investigates the storage potential of certain rabbiteye blueberries relative to controlled atmospheres and short pre-cooling delays. Quality assessments were based on external colour, soluble solids, titratible acidity, firmness and decay development. Furthermore, the respiration and ethylene production rates as well as moisture loss, of various cultivars were determined to characterize fundamental differences amongst cultivars and to gain insight into their postharvest behaviour. Lastly the effect of infection on pigment levels of blueberry flesh and peel was examined for the purpose of laboratory experience. Controlled atmosphere storage had the greatest impact on berry firmness and percentage decay. No off flavours were detected during sensory analysis at the CA levels tested. CAstored berries were firmer and incidence of decay was reduced significantly. Significant decay reduction was challenged by the market tolerance of no more than 2 %. Decay suppression and storage extension was insufficient (for the set period), particularly after the shelf life period. Cultivar and seasonal differences as well as picking maturity and inoculum pressure determine blueberry CA storability. CA may be a valuable technology, however advances must first be made in ensuring optimal blueberry quality to warrant export by sea. Short pre-cooling delays (0, 2, 4, 6 h) at 20 ºC had no effect on colour (L, C, H), total soluble solids, titratable acidity and firmness of blueberry cultivars, ‘Centurion’, ‘Premier’ and ‘Tifblue’. Results for percentage decay indicate that prompt cooling becomes more critical as the duration of storage increases, particularly when market specification of no more than 2 % decay must be met. Berries subjected to longer delays appear to be more susceptible to decay. Differences exist among cultivars and knowledge gained from this research can be used to adapt handling and cooling regimes. Information generated will benefit cultivar selection for marketing (local vs. export), storage (short vs. long term) and logistics (air vs. seafreight). Rabbiteye blueberry cultivars differ considerably in terms of their respiration rate, ethylene production and moisture loss. These quality parameters were evaluated for various cultivars at 15 ºC. ‘Climax’ appears to have the highest respiration rate, ethylene production and moisture loss, whilst ‘Premier’ has the lowest respiration rate and ethylene production was too low to be detected by gas chromatography. The lowest moisture loss proportionality constant was found for ‘Tifblue’ and ‘Centurion’. A change in blueberry flesh colour from white to dark red was noted in infected berries. Artificial inoculation with Botrytis cinerea showed a similar result. The colour change was evaluated by comparing anthocyanin pigment levels (determined by spectrophotometry and HPLC) of the peel and flesh. Anthocyanin content of infected flesh doubled, whilst that of infected peel was less than 50 % of the control. Pigment leakage has been reported in blueberries. It would appear that cell disruption, induced by infection may facilitate migration of anthocyanin from the peel to the flesh. The storage potential of blueberries depends on cultivar, maturity at harvest, climatic conditions as well as the inoculum pressure. Under favourable conditions storage life of blueberries can be manipulated effectively. Further cultivar specific research that targets relevant quality issues should be investigated. Reliable techniques should be developed to quantify blueberry firmness changes. Research on inoculum levels may give insight into the reduction of decay pressure and decay suppressing alternatives such as antibacterial pads can be examined. Peel integrity relative to decay susceptibility can also be researched on a cellular level. / AFRIKAANSE OPSOMMING: Suid-Afrika se bydrae tot wêreld bloubessie produksie is baie klein, ‘n skrale 0.25 %. Hierdie onindrukwekkende statistiek weerspieel egter glad nie die indrukwekkende potensiaal van die Suid-Afrikaanse bloubessie bedryf nie. Die bedryf ondervind tans ‘n dramatiese groei met ‘n klein begin vanaf die huidige 100-150 ton opbrengs tot wat volgens verwagting binne die volgende vyf jaar sal styg tot in die orde van 500-600 ton. Na aanleiding van die verwagte toename in produksie, sal seevrag verskeping oorweeg moet word as alternatief vir uitvoer eerder as lugvrag. Die sukses van seevrag lê in die gebruik van beheerde atmosfeer opberging (BA), waarvan die sukses op sy beurt bepaal word deur bessies van hoogstaande kwaliteit. Om steeds aan die verwagtings van die oorsese mark te voldoen moet grondliggende verskille tussen bloubessie kultivars ondersoek word en daaropvolgend moet hantering en opbergingstelsels aangepas en geoptimeer word. Die navorsing bestudeer die opbergingspotensiaal van verskeie rabbiteye bloubessies relatief tot beheerde atmosfere en kort vertragings in verkoeling. Kwaliteit, gebasseer op eksterne kleur, oplosbare deeltjies, titreerbare sure, fermheid en persentasie bederf, is ondersoek. Die respirasie en etileenproduksie tempos sowel as vogverlies van verskeie kultivars was verder bepaal om die fundamentele verskille tussen kultivars te bepaal, sowel as insig te verwerf in na-oes gedrag. Die effek van infeksie op pigment vlakke van bloubessie vlees en skil was ondersoek vir die doel van laboratorium ondervinding. Beheerde atmosfeer opberging het die grootste effek getoon op bessie fermheid en persentasie bederf. Na aanleiding van sensoriese toetse is daar geen wansmaake aangeteken ten op sigte van die BA vlakke wat getoets is nie. Bessies onderworpe aan beheerde atmosfeeriese toestande was fermer en bederfonderdrukking was beduidend. Die markverdraagsaamheid ten opsigte van bessiebederf, is egter 2 %. Hiervolgens was onderdrukking van verval asook opbergingsvermoë, onvoldoende (spesifiek na die rakleeftyd). Kultivar en seisoenale verskille asook plukrypheid en inokulum druk, bepaal ook die sukses van BA opberging. BA word beskou as ‘n waardevolle tegnologie vir verlenging van opberging. Dit blyk egter dat daar eers ‘n vooruitgang gemaak moet word in die versekering van optimale bessie kwaliteit voordat verskeping oorweeg kan word. Kort vertragings (0, 2, 4, 6 uur by 20 ºC) in verkoeling, het geen invloed gehad op kleur, (L, C, H), totale oplosbare vastestowwe, titreerbare suur en fermheid van bloubessie kultivars ‘Centurion’, ‘Premier’ en ‘Tifblue’ nie. Bederfresultate dui daarop dat onmiddelike verkoeling krities is, veral by verlengde opberging, om aan die 2 % bederf drempelwaarde te voldoen. Bessies onderhewig aan langer vertragings voor verkoeling, blyk meer vatbaar te wees vir bederf. Verskille bestaan tussen kultivars en kennis ingewin tydens hierdie navorsing kan toegepas word om hanteringsprosedures en verkoeling aan te pas. Ingeligte besluitneming kan dus ten opsigte van kultivarspesifieke bemarking (plaaslik en uitvoer), opberging (kort- en langtermyn) en vervoer (lug- en seevrag) gemaak word. Rabbiteye bloubessie kultivars verskil aansienlik ten opsigte van hul respirasietempo, etileenproduksie en vogverlies. Laasgenoemde kwaliteitsbepalers is by verskillende kultivars ondersoek by 15 ºC. ‘Climax’ het die hoogste respirasietempo, etileenproduksie en vogverlies getoon, terwyl ‘Premier’ die laagste respirasietempo gehad het, en die etileenproduksie te laag was om met die gaschromatograaf te bepaal. Die laagste vogverlies proporsionaliteitskonstante is waargeneem tussen ‘Tifblue’ en ‘Centurion’. ‘n Verandering is waargeneem in bloubessie vrugvleeskleur van wit tot donkerrooi by besmette bessies. ‘n Soortgelyke resultaat is verkry met kunsmatige inokulering met Botrytis cinerea. Die kleurverskil is geëvalueer deur vergelyking te tref met die antosianienpigment vlakke tussen die skil en die vlees (bepaal deur spektrofotometrie en HPLC). Antosianieninhoud van besmette vrugvlees het verdubbel, terwyl die van besmette vrugskil minder as 50 % van die kontrole groep was. Pigmentlekkasie is al vermeld by bloubessies. Dit wil voorkom of selskade veroorsaak deur infeksie beweging van antosianien vanaf die skil na die vlees kan aanhelp. Die opbergingspotensiaal van bloubessies hang af van kultivar, rypheid by oes, omgewings toestande sowel as inokulum druk. Onder gunstige toestande kan bloubessies se opbergingsvermoë effektief gemanipuleer word. Verder kultivar-spesifieke navorsing wat relevante kwaliteits kwessies aanspreek, kan gedoen word. Verder kan betroubare tegnieke in die meting van bloubessie fermheid veranderinge ondersoek word. Navorsing ten opsigte van inokulum vlakke mag insig gee in terme van bederf-druk vermindering en die gebruik van bederf-onderdrukking alternatiewe soos anti-bakteriese lappies. Skil integriteit relatief tot bederf-vatbaarheid kan ook op sellulere vlak ondersoek word.

Made available in DSpace on 2014-12-02T11:16:55Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-05-23Bitstream added on 2014-12-02T11:20:55Z : No. of bitstreams: 1 000796943.pdf: 2208541 bytes, checksum: d24ce855c4825c3e32079545cfa14fbb (MD5) / Objetivou-se avaliar as melhores condições pós-colheita para frutos de mangaba. Os experimentos foram conduzidos no laboratório de Tecnologia de Alimentos da Universidade Estadual Paulista (UNESP) Campus de Ilha Solteira. No primeiro experimento, as mangabas nos três estádios de maturação foram acondicionadas em polietileno tereftalato, bandeja de Poliestireno expandido recoberto com filme de policloreto de vinila e saco plástico com fechamento. Os tratamentos foram constituídos das combinações entre os graus de maturação e embalagens e foram avaliadas: perda de massa fresca, firmeza, vitamina C, pH, sólidos solúveis, acidez titulável, índice de maturação, açúcares redutores e aparência visual. A melhor conservação foi nos frutos de vez acondicionados em bandeja de isopor, mantendo classificação ótima em todo período de armazenamento. No segundo experimento, mangabas no estádio de vez foram acondicionadas em bandejas de poliestireno expandido recobertas com filme de policloreto de vinila. Receberam os tratamentos com diferentes concentrações de quitosana (0; 0,25; 0,5; 1 e 2%). As avaliações realizadas foram: perda de massa fresca, firmeza, vitamina C, sólidos solúveis, acidez titulável, índice de maturação, pH, açúcar redutor e aparência visual. Os tratamentos com quitosana nas concentrações de 1% e 2% mostraram-se efetivos com notas máximas até o final do armazenamento. No terceiro experimento, mangabas no estádio de vez foram acondicionadas em bandeja de poliestireno expandido recobertas com filme de policloreto de vinila. Em seguida, receberam os tratamentos para absorver etileno utilizando diferentes concentrações de permanganato de potássio (0; 1; 2 e 3%). As avaliações realizadas foram: perda de massa, firmeza, vitamina C, sólidos solúveis, acidez titulável, índice de maturação, pH, açúcar redutor e aparência visual. Os sachês contendo 1 e 2 gramas de permanganato de potássio ... / This study aimed to evaluate the best conditions for postharvest fruit mangaba. The experiments were conducted in the laboratory of Food Technology of the University Estadual Paulista (UNESP) Campus Ilha Solteira. In the first experiment, the mangabas in three maturity stages were packed in polyethylene terephthalate, polystyrene trays covered with polyvinyl chloride film and plastic bag with closure. The treatments consisted of combinations between the degrees of maturation and packaging and were evaluated: loss of weight, firmness, vitamin C, pH, soluble solids, titratable acidity, maturation index, reducing sugars, polyphenoloxidase activity, peroxidase activity, chlorophyll and visual appearance. The best preservation was once the fruits packed in Styrofoam tray, keeping great rankings throughout the storage period. In the second experiment, mangabas the stadium in time were placed in polystyrene trays covered with polyvinyl chloride film. They received treatment with different chitosan concentrations (0, 0.25, 0.5, 1 and 2 %). Evaluations were loss of weight, firmness, vitamin C, soluble solids, titratable acidity, maturation index, pH, reducing sugar and visual appearance. Treatments with chitosan in concentrations of 1% and 2% were shown to be effective with maximal notes to the final storage. In the third experiment, mangabas the stadium in time were placed in polystyrene trays covered with polyvinyl chloride film. Then, received treatments to absorb ethylene using different concentrations of potassium permanganate (0, 1, 2 and 3%). Evaluations were weight loss, firmness, vitamin C, soluble solids, titratable acidity, maturation index, pH, reducing sugar and visual appearance. Sachets containing 1 and 2 grams of potassium permanganate provides better visual appearance mangabas of time. In the fourth experiment fruits mangaba receiving mild osmotic dehydration for 10 minutes was selected. Then taken to a dryer with forced hot ...

Made available in DSpace on 2014-06-11T19:24:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-07Bitstream added on 2014-06-13T20:32:05Z : No. of bitstreams: 1 cabia_nc_me_botfca.pdf: 821515 bytes, checksum: e6d815e50e0fa89c9f28908416ce032f (MD5) / O abacate é um fruto climatérico altamente perecível, e para sua comercialização é necessário que se faça uso de métodos de conservação pós colheita. O presente trabalho teve como objetivo a conservação do abacate ‘Hass” com a utilização de 1- metilciclopropeno (1-MCP). Os frutos após a colheita foram selecionados e expostos a diferentes concentrações de 1-MCP (200 ppm, 300 ppm e 400 ppm) e após o procedimento foram armazenados sob refrigeração a 10ºC±1 e 90±5% de UR. Foram realizadas análises de perda de massa fresca, atividade respiratória, acidez titulável (AT), pH, sólidos solúveis (SS), índice de maturação, firmeza, compostos fenólicos totais, capacidade antioxidante determinada por DPPH, atividade das enzimas polifenoloxidase (PFO), poligalacturonase (PG) e pectinametilesterase (PME). As análises foram realizadas nos frutos a cada 3 dias, durante 15 dias, depois desse período os mesmos foram transferidos para condições ambiente ( 23±4ºC e 70±5% de UR) para simulação da comercialização. Após 3 dias em condições ambientes foi realizada a última avaliação. O delineamento utilizado foi inteiramente casualizado, com 3 repetições por tratamento, utilizando-se o teste de Tukey a 5% de probabilidade. Nas condições em que o trabalho foi realizado pode-se concluir que a aplicação de 1-MCP associada ao armazenamento refrigerado foi eficiente no controle do amadurecimento dos abacates ‘Hass’. Os frutos sob aplicação de altas doses de 1-MCP apresentaram menor perda de massa ao longo do tempo. Quanto maior a dose de 1-MCP aplicada, menor o pico respiratório dos frutos, sendo que os frutos com aplicação de 400ppm de 1-MCP não apresentaram pico respiratório. O 1- MCP foi eficiente na manutenção da firmeza dos frutos porém não demonstrou efeitos sobre as enzimas poligalacturonase, pectinametilesterase e polifenoloxidase / The avocado is a climacteric fruit highly perishable and their marketing is necessary making use of post harvest preservation methods. The present study aimed at the conservation of avocado 'Hass' with the use of 1-methylcyclopropene (1-MCP). The fruits after harvest were selected and exposed to different concentrations of 1-MCP (200 ppm, 300 ppm and 400 ppm) and after the procedure they were stored at 10 º C ± 1 to 90 ± 5% RH. Analyses of weight loss, respiratory activity, titratable acidity (TA), pH, soluble solids (SS), maturation index, firmness, total phenolics, antioxidant capacity determined by DPPH, enzyme activity of polyphenoloxidase (PPO) polygalacturonase (PG) and pectin (SMEs). The analyzes were performed on fruit every 3 days for 15 days, after this period they were transferred to ambient conditions (23 ± 4 ° C and 70 ± 5% RH) for simulation of marketing. After 3 days at ambient conditions the last appreciation was performed. The experimental design was completely randomized with three replicates per treatment, using the Tukey test at 5% probability. Under conditions in which the work was performed can be concluded that the application of 1-MCP associated with cold storage was effective in controlling the maturation of avocados 'Hass'. The fruits under application of high doses of 1-MCP showed less weight loss over time. The greater amount of 1-MCP applied, the lower respiration of the fruits and fruits with application of 400ppm of MCP-1 showed no respiratory peak. The 1-MCP was effective in maintaining fruit firmness but showed no effect on the enzymes Polygalacturonase, pectin and Polyphenoloxidase

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017. / Agriculture has emerged as a major economic activity in the African continent. Therefore, fruits and vegetables are considered as essential source of vitamins, minerals and proteins. However, fruits and vegetables are perishing rapidly. Thus, the adequate handling starts from the field, by applying appropriate method of storage and preservation in order to reduce post-harvest losses and extend its shelf life. Preservation by removing heat from the products is the most common method of preservation. In rural areas, the access to the grid is expensive or in some cases impossible. Therefore, researchers have been paying more attention to find alternative sources of power to run the cooling units. This study provides proof of a concept for the use of solar energy to cool down harvested fruits and vegetables at the farm level to an adequate farm storage temperature. The target storage temperature range is between 5 and 15 oC. A model refrigerator was designed and constructed in the mechanical engineering workshop of Cape Peninsula University of Technology. It was installed and tested in outdoor conditions to get the effect of different weather conditions. The model consists of a typical vapour compression system powered by a 12 V solar PV system. A DC compressor was used, and therefore, there is no inverter. The model was first tested without a product and then with 20 kg batches of different fruits for a period of two weeks in April 2016. Wind speed, ambient temperature and solar radiation intensity data were monitored and collected from a Campbell Scientific weather station mounted on the roof adjacent to the model. By monitoring the temperatures and compressor current hourly, the refrigeration effect, power consumption and coefficient of performance were determined. The overall COP based on input solar energy was 2.8. It was thus proved that a suitably sized PV system could be designed and implemented at farm level to cool harvested fruits from ambient to storage temperature without the use of an inverter. This could go some way to helping retard deterioration of fruits and vegetables before delivery to a marketplace or to storage.

Orientador: Aparecida Conceição Boliani / Banca: Jacira dos Santos Isepon / Banca: Heloiza Ferreira Alves do Prado / Banca: José Carlos Cavichioli / Banca: Silvia Antoniali do Carmo / Resumo: Objetivou-se avaliar as melhores condições pós-colheita para frutos de mangaba. Os experimentos foram conduzidos no laboratório de Tecnologia de Alimentos da Universidade Estadual Paulista (UNESP) Campus de Ilha Solteira. No primeiro experimento, as mangabas nos três estádios de maturação foram acondicionadas em polietileno tereftalato, bandeja de Poliestireno expandido recoberto com filme de policloreto de vinila e saco plástico com fechamento. Os tratamentos foram constituídos das combinações entre os graus de maturação e embalagens e foram avaliadas: perda de massa fresca, firmeza, vitamina C, pH, sólidos solúveis, acidez titulável, índice de maturação, açúcares redutores e aparência visual. A melhor conservação foi nos frutos de vez acondicionados em bandeja de isopor, mantendo classificação ótima em todo período de armazenamento. No segundo experimento, mangabas no estádio de vez foram acondicionadas em bandejas de poliestireno expandido recobertas com filme de policloreto de vinila. Receberam os tratamentos com diferentes concentrações de quitosana (0; 0,25; 0,5; 1 e 2%). As avaliações realizadas foram: perda de massa fresca, firmeza, vitamina C, sólidos solúveis, acidez titulável, índice de maturação, pH, açúcar redutor e aparência visual. Os tratamentos com quitosana nas concentrações de 1% e 2% mostraram-se efetivos com notas máximas até o final do armazenamento. No terceiro experimento, mangabas no estádio de vez foram acondicionadas em bandeja de poliestireno expandido recobertas com filme de policloreto de vinila. Em seguida, receberam os tratamentos para absorver etileno utilizando diferentes concentrações de permanganato de potássio (0; 1; 2 e 3%). As avaliações realizadas foram: perda de massa, firmeza, vitamina C, sólidos solúveis, acidez titulável, índice de maturação, pH, açúcar redutor e aparência visual. Os sachês contendo 1 e 2 gramas de permanganato de potássio ... / Abstract: This study aimed to evaluate the best conditions for postharvest fruit mangaba. The experiments were conducted in the laboratory of Food Technology of the University Estadual Paulista (UNESP) Campus Ilha Solteira. In the first experiment, the mangabas in three maturity stages were packed in polyethylene terephthalate, polystyrene trays covered with polyvinyl chloride film and plastic bag with closure. The treatments consisted of combinations between the degrees of maturation and packaging and were evaluated: loss of weight, firmness, vitamin C, pH, soluble solids, titratable acidity, maturation index, reducing sugars, polyphenoloxidase activity, peroxidase activity, chlorophyll and visual appearance. The best preservation was once the fruits packed in Styrofoam tray, keeping great rankings throughout the storage period. In the second experiment, mangabas the stadium in time were placed in polystyrene trays covered with polyvinyl chloride film. They received treatment with different chitosan concentrations (0, 0.25, 0.5, 1 and 2 %). Evaluations were loss of weight, firmness, vitamin C, soluble solids, titratable acidity, maturation index, pH, reducing sugar and visual appearance. Treatments with chitosan in concentrations of 1% and 2% were shown to be effective with maximal notes to the final storage. In the third experiment, mangabas the stadium in time were placed in polystyrene trays covered with polyvinyl chloride film. Then, received treatments to absorb ethylene using different concentrations of potassium permanganate (0, 1, 2 and 3%). Evaluations were weight loss, firmness, vitamin C, soluble solids, titratable acidity, maturation index, pH, reducing sugar and visual appearance. Sachets containing 1 and 2 grams of potassium permanganate provides better visual appearance mangabas of time. In the fourth experiment fruits mangaba receiving mild osmotic dehydration for 10 minutes was selected. Then taken to a dryer with forced hot ... / Doutor

Orientador: Rogério Lopes Vieites / Banca: Erica Regina Daiuto / Banca: José Maria Monteiro Sigrist / Resumo: O abacate é um fruto climatérico altamente perecível, e para sua comercialização é necessário que se faça uso de métodos de conservação pós colheita. O presente trabalho teve como objetivo a conservação do abacate 'Hass" com a utilização de 1- metilciclopropeno (1-MCP). Os frutos após a colheita foram selecionados e expostos a diferentes concentrações de 1-MCP (200 ppm, 300 ppm e 400 ppm) e após o procedimento foram armazenados sob refrigeração a 10ºC±1 e 90±5% de UR. Foram realizadas análises de perda de massa fresca, atividade respiratória, acidez titulável (AT), pH, sólidos solúveis (SS), índice de maturação, firmeza, compostos fenólicos totais, capacidade antioxidante determinada por DPPH, atividade das enzimas polifenoloxidase (PFO), poligalacturonase (PG) e pectinametilesterase (PME). As análises foram realizadas nos frutos a cada 3 dias, durante 15 dias, depois desse período os mesmos foram transferidos para condições ambiente ( 23±4ºC e 70±5% de UR) para simulação da comercialização. Após 3 dias em condições ambientes foi realizada a última avaliação. O delineamento utilizado foi inteiramente casualizado, com 3 repetições por tratamento, utilizando-se o teste de Tukey a 5% de probabilidade. Nas condições em que o trabalho foi realizado pode-se concluir que a aplicação de 1-MCP associada ao armazenamento refrigerado foi eficiente no controle do amadurecimento dos abacates 'Hass'. Os frutos sob aplicação de altas doses de 1-MCP apresentaram menor perda de massa ao longo do tempo. Quanto maior a dose de 1-MCP aplicada, menor o pico respiratório dos frutos, sendo que os frutos com aplicação de 400ppm de 1-MCP não apresentaram pico respiratório. O 1- MCP foi eficiente na manutenção da firmeza dos frutos porém não demonstrou efeitos sobre as enzimas poligalacturonase, pectinametilesterase e polifenoloxidase / Abstract: The avocado is a climacteric fruit highly perishable and their marketing is necessary making use of post harvest preservation methods. The present study aimed at the conservation of avocado 'Hass' with the use of 1-methylcyclopropene (1-MCP). The fruits after harvest were selected and exposed to different concentrations of 1-MCP (200 ppm, 300 ppm and 400 ppm) and after the procedure they were stored at 10 º C ± 1 to 90 ± 5% RH. Analyses of weight loss, respiratory activity, titratable acidity (TA), pH, soluble solids (SS), maturation index, firmness, total phenolics, antioxidant capacity determined by DPPH, enzyme activity of polyphenoloxidase (PPO) polygalacturonase (PG) and pectin (SMEs). The analyzes were performed on fruit every 3 days for 15 days, after this period they were transferred to ambient conditions (23 ± 4 ° C and 70 ± 5% RH) for simulation of marketing. After 3 days at ambient conditions the last appreciation was performed. The experimental design was completely randomized with three replicates per treatment, using the Tukey test at 5% probability. Under conditions in which the work was performed can be concluded that the application of 1-MCP associated with cold storage was effective in controlling the maturation of avocados 'Hass'. The fruits under application of high doses of 1-MCP showed less weight loss over time. The greater amount of 1-MCP applied, the lower respiration of the fruits and fruits with application of 400ppm of MCP-1 showed no respiratory peak. The 1-MCP was effective in maintaining fruit firmness but showed no effect on the enzymes Polygalacturonase, pectin and Polyphenoloxidase / Mestre

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South African ‘Eureka’ lemon fruit must be exposed to chilling temperatures (± 0.6°C) as a mandatory quarantine treatment against insect pests for all its overseas markets. Chilling lemon fruit at such temperatures may develop chilling injury (CI) symptoms on the flavedo. This negative effect on fruit quality reduces fruit marketability. This study evaluated postharvest factors influencing physiological, biochemical and ultra-structural mechanisms involved in alleviating CI in lemon fruit. It was hypothesised that treatment with methyl jasmonate (MJ) and salicylic acid (SA) may enhance chilling tolerance in lemon fruit by maintaining cellular integrity and inducing synthesis of enzymatic and non-enzymatic antioxidants. Furthermore, fruit susceptibility to CI was associated with the source of fruit. Lemon fruit were harvested from three locations representative of moderate subtropical, warm temperate and cool subtropical environments. Harvested fruit were treated either with 10 μM MJ, 2 mM SA or 10 μM MJ plus 2 mM SA, stored either at -0.5, 2 or 4.5°C for 0, 7, 14, 21, or 28 days and afterwards transferred to 23°C for a week as shelf-life simulation. Thereafter, fruit were evaluated for alterations in physiological, biochemical and ultra-structural features involved in the manifestation of CI symptoms. Chilling damage was more severe in untreated lemon fruit than in treated lemon fruit. Storing lemon fruit at 4.5°C accelerated the manifestation of CI symptoms more so than at 2°C while storage at -0.5°C delayed the manifestation of CI symptoms. Lemon fruit of moderate subtropical origin were more chilling-tolerant than lemon fruit of warm temperate and cool subtropical origin. Treatment with 10 μM MJ plus 2 mM SA significantly (P < 0.05) improved chilling tolerance in lemon fruit. This treatment effectively maintained membrane integrity, thereby retarding electrolyte leakage and membrane lipid peroxidation as well as mass loss and respiration rate. Treatment with 10 μM MJ plus 2 mM SA was also effective in enhancing the antioxidant concentrations of vitamin E and carotenoids. The production of these antioxidants could have been part of a defence system against chilling damage, reducing CI and maintaining fruit quality. Treatment with 10 μM MJ plus 2 mM SA enhanced the concentration of compounds involved in chilling resistance, such as proline, soluble sugars, ascorbic acid and total phenolics as well as the enzyme phenylalanine ammonia-lyase (PAL). The enhancement of the defence mechanisms may have played a role in enhancing chilling tolerance in lemon fruit. The treatment also inhibited certain enzymes involved in tissue browning, such as peroxidase (POD) which might have contributed to delaying manifestation of symptoms. Polyphenol oxidase (PPO) was found to not be a good biochemical marker of the occurrence of CI. Treatment with 10 μM MJ plus 2 mM SA appeared to be able to enhance chilling tolerance in lemon fruit by maintaining the ultra-structure of the cuticle, cell wall integrity, cell membrane of parenchyma cells of the flavedo. This treatment also preserved the mineral nutrients of the flavedo (carbon, oxygen, phosphorus, potassium, calcium, magnesium, sulphur, sodium, silicon and aluminium) during cold storage. This could have played a role in protecting the fruit against chilling stress and maintaining fruit quality. Treatment with 10 μM MJ plus 2 mM SA reduced ROS production, while the activity of enzymatic antioxidants such as catalyse (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), and accumulation of essential proteins was enhanced. This increase in activity of enzymatic antioxidants and the presence of stress-responsive proteins in the lemon flavedo could have been directly involved in enhancing chilling tolerance. The CI symptoms were accompanied by an increase in membrane permeability, membrane lipid peroxidation as well as phospholipase D (PLD) and lipoxygenase (LOX) activity; however, treatment with 10 μM MJ plus 2 mM SA effectively reduced the membrane permeability, membrane lipid peroxidation, and PLD and LOX activity induced by the cold treatment. This could have contributed to the efficacy of 10 μM MJ plus 2 mM SA in inhibiting the manifestation of CI symptoms. Treatment with 10 μM MJ plus 2 mM SA enhanced flavedo total antioxidant capacity measured by ferric reducing ability of plasma; 2,2-diphenyl-1-picrylhydrazyl; 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) and the oxygen radical absorption capacity assays. The enhancement of antioxidant capacity in lemon flavedo could have contributed to the fruit’s chilling tolerance. Therefore, the effect of 10 μM MJ plus 2 mM SA treatment, enhancing chilling tolerance, may be attributed to its ability to enhance enzymatic and non-enzymatic antioxidants; activate essential proteins and mitigate the effect of ROS accumulation. With the use of 10 μM MJ plus 2 mM SA treatments, the South African citrus industry will be able to meet the quarantine temperature requirements for exportation of lemon fruit whilst reducing economic losses, depending on the preharvest conditions experienced by the fruit in each shipment. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.