‘Fuerte’ makes up 25% of the avocados exported from South Africa to European markets and requires shipping periods of up to 28 days and a correctly managed cold chain. A temperature of 5.5°C and expensive CA and 1-MCP treatments are currently used to delay ripening over this lengthy cold chain; however, fruit still appear on the European market showing signs of softening and physiological disorders. Increased competition on the global market and the disadvantage of a particularly long distance to the European market has challenged the South African export industry. These challenges have necessitated improved road and sea transport logistics, co-ordination with producing countries which supply fruit to European markets over similar periods as South Africa, and research into ultra-low temperature storage to possibly enable future access to new lucrative markets in the USA, China and Japan. It is also known that there are various ‘weak links’ in this cold chain and that cold chain breaks are detrimental to fruit quality, but further research into the negative effects of these cold chain breaks at ultra-low temperatures was needed. Thus, the objective of the study was to determine the potential for shipping ‘Fuerte’ avocados at temperatures of 2°C as well as determining the effects of cold chain breaks on fruit quality, throughout the growing season and possibly for an extended period of 56 days. ‘Fuerte’ avocados were harvested at three different maturity stages reflecting early-, mid- and late-season fruit, with moisture contents of 74%, 68% and 63%, respectively. Fruit were stored at 2°C or 5.5°C, treated with 1-MCP and waxed. Additionally cold chain breaks (24 hour delay and break at 14 days) were implemented. Fruit softening, mass loss, days-to-ripening, external and internal quality as well as antioxidant levels and total sugar levels were determined. The first aim was to determine whether a lower than currently used storage temperature could be a successful alternative to 1-MCP use. A storage temperature of 2°C provided good internal quality as well as reduced mass loss and fruit softening, which is related to the slightly reduced use of C7 sugars at 2°C compared with 5.5°C. Although the overall occurrence of external chilling injury was relatively low, 2°C storage caused a notably higher occurrence of external chilling injury than 5.5°C storage, particularly early in the season, but extended the days-to-ripening. Unfortunately, no correlation between the anti-oxidants in the exocarp and external damage was found. Waxing significantly reduced the external damage on fruit stored at 2°C, so much so, that the treatment combinations of ‘2°C, no 1-MCP, waxed’ showed no external chilling injury throughout the season. Further, waxing fruit at 2°C could eliminate the need for 1-MCP, delivering a product of the required shelf-life and quality. Best results were achieved for mid-season fruit stored at 2°C. Late-season fruit would potentially be the most profitable to store at this low temperature, however, body rots (anthracnose and stem-end rot) were more common in the late-season. Storage at 2°C can therefore maintain the internal quality over a storage period of 28 days and be a potential alternative to 1-MCP use as the season progresses. The effect of cold chain breaks on fruit quality was then investigated and showed that both a delay and a break in the cold chain increased mass loss and fruit softening, reduced days-to-ripening and increased external chilling injury, especially early in the season. Water loss was the main contributor to the decreased fruit quality which resulted from the delay in cooling, increasing external damage significantly, particularly early in the season. The break at 14 days had a marked effect on physiological activity of fruit during storage, seen mainly in the increased metabolic activity, resulting in increased fruit softening and water loss during storage and a decrease in C7 sugars and thus shelf-life, particularly for fruit stored at 5.5°C. Importantly, 1-MCP use and storage at 2°C reduced the effects of cold chain breaks with respect to fruit softening, however, lowering the storage temperature had a greater negating effect than 1-MCP and could be a successful alternative to the use of 1-MCP. The internal quality throughout the experiment was very good, with few internal disorders and no significant treatment effects on internal quality and C7 sugar concentrations. Overall, a break in the cold chain, before and during cold storage, resulted in a marked reduction in fruit quality. The storage temperature of 5.5°C should not be used for a 56 day storage period as it resulted in significant fruit softening during storage, even when 1-MCP was used, and resulted in significantly more external chilling injury in the mid- and late-season than at 2°C. Storage of 1-MCP treated, waxed fruit at 2°C, resulted in the best shelf-life and fruit quality, particularly mid-season fruit which had negligible external chilling injury and 100% sound fruit. Early-season fruit suffered significant external chilling injury at 2°C and late-season fruit had the highest body-rots and internal disorders at this storage temperature. Although mid-season fruit could be successfully stored at 2°C for 56 days, the use of a 56 day storage period is not recommended as a practical storage period, due to the high risk of external damage, particularly if maturity levels are not optimum and trees and fruit are not of the highest quality. Overall this thesis has shown that 1-MCP treatment can play an important role early in the season when fruit are susceptible to external damage, however, storage at 2°C results in good quality fruit and, when used in conjunction with waxing, appears to be a viable alternative to the use of 1-MCP, particularly later in the season. Further, the negative effects of cold chain breaks on fruit quality have been demonstrated and, importantly, the storage temperature of 2°C negates the fruit softening effects of these breaks, even if 1-MCP is not used. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The use of sulphur as a method of postharvest disease control and colour retention in litchis is soon to be restricted by the European Union. It is therefore essential that new postharvest treatments and packaging techniques be developed in order to retain internal and external fruit qualities and thus allow for export. Good litchi quality is not only important for the export market but also for use on the local market. In this study, alternative methods for postharvest quality control were investigated with the aim of extending the litchi storage life to 40 days under modified storage. Packaging the fruit in polypropylene bags significantly decreased fruit water loss and resulted in an increase in shelf life, as determined by red colour and overall rind appearance. There was no distinct advantage of amodified atmosphere. The use of a punnet, lined with absorbent sheeting and placed within the sealed polypropylene bag, further improved the shelf life. The absorbent sheeting reduced the amount of free water and resulted in little pathogen infection, while the punnet was effective in protecting the fruit from damage. It was notable that most water loss occurred within the first 10 days of storage and that the majority would actually take place during the cooling phase. A hydrocooling technique was therefore investigated and was found to not significantly decrease water loss, possibly due to not hydrocooling the fruit for a long enough period of time. Temperature management was extremely important for both colour retention and pathogen control. It was found that treatments stored at 5.5QC showed better colour retention after the 40 days storage than the 1QC storage treatment. The higher storage temperature, however, enhances the potential for postharvest diseases. Three compounds, namely ISR 2000, 'Biosave' and F10, were tested for pathogen control. 'Biosave' showed the best results with the most effective concentration being 100 mill water and good pathogen control occurred when storage was at 10 C. Polyphenol oxidase (PPO) activity in the litchi rind was evaluated as it is thought to be closely related to browning of litchi fruit, probably due to the degradation of phenolics by PPO. Brown fruit had a high PPO activity whilst red fruit had much lower activity. It was also shown that PPO activity decrease over storage time, possibly due to product inhibition of the enzyme. The internal quality of the fruit was determined using the T88: acid ratio of the pulp, as it is well correlated to mean eating quality. For fruit to have excellent taste, it must have a T88: acid ratio of between 31:1 and 60:1. All the fruit had a ratio that met this criterion and would therefore ensure good eating quality. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.

South Africa is the second largest exporter of citrus fruit in the world. There has recently emerged a strong demand for lemons in the world market due to their nutritional value, culinary and non-culinary uses. During exportation, fruit are subjected to low temperature (-0.5°C) for varying periods of time as an obligatory quarantine treatment. However, lemons are sensitive to low temperatures and easily develop chilling injury during this obligatory quarantine treatment. This has become a major limitation to the expansion of South Africa’s lemon industry. Postharvest treatments with methyl jasmonate (MJ) and / or salicylic acid (SA) have been successfully used in horticultural crops to reduce chilling injury. A similar treatment was applied to ‘Eureka’ lemons. During the 2008 harvest season, postharvest fruit were either dipped in 10 or 50 μM MJ or 2 or 2.5 mM SA solutions. A control or no dip treatment was also applied. Three replicates of 15 fruits per treatment were used. During the 2009 harvest season the following postharvest treatments were applied as dips: 10 μM MJ, 2 mM SA, 10 μM MJ & 2 mM SA, 1 μM MJ & 0.2 mM SA, or 0.1 μM MJ & 0.02 mM SA solutions. A control or no dip treatment was also applied. Three replicates of 15 fruits per treatment were used. Subsequently fruit were stored at -0.5ºC for 0, 7, 14, 21, 28, 35, and 42 days, before being transferred to room temperature (25°C) for 7 days where after chilling injury was rated. Treatments with 10 μM MJ and / or 2 mM SA reduced chilling injury symptoms in lemons harvested during the 2009 season. Although no visual symptoms of chilling injury were observed during the 2008 harvest season, treatments with 10 μM MJ and / or 2 mM SA reduced fruit mass loss, delayed the occurrence of stress symptoms such as lipid peroxidation and suppressed accumulation of ROS in the rind. Treatments with 10 μM MJ and / or 2 mM SA were more effective in inducing antioxidant capacity and other defence compounds such as phenolics, ascorbic acid, carbohydrates and chilling injury responses such as accumulation of proline in the rind. This may have increased the chilling tolerance of fruit during the cold storage. Therefore, this study revealed that MJ and SA have the potential to reduce and delay symptoms of chilling injury in lemons. This lead to the suggestion that both, MJ and SA dips should be further tested as treatments to mitigate chilling injury in lemons. Future studies should focus more on preventing the injury itself or preventing the primary event of chilling injury. This could probably reduce the chances of secondary events to take place. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Rind colour is one of the most important external quality characteristics of citrus fruit and plays an important role in purchasing decisions by consumers. Consumers perceive brightlycoloured fruit to be sweet and mature, whereas citrus with a green rind is perceived to be sour and immature. However, there is a poor correlation between rind colour and internal quality, contradicting what is generally assumed by the fruit-buying public. In general, a bright orange rind colour improves consumer acceptance. Thus, it is important to ensure that the rind of citrus fruit is well-coloured on arrival at the market. Various pre-harvest cultural practices and postharvest techniques can be applied to improve rind colour. Degreening with ethylene gas is the most commonly used postharvest technology to improve rind colour, but has various negative side-effects. Degreened fruit are more prone to decay, have rinds which appear dull and flaccid, have been reported to develop off-flavours and have a shorter shelf-life period. Therefore, it is necessary to find alternatives to ethylene degreening and to extend shelf-life of citrus fruit. Under normal orchard conditions, rind colour development is associated with low night temperatures, usually experienced during autumn or following the passing of a cold front. To simulate cold front conditions, a hydrocooler and cold room were used to rapidly drop fruit temperature to 4 ºC for 6 hours, and then fruit were incubated at 20 to 22 ºC for 72 hours. This “cold shock” treatment of ‘Nules Clementine’ mandarin improved rind colour to a level similar to that of degreened fruit in the 2002 season due to a decrease in chlorophyll content and increase in carotenoid content. However, this result could not be repeated. Storage temperature is one of the most important postharvest factors affecting rind colour. Citrus fruit shipped to export markets requiring low temperatures (-0.6 ºC) for pest disinfestations purposes have been reported to arrive with poor rind colour. Shipping under low temperatures results in poor rind colour of fruit on arrival in the market. To comply with the USA’s phytosanitary requirement for imported citrus, fruit is held at -0.6 ºC for a minimum of 22 days. The effect of shipping at various temperatures (-0.6 ºC or 4.5 ºC), durations and the influence of initial rind colour, “orange” or “yellow”, on fruit colour upon arrival in the market was evaluated. Fruit shipped at a higher temperature (4.5 ºC) had a marginally better rind colour than fruit shipped at -0.6 ºC. The perceived loss of rind colour following shipping at sub-zero temperatures is probably due to carotenoid degradation. Therefore, initial rind colour plays a critical role in final product quality. Depending on market destination and shipping temperature, pale-coloured fruit should not be packed for markets sensitive to rind colour. Holding temperature after shipping can be effectively used to improve the rind colour of fruit arriving in the market with undesirable rind colour. An intermediate holding temperature of between 11 and 15 ºC resulted in the greatest improvement in rind colour after 2 weeks. A high holding temperature (20 ºC) caused colour degradation, whereas a low holding temperature (4.5 ºC) resulted in the maintenance of rind colour. By selecting the correct holding temperature, even after shipping at sub-zero temperatures, final colour can be improved. / AFRIKAANSE OPSOMMING: Tyd-temperatuur interaksie op na-oes skilkleur ontwikkeling by sitrus Skilkleur is een van die belangrikste eksterne kwaliteitseienskappe van die sitrusvrug en spëel ʼn belangrikke rol in wat verbruikers koop. Verbruikers verwag dat heldergekleurde vrugte soet en ryp sal wees, terwyl sitrus met ʼn groen skil geassosieer word met onrypheid en ʼn suur smaak. In teenstelling hiermee is daar egter ʼn swak korrelasie tussen skilkleur en interne kwaliteit. Aangesien ʼn heldergekleurde oranje skil verbruikersaanvaarding verbeter, is dit dus belangrik om te verseker dat die sitrusvrug ʼn goeie skilkleur het teen die tyd wat dit die mark bereik. Verskeie voor-oes bestuurspraktyke en na-oes tegnieke kan toegepas word om die skilkleur te verbeter. Ontgroening met etileen gas is die tegnologie wat mees algemeen gebruik word om skilkleur na oes te verbeter, maar dit het egter verskeie newe effekte tot gevolg. Ontgroende vrugte is meer vatbaar vir bederf en verwelkde skille met ʼn dowwe voorkoms. Afsmaake kan voorkom en ʼn verkorte rakleeftyd is al gerapporteer. Dit is dus noodsaaklik om ʼn alternatief vir etileen ontgroening te ontwikkel en die rakleeftyd van sitrusvrugte te verleng. Onder normale boordomstandighede word skilkleur ontwikkeling geassosieer met lae nag temperature wat gewoonlik in die herfs of na ʼn kouefront ondervind word. Om soortgelyke omstandighede na te boots, was ʼn “hydrocooler” en koelkamers gebruik om die temperatuur vinnig te laat daal tot by 4 °C en dit vir 6 uur daar te hou. Die vrugte was dan by 20 tot 22 °C geinkubeer vir 72 uur. Hierdie “koueskok” behandeling van ‘Nules Clementine’ mandaryn het skilkleur verbeter tot ʼn vlak vergelykbaar met ontgroende vrugte in die 2002 seisoen wat ontstaan het weens ʼn verlaging in chlorofil en ʼn toename in die karotinoïed inhoud van die skil. Opbergingstemperatuur is een van die belangrikste na-oes faktore wat skilkleur beinvloed. Sitrusvrugte wat verskeep word na uitvoermarkte wat lae temperature (-0.6 °C) vir disinfestasie vereis arriveer soms by die mark met ʼn swak skilkleur. Om die fitosanitêre vereistes vir die invoer van sitrus deur die VSA na tekom, was vrugte vir ʼn minimum van 22 dae by -0.6 °C gehou. Die effek van verskeping by verskeie temperature (-0.6 °C of 4.5 °C), tydperke en die invloed van aanvanklike skilkleur, “oranje” of “geel” was geevalueer by aankoms in die mark. Vrugte wat by hoër temperature (4.5 °C) verskeep was het ʼn effens beter skilkleur as vrugte by -0.6 °C getoon. Die verlies in skilkleur wat waargeneem word na verskeping onder vriespunt kan moontlik toegeskryf word aan karotenoiëd afbraak. Daarom speel aanvanklike skilkleur ʼn kritieke rol in finale produk kwaliteit. Die finale mark bestemming en verskepingstemperatuur sal bepaal of swakgekleurde vrugte verpak kan word. Opbergingstemperatuur na verskeping kan effektief gebruik word om die skilkleur van vrugte wat swak gekleur was met aankoms by die mark te verbeter. Matige temperature tussen 11 en 15 °C het na 2 weke die beste verbetering in skilkleur gelewer. Hoër temperature (20 °C) het skilkleur nadelig beinvloed, terwyl lae temperature skilkleur behou het. Deur die korrekte temperatuur te kies, selfs na verskeping by temperature onder vriespunt, kan uiteindelike skilkleur steeds verbeter word.

Orientador: Paulo Ademar Martins Leal / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-13T09:54:07Z (GMT). No. of bitstreams: 1 CastilloPizarro_CintyaAlejandra_D.pdf: 538268 bytes, checksum: a0775d761ca852aadb1dc74aa8998449 (MD5) Previous issue date: 2009 / Resumo: O morango é produzido e apreciado nas mais variadas regiões do mundo, sendo a espécie de maior expressão econômica entre as pequenas frutas. O Estado de São Paulo é um dos seus maiores produtores no Brasil. De todo o ciclo produtivo do morango, a comercialização tem se mostrado a fase mais complexa e problemática, podendo afetar mais o lucro do que todas as outras etapas de produção. Isso ocorre devido às características do produto, como fragilidade, manuseio inadequado, alta perecibilidade e falta de embalagens e de refrigeração adequados. Por possuir elevado valor comercial, principalmente no mercado in natura, a tecnologia do frio para sua melhor conservação pós-colheita, pode ser utilizado para manter as boas características de qualidade do fruto. Este trabalho teve por objetivo geral definir qual a melhor condição pós-colheita para conservação de morangos quanto a embalagem cumbucas de tereftalato de polietileno (PET) ou em meia cumbuca de tereftalato de polietileno, envoltas por filme de policloreto de vinila (PVC), resfriamento rápido e armazenamento refrigerado, visando seu consumo in natura. Realizaram-se dois experimentos, sendo um para monitoramento da taxa respiratória dos pseudofrutos a 0°C, 5°C, 10°C e 15°C em dois sistemas (sistema de fluxo contínuo e sistema estático). Outro experimento foi feito para avaliar a resposta da fruta expressa pelos parâmetros respiração, sólidos solúveis, pH e acidez titulável, quando estes foram submetidos a processos de resfriamento rápido e armazenagem. As variedades avaliadas foram Camarosa, Sweet Charlie, Dover e Oso Grande. Neste experimento utilizou-se câmaras de armazenamento com regulagem de 0 e 10°C, e os frutos foram embalados em cumbucas PET e PVC. As frutas foram analisadas a cada dois dias, até ficarem impróprias para o consumo. Verificou-se que o melhor método para avaliação da taxa respiratória é o método do sistema de fluxo contínuo, por possuir um fluxo constante durante todo o experimento, assim como melhor reprodutibilidade dos tempos de retenção e da quantificação do CO2 dentro dos frascos. A temperatura 0°C, foi a que possibilitou a maior vida de prateleira dos frutos. Não se observou diferença entre as embalagens PET e PVC no armazenamento a 0°C e a 10°C. Das variedades avaliadas a Sweet Charlie é a que se mostrou mais indicada para consumo in natura, devido suas características fisico-químicas. Enquanto a variedade Camarosa a mais indicada para indústria. / Abstract: The strawberry is cultivated and appreciated in several regions around the world, being the specie with the most economical value among the small fruits. The São Paulo state is one of the biggest producers in Brazil. From all productive cycle of strawberry the commercialization has shown the most complex and problematic phase, and it can affect more the profit than all the others. This happens due to the product characteristics, such as fragility, improper handling, high perishable, inadequate packaging, and use of cold chain. Since strawberry has high commercial value, mainly on in natura maket, the cold chain technology may be used to keep the good characteristics of fruit quality. The objectives were to define which are the best conditions postharvest for the strawberry fruits in terms of packing PET or PVC, precooling and refrigerated storage aiming the consumption in natura. Two experiments were realized, being one to monitoring and evaluating the respiratory rate of the fruits at the temperatures of 0, 5, 10 and 15°C in two different systems: continuous flow system, and static flow system, in BOD's. The other experiment was to evaluate the answer of biochemical parameters (respiration rate, soluble solids, pH and titratable acidity) submitted to the precooling and refrigerated processes using the Camarosa, Sweet Charlie, Dover, and Oso Grande varieties. For this experiment was used chambers at 0 and 10oC, and the fruits had been packed in packs of tereftalate of polyethylene (PET) clam shell type, and packs of tereftalate of polyethylene (PET) wrap with PVC film. Physical-chemical analyses were carried every two days until the fruits got improper for consumption. The experiment show that the optimum method for evaluation respiratory rate is the one using the continuous flow system since presented a constant flow during all the experiments, and allows better accuracy for the retention time and CO2 quantification inside of the bottles. The temperature of 0°C was the one that shows longest fruits shelf life time. There were not differences between packs of tereftalate of polyethylene (PET) clam shell type and packs of tereftalate of polyethylene (PET) wrap with PVC film storaged at 0 and 10°C. Among the varieties, the Sweet Charlie was the most indicated for in natura consumption, due to its physical-chemical characteristics. Meanwhile the variety Camarosa was the most appropriate for industry use. / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola

Orientador: Barbara Janet Teruel Mederos, Paulo Ademar Martins Leal / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-20T03:40:17Z (GMT). No. of bitstreams: 1 Tinini_RodolphoCesardosReis_M.pdf: 2113855 bytes, checksum: bf35d4b21243161421a237dd2edcc622 (MD5) Previous issue date: 2012 / Resumo: A hortaliça folhosa mais consumida e produzida no Brasil é a alface (Lactuca sativa L.) e seu consumo vem crescendo a cada ano devido a uma tendência da população mundial em adquirir hábitos de vida mais saudáveis. Existem diferentes métodos de resfriamento para conservação pós-colheita, já utilizados e aplicados em olerícolas, porém não se tem conhecimento sobre seus efeitos e benefícios para a alface. O objetivo deste estudo foi avaliar a aplicação de diferentes métodos de resfriamento e sua adequação para diferentes variedades de alface. Os tipos de alfaces analisadas foram a repolhuda crespa ou americana, a solta crespa, a repolhuda lisa e a solta lisa, adquiridas de um produtor da região de Campinas-SP. Foram avaliados três métodos de resfriamento seguidos de acondicionamento em câmara fria a 5ºC: resfriamento com ar forçado (com controle da umidade relativa do ar e sem controle da umidade relativa do ar), resfriamento evaporativo em túnel (nebulização e ventilador-meio poroso) e resfriamento com água fria (imersão e aspersão), sendo que o controle consistiu apenas no acondicionamento do produto em câmara fria a 5ºC, e os parâmetros físico-químicos (pH, ácido ascórbico, clorofila e perda de massa). O delineamento experimental foi inteiramente casualizado (DIC) com cinco repetições por tratamento, observando-se a interação entre os métodos de resfriamento e tempo de armazenamento, e estes parâmetros foram submetidos à análise estatística multivariada aplicando-se a análise de componentes principais. Conclui-se que o melhor método para o resfriamento de alface é o do ar forçado com umidificação, pois equilibra eficiência de resfriamento e menor degradação do produto. O resfriamento da alface pelo método evaporativo apresenta uma lenta retirada de calor especifico, desfavorecendo a manutenção da vida útil do produto, assim como o método por água fria que causa acúmulo de água no interior do produto facilitando as reações de deterioração. Com relação à análise de custo energético, o resfriamento de alface pelo método ar forçado se torna mais interessante em termos de aplicabilidade e manutenção da qualidade do produto, mesmo apresentando um maior custo se comparado ao resfriamento de alface pelo método evaporativo / Abstract: The leafy vegetable most consumed and produced in Brazil is the lettuce (Lactuca sativa L.) and its consumption is growing up every year due a tendency of world population to acquire healthier lifestyle. There are different cooling methods for post-harvest quality, already used and applied in vegetable crops, but there is no knowledge about yours effects and benefits for lettuce. The objective of this study was evaluating the application of different cooling methods and their suitability for different varieties of lettuce. The types of lettuce analyzed were "repolhuda crespa" ou "americana", a "solta crespa", a "repolhuda lisa" e a "solta lisa", acquired from a region producer in Campinas-SP. We evaluated three cooling methods followed to a storage in cold chamber at 5 ° C: forced air cooling (with relative humidity control and no relative humidity control), evaporative cooling tunnel (misting and porous-fan) and hydroccoling (immersion and spray), and control consisted in the product cold storage at 5°C, was evaluate the physic-chemical parameters (pH, ascorbic acid, chlorophyll and weight loss). The experimental design was completely randomized, with five replicates per treatment, observing the interaction between cooling methods and storage time, and these parameters were subjected to multivariate statistical analysis with applying the principal component analysis. It is concluded that the best method for cooling lettuce is forced air with humidification it balances cooling efficiency and less degradation of the product. The cooling of the lettuce by evaporative method has a slower specific heat removed, which does not favor the maintenance product shelf-life, as well as the hydrocooling causes water accumulation in the product facilitates the degradation reactions. Regarding the analysis of cost energy, the cooling lettuce by forced air method becomes more interesting in terms of applicability and maintenance at product quality, even with a higher cost compared to the cooling of lettuce evaporative method / Mestrado / Tecnologia Pós-Colheita / Mestre em Engenharia Agrícola

Orientador: Kil Jin Park / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-04T17:29:42Z (GMT). No. of bitstreams: 1 Silva_Francelida_D.pdf: 2636831 bytes, checksum: b62ffc8d2eda94de17cee0e541f7b44b (MD5) Previous issue date: 2005 / Resumo: No Brasil o uso terapêutico de plantas medicinais está cada vez mais crescente. Várias empresas nacionais e internacionais empregam matéria-prima vegetal na elaboração de seus produtos, o que torna indispensável o cultivo comercial e o beneficiamento pós-colheita destas espécies. O objetivo deste trabalho foi estudo pós-colheita de duas espécies medicinais de importância econômica, a calêndula (Calendula officinalis L.) e a carqueja (Baccharis genistelloides var. trimera (Less). Baker var. trimera (Less). Backer). Nas duas espécies foi avaliado o melhor processo de secagem, utilizando três diferentes secadores, secador convectivo vertical, secador a gás e estufa com circulação forçada de ar, em três diferentes temperaturas, 30, 45 e 60°C, bem como o armazenamento das mesmas em três embalagens diferentes, polietileno de baixa densidade, vidro e papel kraft. Os processos de secagem foram avaliados em função do teor de óleo essencial de cada espécie e sua composição química. As isotermas e as curvas de secagem foram levantadas e tratadas com os modelos matemáticos, Bet, Bet linear, Peleg. Gab, Hasley, Lagmuir, Oswin, Henderson e Chung. As diferentes temperaturas não interferiram nos parâmetros avaliados, quanto ao óleo de calêndula, em todos os secadores, mas diferiram entre os diferentes secadores utilizados, sendo que, entre os secadores o que manteve os maiores teores de óleo de calêndula foi o secador convectivo vertical. No caso da carqueja, não houve diferenças relacionadas com as temperaturas e nem com os tipos de secadores. Ao longo do armazenamento, a embalagem Kraft foi a que melhor preservou a integridade física e química do produto, assim como, manteve o teor de óleo ao longo de um ano de armazenamento nas duas espécies / Abstract: In Brazil, the therapeutical use of medicinal plants is increasing each time. Some national and international companies use vegetal raw material in the elaboration of its products, so the commercial cultivation and the improvement of harvest of these species becomes indispensable. The objective of this work was to study post-harvest of two medicinal species with economic importance: calendula (Calendula officinalis L.) and carqueja (Baccharis genistelloides var. trimera (Less). Baker). In these two species the best process of drying was evaluated, using three different dryers, convective vertical dryer, the gas dryer, and oven with forced air circulation, with three different temperatures, 30, 45 and 60°C, as well as using three different packing materials: polyethylene of low density, glass and kraft paper. The drying processes was evaluated in relation of the essential oil and its chemical composition of species. The isotherms and the drying curves were obtained and treated with mathematical model, Bet, Bet linear, Peleg. Gab, Hasley, Lagmuir, Oswin, Henderson e Chung. The differents temperatures did not show the difference in the process of drying in calendula in each different driers, but they differed among the driers, and the drier that kept more oil content of calendula was the convective vertical dryer. In the case of carqueja, no differences were found in the different temperatures or the different driers used in drying. During the storage, the kraft packing material was the one that better preserved the physical and chemical integrity of the product, as well as, it kept the oil content throughout one year of storage time for these two species / Doutorado / Tecnologia Pós-Colheita / Doutor em Engenharia Agrícola

[EN] In recent years, persimmon crop has become very relevant in Mediterranean Spain, where the production of this fruit centres on only one variety, persimmon cv. Rojo Brillante, majorly located in the Valencian Community. The main postharvest disorders manifested by 'Rojo Brillante' persimmons are flesh browning, which is associated with mechanical damage and chilling injury displayed after low-temperature storage. Previous research has determined the postharvest conditions that lead fruit to develop such alterations. However, the biochemical process behind flesh browning and chilling injury disorders is still unknown. Currently, there is special interest in introducing cultivars from other countries to broaden the varietal range. Besides, prolonging the fruit storage period to supply the markets according to the demand is one of the main challenges. In this context, the present Thesis approached three main objectives: 1) Studying the biochemical process implied in the main physiological postharvest disorders manifested in persimmon fruits by focusing on changes in the fruit redox state; 2) Evaluating postharvest treatments to preserve fruit quality during cold storage; 3) Assessing the physico-chemical and nutritional quality of persimmon cultivars introduced from other countries to increase the varietal range. Biochemical, chromatographic and microstructural studies have revealed that flesh browning manifested by fruits submitted to mechanical damage after removing astringency is associated with a tannins oxidation process caused by a stress oxidative situation. A new flesh disorder, "pinkish bruising", has been described on fruits submitted to mechanical impacts while showing high astringency levels. Sensitiveness to the flesh browning disorder has also been evaluated on different cultivars introduced from other countries. The implication of the redox system in the chilling injury manifestation on 'Rojo Brillante' persimmon has been determined. Moreover, we described the changes in this system associated with chilling injury alleviation by 1-MCP treatment. The effect of a controlled atmosphere based on 4-5% O2 + N2 to prolong the storage of cultivars 'Rojo Brillante' and 'Triumph' has been seen to strongly depend on variety. The results were highly positive on cultivar 'Triumph', in which the evaluated atmosphere extended the storage period up to 3 months. The use of short-term high CO2 treatments was another technology assayed to alleviate chilling injury in non-astringent cultivar 'Fuyu'. This treatment significantly reduced the main chilling injury symptom manifested by this cultivar, which is flesh gelling. This effect was related to cell structure preservation. Recent studies have shown that ethyl formate treatment is highly effective for pest control of persimmon 'Fuyu'. However, this treatment induces fruit softening, which causes quality loss. This Thesis revealed that ethyl formate treatment induces the activity of ethylene synthesis-related genes and that flesh softening is mediated by this hormone. It also demonstrated that by applying 1-MPC pretreatment, fruit softening associated with ethyl formate can be controlled. Therefore, the combined used of both treatments is seen as a potential treatment to disinfect persimmon fruits while preserving quality. Finally, the study of ten cultivars introduced from other countries helped select the most interesting cultivars to broaden the varietal range according to their maturation date and their response to deastringency treatment. The main nutritional compounds of persimmon and how they are affected by CO2 deastringency treatment are described. / [ES] El caqui es un cultivo de gran relevancia en el área mediterránea de España, estando la producción centrada en una única variedad, el cv. Rojo Brillante, y localizada principalmente en la Comunidad Valenciana. Las principales alteraciones presentadas por el caqui 'Rojo Brillante' durante el periodo postcosecha son el pardeamiento de la pulpa asociado a los daños mecánicos y los daños por frío manifestados tras la conservación a bajas temperaturas. Las investigaciones previas han determinado las condiciones de manejo bajo las cuales se desarrollan dichas alteraciones, sin embargo los procesos bioquímicos involucrados en la manifestación de estos desórdenes no se conocen en profundidad. Actualmente uno de los principales retos es la introducción de nuevas variedades que permitan ampliar la gama varietal, así como prolongar los periodos de conservación del caqui con el fin de poder escalonar la puesta en el mercado en función de la demanda. En la presente Tesis se han abordado tres objetivos principales: 1) Estudiar los procesos bioquímicos implicados en los principales desórdenes postcosecha del caqui, prestando especial atención a los cambios en el sistema redox del fruto; 2) Evaluar diferentes tratamientos postcosecha para preservar la calidad del fruto durante la conservación frigorífica; 3) Evaluar la calidad físico-química y nutricional de diferentes variedades de caqui introducidas desde otros países para ampliar la gama varietal. Estudios bioquímicos, cromatográficos y microestructurales, han revelado que el pardeamiento de la pulpa o "browning", manifestado por la fruta que ha sufrido daños mecánicos tras la eliminación de la astringencia está asociado a un proceso de oxidación de taninos motivado por una situación de estrés oxidativo. Además se ha descrito una nueva alteración de la pulpa, "pinkish bruising", manifestada por los frutos sometidos a daño mecánico con alto nivel de astringencia. También se ha evaluado la sensibilidad al pardeamiento de diferentes variedades introducidas desde otros países. Con el objetivo de prolongar la conservación del fruto se ha ensayado el uso de la atmósfera controlada basada en 4-5% O2 + N2 sobre las variedades 'Rojo Brillante' y 'Triumph', observándose que la respuesta a esta tecnología depende de manera muy importante de la variedad. Los resultados fueron especialmente positivos en el caso del cultivar 'Triumph', en el que la atmósfera ensayada permitió prolongar la conservación frigorífica hasta tres meses. Otra tecnología ensayada para el control de los daños por frío fue la aplicación de choques con altas concentraciones de CO2 en el cultivar no astringente 'Fuyu'. Este tratamiento alivió el principal síntoma de daño por frío manifestado por esta variedad, la gelificación de la pulpa. Este efecto se ha relacionado con la preservación de la estructura celular de la pulpa del fruto. Estudios recientes han mostrado que el tratamiento con etil formato es altamente efectivo en el control de insectos durante la conservación y comercialización del caqui 'Fuyu', sin embargo este tratamiento provoca un ablandamiento del fruto mermando su calidad. En esta Tesis se ha demostrado que las aplicaciones de etil formato activan los genes de síntesis de etileno, siendo está hormona mediadora del ablandamiento. Los estudios también revelaron que la aplicación de un tratamiento previo con 1-MCP reduce el ablandamiento del fruto asociado al etil formato, por lo que el uso combinado de ambos tratamientos puede ser considerado una alternativa para la desinfección de los frutos sin detrimento de su calidad. Por último, el estudio de diez variedades introducidas desde otros países permitió seleccionar en base a su momento de maduración y respuesta al tratamiento de desastringencia aquellas variedades de mayor interés para ampliar la gama varietal. Además, se identificaron los principales compuestos nutricionales del caqui y / [CAT] El caqui s'ha convertit en els últims anys en un cultiu de gran rellevància en l'àrea mediterrània d'Espanya, estant la producció centrada en una única varietat, el cv. Rojo Brillante, i localitzada principalment a la Comunitat Valenciana. Les principals alteracions presentades pel caqui 'Rojo Brillante' durant el període postcollita són l'enfosquiment de la polpa associat als danys mecànics i els danys per fred manifestats després de la conservació a baixes temperatures. Les investigacions prèvies han determinat les condicions de maneig sota les quals es desenvolupen estes alteracions, però els processos bioquímics involucrats en la manifestació d'estos desordres no es coneixen en profunditat. D'altra banda, actualment un dels principals reptes és la introducció de noves varietats que permetin ampliar la gamma varietal, així com prolongar els períodes de conservació del caqui per tal de poder escalonar la posada en el mercat en funció de la demanda. En este context, en la present Tesi s'han abordat tres objectius principals: 1) Estudiar els processos bioquímics implicats en els principals desordres postcollita del caqui, posant especial atenció als canvis en el sistema redox del fruit; 2) Avaluar diferents tractaments postcollita per preservar la qualitat del fruit durant la conservació frigorífica; 3) Avaluar la qualitat fisicoquímica i nutricional de diferents varietats de caqui introduïdes des d'altres països per ampliar la gamma varietal. Estudis bioquímics, cromatogràfics i microestructurals, han revelat que l'enfosquiment de la polpa o "Browning", manifestat per fruita que ha patit danys mecànics després de l'eliminació de l'astringència està associat a un procés d'oxidació de tanins motivat per una situació d'estrès oxidatiu. A més s'ha descrit una nova alteració de la polpa, "pinkish bruising", manifestada pels fruits sotmesos a dany mecànic amb alt nivell d'astringència. També s'ha avaluat la sensibilitat a l'enfosquiment de diferents varietats introduïdes des d'altres països. Amb l'objectiu de perllongar la conservació del fruit s'ha assajat l'ús de l'atmosfera controlada basada en 4-5% O2 + N2 sobre les varietats 'Rojo Brillante' i 'Triumph', observant-se que la resposta a esta tecnologia depèn de manera molt important de la varietat. Els resultats van ser especialment positius en el cas del cultivar 'Triumph', en què l'atmosfera assajada va permetre prolongar la conservació frigorífica fins a tres mesos. Una altra tecnologia assajada per al control dels danys per fred va ser l'aplicació de xocs amb altes concentracions de CO2 en el cultivar no astringent 'Fuyu'. Este tractament va alleujar el principal símptoma de dany per fred manifestat per esta varietat, la gelificació de la polpa. Este efecte s'ha relacionat amb la preservació de l'estructura cel¿lular de la polpa del fruit. Estudis recents han mostrat que el tractament amb etil format és altament efectiu en el control d'insectes durant la conservació i comercialització del caqui 'Fuyu', però este tractament provoca un estovament del fruit minvant la seua qualitat. En esta Tesi s'ha demostrat que les aplicacions d'etil format activen els gens de síntesi d'etilè, sent esta hormona mediadora de l'estovament. Els estudis també van revelar que l'aplicació d'un tractament previ amb 1-MCP redueix l'estovament del fruit associat a l'etil format, per la qual cosa l'ús combinat de tots dos tractaments pot ser considerat una alternativa per a la desinfecció dels fruits sense detriment de la seua qualitat. Finalment, l'estudi de deu varietats introduïdes des d'altres països va permetre seleccionar en base al seu moment de maduració i resposta al tractament de desastringència aquelles varietats de més interès per ampliar la gamma varietal. A més, es van identificar els principals compostos nutricionals del caqui i es va avaluar l'efecte del tractament de desastringència amb CO2 sobre els mat / Novillo Borrás, P. (2015). HARVEST AND POSTHARVEST QUALITY OF PERSIMMON FRUIT:PHYSICOCHEMICAL AND NUTRITIONAL ASPECTS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/58270 / TESIS

Tesis por compendio / [ES] En los últimos años España ha experimentado una sobreproducción de caqui, provocando una importante caída del precio y el aumento del desperdicio de fruta. Además, diferentes factores pre y postcosecha, pueden dar lugar a importantes pérdidas tras la cosecha. En este contexto, esta Tesis aborda diferentes estrategias para aumentar la rentabilidad del cultivo del caqui mediante la reducción de pérdidas postcosecha y la revalorización de la fruta descartada y de los excedentes de producción. Para ello, se estudian aspectos pre y postcosecha implicados en la calidad del fruto y se propone el secado de la fruta entera como una nueva estrategia de valorización de los frutos que no se destinan para fresco. Entre los aspectos precosecha, el estado nutricional de la planta es un factor clave que afecta a la composición del material vegetal y a las características del fruto. Los Capítulos I y II abordan el estudio de las concentraciones de macro y micronutrientes en hojas y frutos procedentes de parcelas cultivada bajo condiciones de manejo ecológico y convencional, y su relación con los principales parámetros de calidad del caqui 'Rojo Brillante'. Los resultados obtenidos aportan nueva información sobre la composición nutricional del caqui y refuerzan la necesidad de una fertilización equilibrada para conseguir una buena calidad del fruto. Otro aspecto precosecha a tener en cuenta en el manejo del caqui es la aplicación de fitorreguladores. En 'Rojo Brillante', es habitual el uso de etefón para adelantar la cosecha, y del ácido giberélico (AG3) para retrasar su maduración. Además, el tratamiento postcosecha con 1-MCP se aplica habitualmente para garantizar la calidad de la fruta tras la cosecha. Sin embargo, la aplicación precosecha de 1-MCP es un novedoso tratamiento eficaz para otras frutas. En el Capítulo III, en el que se evaluó este tratamiento en diferentes escenarios, se comprobó que, en fruta tratada con etefón, amplió la ventana de cosecha y prolongó el periodo de comercialización. En la fruta tratada con GA3, el 1-MCP precosecha puede sustituir a la aplicación de 1-MCP postcosecha, lo que lo convierte en una herramienta útil para optimizar las operaciones en las centrales de manejo. En el caso del 'Rojo Brillante', se ha observado un efecto del momento de cosecha sobre el comportamiento del fruto durante la frigoconservación. Para explicar estas diferencias, en el Capítulo IV se llevó a cabo la caracterización fisicoquímica y microestructural de frutos recolectados en cinco momentos y se evaluaron los cambios de firmeza durante el almacenamiento frigorífico. Pequeñas diferencias en la firmeza del fruto en cosecha afectaron de manera importante al mantenimiento de la calidad en conservación, lo que se relacionó con la estructura del parénquima en el momento de recolección. Por otro lado, hay que tener en cuenta que el tratamiento postcosecha de desastringencia se asocia a importantes pérdidas de calidad. En el Capítulo V se estudió el efecto del tratamiento de desastringencia con CO2 y etanol en la calidad postcosecha del cv. Giombo. Los resultados sugieren que, aunque el etanol es el tratamiento habitual de desastringencia para esta variedad, se recomiendan las altas concentraciones de CO2 para conseguir una insolubilización más rápida de los taninos y el mantenimiento de la firmeza de la pulpa durante la frigoconservación. En esta Tesis también se propone el secado de fruto entero como una nueva estrategia para valorizar los frutos descartados y los excedentes de producción del 'Rojo Brillante'. En el Capítulo VI se estudiaron los cambios fisicoquímicos y microestructurales que se producen en el fruto durante el secado natural, revelando que esta variedad es apta para ser sometida al proceso de secado. Para mejorar el proceso, también se evaluó el secado por aire caliente a tres temperaturas (Capítulo VII). Las características finales dependieron de la temperatura de secado, especialmente en términos de textura. / [CA] En els últims anys Espanya ha experimentat una sobreproducció de caqui, provocant una important caiguda del preu i l'augment del desaprofitament de fruita. A més, diferents factors pre i postcollita, poden donar lloc a importants pèrdues després de la collita. En este context, esta Tesi aborda diferents estratègies per a augmentar la rendibilitat del cultiu del caqui mitjançant la reducció de pèrdues postcollita i la revalorització de la fruita descartada i dels excedents de producció. Per a això, s'estudien aspectes pre i postcollita implicats en la qualitat del fruit i es proposa l'assecat de la fruita sencera com una nova estratègia de valorització dels fruits que no es destinen per a fresc. Entre els aspectes precollita, l'estat nutricional de la planta és un factor clau que afecta a la composició del material vegetal i a les característiques del fruit. Els Capítols I i II aborden l'estudi de les concentracions de macro i micronutrients en fulles i fruits procedents de parcel·les cultivades sota condicions de maneig ecològic i convencional, i la seua relació amb els principals paràmetres de qualitat del caqui 'Rojo Brillante'. Els resultats obtinguts aporten nova informació sobre la composició nutricional del caqui i reforcen la necessitat d'una fertilització equilibrada per a aconseguir una bona qualitat del fruit. Un altre aspecte precollita a tindre en compte en el maneig del caqui és l'aplicació de fitorreguladors. En 'Rojo Brillante', és habitual l'ús de etefon per a avançar la collita, i de l'àcid gibberèl·lic (AG3) per a retardar la seua maduració. A més, el tractament postcollita amb 1-MCP s'aplica habitualment per a garantir la qualitat de la fruita després de la collita. No obstant això, l'aplicació precollita de 1-MCP és un nou tractament eficaç per a altres fruites. En el Capítol III, en el qual es va avaluar este tractament en diferents escenaris, es va comprovar que, en fruita tractada amb etefon, va ampliar la finestra de collita i va prolongar el període de comercialització. En la fruita tractada amb GA3, el 1-MCP aplicat en precollita pot substituir a l'aplicació de 1-MCP postcollita, la qual cosa ho converteix en una eina útil per a optimitzar les operacions en les centrals de maneig. En el cas del 'Rojo Brillante', s'ha observat un efecte del moment de collita sobre el comportament del fruit durant la frigoconservació. Per a explicar estes diferències, en el Capítol IV es va dur a terme la caracterització fisicoquímica i microestructural de fruits recol·lectats en cinc moments i es van avaluar els canvis de fermesa durant l'emmagatzematge frigorífic. Xicotetes diferències en la fermesa del fruit en collita van afectar de manera important al manteniment de la qualitat en conservació, la qual cosa es va relacionar amb l'estructura del parènquima en el moment de recol·lecció. D'altra banda, cal tindre en compte que el tractament postcollita de desastringència s'associa a importants pèrdues de qualitat. En el Capítol V es va estudiar l'efecte del tractament de desastringència amb CO¿ i etanol en la qualitat postcollita del cv. Giombo. Els resultats suggereixen que, encara que l'etanol és el tractament habitual de desastringència per a esta varietat, es recomanen les altes concentracions de CO¿ per a aconseguir una insolubilització més ràpida dels tanins i el manteniment de la fermesa de la polpa durant la frigoconservació. En esta Tesi també es proposa l'assecat de fruit sencer com una nova estratègia per a valorar els fruits descartats i els excedents de producció del 'Rojo Brillante'. En el Capítol VI es van estudiar els canvis fisicoquímics i microestructurals que es produeixen en el fruit durant l'assecat natural, revelant que esta varietat és apta per a ser sotmesa al procés d'assecat. Per a millorar el procés, també es va avaluar l'assecat per aire calent a tres temperatures (Capítol VII). Les característiques finals van dependre de la temperatura d'assecat, especialment en termes de textuta. / [EN] In recent years Spain has experienced overproduction, which has led to important economic losses and increased fruit waste. Moreover, different preharvest factors, which affect fruit quality, and an inadequate postharvest management, can lead to important postharvest losses. In this context, the objective of the present Thesis is to study strategies to increase persimmon crop profitability by reducing postharvest losses and revalorizing discarded fruit and surplus production. Thus, the pre- and postharvest aspects involved in persimmon fruit quality are discussed and the whole fruit drying is proposed as a new valorization strategy. Of the preharvest aspects related to fruit quality parameters, the plant nutritional status is a major factor that can affect plant material composition and fruit characteristics. Thus, Chapters I and II addressed the study of macro- and micronutrients concentrations in the leaves and fruit from organic and conventional management systems, and their relation to the main fruit quality parameters in 'Rojo Brillante' persimmon. The results obtained in this study provide new information about the nutritional composition of persimmon and reinforce the need for balanced fertilization to achieve good fruit quality. Another important preharvest aspect is the application of phytoregulators to prolong the harvesting season. For 'Rojo Brillante', ethephon use is normal to advance harvest, as is gibberellic acid (GA3) to delay maturation. These treatments can affect fruit quality at both harvest and postharvest. Therefore, the postharvest 1-methylciclopropene (1-MCP) treatment is commonly applied to guarantee fruit quality. However, the preharvest 1-MCP application has been shown to be a novel effective treatment for other fruit. In Chapter III, in which this treatment was evaluated in different scenarios for persimmon, it was proved that it extended the harvest window and prolonged the commercialization period when applied to the ethephon-treated fruit. In the GA3-treated fruit, the preharvest 1-MCP can replace the 1-MCP postharvest application, which could be a useful tool for optimizing handling operations in packinghouses. For 'Rojo Brillante', an effect of harvest moment on fruit behavior during cold storage has been commercially documented. To explain these differences, in Chapter IV an in-depth physico-chemical and microstructural characterization of fruit during five commercial harvests is carried out and the changes in fruit firmness changes during cold storage was evaluated. The minor differences revealed in persimmon firmness at harvest strongly influenced fruit postharvest behavior, which was associated with structural parenchyma of flesh fruit at harvest. On the other hand, it is noteworthy that deastringency treatment is a critical step of postharvest handling because it directly influences fruit quality. This thesis (Chapter V) addressed the study of the effect of deastringency treatment with CO2 and ethanol on postharvest quality of cv. Giombo. The results suggested that, although ethanol is the usual deastringency treatment for this variety, high concentrations of CO2 are recommended to achieve faster insolubilization of tannins and to maintain higher fruit quality during cold storage. To valorize discarded persimmon fruit and surplus production, whole fruit drying is proposed as a new strategy for 'Rojo Brillante'. A first study (Chapter VI), which deals with the physicochemical and microstructural changes that occur during natural air drying, shows that this variety is suitable for drying as whole fruit. To improve the process, convective hot-air drying is also evaluated at three temperatures (Chapter VII). The results showed that the higher the drying temperature, the faster the drying process was, and the final product characteristics depended on the drying temperature, especially in texture terms. / This research was funded by the Ministerio de Ciencia e Innovación of Spain, through project RTA2017-00045-C02, the European Regional Development Fund (FEDER) through Project IVIA-51910 and by the company Agrofresh Spain / Quaresma Vilhena, N. (2023). Reducing Postharvest Losses in Persimmon. Pre and Postharvest Aspects Involved in Fruit Quality and New Strategies for Valorization [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203088 / Compendio

The South African Citrus Industry is the second largest exporter of citrus, after Spain. The industry is under pressure to supply high quality fruit as well as to expand into new, high paying markets. However, high paying markets such as Japan and the USA require cold sterilised fruit as obligatory quarantine treatments against Mediterranean fruit fly (Ceratitis capitata) in order to reduce any possible spread of the pest. Citrus fruit originated from tropical climates and hence are chilling susceptible. Chilling injury symptoms appear as dark brown spots, pitting and/or decay when fruit are transferred to shelf temperatures; thus reducing the marketability of citrus fruit. Therefore, there is need for methods to mitigate chilling injury. Previous studies have shown silicon to mitigate many forms of stress without any hazardous effect on human health. Thus, the aim of the study was to investigate the potential of post-harvest silicon dips in mitigating chilling symptoms in citrus fruit. Briefly, fruit from two sources (Ukulinga Research Farm and Ithala Farm) were dipped in different silicon concentrations (0, 50, 150, and 250 mg ℓ-1) for 30 minutes and thereafter stored at -0.5 or 2⁰C for up to 28 days with weekly evaluation for chilling injury symptoms. Total antioxidants were determined using FRAP, ABTS, and DPPH assays under spectrophotometer. In addition, sugars, ascorbic acid, phenolics and flavonoids were analysed using High Performance Liquid Chromatography (HPLC). Fruit from Ukulinga Research Farm showed significantly higher total antioxidants (ascorbic acid total phenolics and specific flavonoids hesperidin and naringin) and sugars relative to fruit from Ithala Farm. Low concentrations of silicon dips significantly reduced the appearance of chilling injury symptoms by inducing an enzymatic conversion of glucose to ascorbic acid, thereby increasing the antioxidant capacity of chilling susceptible fruit. Moreover, silicon increased the concentration of total antioxidants, total phenolics and total flavonoids. High silicon concentrations had a negative effect on post-harvest quality of lemons by increasing fruit weight loss and electrolyte leakage, resulting in appearance of chilling symptoms. In conclusion, the study showed that silicon had potential to reduce chilling injury. However, high silicon concentrations raised concern, in particularly, on fruit appearance. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.