New emerging markets such as Japan and the United States require cold sterilisation of South African citrus fruit as a phytosanitary standard against fruit fly. However, citrus fruit are chilling susceptible, with lemons being the second-most chilling susceptible after grapefruit. Chilling injury is a physiological rind disorder; the occurrence of which is despite its prevalence in horticultural commodities, not well understood. Therefore, the aim of this study was to investigate physiological compounds regulating chilling susceptibility or resistance in citrus fruit, with special emphasis on lemons. Furthermore, the potential of hot water dips or “molybdenum soaks” to maintain a certain level of physiological compounds which determine manifestation of chilling injury symptoms in citrus fruit was investigated. Moreover, it was attempted to create an understanding of the order in which physiological compounds mitigate chilling injury. Lemon fruit from different farms known to be chilling susceptible or resistant were obtained during the 2007 and 2008 harvest season. Thereafter, fruit were treated by soaking for 30 min in 1μM NaMo04.2H20 solution followed by a 2 min HWD 47 or 53°C. Treated fruit were waxed, weighed and stored at -0.5°C for up to 28 days and sampled for chilling injury evaluation 7, 14, 21, or 28 days into cold storage. A second evaluation was carried out five days after withdrawal from cold storage to allow development of chilling injury symptoms as a shelf-life simulation. After the second evaluation fruit were peeled, peel freeze-dried, milled using mortar and pestle and stored at -21°C for further physiological analysis. Freeze-dried peel was analysed for soluble sugars (glucose, fructose, sucrose), vitamin C (ascorbic acid), vitamin E (α-tocopherol), β-carotene, polyamines (putrescine, spermine, spermidine), specific flavanones (naringin and hesperidin) using HPLC-UV-Vis detector and proline, total antioxidant assays (FRAP, ABTS, DPPH), total phenolics, total flavonoids, lipid peroxidation using spectrophotometry, as well as for the heat shock protein (HSP70) using electrophoresis and silver-staining. Chilling susceptibility of lemon fruit varied with fruit source; those sourced from Ukulinga and Eston Estates were chilling resistant, while fruit from Sun Valley Estates showed chilling injury symptoms after 28 days of cold storage plus five days shelf-life. Furthermore, hot water dips (HW) 53°C, 1 μM Molybdenum (Mo) and 10 μM Mo plus HW 53°C significantly reduced chilling injury symptoms compared with the control and HW 47°C. In addition, Sun Valley Estates fruit also showed higher fruit weight loss compared with non-chilling resistant lemons. The alignment of higher fruit weight loss during storage with chilling susceptibility ascertains the use of weight loss as a non-destructive parameter for chilling susceptibility. With respect to flavedo sugars, glucose was found to be the dominant soluble sugar with multi-functional roles during cold storage. This plays a significant role in mitigating cellular stress. Chilling susceptible lemons from Sun Valley Estates had low flavedo glucose concentrations and, therefore, little conversion of glucose to ascorbic acid was possible resulting in a low antioxidant capacity. However, treatments with HW 53°C and Mo soaks seemed to enhance the enzymatic conversion of glucose to ascorbic acid leading to a higher antioxidant capacity in the flavedo of such treated fruit. Furthermore, glucose also feeds into the pentose phosphate pathway which is coupled with the shikimate pathway synthesizing secondary metabolites, especially of the phenolics group. The decrease in glucose was aligned to the levels of total phenolics, but not to that of β-carotene, naringin and hesperidin through 28 days into cold storage period. Moreover, as glucose also feeds into shikimate pathway, simultaneously an increase in proline flavedo concentration was observed. Proline is an antioxidant synthesized from glutamate; as cellular glucose decreases so does the total antioxidant capacity during cold storage. Ascorbic acid is a dominant and potent antioxidant in lemon flavedo as proven with the FRAP, ABTS and DPPH assays. Chilling resistant fruit have significantly higher ascorbic acid conversion. Furthermore, ascorbic acid also acts to generate the α-tocopheroxy radical to further important membrane-bound antioxidant, vitamin E (α-tocopherol equivalent). Furthermore, the DPPH assay was found to be effective in quantifying total antioxidants in lemon flavedo since it detects both lipophilic and hydrophilic antioxidants compared with the ABTS and FRAP assays which are bias to the estimation of liphophilic or hydrophilic antioxidants, respectively. The hot water and molybdenum treatments increased total antioxidants (DPPH assay) with reduced lipid peroxidation 7 days into cold storage and therefore, reduced chilling symptoms in fruit from Sun Valley Estates. The capacity of antioxidant to scavenge reactive oxygen species (ROS) was increased during cold storage and membrane stability significantly improved. Furthermore, putrescine as low valency polyamine was reduced as such compound acted as precursor to the synthesis of the high valency polyamines, spermine and spermidine. Chilling susceptible lemons from Sun Valley Estates showed increased soluble-conjugated polyamines as a response to stress. Furthermore, HW 53°C, 1 μM Mo and 10 μM Mo plus HW 53°C significantly increased the protein concentration and, therefore, likely also the occurrence of proteins with 70kDa (as estimator of HSP70). Additionally, the concentration of conjugated high valency polyamines was also increased, resulting in reduced chilling injury symptoms. The effect of ROS has only been viewed as damaging, while recently their role has also been viewed as stress acclamatory signalling compounds when produced concentrations below critical damaging threshold. Therefore, hot water dips seems to signals synthesis of total protein which include HSPs which then act throughout cold stress to protect other protein and channel other damaged proteins towards proteolysis. While molybdenum increased ROS production below damaging critical threshold, with ROS signalling stress acclimation by further signalling production of bioactive compound with antioxidant properties. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

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.

Made available in DSpace on 2014-06-11T19:33:39Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-05-29Bitstream added on 2014-06-13T20:25:30Z : No. of bitstreams: 1 durigan_mfb_dr_jabo.pdf: 3249388 bytes, checksum: 9f67b354f51854cbee43a06c30c8f27a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Gerbera jamesonii Bolus é uma espécie da família Compositae. O capítulo, com diâmetro de 8 – 14 cm, possui flores liguladas de cores vivas organizadas ao redor do centro, que contém os botões florais. Esta inflorescência é sustentada por uma haste longa e sem folhas. Atualmente é uma das dez flores mais comercializadas no Brasil e está entre as três principais flores de corte. A utilização de soluções conservantes, tratamentos de “pulsing”, ou fortalecimento, e baixas temperaturas de armazenamento visa prolongar a vida e manter por mais tempo a qualidade das flores cortadas. Neste contexto, este trabalho teve por objetivos avaliar o efeito de diferentes práticas de manejo na pós-colheita sobre a fisiologia e conservação de inflorescências de gérberas. Para os quatro primeiro experimentos foi utilizada a gérbera cv. Suzanne, de coloração laranja. Os experimentos foram conduzidos em delineamento inteiramente casualizado, em esquema fatorial. No primeiro experimento, as inflorescências permaneceram nas seguintes soluções de manutenção: 1) Água destilada; 2) Cloro a 100 mg.L-1; 3) 8-hidroxiquinolina (8-HQC) a 100 mg.L-1; 4) 8-HQC a 200 mg.L-1; e 5) 8- HQC a 400 mg.L-1, cujas hastes foram mantidas em condição controlada de laboratório (20°C; 70% UR). Este experimento possibilitou observar danos nas bases das hastes, causados pelos tratamentos com cloro a 100 mg.L-1 e com as doses mais elevadas de 8-HQC. A manutenção da boa qualidade foi observada no tratamento com 8-HQC a 200 mg.L-1. A longevidade média foi de 12 dias em vaso. No segundo experimento foram utilizadas, durante o armazenamento a 20°C e 70% UR, as soluções: 1) Água destilada; 2) Ácido cítrico a 64 g.L-1; 3) Cloro a 25 mg.L-1 4) Cloro a 50 mg.L-1 5) 8-HQC a 25 mg.L- 1 e 6) 8-HQC a 50 mg.L-1. Com os resultados verificou-se a baixa eficiência do... / Gerbera jamesonii belongs to the Compositae family. The inflorescence, with diameter of 8 – 14 cm, is a capitulum with ligules with vivid color organized around de center, that contain flower buds, which can be in a variety of colors. This colorful flower is supported by a long stem, without leaves. Nowadays it is one of the ten most commercialized flowers in Brazil and is one of the three main cut flowers. The use of keeping-quality solutions, pulsing treatments and low temperature during the vase life seeks to prolong vase life and to maintain the quality of cut flowers. In this context, this research was conducted, at FCAV-UNESP, Jaboticabal, SP, Brazil, to evaluate the effects of several handling techniques on postharvest physiology gerbera cut flowers. The experiments followed complete randomized design, in factorial arrangement. On the first one, the inflorescences remained in the following solutions: 1) Distilled water; 2) Chlorine at 100 mg.L-1; 3) 8-hydroxyquinolin (8-HQC) at 100 mg.L-1; 4) 8-HQC at 200 mg.L-1; and 5) 8-HQC at 400 mg.L-1, which the stems remained in environmental conditions (20°C; 70% RH). On this experiment, it was possible to observe the damage caused by the treatments using chlorine at 100 mg.L-1 and high dosage of 8-HQC. The good quality where kept by using 8-HQC at 200 mg.L-1 and the average longevity of the experiment was 12 days. On the second experiment, the gerberas remained, during storage, in the following solutions: 1) Distilled water; 2) Citric acid at 64 g.L-1; 3) Chlorine at 25 mg.L-14) Chlorine at 50 mg.L-1; 5) 8-HQC at 25 mg.L-1 ; and 6) 8-HQC at 50 mg.L-1. With the results it was possible to verify the low efficiency of the citric acid at the used concentration and the lower damage by lower concentrations of chlorine and 8-HQC than the usually recommended, which kept the good quality of the flowers for... (Complete abstract, click electronic access below)

Made available in DSpace on 2015-03-26T13:36:44Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1666363 bytes, checksum: 16bb41c070d91b6aef206286ce710e6f (MD5) Previous issue date: 2012-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In the palm heart we can distinguish three parts: basal or stalk, middle or leaf palm heart, and apex leaf palm heart. The conventional processing of palm heart usually discards the apical and basal parts, being desirable, however, its full use. We aimed at evaluating physical-chemical, anatomy, and physiology characteristics of the three parts of peach palm, seeking to increase its usage potential when marketed in a minimally processed form. The characterization was performed in two steps: characterization of raw material and characterization during cold storage. In the first step, we performed productivity, firmness profile, chemical, production of carbon dioxide and ethylene, and anatomical characterization analyses. In the second stage, the palm heart was processed according to the steps of minimal processing: washing and removal of the protective sheaths, cutting (separation of the apex, middle and basal parts), sanitation, drainage, and packing. The parts were stored at 5°C for 15 days. We evaluated fresh mass loss, color, and carbohydrates, besides the histochemical characterization for lignin identification. The total use of the palm heart, standardized to 70 cm was 85% and 68% due to the length and fresh mass, respectively. Along the length of the palm heart there was an increase of the values of firmness toward the extremes. The middle part showed higher concentrations of the chemical parameters evaluated. At the end of storage, the mass loss was 1.6% for the apical, 1.8% for the middle, and 1.3% for the basal part. A superficial yellowing occurred in all parts, evidenced by an increase in b* coordinate values. The apical and middle parts showed higher respiration rates. After stabilization, the rates of the parts, both whole and cut, differed little. There was an increase in ethylene production between the parts due to cutting intensity. The middle part, both whole and cut, had higher ethylene production even after the stabilization period. The three parts had different degrees of tissue differentiation. The greater proportion of fiber differentiation in certain parts may be related to the firmness, although the degree of lignification does not differentiate between the parts after cold storage. Thus, the apical and basal parts can be utilized in order to minimize the waste generated at the minimal processing, increasing the yield. Minimal processing of heart palm should consider the differences between cut and whole parts, in order to pack and preserve compatible areas in relation to the respiration rate, ethylene production and firmness. / No palmito se distinguem três regiões: basal ou palmito caulinar; mediana ou palmito foliar e palmito foliar apical. O processamento convencional do palmito geralmente descarta as regiões apical e basal, sendo, no entanto, desejável seu aproveitamento integral. Objetivou-se avaliar características físico-químicas, anatômicas e fisiológicas das três regiões de palmito pupunha, visando ampliar o seu potencial de aproveitamento quando comercializado na forma minimamente processada. A caracterização foi realizada em duas etapas: caracterização da matéria-prima e caracterização durante a conservação refrigerada. Na primeira etapa, foram realizadas análises de rendimento, perfil de firmeza, análises químicas, produção de gás carbônico e etileno, e caracterização anatômica. Na segunda etapa, palmitos foram processados seguindo as etapas do processamento mínimo: lavagem e retirada das bainhas de proteção, corte (separação das regiões apical, mediana e basal), sanitização, drenagem e embalagem. As regiões foram conservadas a 5 oC, por 15 dias. Avaliou-se perda de massa fresca, cor, carboidratos além da caracterização histoquímica para identificação de lignina. O aproveitamento total do palmito, padronizado com 70 cm, foi de 85% e 68% em função do comprimento e massa fresca, respectivamente. Ao longo do comprimento do palmito observou-se aumento dos valores de firmeza em direção aos extremos. A região mediana apresentou maiores teores dos parâmetros químicos avaliados. Ao final da conservação, a perda de massa foi de 1,6% para região apical, 1,8% para mediana e 1,3% para a região basal. Ocorreu amarelecimento superficial em todas as regiões evidenciado pelo aumento dos valores da coordenada b*. As regiões apical e mediana apresentaram maiores taxas respiratórias. Após estabilização, as taxas das regiões, tanto inteira quanto cortada, pouco se diferenciaram. Ocorreu aumento na produção de etileno entre regiões em função da intensidade de corte. A região mediana, tanto inteira quanto cortada, apresentou maior produção de etileno mesmo após o período de estabilização. As três regiões apresentaram diferentes graus de diferenciação dos tecidos. A maior proporção de fibras em diferenciação em determinadas regiões pode estar relacionada com a firmeza, embora o grau de lignificação não apresente diferença entre as regiões após conservação refrigerada. Desse modo, as regiões apical e basal podem ser aproveitadas a fim de minimizar os resíduos gerados no processamento mínimo, aumentando o rendimento. O processamento mínimo de palmito deve considerar as diferenças encontradas entre regiões inteiras e cortadas, com vista a embalar e conservar regiões compatíveis com relação às taxas respiratórias, produção de etileno e firmeza.

Made available in DSpace on 2014-08-20T13:42:06Z (GMT). No. of bitstreams: 1 Tese_ Amauri_Costa_da_Costa.pdf: 821830 bytes, checksum: 461372c264b8901d1eddb80605e2c297 (MD5) Previous issue date: 2010-07-06 / Enzymatic browning and softening are the main changes on fresh-cut peaches. Initially we studied the combination of antioxidant molecules and protective texture control enzymatic activities of peroxidase (POD) and polyphenoloxidase (PPO), enzymatic browning and softening the flesh of peaches cv. Esmeralda, minimally processed and refrigerated. For this we tested the use of L-cysteine (Cis), L-ascorbic acid (AA) and calcium chloride (CC), alone or in combination: (i) water (control); (ii) AA+CC; (iii) Cis+CC; e, (iv) Cis+AA+CC. After treatment, the slices were packed in packages sealed with PVC film 30μm and stored for six days at 4±1ºC and 85±3 RH. The samples were evaluated under physical-chemical, enzymatic and sensory every two days. Treatment Cis+AA+CC had the highest values of L* and h°, ie was more effective in preventing browning. Treatments with L-cysteine showed a lower PPO activity and treatment Cis+AA+CC was the most effective in containing the POD activity, indicating that the best performance of this treatment is associated with lower activity of these enzymes. The sensory evaluation indicated that the treatment Cis+AA+CC was the most efficient, providing the maintenance of the sensory characteristics acceptable of fresh-cut peaches, cv. Esmeralda. In sequence was tested using ultraviolet radiation type C (UV-C) radiation as a means of increasing the conservation value of these fruits as well as to increase the synthesis of compounds of nutritional value and functional. That were applied to the following treatments: (i) fruit without UV-C, peeled, sliced and stored under refrigeration (control); (ii) fruits treated with UV-C and immediately peeled, sliced and stored under refrigeration (UV-C 0); (iii) fruits treated with UV-C and kept at room temperature 24h before processing (UV-C 24), (iv) fruits treated with UV-C and kept at room temperature 48h before processing (UV-C 48); and (v) fruit without treatment with UV-C, processed and treated with metabisulphite K (MB K). Evaluations, color (L* and hue angle), firmness, ascorbic acid and phenolic compounds, antioxidant activity and transcriptional expression of genes supposedly related to physiological changes were taken immediately after processing and every 24h for six days. The application of UV-C resulted in a significant improvement in the storage potential of the peaches. But for that to happen, it was necessary to wait 24 to 48h before processing. With this procedure there was a stimulus to the transcription of genes in the metabolism of ethylene, cell wall synthesis and oxidation of phenolic compounds. Still, there was less browning of fruits treated with UV-C, indicating that this change is not only dependent on the concentration of total phenolics and PPO activity. / O escurecimento enzimático e o amolecimento são as principais alterações em pêssegos minimamente processados. Inicialmente estudou-se a combinação de moléculas antioxidantes e protetores de textura no controle da atividade das enzimas polifenoloxidase (PPO) e peroxidase (POD), do escurecimento enzimático e do amolecimento da polpa de pêssegos, cv. Esmeralda, minimamente processados e refrigerados (MPR). Para isso testou-se o uso de L-cisteína (Cis), ácido L-ascórbico (AA) e cloreto de cálcio (CC), isolados ou em combinação: (i) água (controle); (ii) AA+CC; (iii) Cis+CC; e, (iv) Cis+AA+CC. Após o tratamento, as fatias foram acondicionadas em embalagens rígidas envoltas com filme PVC 30μm e armazenadas durante seis dias a 4±1ºC e 85±3 UR. As amostras foram avaliadas sob aspectos físico-químicos, enzimáticos e sensoriais a cada dois dias. O tratamento Cis+AA+CC apresentou os maiores valores de L* e hº, ou seja, foi o mais eficaz na prevenção do escurecimento. Os tratamentos com L-cisteína apresentaram menor atividade da PPO e o tratamento Cis+AA+CC foi o mais efetivo na contenção da atividade da POD, indicando que o melhor desempenho desse tratamento está associado à menor atividade dessas enzimas. A avaliação sensorial indicou que o tratamento Cis+AA+CC foi o mais eficiente, proporcionando a manutenção de características sensoriais aceitáveis aos pêssegos MPR, cv. Esmeralda. Em sequência testou-se o uso de radiação ultravioleta tipo C (UV-C) como meio de aumentar o potencial de conservação desses frutos, assim como para aumentar a síntese de compostos de interesse nutricional e funcional. Para isso foram aplicados os seguintes tratamentos: (i) frutos sem UV-C, pelados, fatiados e armazenados sob refrigeração (AR) (controle); (ii) frutos tratados com UV-C e imediatamente pelados, fatiados e armazenados em AR (UV-C 0); (iii) frutos tratados com UV-C e mantidos 24h à temperatura ambiente (TA) antes do processamento (UV-C 24); (iv) frutos tratados com UV-C e mantidos 48h a TA antes do processamento; e (v) frutos sem tratamento com UV-C, processados e tratados com metabissulfito de K (MB K). As avaliações, coloração (L* e ângulo hº), firmeza de polpa, teor de ácido ascórbico e compostos fenólicos, atividade antioxidante e a expressão transcricional de genes supostamente relacionados às alterações fisiológicas, foram realizadas imediatamente após o processamento e a cada 24h por seis dias. A aplicação da radiação UV-C provocou uma significativa melhora no potencial de conservação dos pêssegos. Mas para que isso ocorresse, foi necessário se aguardar de 24 à 48h antes do processamento. Com esse procedimento houve estímulo à transcrição de genes do metabolismo do etileno, da parede celular e da síntese e oxidação de compostos fenólicos totais (CFT). Mesmo assim, houve menor escurecimento dos frutos tratados com UV-C, indicando que essa alteração não é apenas dependente da concentração de CFT e da atividade da PPO.

Depuis plusieurs années de nouveaux procédés industriels destinés à la réfrigération et à la climatisation sont étudiés et mis sur le marché. Parmi ceux qui commencent à connaître des débouchés commerciaux on compte les systèmes utilisant des fluides frigoporteurs diphasiques solide/liquide. Ces dispositifs offrent en effet les avantages de réduire l’utilisation des fluides frigorigènes de plus en plus réglementée et de pouvoir lisser la production de froid sur 24 heures grâce à la possibilité de stocker ces fluides diphasiques. Le domaine de la réfrigération connaît au niveau européen, grâce à plusieurs industriels, un premier essor de l’utilisation de « coulis » ou « sorbet » de glace. La climatisation industrielle ou collective représente également un enjeu énergétique majeur tant du point de vue de la consommation énergétique instantanée qu’elle nécessite que du point de vue des “pics” qu’elle génère à certaine périodes de la journée.Dans ce domaine et sur le continent asiatique (particulièrement au Japon), l’utilisation de sorbets est également en phase d’expansion. Dans ce cas, les sorbets utilisés sont des « coulis d’hydrates » qui présentent l’intérêt de cristalliser à des températures positives plus adaptées à la climatisation que celles des « coulis de glace ».Ces travaux de thèse ont donc consisté à adapter une technologie de réfrigération disponible sur le marché européen au domaine de la climatisation. Le fluide utilisé est une solution de TBAB (Bromure de Tetra-ButylAmmonium) qui est une solution aqueuse dont la température de cristallisation à pression atmosphérique peut être ajustée entre environ 6 et 12°C. Le dispositif expérimental conçu et construit est donc un prototype industriel de taille réelle capable de climatiser 4 pièces. A la fois démonstrateur industriel et banc d’essais instrumenté, il est destiné à mener à bien des séances d’essais afin de démontrer la faisabilité du procédé, de diagnostiquer des améliorations et de prévoir de nouvelles évolutions. Parallèlement aux travaux de construction et aux séances d’essais, des mesures complémentaires concernant certaines caractéristiques thermo-physiques des sorbets d’hydrates de TBAB ont été menées en laboratoire. Enfin, un outil de modélisation a également été développé afin de rattacher les expériences à des phénomènes thermo-physiques théoriques. Cette modélisation a pour but d’être un outil prédicatif à la conception de nouvelles installations et au développement du prototype. / For some years, new industrial processes have been developed and marketed in the refrigeration and air conditioning fields. Among systems which begin to have good business opportunities some are using two-phase secondary refrigerants solid / liquid. This kind of technology offers the advantages of reducing the use of classical refrigerants which are regulated and can smooth the production of cold over 24 hours with its ability to store the slurry. At the European level, thanks to the efforts of several manufacturers, the refrigeration field is developing fast with respect to the use of ice slurries. Moreover the industrial or district air conditioning field is a major energetic issue in terms of the immediate energy it requires as well as in terms of "peaks" generated during certain periods of the day.In this field, especially in Japan, the use of “PCM” (Phase Change Material) is additionally developing. In this technological segment, the PCM used are hydrate slurries. This solution has the advantage of crystallizing at positive temperatures which is more suited for the air conditioning than ice slurries.This research work deals with the adaption of a refrigeration technology available on the European market to the field of air conditioning. The fluid used is an aqueous solution of TBAB (Tetra-Butylammonium Bromide) with a crystallization temperature at atmospheric pressure which can be adjusted to a temperature between 6 and 12°C. The experimental device designed and installed is a real size prototype able to cool 4 rooms. Both the industrial demonstrator as well as instrumented test bench allowed us to carry out practice sessions which demonstrated the feasibility of the process. It also allowed us to design improvements and new developments. In parallel to the construction and the experiments, additional measurements concerning some thermo-physical characteristics of TBAB hydrate slurries were conducted in specialised laboratory. Finally, a modelling tool was also developed in order to relate our experiments with theoretical thermo-physical phenomena. This numerical model is intended to be a predicative tool for the design of new installations and for the development of the prototype.

The field of a research of this diploma thesis is building with controlled internal temperature. The research is focused on main heat fluxes at this type of buildings and how it contributes to the energy consumption of the building. The main objective of the analysis is heat loss caused by heat flux through the building envelope and air exchange at the building. As next it is described heat gain resulting from the operation inside of the building. To obtain the results of the research part is used software on the platform Delphi Pascal, temporarily called SIM_Chlad. The aim of this computer modeling is non-stationary heat fluxes from the mentioned heat sources in the building. The computed heat balance analyzes the energy consumption of the building for a period of one year. The diploma thesis evaluates impacts reflecting local weather conditions, the structural system of the building and the operation in the building. A cooling machinery analysis is not the subject of the research at this diploma thesis.

La gestión de cadena de suministro, cada vez está tomando mayor importancia a nivel mundial, debido ya que es crítico para el logro de un buen producto final. Esta investigación describe la viabilidad de los procesos en la industria logística de la cadena de frío de la frambuesa en el Perú. El cultivo de frambuesas se encuentra en la etapa de oportunidades potenciales de crecimiento para la agroindustria. La logística de producción es una parte esencial de la gestión de la cadena de suministro de alimentos; esto mejora el rendimiento y la calidad del producto fresco. La cadena de frío y las buenas prácticas agrícolas preservan la calidad y reducen las pérdidas de producción de frambuesa en un 9%. Además, la implementación de una Gestión por procesos, en el tramo de pos cosecha hasta la llegada al aeropuerto, hicieron que este berrie, tenga la posibilidad de exportarse de tipo orgánica y estar al nivel de la competencia. Este modelo se basa en artículos científicos que son los pilares teóricos de la metodología de proceso que desarrolla la competitividad del producto. / Supply chain management is becoming increasingly important worldwide, as it is critical to achieving a good final product. This research describes the viability of the processes in the logistics industry of the raspberry cold chain in Peru. Raspberry cultivation is in the stage of potential growth opportunities for agribusiness. Production logistics is an essential part of managing the food supply chain; This improves the yield and quality of the fresh product. The cold chain and good agricultural practices preserve quality and reduce raspberry production losses by 9%. In addition, the implementation of a Management by processes, in the post-harvest section until arrival at the airport, made this berrie have the possibility of being exported organically and being at the level of the competition. This model is based on scientific articles that are the theoretical pillars of the process methodology that develops the competitiveness of the product. / Trabajo de suficiencia profesional

Thesis (M.Sc. Agriculture (Horticultrure)) -- University of Limpopo, 2017 / The current South African ‘Hass’ type avocado cultivars are inadequate to enhance competitiveness, cultivar diversity and profitability. In an effort to ensure competitiveness and maintain sustainability, the Agricultural Research CouncilInstitute for Tropical and Subtropical Crops (ARC-ITSC) as one the South African Avocado Industry’s (SAAI) main stakeholder, has bred and selected new superior ‘Hass’ type avocado selections. However, the cold storage potential and associated physico-chemical ripening properties of these selections (‘Jalna’, ‘OA 184’ and ‘Balboa’) have not been documented. Therefore, the objective of this study was to evaluate the effect of cold storage on internal and external physico-chemical ripening variables of the new ‘Hass’ type avocado selections. New ‘Hass’ type avocado fruit maturity was evaluated using moisture content, thereafter, harvested, sorted, graded and stored under two temperature regimes (2.0°C and 5.5°C) for 28 days to simulate export conditions. The experiment was a completely randomised factorial design with three treatment factors; temperature regimes (2.0°C and 5.5°C), days to ripening and ‘Hass’ type avocado selections fruit and control (commercial ‘Hass’) replicated three times. After withdrawal from cold storage, fruit were ripened at ambient temperature and evaluated for electrical conductivity, external chilling injury, fruit water loss, skin colour change, ripening percentage, firmness, respiration rate and seed:fruit weight ratio. Results indicated that treatment factors had no significant effect on moisture content (P=0.733) and chilling injury (P=0.776). Treatment factors had a significant effect on electrical conductivity (P=0.004), skin colour parameters; eye colour (P<0.001), hue angle (P<0.001), lightness (P=0.011) and chroma (P=0.042). Selection ‘Jalna’ fruit started changing colour whilst in storage (2.0°C and 5.5°C). Furthermore, ‘Hass’ type avocado selection fruit followed a declining pattern for lightness, chroma and hue angle in agreement with commercial ‘Hass’. Moreover, results indicated that treatment factors had a significant effect (P<0.001) on respiration rate, fruit firmness, ripening percentage and seed:fruit weight ratio. Selection ‘Jalna’ and ‘OA 184’ desynchronised mesocarp softening with exocarp due to genetically non-softening exocarp. Treatment factors had no significant effect (P=0.998) on fruit water loss during ripening. Selection ‘OA 184’ fruit showed export potential due to its good storage, ripening physico-chemical and shelf-life properties. Studies on cold sterilisation would add more value on generated scientific information, as such would enable the SAAI to gain access to high paying export markets. In addition, the selections should be planted and evaluated in other avocado producing region

El presente trabajo está justificado por la necesidad real constatada por las empresas hortofrutícolas de mejorar la calidad de la lechuga Iceberg en vistas a su exportación a los países de la Unión Europea y, también, con el propósito de conocer el comportamiento fisiológico de esta hortaliza cultivada en la comarca del Campo de Cartagena de la Región de Murcia (España). La mejora de la calidad hace referencia a conseguir mantenerla desde la cosecha hasta el lugar de consumo, ya que la calidad del producto cosechado suele ser bastante buena. Respecto al comportamiento fisiológico, se ha pretendido conocer el potencial de conservación de la lechuga y el efecto del preenfriamiento y uso de las atmósferas modificadas en el mantenimiento de la calidad. También se han estudiado las alteraciones fisiológicas y microbianas que aparecen en las lechugas del Campo de Cartagena y el efecto de la refrigeración y coadyuvantes durante su almacenamiento. Como un complemento necesa rio al estudio de la calidad, se han determinado las características de permeación a los gases metabólicos de los envases plásticos destinados a la conservación de los productos vegetales en atmósferas modificadas y el comportamiento respiratorio de la lechuga con el fin de obtener una estrategia de diseño de envase que permita conocer las exigencias de este producto en relación al tipo de envasado que requiere. Los resultados han puesto de manifiesto que la lechuga Iceberg cultivada en el Campo de Cartagena es muy sensible a las alteraciones fisiológicas de nervaduras rosáceas y mancha canela sin mediación del etileno, que constituyen los principales problemas en su exportación. La solución planteada pasa por sustituir el envase actual, polipropileno macroperforado, por polipropilenos no perforados, biorientados o de tipo estándar, que han permitido reducir de forma drástica la incidencia de estas dos alteraciones y mantener un mejor aspecto visual incluso tras dos semanas de almacenamiento refrigerado. Si embargo, se debe controlar correctamente la temperatura y mantener la cadena de frío, ya que el envasado de la lechuga en estos polímeros no perforados presenta riesgos de incidencia de otras alteraciones fisiológicas como la mancha parda y el daño del cogollo interior. La reducción de las alteraciones en atmósfera modificada se ha atribuido a los niveles favorables de O2 (no menos del 10% y no más del 15%) y de CO2 (entre el 1 y el 4%) y su efecto beneficioso para frenar el metabolismo combinado con la reducción de la temperatura de refrigeración. / This study was accomplished because of horticultural Spanish companies needed to improve Iceberg lettuce quality to be exported towards the European Community countries and, at the same time, to know the physiological behaviour of this vegetable grown in the Campo de Cartagena area of the Murcia Region (Spain). The quality improvement consists of maintaining the lettuce quality from harvest to consumption, since the lettuce quality was usually quite good at harvest. Regarding to physiological behaviour, in this work it was searched both the lettuce shelf life and the effect of cooling and modified atmosphere packaging on maintaining quality. In the same way, the physiological and microbiological disorders which appeared in the lettuces grown in the Campo de Cartagena and the effect of chilling storage and other techniques were studied. In addition to this quality study, lettuce respiration and metabolic gas permeation throughout polymeric packages for using in modifi ed atmosphere packaging were studied. The data obtained permit to know the film requirements and to design an optimum modified atmosphere packaging for Iceberg lettuce. The results demonstrated that Iceberg lettuce grown in Campo de Cartagena is very sensitive to physiological disorders ‘pink rib’ and ‘russet spotting’ this last one without ethylene releasing. These are the main problems when lettuces are exported. Both non-perforated bioriented polypropylene and standard polypropylene were proposed as alternatives to substitute the conventional macroperforated polypropylene. The gas composition reached within packages with these films permitted to reduce drastically the above mentioned disorders and to maintain the overall quality for periods longer than two weeks under chilling. Both temperature and cold chain must be correctly kept so that no risks of either ‘brown stain’ or ‘heart-leaf injury’ can appear due to an inadequate use of non-perforated films. The disorders red uction was attributed to levels of O2 (between 10 to 15%) and CO2 (between 1 and 4%) within the packages and the favourable effects of those atmospheres combined with the use of chilling storage temperatures on restraining lettuce metabolism.