Thesis (M.Sc. Agriculture (Horticulture)) -- University of Limpopo, 2022 / The most common postharvest limitation of litchi fruit is pericarp browning, which leads to consumer rejection of the solid fruit in the market even when the edible portion is not affected. Previously, sulphur dioxide (SO2) fumigation was used to control the browning and extend shelf life of litchi fruit. However, SO2 fumigation leaves undesirable residues, alters the fruit taste and may results in health hazards for consumers. An alternative method, namely, minimal processing was used to control pericarp browning and curb postharvest losses in litchi. Litchi fruit were harvested at two maturity stages (early harvest; 120 days after full bloom (DAFB), late harvest; 130 DAFB), peeled and immersed for two (2) minutes in three (3) solutions that represented treatments, namely 1) 1% citric acid 2) 1% calcium lactate and 3) a combination of citric acid and calcium lactate both at 1% measure. The untreated arils were dipped in sodium hypochloride (NaOCl) solution for 1 minute and represented the control samples. The treated arils were packed in sterilized clamshell containers and stored at 1±0.5°C and 95% relative humidity for 12 days, then held at 10±0.5°C for 2 days for shelf life study. As a result of the interaction effect of harvest stages and postharvest pre-treatments, least mass loss percentage (1.32%), juice leakage (1.8 ml per 120 g of fruit) and pH (4.18) was observed in litchi arils harvested late and treated with 1% citric acid only under cold storage. Under shelf life study, H2 control samples presented lower mass loss (2.8%) and juice leakage (4.2 ml per 120 g of fruit). At the end of cold storage, litchi arils harvested early and treated with 1% citric acid combined with 1% calcium lactate presented better tissue strength (56.0 N) and radical scavenging activity (36.6 mmol AAE/mL), while those harvested late presented higher ascorbic acid content (72.9 µg/mL), least microbial population and total colour change (3.5). However, at the end of shelf life storage, litchi arils harvested early and treated with 1% citric acid combined with 1% calcium lactate presented lower (3.1) total change in colour. Overall, harvesting the fruit late and treating with citric acid alone or combined with calcium lactate showed the potential of maintaining better aril quality with least microbial population for up to 12 days under 1±0.5°C storage, whereas harvesteing the fruit early and treating with citric acid alone or combined with calcium lactate showed the potential of maintaining better aril quality under shelf life storage. Keywords: Litchi chinesis sonn; calcium lactate; citric acid; maturity; fresh-cut. / Agricultural Research Council (ARC), National Research Foundation (NRF) and Agri-Seta

Thesis (M.Sc. (Animal Production)) -- University of Limpopo, 2023 / Two experiments were conducted to determine the effect of citric acid inclusion level in the diet on growth performance, carcass weight, tibia bone breaking strength and ash content of male Ross 308 broiler chickens aged one to 35 days. The first experiment determined the effect of citric acid inclusion level in the diet on growth performance traits of male Ross 308 broiler chickens aged one to 21 days. The experiment commenced with 200 male day-old Ross 308 broiler chickens with an initial average live weight of 40±1.6g per chick. The chicks were assigned to five treatment groups in a completely randomized design, each replicated five times, and each replicate having ten chicks. The citric acid inclusion levels were at 0, 12.5, 25 or 50g per kg DM of feed. The second experiment determined the effect of citric acid inclusion level in the diet on growth performance, carcass weight, tibia bone breaking strength and ash content traits of male Ross 308 broiler chickens aged 22 to 35 days. The experiment commenced with 180 male Ross 308 broiler chickens aged 22 days. The chickens were assigned to four treatment groups, each having three replicate pens of eight chickens per replicate in a completely randomized design. Data was analysed using the General Linear model (GLM) procedures of the Statistical Analysis of System, version 9.3.1 software program. Where there were significant differences (P<0.05) between the treatment means, Tukey Multiple Comparison Test was used for mean separation. Citric acid inclusion in the starter diets improved (P<0.05) live weight and growth rate of male Ross 308 broiler chickens aged one to 21 days. Citric acid inclusion in the starter diets did not affect (P>0.05) daily feed intake, body weight gain and feed conversion ratio of male Ross 308 broiler chickens aged one to 21 days. The inclusion of citric acid did affect (P<0.05) live weight, body weight gain, feed conversion ratio and growth rate of chickens aged 22 to 35 days. Citric acid inclusion levels used in the present study influenced (P<0.05) DM and CP digestibility, ME intake and N-retention of male broiler chickens aged 22 to 35 days. The results of the current study showed that citric acid inclusion in a diet improved (P<0.05) chicken bone morphology. Thus, positive relationships were observed between citric acid inclusion level and right tibia bone weight, diameter, calcium, phosphorous and Magnesium contents of chicken bones aged 35 days. There were positive relationships between citric acid inclusion level and breast weight of male Ross 308 broiler chickens aged 35 days. Further studies are recommended to ascertain these findings. / National Research Foundation (NRF)

The influence of plasticization and other formulation factors on the properties of hot-melt extruded dosage forms for the controlled release of water-soluble active compounds was investigated. Citric acid monohydrate was demonstrated to function as a solid-state plasticizer in hot-melt extruded Eudragit® RS PO tablets and in cast films when concentrations below the compatibility limit were employed. Melting of the organic acid and solubilization in the polymer during extrusion were necessary to observe the plasticizing effect. The release rate of diltiazem hydrochloride, used as a high-melting, water-soluble model drug, from melt extruded Eudragit® RS PO matrix tablets increased and became independent of the original drug particle size in the presence of citric acid monohydrate. Thermal analysis of physical mixtures demonstrated that citric acid promoted drug melting during extrusion by interaction and melting point depression. Diltiazem hydrochloride remained amorphous in the final dosage form, and leaching of citric acid monohydrate enhanced drug diffusion by increasing the matrix porosity. Delayed-release matrix pellets with particle sizes below one mm were prepared by hot-melt extrusion, and the influence of the matrix forming polymer and the type and level of plasticizer on the processibility and release properties was investigated. Pellets complied with the USP requirement for delayed release articles to release less than 10% drug at pH 1.2 after 2 hours when plasticized Eudragit® S100 was used as the release-controlling material. High levels of efficient plasticizers had to be employed to decrease the polymeric melt viscosity, increase the process yield and enable extrusion at moderate temperatures to avoid instabilities during processing and storage. The aqueous solubility of the plasticizer further impacted the drug release rate in acid. A novel application of hot-melt extrusion for the preparation of monolithic matrices comprising enteric coated particles was studied. The influence of the mechanical strength of the multiparticulates, pellet loading and nature of the hydrophilic carrier material on the preservation of the delayed-release properties after extrusion was investigated. Soft particles coated with brittle films remained intact when low-melting carriers that did not solubilize the enteric film during extrusion were used, and the dissolution profile was stable over one year. / text

The ability of yeasts to grow and adapt under extreme environmental conditions including within the presence of weak organic acid preservatives has led to substantial economic losses through manufactured food and beverage spoilage. The food industry has employed the use of various weak organic acids such as sorbic, benzoic and acetic acid as preservatives to help prevent spoilage by yeasts and moulds. The mechanisms by which S. cerevisiae is able to adapt to these weak organic acids have been extensively studied. A lesser studied weak organic acid preservative is citric acid. The aim of this study was to gain further information on the mechanisms of citric acid adaptation and through this identify potential targets for new preservation strategies. Current knowledge indicates the involvement of the HOG pathway in citric acid adaptation. A citric acid sensitivity screen from a previous study also isolated a SR protein kinase Sky1p, involved in polyamine metabolism, which has been connected with other crucial cellular processes including modulation of ion homeostasis and osmotic shock. In this study we have undertaken a systematic screen for genes that confer increased sensitivity to citric acid paying particular attention to those involved in polyamine metabolism and those known to encode proteins which have evidence of interactions with Sky1p. Many of the deletion strains tested exhibited hypersensitivity to citric acid including Δsky1. Protein-protein interaction maps for Sky1p highlighted an interesting secondary interacting protein Nmd5p, an importin crucial for the nuclear localization of Hog1p. This information suggested there may be the possibility of linkage between Sky1p and Hog1p and their roles in citric acid tolerance, perhaps through Nmd5p. This provided an incentive to perform a range of experiments to test this theory. Proteomic and phosphoproteomic analyses were carried out to study protein expression and phosphorylation changes in response to citric acid stress. Comparative proteomic analyses for Δsky1, Δhog1 and BY4741a with and without citric acid identified four instances of analogous protein expression responses in both Δsky1 and Δhog1, suggesting functional overlap upon exposure to citric acid. Epistasis studies of Δhog1Δsky1 suggested that the two protein kinases do not function on the same pathway. However, overexpression analyses did suggest some functional interaction between Hog1p and Sky1p in mediating citric acid resistance since overexpression of Sky1p in Δhog1 resulted in partial rescue of growth. Further supporting evidence for some functional interaction or linkage was provided by Hog1p phosphorylation and localisation studies. Δsky1 exhibited dual phosphorylation of Hog1p in the absence of citric acid stress; implying that loss of SKY1 results in dual phosphorylation of Hog1p by either prompting phosphorylation or perhaps by interfering with dephosphorylation of Hog1p. Localisation studies of Hog1p proved that like osmotic stress, citric acid stress results in nuclear translocation of Hog1p and deletion of SKY1 seemed to interfere with this localisation to some extent. In light of the results attained in this study we believe we have evidence to propose a novel role for Sky1p in mediating resistance to citric acid and that there is also substantial evidence to suggest that Sky1p shares some functional redundancy and perhaps functional linkage with Hog1p in citric acid adaptation.

Analisou-se a influência da aplicação do ácido cítrico em três concentrações, EDTA-T e EDTA-C no vedamento marginal apical de canais radiculares em 90 caninos humanos extraídos. O preparo químico-cirúrgico dos canais radiculares foi realizado pela técnica de Paiva & Antoniazzi, sendo esses dentes posteriormente distribuídos aleatoriamente em seis grupos. Cada grupo de dentes recebeu um tratamento químico específico efetuado pela repleção do canal radicular por 3 minutos com uma das seguintes substâncias: soro fisiológico, ácido cítrico a 10%, ácido cítrico a 15%, ácido cítrico a 20%, EDTA-T a 17% e EDTA-C a 17%. Posteriormente, todos os canais radiculares foram obturados com cones de guta-percha e cimento N-Rickert pela técnica de cones múltiplos com condensação vertical. Foi observado um aumento crescente de infiltração do corante azul-de-metileno nos canais tratados com ácido cítrico correspondente ao aumento da concentração do ácido. A maior média de infiltração verificada ocorreu nos canais radiculares tratados com EDTA-C e as menores registradas naqueles tratados com soro fisiológico ou EDTA-T. As diferenças entre as médias de infiltração apical nos seis grupos experimentais, analisadas conjuntamente, não foram estatisticamente significantes. Em comparações individualizadas, houve diferença significante (p < 0,05) entre o grupo G6 (EDTA-C) tanto em relação ao grupo G5 (EDTA-T) quanto ao grupo G1 (soro fisiológico). / Ninety extracted human teeth were analysed in this work to verify the influence of citric acid application under three concentrations, EDTA-T and EDTA-C in the apical marginal sealing of root canals. Chemical and surgical root canal preparations were performed by Paiva & Antoniazzi technique, being these teeth randomly distributed in six groups. Each group had specific chemical treatment of filling the root canal for 3 minutes with one of the following substances: saline solution, 10% citric acid, 15% citric acid, 20% citric acid, 17% EDTA-T and 17% EDTA-C. All root canals were filled with gutta-percha cones and N-Rickert cement by the multiple cone technique with vertical condensation. A crescent increase of methylene blue dye penetration could be observed in the root canals treated with citric acid equivalent to the increase in acid concentration. The highest penetration mean was shown in the root canals treated with EDTA-C and the lowest in those treated wint saline solution or EDTA-T. The differences between the apical penetration means in the six experimental groups that had been together analysed showed no statistical significance. When individually compared, there was a significant difference (p<0,05) between group G6 (EDTA-C), group G5 (EDTA-T) and group G1 (saline solution).

A quantificação dos componentes bioquímicos como frutose, ácido cítrico e proteína total existentes no plasma seminal de caprinos e ovinos localizados na região Centro-Oeste do Brasil é uma forma de avaliar a atividade fisiológica e bioquímica espermáticas. Estes dados servem como indicadores de prováveis problemas com os testículos e glândulas acessórias desses animais e de sua respectiva fertilidade. A frutose e o ácido cítrico são importantes para o sêmen como fonte de energia metabólica e como componente de sistema tampão, respectivamente. A frutose é um marcador da função secretora das vesículas seminais, e é um componente importante para a sobrevivência dos espermatozóides em condições anaeróbicas e está estreitamente relacionada com a motilidade inicial das células espermáticas. Sendo assim, os objetivos do presente projeto foram analisar quantitativamente esses componentes do plasma seminal de bodes e carneiros sob latitude 20&deg;31\'S em quatro épocas do ano e purificar, através de técnicas cromatográficas, a enzima fosfolipase A2, importante proteína presente no plasma seminal. As análises bioquímicas foram feitas usando-se um espectrofotômetro UV/Vis para obtenção da curva padrão e para a determinação das concentraçõoes mensais e da concentração anual média dos constituintes analisados. A purificação da PLA2 foi feita por cromatografia líquida preparativa usando-se como fase estacionária a coluna Superdex 75-16/60 (GE HealthCare) de exclusão por tamanho e membranas semipermeáveis de 10 e 30 kDa. Como resultado das análises bioquímicas, obteve-se a concentração anual média de proteínas totais de 3,27 &plusmn; 0,60 g/dL para ovinos e de 5,02 &plusmn; 0,43 para caprinos, ácido cítrico de 1015,33 &plusmn; 66,50 µg/mL para ovinos e de 1584,35 &plusmn; 143,90 µg/mL para caprinos e frutose de 23,40 &plusmn; 4,80 mg/dL para ovinos e 72,73 &plusmn; 18,50 mg/dL para caprinos. Os resultados mostraram que a PLA2 extraída do plasma seminal de ovinos tem massa molecular próxima de 13,8 kDa e a PLA2 do plasma seminal de caprinos tem massa molecular próxima a 12,8 kDa. / Quantification of biochemical components in seminal plasma including fructose, citric acid and total protein of goat and sheep of the Midwest region of Brazil is one way of evaluating the biochemical and physiological activity of the sperm. These data serve as indicators of potential problems with the testicles and accessory glands of these animals and their relative fertility. The fructose and citric acid are important for the semen as a source of metabolic energy and as a component of a buffer, respectively. Fructose is a marker of secretory function of seminal vesicles, important for the survival of spermatozoa under anaerobic conditions, and is closely related to the initial motility of sperm cells. Therefore, the objectives of this project were to quantitatively analyze these components in the seminal plasma of goats and sheep in latitude 20&deg;31\'S 3 1\'S in four seasons and purify by chromatographic techniques the enzyme phospholipase A2, an important protein in the seminal plasma. Biochemical analysis were done using a spectrophotometer UV / Vis to obtaining the standard curve and to determine the monthly and annual average concentration of the constituents analyzed. The purification of PLA2 was performed by preparative liquid chromatography using the column as stationary phase Superdex 75-16/60 (GE HealthCare) by size exclusion and semipermeable membranes 10 and 30 kDa. As a result of biochemical analysis, we obtained the annual average concentration of total protein of 3,27 &plusmn; 0,60 g / dL for sheep and 5,02 &plusmn; 0,43 g/dL for goats, citric acid of 1015,33 &plusmn; 66, 50 g / mL for sheep and 1584,35 &plusmn; 143,90 g / mL for goats and fructose 23,40 &plusmn; 4,80 mg / dL for sheep and 72,73 &plusmn; 18,50 mg / dL for goats. The results showed that the PLA2 extracted from seminal plasma of sheep has a molecular mass of 13,8 kDa and the next PLA2 from goat seminal plasma has a molecular mass close to 12,8 kDa.

O presente estudo teve como objetivo avaliar a ação das soluções de quitosana, EDTA e ácido cítrico sobre a microdureza da dentina radicular. Utilizaram-se 10 incisivos centrais superiores humanos, os quais tiveram suas coroas seccionadas transversalmente e desprezadas. As raízes foram incluídas em resina acrílica de rápida polimerização e o bloco formado raiz/resina adaptado a máquina de corte. Desprezou-se o primeiro corte transversal da porção cervical e dividiu-se o segundo, em quatro quadrantes. Cada quarto foi destinado à confecção do corpo de prova obtendo-se 4 espécimes para cada raiz, um para cada solução (n=10): G1- EDTA 15%; G2- ácido cítrico; G3- quitosana 0,2% e G4- controle. Os espécimes receberam 50 &mu;L da solução por 5 minutos, sendo em seguida, lavados com água deionizada. Utilizou-se um microdurômetro (dureza Knoop) com carga de 10 g durante 15 segundos. Os resultados mostraram que todas as soluções avaliadas apresentaram capacidade de reduzir a microdureza da dentina radicular de forma semelhante entre si e estatisticamente diferente a do grupo controle (p<0,01). Concluiu-se as soluções de quitosana 0,2%, EDTA 15% e ácido cítrico 10% apresentam efeito semelhante na redução da microdureza dentinária. / The aim of this study was to evaluate the action of solutions: chitosan, EDTA and citric acid on the microhardness of the root dentin. There were used 10 human maxillary central incisors which ones had their crown cross-sectioned and discarded. The roots were embedded in acrylic resin of rapid polymerization and the block formed root/resin suitable by cutting machine. Neglecting the first cross-section of the cervical portion and the second was divided in four quadrants. Each quarter was destined to the confection of the specimen and it was got 4 specimen to each root, one for each solution (n=10): G1- EDTA 15%; G2- citric acid;G3- chitosan 0,2 % and G4- control. The specimen received 50 &mu;L of the solution for 5 minutes, and following up they were washed by deionized water. It was used a microhardness (Knoop hardness) with a load of 10g during 15 seconds. The results showed that all the solutions evaluated presented a capacity to reduce the microhardness of the root dentin in a similar way between them, and statically differ from the control group (p<0,01). It was concluded that chitosan 0,2% EDTA 15% and the citric acid 10% presented a similar effect in the reduction of the dentin microhardness.

O processo de desmineralização óssea tem sido mostrado vantajoso em procedimentos de enxertia óssea empregando blocos osseos, porem a sua utilização na periodontia em enxertos osseos autógenos particulados não esta ainda descrita na literatura. De acordo com a literatura é possível observar que existem diferentes agentes demineralizantes na pratica clinica os quais podem ser empregados no processo de desmineralização óssea, razão pela qual este estudo teve como objetivo comparar dois diferentes agentes desmineralizantes de enxertos ósseos autógenos particulados (ácido cítrico pH1 a 50% e tetraciclina hidroclorada a 50mg/ml) em diferentes tempos de aplicação, quanto ao efeito produzido no reparo de defeitos críticos em calvária de ratos. Foram utilizados 120 ratos adultos machos com aproximadamente 4 meses de vida. Neste estudo foi utilizado o modelo de defeito crítico de 8 mm, esses animais foram divididos em 8 grupos de estudo formados por 15 animais (5 em cada período experimental): CN (controle negativo): os defeitos permaneceram sem enxerto; CP (controle positivo): os defeitos foram preenchidos por osso particulado não desmineralizado; AC 15: os defeitos foram preenchidos com osso particulado desmineralizado por ácido cítrico durante 15 segundos; AC 30: os defeitos foram preenchidos com osso particulado desmineralizado por ácido cítrico durante 30 segundos; AC 60: os defeitos foram preenchidos com osso particulado desmineralizado por ácido cítrico durante 60 segundos; TCN 15: os defeitos foram preenchidos com osso particulado desmineralizado por tetraciclina durante 15 segundos; TCN 30: os defeitos foram preenchidos com osso particulado desmineralizado por tetraciclina durante 30 segundos; TCN 60: os defeitos foram preenchidos com osso particulado desmineralizado por tetraciclina durante 60 segundos. Foi realizada aeutanasia dos animais aos 7, 30 e 60 dias para realização de microtomografia computadorizada e analise histomorfometrica, para avaliar a área, volume e densidade óssea nos defeitos após os tempos experimentais definidos. Aos 7 dias, não era esperada formação de tecido ósseo significante, mas surpreendentemente, os espécimes desmineralizados com ácido cítrico demonstraram precocidade na produção de eventos regenerativos já nesse período. Durante os períodos experimentais foi possível observar como os espécimes tratados com acido cítrico apresentavam maior formação óssea nos defeito quando comparados com os controles e com os grupos onde empregados tetraciclina. Efeito provavelmente relacionado com a eliminação da parte mineral do osso e liberação de Proteinas morfogeneticas ósseas e fatores de crescimentos, liberados a partir da matriz ossea Concluiu-se que a desmineralização com ácido cítrico do osso autógeno particulado enxertado em defeitos críticos promoveu maior área, volume e densidade de formação óssea do que a desmineralização com tetraciclina e do que a não desmineralização. Observando-se melhores resultados aos 15 e 30 segundos de desmineralização. / Bone demineralization process has been shown useful in bone grafting procedures using onlay bone grafting, however its use in periodontics in bony autogenous particulate graft is not yet described in the literature. According to the literature you can see that there are different demineralizantes agents in clinical practice which can be used in bone demineralization process, which is why this study was to compare two different demineralization agents of bone autogenous particulate graft (citric acid pH1 the 50% tetracycline Hydrochloride and 50mg / ml) in different application time, the effect produced in the repair of critical defects in rat calvarium. 120 adult male rats with approximately 4 months of age were used. In this study we used the 8mm critical defect model, the animals were divided into 8 study groups consisting of 15 animals (5 in each experimental period): CN (negative control): the defect remained free graft; CP (positive control): the defects were filled by nondemineralized bone particles; AC 15: The defects were filled with demineralized bone particles of citric acid for 15 seconds; AC 30: defects were filled with demineralized bone particles of citric acid for 30 seconds; AC 60: The defects were filled with demineralized bone particles of citric acid for 60 seconds; TCN 15: defects were filled with demineralized bone particles tetracycline for 15 seconds; TCN 30: defects were filled with demineralized bone particles tetracycline for 30 seconds; TCN 60: defects were filled with demineralized bone particles tetracycline for 60 seconds. aeutanasia animals was performed at 7, 30 and 60 days for performing computed microtomography and histomorphometric analysis to assess the area, bone volume and density of the defects after the defined experimental times. At 7 days, it was not expected significant formation of bone tissue, but surprisingly, samples demineralized with citric acid demonstrated earliness in the production of regenerative events already during this period. During the experimental periods was possible to observe how the specimens treated with citric acid showed increased bone formation in defects when compared to controls and to groups where employees tetracycline. Effect probably related to the disposal of the mineral part of bone and release of bone morphogenetic proteins and factors of growth, released from the bone matrix concluded that the demineralisation by citric acid particulate autogenous bone graft in critical defects caused greater area, volume formation and bone density than tetracycline demineralization and demineralization that do not. Observing better results at 15 and 30 seconds demineralization.

Este trabalho é composto por dois artigos que visam analisar as margens relativas e absolutas de comercialização da indústria de processamento de laranja e a viabilidade econômico-financeira para a implantação deste empreendimento no estado de São Paulo. Embora seja uma cadeia produtiva importante no agronegócio do país, vem sendo constatada uma deterioração das relações entre os citricultores e a indústria processadora de suco de laranja. Após uma breve introdução e fundamentação do problema no primeiro capítulo, analisa-se no segundo capítulo as margens de comercialização da indústria de citros. Contatou-se que a indústria tem operado com margens relativas positivas e elevadas, principalmente, quando é incluída a receita obtida com as exportações dos subprodutos. No segundo artigo (terceiro capítulo desta dissertação), são consideradas três plantas industriais de processamento de citros na análise de investimento, com base no mix de produção, além de incorporar um mecanismo de precificação para a caixa de laranja a ser paga ao citricultor, através do modelo CONSECITRUS. Utilizou-se a metodologia de fluxos de caixa descontados, calculando os indicadores de Valor Presente Líquido - VPL, Taxa Interna de Retorno - TIR, Payback - PB e Payback descontado - PBD para os projetos. Os resultados indicaram que há viabilidade em todos os modelos e cenários analisados. Porém, através da análise probabilística, constatou-se a existência de um risco financeiro elevado, mensurado através do quantil negativo da distribuição do VPL. Embora o risco financeiro seja expressivo, verificou-se que o modelo CONSECITRUS proporcionaria à indústria um grau de risco, moderadamente, menor do que aquele que vigora atualmente. Neste contexto, a citricultura brasileira mostra-se como uma atividade razoavelmente rentável no longo prazo, embora esteja sujeita a um elevado nível de risco. / This study is composed of two articles aimed to analyze the relative and absolute margins of commercialization of orange processing industry and the economic and financial feasibility for the implementation of this venture in the state of São Paulo. Although it is an important agribusiness production chain for the country, it observed a deterioration of relations between citrus fruit growers and the processing industry of orange juice. After a brief introduction and justification of the problem in the first chapter, in the second chapter it is possible to analyze marketing margins of the citrus industry. When the revenue from exports of by-products is included, it was found that the industry has operated with positive and higher relative margins. In the second article (the third chapter of this dissertation), three industrial plants of citrus processing are considered in the financial analysis, based on the mix of production, in addition to incorporate a pricing mechanism for the orange box to be paid to the grower through the CONSECITRUS model. The methodology of discounted cash flows was used for calculating the net present value of indicators - NPV, internal rate of return - IRR, Payback - PB and Payback discounted - PBD for the projects. The results indicated that there is feasibility in all models and scenarios analyzed. However, through the probabilistic analysis it was found that there is a high financial risk, measured through the negative quantile of the NPV distribution. Although the financial risk is significant, it appeared that the CONSECITRUS model would offer the industry a risk, lower than the one currently in effect. In this context, the Brazilian citrus industry proves to be a reasonably profitable activity in the long term, although it is subject to a high level of risk.

A cana-de-açúcar é um alimento bem aceito por toda a população em geral, podendo ser consumido na forma de toletes (in natura) ou na forma de caldo, podendo ser apreciado com gelo somente, ou adicionado de sucos cítricos, mas nem sempre tratada com algum sanitizante ou outro produto para manutenção de sua qualidade. A cana-de-açúcar também pode ser consumida na forma de minimamente processada, sanitizada e embalada, facilitando sua utilização em redes de alimentação. Embora o processamento mínimo de vegetais aumente a suscetibilidade ao ataque de microrganismos e escurecimento enzimático, essas alterações podem ser reduzidas com o uso de tratamentos adequados, como sanitizantes e agentes antioxidantes. Em vista disso, procurou-se nesse trabalho avaliar a qualidade da cana-de-açúcar minimamente processada, tratada com antioxidantes e radiação gama. Os tratamentos aplicados para a conservação dos toletes de cana-de-açúcar foram: ácido cítrico nas concentrações de 1,5% e 3,0%; cloridato de L-cisteína a 1,0% e 2,0%; radiação gama com as doses de 2,0 e 4,0 kGy. Antes de receberem os tratamentos, os toletes de cana-de-açúcar foram processados e sanitizados com solução de hipoclorito de sódio. Após a drenagem, os toletes foram acondicionados em embalagens de polietileno de alta densidade e refrigerados a 4°C. Os produtos foram analisados após 1, 7 e 14 dias de armazenamento. Todos os tratamentos apresentaram-se em condições sanitárias adequadas para o consumo, independente das concentrações e dosagens. Os toletes de canas-de-açúcar tratados com ácido cítrico e cloridrato de L-cisteína apresentaram os melhores resultados quanto à inibição das enzimas de escurecimento, polifenoloxidase e peroxidase, sendo a cana-de-açúcar tratada com L-cisteína a que apresentou o caldo com melhores resultados quanto à inibição de seu escurecimento e níveis de açúcares. Todos os tratamentos inibiram o desenvolvimento de microrganismos / Sugar cane is a well-accepted food for the general population and can be consumed in the form of straw (in natura) or in the form of juice, which can be enjoyed with ice only, or added with citrus juice, but always treated with some sanitizing agent or other product to maintain its quality. Sugarcane can also be consumed in the form of minimally processed, sanitized and packaged sugarcane, improving its use in food networks. Unless, minimal processing of vegetables increases susceptibility to microorganism attack and enzymatic browning, but such changes can be reduced with the use of appropriate treatments such as sanitizers and antioxidants. The aim of this work was to evaluate the quality of minimally processed sugar cane treated with antioxidants or gamma radiation. The treatments applied for the preservation of sugarcane straw were: citric acid at concentrations of 1.5% and 3.0%; L-cysteine at concentrations of 1.0% and 2.0%, and gamma irradiation at doses of 2.0 and 4.0 kGy. Before receiving the treatments, the sugar cane straws were processed and sanitized with sodium hypochlorite solution. After draining, the straws were packed in high-density polyethylene packages and refrigerated at 4°C. The products were analyzed after 1, 7 and 14 days of storage. All treatments were in sanitary conditions suitable for the consumption, independent of the concentrations and dosages. The sugarcane treated with citric acid and L-cysteine presented the best results regarding the inhibition of the darkening enzymes, polyphenoloxidase and peroxidase. Sugarcane treated with L-cysteine presented the juice with better sugar levels and inhibition of browning. All treatments showed effective inhibiton of the microorganisms development