A lichia é uma fruta exótica de origem chinesa que cada vez mais tem ganhado espaço no mercado interno brasileiro, contudo problemas de pós-colheita existentes prejudicam a comercialização e a exportação de forma significativa. Diversos métodos são utilizados na tentativa de controlar estes problemas, um destes sendo a irradiação ionizante. Desta forma este trabalho tem como objetivo avaliar os efeitos de diferentes doses de radiação e de diferentes temperaturas nas características físico-químicas de frutos de lichia. Os frutos foram obtidos com produtores da região de Piracicaba e irradiados no Centro de Energia Nuclear na Agricultura em uma fonte de 60Co em um irradiador GammaCell 220 nas doses de 0 (testemunha), 0,5kGy, 1,0kGy e 2,0kGy com uma taxa de 0,259 kGy/h. Foram realizadas análises de pH, de cor da casca e da polpa, de teor aparente de sólidos solúveis, de acidez total e de teor de ácido ascórbico. Os resultados obtidos foram submetidos à análise de variância através de teste F a 95% de confiança e posteriormente a teste de Tukey a 5% de significância. As doses de irradiação apresentaram resultados variados dependendo da característica analisada, porém a dose de 1,0kGy apresentou os resultados mais favoráveis no geral. A redução da temperatura causou alterações desejáveis nos parâmetros estudados. Concluiu-se que os frutos de lichia armazenados a 8°C e irradiados a 1,0 kGy apresentaram melhoria significativa. / The lychee is a Chinese exotic fruit that has increasingly gained ground in the Brazilian domestic market, however existing post-harvest problems hinder the marketing and export significantly. Various methods are used in attempts to control these problems, one of these being ionizing irradiation. Thus this work aims to evaluate the effects of different radiation doses and different temperature on the physicochemical characteristics of litchi fruit. The fruits were obtained with producers of Piracicaba region and irradiated in the Center for Nuclear Energy in Agriculture into a source of 60Co in Gammacell 220 radiator at doses of 0 (control), 0.5kGy, 1.0kGy and 2.0kGy at a rate of 0,259kGy / hr. Were performed pH analyzes, color ratings, apparent soluble solids content measurement, total acidity and ascorbic acid content measurement. The obtained results were submitted to variance analysis by F test at 95% confidence and later to Tukey test at 5% significance. The irradiation doses showed varied results depending on the characteristic analyzed, but the dose of 1.0kGy presented the most favorable results in general. The temperature reduction caused desirable changes in the studied parameters. It was concluded that fruits stored at 8°C and irradiated at 1.0 KGy exhibited significant improvement in the physicochemical characteristics of the litchi fruits

Shelf life studies of raw Macadamia integrifolia nuts were carried out at different storage temperatures, relative humidities and time. An accelerated shelf life test was conducted, and the influence of water activity on kernel texture was studied. The antioxidants naturally present were identified by the use of thin layer chromatography. Accelerated shelf life tests showed that hydrolytic rancidity followed apparent zero order kinetics within the water activity range of 0.3 to 0.5. Oxidative rancidity measured by peroxide value appeared to follow different orders of reaction at different temperatures. At two months of storage rancidity was detected at which the headspace concentration of hexanal was 0.39 ppm and a peroxide value of 0.37 meq/kg. Headspace gas chromatography was done to find a quick and effective method for measuring oxidative rancidity. The presence of natural antioxidants was verified to explain the shelf life of macadamia nuts. In textural study, correlations were found between subjective and objective measurements. The product became unacceptable organoleptically above water activity 0.415 when stored at 20 degrees C. This level was established as the critical water activity. There is a need to establish a water activity at which the consumer is likely to reject the product. / Master of Science (Hons) (Food Science and Nutrition)

Probiotic bacteria are added to commercial yoghurts as adjunct cultures, to impart health benefits to consumers. To gain maximum therapeutic benefit, the bacteria must remain viable over the shelf life of the yoghurt. Studies have shown, however, that the viability of these bacteria decreases significantly over this period and in some products, is negligible prior to the expiry date. Some strains of probiotic bacteria are oxygen sensitive. Yoghurt has been found to contain a significant concentration of dissolved oxygen and it has been proposed that this has a negative effect on probiotic viability. In this research, several tests were conducted and observations made. Experiments were conducted with non-commercial probiotic cultures to observe the effect of low oxygen environment on probiotic viability. No significant difference existed in viability between probiotic bacteria stored in oxygen reduced yoghurt and regular yoghurt. All yoghurt stored in oxygen barrier packaging material displayed enhanced shelf-life properties, this was observed in replicated experiments. Oxygen barrier packaging combined with an oxygen scavenging material was found to be the most effective oxygen removal system, particularly when used with set type yoghurt. / Doctor of Philosophy (PhD)

Freshness is a holistic attribute of a food product, with a meaning that most often includes how recently produced or harvested a food currently is and to what extent it has been preserved. Without knowledge of production date, consumers will judge perceived freshness by the sensory properties of foods. However, these properties are not easily identified and described, as they vary considerably between different product types. The objective of this thesis, was to determine the sensory properties that consumers most associate with baked product freshness, and to determine the volatile composition responsible for "fresh-baked" flavour. In addition, relationships were determined and modelled between volatile composition, sensory properties and perceived freshness, in order to predict perceived freshness without the need for further consumer testing. Two consumer studies were carried, where perceived freshness of 10 breads, 5 cakes and 5 biscuits was measured based on appearance, flavour and texture, and by product odour only. Individual differences in perceived freshness were represented on two-dimensional Freshness Maps generated using Principal Component Analysis (PCA). Consumers used similar terms to describe product freshness, but different terms were associated with specific product types. An understanding of the sensory characteristics associated with perceived freshness was determined by examining relationships between perceived freshness and descriptive analysis (DA). Sensory characteristics perceived to convey freshness in one product type did not necessarily convey freshness in another. Further relationships between perceived freshness and sensory characteristics were determined for 20 bread types. Descriptive analysis was carried out with all breads, whereas perceived freshness was measured for 10 of these. Three consumer clusters were identified that were homogenous in their freshness perceptions, indicating that perceived bread freshness varied among consumers. Perceived freshness of breads not evaluated by consumers, but assessed by descriptive sensory analysis, were predicted for each consumer cluster using Partial Least Squares Regression (PLSR). Most fresh breads were described as having "porous" appearance, "floury", "toasted" and "malty" odour, "sweet", "buttery", and "oily" flavour, and "sweet" aftertaste. Least fresh breads were described as "musty" odour, "sour" flavour and "sour" aftertaste. In addition, Proton Transfer Reaction Mass Spectrometry (PTR-MS) measured the volatile composition of all 20 bread types. Thirty-three mass ions significantly discriminated between bread types. Relationships were determined between odour and flavour sensory attributes, and mass spectral data using 15 of the 20 breads. PLSR models predicted the sensory properties and perceived freshness of all breads including five types not included in the construction of models. Bread perceived to be most fresh shared a similar combination of positively correlated mass ions, m/z 87, 97 and 117, also represented by "dairy" odour and "buttery" flavour, whilst the masses m/z 63, 69 and 91 were negatively associated with bread freshness, represented by the sensory attributes "grain", and "musty" odour, and "sour" flavour. The influence of sweetener, fat type and time from baking on perceived freshness was determined for cakes. Four sweeteners (sucrose, glucose, xylitol, isomaltose), three fat types (butter, margarine, shortening) and two times from baking (days zero and 15) were investigated. Descriptive analysis was carried out using a trained panel, and volatile composition of measured using PTR-MS. Twelve cake samples with the largest sensory variation were further selected for consumer testing for perceived freshness. Results demonstrated that sweetener type, fat type, time from baking and their interaction significantly influenced the sensory properties, volatile composition, and perceived freshness of cakes. There was no evidence of perceived freshness segmentation among consumers. Perceived freshness of the twelve cakes not evaluated by consumers was predicted using sensory properties, volatile composition, and their combination. The freshest cakes were evaluated on the day of baking, and contained a combination of margarine and sucrose, and butter and sucrose. The least fresh cakes were evaluated after 15 days of storage and contained a combination of shortening and isomaltose, and butter and isomaltose. The most fresh samples were positively correlated with mass ions m/z 124, 74, 97 and 93, and sensory characteristics of "buttery" odour, and "buttery", "eggy" flavour. The least fresh samples were negatively correlated with mass ions m/z 110 and 95, and sensory characteristics of "rancid", "dusty" and "fatty" odour. Best predictions were obtained for cakes evaluated on day zero that contained a combination of shortening and sucrose. This research established an objective knowledge of consumers' perceived freshness of baked product types in terms of sensory properties and volatile composition. This approach enabled the understanding of ingredients and time from baking influences, as well their interaction on baked product freshness. The predictive models developed that examined relationships between PTR-MS spectra, sensory characteristics and consumer perceived freshness can be applied to predict freshness of baked products not assessed by consumers.

Wilting during shelf life is a major cause of postharvest shrink for bedding plants shipped long distances from production greenhouses to retail outlets. The objective of this research was to determine if irrigation at lower, constant substrate moisture content (SMC) during greenhouse production would be a feasible way to acclimate plants for reduced shrinkage during shelf life, while potentially conserving irrigation water. Rooted plugs of Angelonia angustifolia 'Angelface Blue' were grown in greenhouse production until a marketable stage in substrates irrigated at SMC levels of 10, 20, 30, and 40% using a controlled irrigation system. At the end of the greenhouse production stage, plants were irrigated to container capacity and subjected to a simulated shipping environment, in shipping boxes in the dark for two days. After shipping, plants were placed back in the greenhouse and watered minimally to simulate a retail environment. Data was taken at the end of each stage i.e. greenhouse production, simulated shipping, and simulated retail. Parameters measured at the end of the production stage were fresh and senesced flower number, stem number, pre-dawn and mid-day water potential, SPAD meter readings (Experiment 2), and plant height and node number segmented into vegetative, flowering, and bud area. Plant quality was observed and rated. At the end of the simulated retail stage, the same data was taken, along with fresh and dry shoot and root weight. Results indicated that as SMC decreased from 40 to 10%, plants were shorter in height, but had proportional flowering sections (Experiment 1) or more compact flowering sections (Experiment 2). The volume of water received by the 40% SMC plants was three times greater (Experiment 1) and 12 times greater (Experiment 2) than the 20% SMC plants during greenhouse production, and two times greater (Experiment 1) and nine time greater (Experiment 2) during simulated retail. Additionally, the 40% SMC plants used 15 liters (Experiment 1) and 38 liters (Experiment 2) of water during greenhouse production compared to the 20% SMC plants using only three liters in both experiments. During simulated retail the 40% SMC plants used six liters (Experiment 1) and nine liters (Experiment 2) of water while the 20% SMC plants used five liters (Experiment 1) and three liters (Experiment 2) of water. During production, mid-day water potentials decreased as the SMC levels decreased, but at the end of the simulated retail (Experiment 1), the mid-day water potentials were all the same, suggesting plants that were drought stressed during production area were acclimated to lower water levels experienced in retail settings. Overall, the 20% SMC treatment produced the best postharvest quality plant due to reduced plant height without detrimental effects on flowering. The results demonstrate that while conserving water, controlled irrigation at a medium-low SMC can produce high quality plants that have equal shelf life to those that are irrigated at high levels.

The consumption of fresh-cut fruits has been increasing in recent years due to their health benefits. Fresh-cut cantaloupe (Cucumis melo L.) represents a great snack alternative due to its low caloric content, freshness, and basic component of a healthy diet. One of the latest alternatives to reduce the decay of quality brought by minimal processing of fruits is the development of edible coatings. Acting as a barrier to moisture and gases, the coatings are expected to extend the shelf-life of fresh-cut products, thus the main objective of this research was to determine the effectiveness of an antimicrobial edible coating on the shelf-life of fresh cut cantaloupe (stored at 4 degrees C for 15 days) while maintaining its quality attributes. The effect of different coating compositions and their concentrations on a product's chemical properties and quality attributes was studied. A set of solutions containing chitosan, beta-cyclodextrin, trans-cinnamaldehyde, pectin and calcium chloride were used as coating systems for the fruit using the layer-by-layer method. Quality was measured in terms of texture, color, weight loss, moisture, acidity, and pH. In addition, a consumer sensory test was carried out to support the findings from the objective quality data. Microbiological tests were carried out to determine the effectiveness of trans-cinnamaldehyde as antimicrobial agent within the coating. Uncoated fresh-cut cantaloupe samples stored at 4 degrees C served as controls. In terms of microbiological and physicochemical quality attributes, the antimicrobial coating improved the shelf-life of fresh-cut cantaloupe (up to 12 days), compared to the controls (only 6 days). The coating composed of 2% antimicrobial, 2% chitosan and 1% pectin was the most effective in terms of consumer's acceptance (P<0.05) and shelf-life extension. The results indicated that different ratios between solutions present a variation for each specific quality attribute. The thicker the coating, the firmer the fruit and different thicknesses resulted in different amounts of antimicrobial compound in the coating, thus critically affecting the shelf-life of the product. This study demonstrates the feasibility of a new generation of edible coating for fresh-cut cantaloupe, the coating consists of using a system specially designed to allow the incorporation of natural antimicrobial agents by means of the application of microencapsulation and the layer-by-layer assembly.

Mushrooms are one of the protein rich foods, however they have a short pro-harvest life (2 to 3 days) compared to most vegetables. The aim of this study was to evaluate whether applying an anti-browning solution using vacuum impregnation and then electron beam irradiation can be used to extend the shelf life of fresh-cut mushrooms (Agaricus bisporus). Solutions made with (a) 2% ascorbic acid + 1% calcium lactate, (b) 2% citric acid + 1% calcium lactate, (c) 1% chitosan + 1% calcium lactate, and (d) 1% calcium lactate were used to impregnate mushroom slices at different vacuum pressures, vacuum pressure times, and atmospheric restoration times. Mushrooms were also irradiated at a dose of 1 kGy using a 1.35 MeV e-beam accelerator and their quality was evaluated in terms of color, texture, and microbial growth during 15 days storage at 4 degrees C. The best vacuum impregnation treatment was the 2% ascorbic acid and 1% calcium lactate solution using a vacuum pressure of 50 mmHg for 5 minutes and an atmospheric restoration time of 5 minutes. The control (not treated) and impregnated samples lost their structure (softening) during storage. The irradiated samples lost their firmness by day 4 of storage. The addition of calcium lactate to the samples during the treatment helped to keep the product’s texture during the 15 days storage time. Color of the mushrooms changed during storage for all the control and impregnated samples and only the irradiated samples showed an acceptable color by the end of day 15. Aerobics and psychrotrophics counts were significantly reduced by irradiation; while yeast and molds population increased by day 9 and were not completely inactivated with a dose of 1 kGy. Sensory panelists preferred the treated samples over the controls. The best treatment was the combination of vacuum impregnation with irradiation according to the consumer studies.

The validation and potential use of mathematical models to estimate the shelf-life of refrigerated food exposed to temperature abuse and basing such estimations on microbial growth was analyzed. Combined heat transfer, microbial growth models, and non-parametric statistical procedures formed a computer-based predictive tool to assess shelf-life and estimate the accuracy of the prediction. Experiments were carried out to assess the precision of the combined model parameters. The different situations analyzed considered stepwise fluctuations in environmental temperature and a change in package characteristic (size and packaging material). Computer simulations showed that even when the temperature abuse period constitutes a small fraction of the total exposure time (2%-3%), shelf-life can be highly affected (20%-30%). To analyze the precision of the combined model response, two sources of variation were considered, microbial growth and heat transfer parameters. First order, pseudo-zero order kinetics and Arrhenius model formed the basis for the microbial model. The accuracy of lag and exponential phase of microbial growth for a mixture of three microorganisms (P. fluorescens, S. aureus, and A. Iwoffi) was assessed using a nonparametric statistical procedure based on the bootstrap method. The activation energy (E [subscript a]) and the logarithm of the frequency factor (InK₀) were found to be 109±3.4 J/mole and 48.3±1.5 for the exponential phase of this microbial mixture. The values for the exponential phase were 152±4 J/mole and 64.0±1.7, respectively. These parameters together with experimental values for the overall heat transfer coefficient were used to analyze the precision of the model response. This precision was not affected by a change in environmental temperature and packaging characteristics and remained constant at ±1 day. Two different temperature abuse situations yield estimated shelf-life of 4.8±1 and 8.9±1 day, respectively. This result can not be generalized as it depends on the particular examples analyzed. / Graduation date: 1993

Orientador: Valdemiro Carlos Sgarbieri / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T21:56:49Z (GMT). No. of bitstreams: 1 Ziegler_FabianeLaFlor_M.pdf: 1806557 bytes, checksum: c7746abef0196b047e712da90766b294 (MD5) Previous issue date: 2006 / Resumo: O principal objetivo da presente pesquisa foi desenvolver um produto dietético funcional para idosos desnutridos. Para tal, realizou-se inicialmente a caracterização físico-química e nutricional das fontes protéicas: isolado protéico do soro de leite bovino (WPI) e hidrolisado de colágeno bovino (HCB), buscando-se adequar a proporção entre elas, bem como, avaliar algumas de suas propriedades físicas, composição, perfil de aminoácidos e propriedade nutricional. Posteriormente foi realizado o desenvolvimento do produto através de testes preliminares, caracterização físico-química, testes sensoriais e de vida de prateleira. Na 1ª etapa do trabalho observou-se que o componente de maior concentração foi a proteína para as duas amostras (~ 92%). A solubilidade foi elevada tanto do WPI como do HCB o que refletiu, conseqüentemente, na solubilidade da mistura dessas proteínas. O perfil de aminoácidos essenciais (EAE) do WPI atende às recomendações da Food and Agriculture Organization (FAO)/World Health Organization (WHO), no entanto o HCB apresenta deficiência em vários aminoácidos essenciais, particularmente em triptofano e aminoácidos sulfurados. Do ponto de vista nutritivo, os índices quociente de eficiência protéica (PER), utilização líquida da proteína (NPU), valor biológico aparente (VBa) e balanço de nitrogênio (BN), as misturas WPI:HCB (60:40 e 80:20) não diferiram estatisticamente entre si e do WPI (p > 0,05), sendo inferior (p < 0,05) à caseína comercial (CC) usada como referência. Em função dos resultados obtidos, optouse pela mistura 60% WPI: 40% HCB como componente protéico na formulação do produto dietético funcional, por razões econômicas. Nos testes preliminares avaliaram-se diferentes combinações e proporções entre os ingredientes para a obtenção da melhor formulação, principalmente em relação à solubilidade e ao aspecto sensorial. A escolha destes ingredientes, bem como a quantidade usada foi baseada em pesquisas na literatura a respeito do perfil nutricional de idosos e suas principais deficiências. Através da análise sensorial (testes de aceitação, ideal de doçura e intenção de compra) com idosos foram escolhidas as formulações sabor chocolate e sem adição de sabor dentre seis opções, as quais receberam médias de aceitação de 6,87 e 6,60, respectivamente, numa escala de nove pontos. Essas formulações apresentaram em torno de 12% de proteína e 80% de carboidratos com adição de inulina, frutooligossacarídeos (FOS), cálcio, zinco, magnésio, selênio e as vitaminas B1, B6, ácido fólico, B12, A, C e E. Com as formulações foi realizado estudo da vida útil do produto durante 30 dias de estocagem em temperatura ambiente e a 35 °C usando-se filme de polipropileno como material de embalagem. Realizaram-se análises de umidade, atividade de água (aw), isoterma de adsorção, taxa de permeabilidade ao vapor de água (TPVA), cor, avaliação sensorial e perda de vitaminas. O produto apresentou aw inicial abaixo de 0,3, valor característico de alimentos desidratados. As isotermas de adsorção foram utilizadas para determinação dos valores de aw crítica (0,5), umidade crítica (5,1%) e umidade inicial (~2,0%), os quais foram usados nos cálculos da estimativa da vida útil do produto. Observou-se pequena variação na cor (_E* = 0,4 para formulação sem saborizante e 0,6 para a formulação chocolate) durante os 30 dias de estocagem. A qualidade sensorial manteve-se satisfatória nas três avaliações (tempo zero, 15 e 30 dias), obtendo-se médias de aceitação acima de 5 para os todos atributos. Mais de 65% dos provadores tiveram intenção de compra entre ¿certamente compraria¿ e ¿tenho dúvidas se compraria¿. Através desses resultados, constatouse uma maior preferência pela formulação chocolate. Verificou-se uma diminuição apreciável no teor das vitaminas B1, C, A e E ao final da estocagem. Através do ganho de peso das formulações estimou-se a vida de prateleira do produto, a qual foi de aproximadamente 4 meses. Dessa forma, recomenda-se o uso de embalagens com maior proteção, no caso de uma possível comercialização ou administração a idosos, evitando-se a degradação dos nutrientes mais sensíveis e conseqüente diminuição do valor nutricional do produto / Abstract: The main objective of the present investigation was the development of a functional dietetic product for undernourished elderly. First step was the chemical, physical and nutritional characterization of protein component, a mixture of whey protein isolate (WPI) and a bovine collagen hydrolysate (HCB) both materials containing around 92% protein and showing high solubility in water. The essential amino acid profile (EAE) of the WPI reaches all the requirements of the FAO/WHO reference standard, however the HCB is deficient in all essential amino acids, particularly in cysteine and tryptophan which is totally absent in collagen. The nutritional indices PER, NPU, VBa and nitrogen balance (NB) of the two mixtures WPI:HCB (60:40 and 80:20) respectively, did not show statistical difference (p > 0.05) among themselves and with the WPI. Nevertheless they were inferior (p < 0.05) to a commercial casein (CC) used as reference. The choice was for the mixture WPI:HCB (60:40) for economical reasons. The choice of ingredients, composition and concentrations in the formulation was based mainly in three criteria, i.e., solubility, sensorial aspects and nutritional deficiencies of elderly population, based on literature surveys. In sensorial tests (acceptance, ideal sweetness and buying attitude) conducted with an elderly group for six different formulations, the choice was for the formula dissolved in milk with chocolate flavor and the other with no flavouring added. The acceptance scoring was 6.87 and 6.60 respectively, for the two formulations using a 9 ¿ point scale. The two formulations contained around 12% protein and 80% carbohydrate in addition to inuline, frutooligosaccharides (FOS), calcium, zinc, magnesium, selenium and the vitamins B1, B6, folic acid, B12, vitamin A, C and E. A shelf life study was conducted with the two formulations during 30 days under the laboratory environmental conditions and at 35 °C. Humidity, water activity (aw), adsorption isotherm, water vapor permeability rate (WVPR), color, sensorial evaluation, mineral and vitamin analysis were performed. Water activity at time zero (T0) was below 0.3, characteristic of dehydrated powder. The adsorption isotherms were used for determination of the critical aw (0.5), critical moisture content of 5.1% and initial moisture of about 2.0%, which were used for the estimation of the product shelf life. A small color variation was observed (_E* 0.4 for the formulation without flavouring and 0.6 for the chocolate formula), during the 30 days of storage. Sensorial qualities were satisfactory for all three storage time (T0, T15 and T30), with an average acceptance score above 5. More than 65% of the panel demonstrated buying intention between ¿certainty of buying¿ and ¿doubt of buying¿. Higher preference was for the chocolate formula. Appreciable losses of the vitamins B1, C, A and E were detected during storage in both samples, independently of the storage condition. The shelf life estimated was of approximately 4 months for both formulations. It is recommended that a packaging material with more barrier to water vapor, light and oxygen must be used for product to minimize losses of the more unstable vitamins / Mestrado / Nutrição Experimental e Aplicada à Tecnologia de Alimentos / Mestre em Alimentos e Nutrição

A lichia é uma fruta exótica de origem chinesa que cada vez mais tem ganhado espaço no mercado interno brasileiro, contudo problemas de pós-colheita existentes prejudicam a comercialização e a exportação de forma significativa. Diversos métodos são utilizados na tentativa de controlar estes problemas, um destes sendo a irradiação ionizante. Desta forma este trabalho tem como objetivo avaliar os efeitos de diferentes doses de radiação e de diferentes temperaturas nas características físico-químicas de frutos de lichia. Os frutos foram obtidos com produtores da região de Piracicaba e irradiados no Centro de Energia Nuclear na Agricultura em uma fonte de 60Co em um irradiador GammaCell 220 nas doses de 0 (testemunha), 0,5kGy, 1,0kGy e 2,0kGy com uma taxa de 0,259 kGy/h. Foram realizadas análises de pH, de cor da casca e da polpa, de teor aparente de sólidos solúveis, de acidez total e de teor de ácido ascórbico. Os resultados obtidos foram submetidos à análise de variância através de teste F a 95% de confiança e posteriormente a teste de Tukey a 5% de significância. As doses de irradiação apresentaram resultados variados dependendo da característica analisada, porém a dose de 1,0kGy apresentou os resultados mais favoráveis no geral. A redução da temperatura causou alterações desejáveis nos parâmetros estudados. Concluiu-se que os frutos de lichia armazenados a 8°C e irradiados a 1,0 kGy apresentaram melhoria significativa. / The lychee is a Chinese exotic fruit that has increasingly gained ground in the Brazilian domestic market, however existing post-harvest problems hinder the marketing and export significantly. Various methods are used in attempts to control these problems, one of these being ionizing irradiation. Thus this work aims to evaluate the effects of different radiation doses and different temperature on the physicochemical characteristics of litchi fruit. The fruits were obtained with producers of Piracicaba region and irradiated in the Center for Nuclear Energy in Agriculture into a source of 60Co in Gammacell 220 radiator at doses of 0 (control), 0.5kGy, 1.0kGy and 2.0kGy at a rate of 0,259kGy / hr. Were performed pH analyzes, color ratings, apparent soluble solids content measurement, total acidity and ascorbic acid content measurement. The obtained results were submitted to variance analysis by F test at 95% confidence and later to Tukey test at 5% significance. The irradiation doses showed varied results depending on the characteristic analyzed, but the dose of 1.0kGy presented the most favorable results in general. The temperature reduction caused desirable changes in the studied parameters. It was concluded that fruits stored at 8°C and irradiated at 1.0 KGy exhibited significant improvement in the physicochemical characteristics of the litchi fruits