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Thesis (MSc Food Sc )--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Dried fruit is a well-known food product that has been produced for many years. The product characteristics have remained constant throughout this time with a moisture content of ca. 18 - 26% (mlm). However, in recent times there has been a definite trend towards a fmal dried fruit product in the intermediate moisture range with a moisture content of ca. 36%. The high water activity (aw) of the product (ca. 0.85) makes the product susceptible to microbiological spoilage and the product therefore requires a subsequent pasteurisation step to ensure a safe product. A further consequence of the increased moisture content, higher aw and the temperature of the pasteurisation step, is the increased rate of non-enzymatic browning reactions. Currently the shelf life is only 15 weeks while a minimum shelf life of 30 weeks is required to enable product export. Moisture sorption isotherms may be used to depict the relationship between moisture content and aw. Moisture sorption isotherms were thus determined for Royal type apricots and nectarines at 25° and 40°C. Samples, equilibrated at relative humidities in the range of 11-97%, were obtained using saturated salt solutions and a static gravimetric method. Isotherms were found to be of type I, typical of dried fruit. Six mathematical models namely; BET, GAB, Iglesias and Chirife, Halsey, Henderson, and Chung and Pfost, were fitted to experimental data. The GAB model predicted the aw of both apricots and nectarines the best at 25° and 40°C with the Henderson equation second best in all instances. The binding energy, as a function of moisture content, was calculated to determine energy requirements for drying. At low moisture contents « 20%) an increase of energy was required for drying. Discolouration of macerated dried Royal type apricots and nectarines during accelerated storage as affected by moisture (32, 36, and 40%, mlm) and sulphur dioxide (S02) content (2500, 3000 and 3300 mg.kg" for apricots; 1800, 2200 and 2600 mg.kg" for nectarines) was investigated. The macerated samples were stored at 30°, 40°, 50° and 60°C. Colour was quantified in terms of the L* value of the CIELab system (used throughout the study). Moisture and S02 contents affected both the initial fruit colour and the rate of discolouration. The highest L* values, i.e. lightest fruit colour, were obtained for fruit at 40% moisture content and the highest S02 levels. Increasing storage temperature accelerated the loss of moisture and S02. The influence of a 10°C increase in storage temperature on the rate of browning and thus shelf life was described in terms of the QIO value. QIO and aw values of apricots ranged from 1.96 - 2.47 and 0.833 - 0.890, respectively, while QIO values of 1.50 - 4.61 and aw values ofO.844 to 0.890 were obtained for nectarines. Discolouration of dried nectarine halves during accelerated storage at 40°C as affected by rehydration method, moisture content, packaging atmosphere and pasteurisation method, was investigated. The fruit halves were rehydrated using three different methods to obtain moisture contents of 36 and 40%, respectively. Dry heat and steam pasteurisation techniques were used to render a microbiologically safe product. Commercial packaging material was used and the atmosphere was modified with CO2 to lower the O2 concentration in the headspace. A two-step rehydration at 45°C, steam pasteurisation at 90°C for 150 minutes and packaging under a high CO2 atmosphere rendered a product with the best colour retention under accelerated storage conditions of 40°C for eight weeks. To confirm the results obtained with accelerated storage at temperatures that the product would normally be retailed at, shelf life tests were also performed at 5° and 25°C. Discolouration of whole dried Royal type apricot and nectarine halves as affected by rehydration method, moisture content, packaging atmosphere and pasteurisation method was investigated. The methodology for rehydrating, pasteurising and packaging the high moisture dried fruit developed in this study was compared against the standard method used by the industry. The new processing method increased shelf life. Samples were stored for a period of 30 weeks and were tested every five weeks to determine CO2 concentration in headspace, colour retention and S02 concentration of the fruit. Both apricots and nectarines achieved a shelf life of 30 weeks at both storage temperatures and an extrapolated shelf life of 89 weeks at 5°C, but only 32 weeks at 25°C. / AFRIKAANSE OPSOMMING: Droë vrugte is 'n welbekende voedselproduk en word reeds vir baie jare vervaardig. Die produkeienskappe het konstant gebly gedurende hierdie tydperk met 'n produkvoginhoud van ca. 18 - 26% (mlm). Daar is egter 'n tendens die afgelope tyd na 'n finale produk in die intermediêre voggebied met 'n voginhoud van ca. 36% en 'n water aktiwiteit (aw) van ca. 0.85. Hierdie verandering in voginhoud en aw maak die produk vatbaar vir mikrobiologiese bederf, en gevolglik word pasteurisasie benodig om dit te preserveer. 'n Verdere gevolg van die verhoogde voginhoud en aw en die hoë temperature van pasteurisasie, is die verhoogde tempo van nieensiematiese verbruiningsreaksies. Huidig is die produk se rakleeftyd 15 weke terwyl 'n minimum van 30 weke benodig word om hierdie produk suksesvol uit te voer. Vogsorpsie-isoterme kan gebruik word om die verwantskap tussen voginhoud en aw uit te beeld. Vogsorpsie-isoterme van Royal tipe applekose en nektariens is gevolglik bepaal by 25° en 40°C. Monsters, geëkwilibreer by relatiewe humiditeite van 11 - 97%, is verkry deur gebruik te maak van versadigde soutoplossings en 'n statiese gravimetriese metode. Tipe I isoterme, wat tipies van droëvrugte is, is verkry. Ses wiskundige modelle naamlik; BET, GAB, Iglesias en Chirife, Halsey, Henderson, en Chung en Pfost, is gepas op die data. Die GAB model het die aw van beide appelkose en nektariens by 25° en 40°C die beste voorspel en die Henderson model die tweede beste in al die gevalle. Die bindingsenergie as 'n funksie van voginhoud is bereken om die energie vereistes van droging te bepaal. By lae voginhoude (<20%) is 'n skerp styging in benodigde energie waargeneem. Die verkleuring van gemaalde gedroogde Royal tipe appelkose en nektariens gedurende versnelde opberging en die invloed van voginhoud (32, 36, en 40%, mlm) en swaweldioksied (S02) konsentrasie (2500, 3000 en 3300 mg.kg' vir appelkose; 1800, 2200 en 2600 mg.kg" vir nektariens) is ondersoek. Die gemaalde monsters is gestoor by 30°, 40°, 50° en 60°C. Kleur is gekwantifiseer in terme van L* waardes van die CIELab sisteem (ook gebruik vir daaropvolgende ondersoeke). Vog en S02 het albei die aanvanklike kleur asook die tempo van verbruining beïnvloed. Die hoogste L* waardes, d.i. die ligste kleur, is verkry vir die monsters met 40% voginhoud en die hoogte S02 vlakke. Verhoogde temperature tydens opberging het aanleiding gegee tot verhoogde verliese van vog en S02. Die invloed van 'n 10°C verhoging in opbergingstemperatuur op die tempo van verbruining en dus rakleeftyd, word beskryf in terme van QIO waardes. QIO en aw waardes van die appelkose het gestrek van 1.96 - 2.47 en 0.833 - 0.890, onderskeidelik, terwyl QIO waardes van 1.50 - 4.61 en aw waardes van 0.844 tot 0.890 verkry is vir die nektariens. Verkleuring van gedroogde nektarien halwes gedurende versnelde opberging by 40°C en die invloed van rehidrasie metode, voginhoud, verpakkingsatmosfeer en pasteurisasiemetode is ondersoek. Die vrughalwes is gerehidreer deur middel van drie metodes om die voginhoud te verhoog tot 36 en 40%, onderskeidelik. Droë hitte en stoompasteurisasie metodes is gebruik om 'n mikrobiologiese veilige produk daar te stel. Kommersiële verpakkingsmateriaal is gebruik en die CO2 konsentrasie van die atmosfeer in die verpakking is verhoog om die invloed daarvan te bepaal. 'n Twee-stap-rehidrasie by 45°C, stoompasteurisasie by 90°C vir 150 minute en 'n hoë C02 atmofeer het aanleiding gegee tot die monster met die beste kleurbehoud tydens versnelde opberging by 40°C vir agt weke. Om die resultate, verkry met die versnelde rakleeftyd studie, te bevestig by temperature waarby die produk normaalweg blootgestel sal word tydens kleinhandel, is 'n rakleeftyd studie uitgevoer by 5° en 25°C. Verkleuring van heel gedroogde Royal tipe appelkoos en nektarien halwes, die invloed van rehidrasie metode, voginhoud, verpakkingsatmosfeer en pasteurisasiemetode is ondersoek. Die metodiek vir die rehidrasie, pasteurisasie en verpakking van hoë vog droëvrugte ontwikkel in hierdie studie, is getoets teen die standaardmetode wat deur die industrie gebruik word. Die nuwe prosesseringsmetode het aanleiding gegee tot 'n langer rakleeftyd. Monsters is opgeberg vir 'n tydperk van 30 weke om die rakleeftyd te bepaal. Die CO2 konsentrasie in die pakkie, kleurbehoud en S02 konsentrasie van die vrugte is elke vyf weke getoets. Beide appelkose en nektariens het 'n rakleeftyd van 30 weke by albei opbergingstemperature behaal, terwyl 'n ekstra-gepoleerde rakleeftyd van 89 weke by 5°C en 32 weke by 25°C behaal is.

Orientador: Celso Costa Lopes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-03T10:03:47Z (GMT). No. of bitstreams: 1 Hofsetz_Kelly_M.pdf: 6785149 bytes, checksum: 5d205e8078f26beba5c4f004900f07ed (MD5) Previous issue date: 2003 / Resumo: Este trabalho estudou o processo de obtenção de banana nanica crocante através da secagem a altas temperaturas e curto período de tempo (HTST - High Temperature and Short Time). O processo consistiu de um pré-tratamento a 70°C durante 5 minutos, de uma etapa à alta temperatura (130°C, 1400C e 150°C) e curto tempo (9, 12 e 15 minutos) e de uma etapa à temperatura de 70°C até atividade de água em torno de 0,320. De modo a verificar a influência da etapa HTST no processo, montou-se um planejamento experimental fatorial 22 com 3 pontos centrais, cujas respostas do processo foram o grau de reidratação, o parâmetro k do modelo de Lewis (para a etapa HTST, 70°C e secagem completa) e a crocância, avaliada por medidas sensoriais e instrumentais de textura. O planejamento experimental resultou numa matriz com as condições de ensaios de 130°C-9min, 130°C-15min, 150°C-9min, 150°C-15min e três pontos centrais a 140°C-12min. Banana crocante foi obtida com as condições de 140°C-12min e 150°C-15min de etapa HTST, com atividade de água de 0,345 e 0,363, respectivamente. Os resultados mostram que o melhor grau de reidratação ocorreu para os tempos de 10 e 5 minutos e que existe uma significativa relação entre a crocância e a temperatura da fase HTST. Não foi possível encontrar um ajuste adequado ao parâmetro k do modelo de Lewis para a etapa HTST e a 70°C, porque as umidades iniciais eram diferentes e promoveram grande diferença nos valores desse parâmetro. Adicionalmente, caracterizou-se a crocância de frutas comerciais liofilizadas e determinou-se a aw. Os resultados obtidos para a banana comercial liofilizada foram comparados com os da banana desidratada obtida neste estudo. As medidas instrumentais e sensoriais mostraram que ambas foram consideradas crocantes / Abstract: We present here a study about producing crispy banana using a HTST (High Temperature Short Time) process. The process involves pretreatment of the fruit during 5 minutes at 70°C, a dry HTST stage (130, 140 and 150°C and 9, 12 and 15 minutes) and, finally, a dry stage at 70°C until the water activity (aw) is near 0,300. In order to evaluate the HTST stage in the process, we used a factorial 22 design with 3 center points. The results produced by this analysis were the rehydratation degree, the model parameter of Lewis k (considering either the complete process, the HTST stage and the dry stage at 70°C). Also, crispness was analyzed according to sensorial and instrumental measurements. This process generated a matrix containing the results of several trial runs for the following settings: 130°C-9min, 130°C-15min, 150°C-9min, 150°C-15min and 3 center points at 140°C-12min. Crispy banana was obtained only with 140°C-12min and 150°C15min, where aw = 0,345 and aw = 0,363, respectively. The results show that the best rehydration degree occurs for 10 and 5 minutes. Also, there exists a relationship between the crispness (sensorial and instrumental) and the HTST stage. However, it was not possible to find a suitable value to the Lewis Model parameter k to HTST and 70°C dry stages. This is because the initial moisture of the fruits was not the same for all tests, which produced different values for k. In addition, we evaluated the crispness of commercial freeze-dried fruits and the water activity value. Finally, we compared measurements of the commercial banana with the dried banana obtained in this work. Both were considered crispy / Mestrado / Mestre em Engenharia de Alimentos

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Made available in DSpace on 2014-12-17T15:01:48Z (GMT). No. of bitstreams: 1 AntonioRSC_D.pdf: 2507020 bytes, checksum: a37e1d7dab2eac259aaf027c888b3f3d (MD5) Previous issue date: 2008-01-30 / In this study were projected, built and tested an electric solar dryer consisting of a solar collector, a drying chamber, an exhaust fan and a fan to promote forced hot air convection. Banana drying experiments were also carried out in a static column dryer to model the drying and to obtain parameters that can be used as a first approximation in the modeling of an electric solar dryer, depending on the similarity of the experimental conditions between the two drying systems. From the banana drying experiments conducted in the static column dryer, we obtained food weight data as a function of aqueous concentration and temperature. Simplified mathematical models of the banana drying were made, based on Fick s and Fourier s second equations, which were tested with the experimental data. We determined and/or modeled parameters such as banana moisture content, density, thin layer drying curves, equilibrium moisture content, molecular diffusivity of the water in banana DAB, external mass transfer coefficient kM, specific heat Cp, thermal conductivity k, latent heat of water evaporation in the food Lfood, time to heat food, and minimum energy and power required to heat the food and evaporate the water. When we considered the shrinkage of radius R of a banana, the calculated values of DAB and kM generally better represent the phenomenon of water diffusion in a solid. The latent heat of water evaporation in the food Lfood calculated by modeling is higher than the latent heat of pure water evaporation Lwater. The values calculated for DAB and KM that best represent the drying were obtained with the analytical model of the present paper. These values had good agreement with those assessed with a numeric model described in the literature, in which convective boundary condition and food shrinkage are considered. Using parameters such as Cp, DAB, k, kM and Lfood, one can elaborate the preliminary dryer project and calculate the economy using only solar energy rather than using solar energy along with electrical energy / Neste trabalho foi projetado, constru?do e testado um secador el?trico-solar composto por um coletor solar, uma c?mara de secagem, um exaustor e?lico e um ventilador para promover a convec??o for?ada do ar quente. Tamb?m foram realizados experimentos de secagem de banana em um secador de coluna est?tica, para modelar a secagem e obter par?metros que podem ser usados, como uma primeira aproxima??o, na modelagem de um secador el?trico-solar, dependendo da similaridade das condi??es experimentais entre os dois sistemas de secagem. Dos experimentos de secagem de banana no secador de coluna est?tica, foram obtidos dados do peso do alimento em fun??o da concentra??o aquosa e temperatura. Foram feitas modelagens matem?ticas simplificadas da secagem de bananas, baseadas na 2a equa??o de Fick e na 2a de Fourier, as quais foram testadas com dados experimentais. Foram determinados e/ou modelados par?metros como teor de umidade de banana, densidade, curvas de secagem em camada delgada, umidade de equil?brio, difusividade molecular de ?gua em banana DAB, coeficiente externo de transfer?ncia de mat?ria kM, calor espec?fico Cp, condutividade t?rmica k, calor latente de vaporiza??o de ?gua no alimento Lalim, tempo para aquecer o alimento, energia e pot?ncia m?nima para aquecer o alimento e evaporar ?gua. Quando foi considerado o encolhimento no raio R de uma banana, em geral, os valores calculados de DAB e kM representaram melhor o fen?meno de difus?o de ?gua no s?lido. O calor latente de vaporiza??o da ?gua no alimento Lalim calculado pela modelagem ? maior que o calor latente de vaporiza??o da ?gua pura L?gua. Os valores calculados de DAB e kM que melhor representam a secagem foram obtidos com o modelo anal?tico da presente tese, os quais tiveram boa concord?ncia com os valores avaliados com um modelo num?rico da literatura, no qual se considera condi??o de contorno convectiva e encolhimento do alimento. Usando par?metros como, por exemplo, Cp, DAB, k, kM e Lalim, se pode fazer o projeto preliminar de um secador e calcular a economia empregando somente energia solar, em vez de usar energia solar combinada com energia el?trica

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-09-28T16:02:22Z No. of bitstreams: 1 ILZA MARIA DO NASCIMENTO BRASILEIRO - DISSERTAÇÃO PPGEQ 1999..pdf: 7639390 bytes, checksum: b724d32e2a6b516b75a4b5d4b5ba3a6f (MD5) / Made available in DSpace on 2018-09-28T16:02:22Z (GMT). No. of bitstreams: 1 ILZA MARIA DO NASCIMENTO BRASILEIRO - DISSERTAÇÃO PPGEQ 1999..pdf: 7639390 bytes, checksum: b724d32e2a6b516b75a4b5d4b5ba3a6f (MD5) Previous issue date: 1999-03-26 / Capes / Cultivada há mais de cinquenta anos aqui no Brasil e com potencial em ácido ascórbico cem vezes superior ao da laranja, a acerola (Malpighia emarginata DC) poderia vir a ser a solução natural para a obtenção da vitamina C nacional. A maioria dos produtos vegetais são constituídos por mais de 80% de água, sendo facilmente perecíveis. A acerola possui um teor de umidade em torno de 90%. Como todas as frutas, grande parte da colheita de acerola é comercializada "in natura", havendo, portanto necessidade de um processo que possibilite sua armazenagem e comercialização por um maior período de tempo. A secagem é um dos procedimentos mais importantes de conservação de alimentos, por diminuição de sua atividade de água, evitando a deterioração sob a ação de fungos e outros microorganismos. Neste trabalho foi estudada a cinética de secagem de acerola "in natura" em monocamada utilizando um secador em escala de laboratório. Foi analisado o efeito da temperatura do ar de secagem entre 60 - 90°C, velocidade do ar de secagem entre 0,7 - 1,5m/s e também o encolhimento e a degradação da cor da acerola. Nos experimentos, comprovou-se que a velocidade do ar pouco influência na taxa de secagem, mas um considerável aumento da taxa de secagem foi obtido com o aumento da temperatura do ar de secagem. Observou-se o encolhimento e a degradação da cor da acerola, ao longo do processo de secagem, através de fotografias. Foram propostas equações empíricas para descrever a cinética de secagem de acerola, incluindo o efeito de encolhimento. / The West Indian cherry {Malpighia emarginata DC) also called acerola, has been cultivated in Brazil since more than fifty years ago. It has an ascorbic acid content a hundred time greater then the orange's one. Then, the West Indian cherry could be the natural solution to national vitamin C production. Almost ali of the vegetable products are constituted by more than 80% water. Because of this high moisture content they are very perishable. The West Indian cherry has a moisture content by about 90%. A great portion of the West Indian cherry harvest is commercialized "in natura", needing a process to storage and trade for a longer time period. The drying is one of the most important procedures to preserve foods, by decreasing their water activity, avoiding the deterioration under the fungi and other microorganisms action. In this work it was studied the drying kinetics of the West Indian cherry "in natura" in mono layer, using a laboratory scale dryer. The effect of the drying air temperature between 60 - 90°C, drying air velocity between 0,7 - 1,5 m/s and also the shrinkage and degradation of West Indian cherry color were analyzed. In the experiments, it was confirmed that the air velocity has a little effect on the drying rate. Nevertheless, the drying rate is strongly affected by the air temperature, increasing significantly at high temperatures. The shrinkage and degradation of West Indian cherry color, was observed along the drying process, by means of pictures. Empiric equations to describe the West Indian cherry drying kinetics were proposed, including the shrinkage effect.

This study investigated the quality and safety of solar dried fruits and vegetables produced by households in three locations in the Butha-Buthe district of Lesotho from November 2002 to March 2003. The aim of the study was to enhance year round availability of fruits and vegetables and reduce post-harvest losses, contributing to increased food availability and accessibility in the district. The study analysed the quality and safety of dried fruits and vegetables by assessing the processing techniques applied by the respondents during the production of dried fruits and vegetables, analysing the quality of dried fruits and vegetable samples produced by the study respondents using Appropriate Technology Section (ATS) solar driers, and by identifying the constraints that hamper the improvement of quality and safety of solar dried fruits and vegetables in the study area. Data was collected through focus group discussions, interviews, and laboratory food quality analysis of dried fruit and vegetable samples provided by the respondents. The dried fruits and vegetables produced by the respondents were of low quality due to poor processing techniques and unhygienic practices that increased chances of contamination and deterioration during processing and storage. Lack of processing skills and information, particularly on quality and safety standards, and weak extension support contributed to poor product. For the respondents to improve the quality and safety of dried fruits and vegetables, they need training and support with respect to quality and safety that includes training on the importance of food safety, best processing and storage practices and marketing of dried produce. / Thesis (M.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Submitted by Lucienne Costa (lucienneferreira@ufcg.edu.br) on 2018-04-10T19:01:23Z No. of bitstreams: 1 TARCISIO OLIVEIRA TRAJANO – DISSERTAÇÃO (PPGEM) 2017.pdf: 2697792 bytes, checksum: 3b2e76dd99d5771faa121f9c71b64ab6 (MD5) / Made available in DSpace on 2018-04-10T19:01:23Z (GMT). No. of bitstreams: 1 TARCISIO OLIVEIRA TRAJANO – DISSERTAÇÃO (PPGEM) 2017.pdf: 2697792 bytes, checksum: 3b2e76dd99d5771faa121f9c71b64ab6 (MD5) Previous issue date: 2017-09-01 / Automatizar o processo de medição da variação de massa do produto em um secador solar é um avanço em relação ao procedimento atualmente utilizado que é manual. O objetivo deste trabalho é desenvolver essa automatização utilizando tecnologia apropriada para ser incorporada ao secador solar em desenvolvimento na Universidade Federal de Campina Grande (UFCG). Esses secadores precisam ser simples e de baixo custo para serem utilizados pelo ambiente da agricultura familiar. O processo utilizado consistiu na construção e teste de um protótipo de uma câmara de secagem com forma retangular, de dimensões 32,2 x 43,0 x 34,0 cm, acoplado ao coletor solar. No sistema de medição automatizado foi utilizado uma balança com bandeja em tela de alumínio, de dimensões 37,0 x 21,0 x 6,0 cm, fixada por uma haste de madeira a uma célula de carga, tipo extensômetro de folha, que envia sinais de tensão, proporcionais à variação de massa do produto que esta sendo seco, a uma plataforma de aquisição de dados com Arduino UNO integrada ao equipamento. A célula de carga fixada a bandeja foi instalada dentro e, num experimento seguinte, fora da câmara de secagem. O sistema de aquisição e tratamento de dados também foi instalado na parte externa da câmara de secagem. Foram realizados testes preliminares de medição com a utilização de lâmpadas halógenas, e os resultados obtidos mostraram temperaturas, no interior da câmara, de aproximadamente 45°C ±5ºC, utilizando um peso padrão de 100g. Os resultados obtidos durante a secagem da banana prata (Musa spp), permitiram a construção das curvas de variação de massa de banana e a curva de cinética de secagem. Também foram obtidas as curvas que mostram a variação da temperatura do ar de secagem no interior da câmara. Essa temperatura ficou na faixa de 30ºC a 40ºC, abaixo do esperado que era de 50°C ±10ºC. Por isso a banana atingiu apenas o valor de 44% de teor de umidade em base úmida, acima dos 25% que noBrasil é o máximo para que a banana seca seja considerada banana passa. Foram observadas interferências indesejáveis durante o processo de medição automatizada, as estratégias utilizadas (filtros) para reduzir as interferências não foram suficientes para reduzi-las totalmente e seguirão sendo estudadas em trabalhos futuros. / Automating the process of measuring the mass variation of the product in a solar dryer is an advance over the currently used procedure which is manual. The objective of this work is to develop this automation using appropriate technology to be incorporated into the developing solar dryer at the Federal University of Campina Grande (UFCG). These dryers need to be simple and inexpensive to be used by the family farming environment. The process used consisted in the construction and testing of a prototype of a drying chamber with rectangular shape, dimensions 32.2 x 43.0 x 34.0 cm, coupled to the solar collector. In the automated measurement system, a scale was used with aluminum tray, measuring 37.0 x 21.0 x 6.0 cm, fixed by a wooden rod to a load cell, type extensometer of sheet, which sends voltage signals, proportional to the mass variation of the product being dried, to a data acquisition platform with Arduino UNO integrated to the equipment. The loading cell attached to the tray was installed inside and, in a subsequent experiment, outside the drying chamber. The data acquisition and processing system was also installed on the outside of the drying chamber. Preliminary measurement tests were carried out with the use of halogen lamps, and the results obtained showed temperatures within the chamber of approximately 45°C ± 5°C, using a standard weight of 100 g. The results obtained during the drying of the silver banana (Musa spp) allowed the construction of the banana mass variation curves and the drying kinetic curve. Curves showing the temperature of the drying air inside the chamber were also obtained. This temperature was in the range of 30°C to 40°C, below that expected to be 50°C ± 10°C as a consequence of the low intensity of solar radiation on the days of experiment. Therefore the banana reached only the value of 44% moisture content on wet basis, above the desirable 25%. Undesirable interferences were observed during the automated measurement process, the strategies used (filters) to reduce interferences were not enough to reduce them completely and will continue to be studied in future works.

Orientador: Ana Maria Frattini Fileti / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-22T17:41:17Z (GMT). No. of bitstreams: 1 Silva_BrunoGuzzoda_M.pdf: 3572224 bytes, checksum: 769121ab368a29b801674c746404c405 (MD5) Previous issue date: 2013 / Resumo: A pimenta-rosa, produzida a partir dos frutos da aroeira-vermelha (Schinus terebinthifolius Raddi), é um dos mais sofisticados condimentos da culinária internacional e que vem apresentando um aumento na sua demanda. No entanto, na literatura encontram-se poucos estudos sobre o seu processamento, em que a secagem é uma etapa indispensável e que ainda é realizada de forma empírica. Nas empresas beneficiadoras, a etapa de secagem tem por finalidade aumentar a vida de prateleira do produto, além de agregar valor aos frutos da aroeira-vermelha. Neste contexto, este trabalho teve por objetivo realizar investigações no processo de secagem de frutos de aroeira-vermelha, focando principalmente no estudo de modelos matemáticos para a simulação do processo. As amostras de frutos de aroeira-vermelha, utilizadas nos ensaios de caracterização e secagem, foram classificadas manualmente e reumidificadas artificialmente. Para a caracterização do sistema particulado, os seguintes parâmetros foram determinados: teor de umidade em base seca; diâmetro médio e massa específica aparente dos frutos; e massa específica e porosidade do leito de frutos. Também foram determinadas, através do método estático, as isotermas de dessorção de umidade dos frutos em temperaturas de 30, 50 e 70 ºC. Um Delineamento Composto Central Rotacional (DCCR) com 11 experimentos foi desenvolvido e foram investigadas as influências da temperatura (40 a 70 ºC) e da velocidade do ar de secagem (0,4 a 0,8 m/s) no processo. Em cada um dos ensaios do DCCR foram analisadas a cinética de secagem e a curva de taxas de secagem dos frutos de aroeira-vermelha. Os modelos de difusão, de Lewis, de Henderson e Pabis, de Page modificado e de Henderson foram ajustados aos dados experimentais da cinética de secagem, sendo realizada a comparação destes modelos com um modelo fundamentado na Inteligência Artificial. Os resultados revelaram que, para as condições operacionais estudadas neste trabalho, a temperatura do ar de secagem apresenta uma influência maior no processo. A cinética de secagem ocorre principalmente no período de taxa decrescente. Isto indica que a secagem ocorre pela remoção da umidade interna do sólido. O modelo via Redes Neurais Artificiais (RNA's) e o modelo de Henderson apresentaram os resultados mais satisfatórios no ajuste aos dados da cinética de secagem dos frutos de aroeira-vermelha. No entanto, observou-se que a principal vantagem do modelo de RNA, em relação aos modelos clássicos, foi a sua generalidade. O modelo de RNA foi capaz de descrever uma série de experiências com precisão, enquanto que a aplicação de modelos clássicos foi limitada a uma experiência específica. Para o modelo neural, esta gama de condições experimentais pode ser expandida através da adição de novos conjuntos de experimentos de treinamento. Deste modo, os resultados satisfatórios da utilização de um modelo baseado em RNA's em processos de secagem indicam a potencialidade da aplicação desta ferramenta na modelagem de processos industriais de secagem / Abstract: The pink pepper, produced from the Brazilian pepper-tree fruits (Schinus terebinthifolius Raddi), is one of the most sophisticated condiments of the international cuisine. The demand for pink pepper is increasing because it adds taste and refinement to international cuisine. Until now, rare are the studies that investigated the drying of Brazilian pepper?tree fruits. In the processing companies, the process is carried out empirically and the drying operation is an important step. The Brazilian pepper?tree fruits are dried to inhibit microbial development and quality decay. Another benefit of drying is a reduction in weight. In this context, this study aimed to perform investigations in the drying process of Brazilian pepper?tree fruits, focusing mainly in the study of mathematical models to simulate drying kinetics. Before each test, the fruits were sorted manually and humidified artificially. In this study, physical characterization of Brazilian pepper?tree fruits was obtained by evaluating the moisture content on dry basis; mean diameter and apparent density; bulk density and porosity. The moisture sorption isotherm, at temperatures of 30, 50 and 70 ºC, were determined by the static method. A Central Composite Rotable Design (CCRD) with 11 experiments was developed. In each experiment, the drying kinetics and the drying rate were investigated, as well as the influence of input variables on the drying process. Classical models were fitted to the drying data, as well as a model based on Artificial Intelligence. In the operating conditions of this study, the results revealed that the air temperature has a greater influence on the thin layer drying process of Brazilian pepper?tree fruits. The drying kinetics occurs mainly in the falling-rate period of drying. This indicates that drying occurs mainly by removal of internal moisture of the solid. The artificial neural network model and the Henderson model fitted to the experimental data more accurately in comparison to the various mathematical models. However, it was observed that the main advantage of the artificial neural network model over classical models was their generality. The ANN model was able to describe a range of experiments accurately, while the application of classical models is limited to a specific experiment. For the neural model, this range of experimental conditions may be expanded by addition of new sets of experiments in training / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestre em Engenharia Química

<p>  </p> <p>Dried fruits have traditionally received little food safety attention despite multiple <em>Salmonella</em> and <em>E. coli</em> outbreaks associated with low-moisture foods. Given the popularity of dried apples, many consumers produce dried apples at home. However, little is known about this niche population, their apple drying practices and their sources of food safety information. Therefore, this thesis aimed to use apple drying as a case study to i) identify the fruit drying practices in a domestic setting, ii) determine the factors influencing the associated behaviors and iii) evaluate the food safety information in fruit drying recipes.</p> <p><br></p> <p>The first two studies used quantitative methods with survey data on home apple dryers in the United States. In the first, apple drying practices were identified and evaluated for level of food safety using a safe practice index. Then, regression analyses showed the influence of demographic factors, attitudes, perceived behavioral control (PBC), subjective norms, risk perception and exposure to food safety information on selected apple drying practices. The third study was a content analysis using a qualitative approach to analyze recipe information on blogs, YouTube videos, cookbooks and university extension publications.</p> <p><br></p> <p>Findings revealed that the level of safe food handling in home apple drying was low. Home apple dryers had inadequate frequency of handwashing during apple preparation, potential points of cross-contamination from kitchen tools, a lack of hurdle technology without an apple pre-treatment step, failure to incorporate a thermal kill step during drying, and a lack of objective measurements to ensure that target parameters are attained. The investigated demographic factors, risk perception and food safety information or training had significant influence on current safe apple handling behaviors. Attitudes, PBC and subjective norms were strong predictors of behavior intention. An evaluation of apple drying recipes showed that food safety emphasis was missing. There were omission of food safety controls and a lack of standardization in the recommended procedures.</p> <p><br></p> <p>The results provided handling practice data to support the development of more accurate food safety risk assessment models, and to guide the development of food safety education for home apple dryers. It urged the need for food safety improvement not only in home apple dryers’ practices, but also the information disseminated to them.</p>