The feasibility of using Artificial Neural Network (ANN) models for application in thermal process calculations was studied. / For a better understanding of the effect of process parameters on the evaluation of thermal process, the accuracy of several formula methods (Steele & Board, Ball, Stumbo and Pham) were studied over a wide range of commercial conditions. A computer simulation based on finite difference method of numerical solutions of heat transfer to packaged foods in cylindrical containers was applied to obtain the time-temperature data for designed conditions (retort and initial temperatures, thermal diffusivity, package sizes and processing time). Moreover, the process time and process lethality from this simulation were used as the reference values for the purpose of comparison. The accuracy of methods was evaluated based on the variation of each parameter over the range of conditions employed in the study. / As the final goal of the study, a multi-layer ANN model was developed as an alternative to thermal process calculations. (Abstract shortened by UMI.)

Graduation date: 1951

Graduation date: 1953

Graduation date: 1991

Orientador: Flávio Luis Schmidt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-18T02:07:59Z (GMT). No. of bitstreams: 1 Silva_ElaineBergesda_D.pdf: 4524403 bytes, checksum: aabc8930b1bedbdff633b05a11eb22e7 (MD5) Previous issue date: 2011 / Resumo: Os alimentos enlatados sob alto vácuo, também conhecidos como solid pack, contêm aproximadamente 10% de líquido em relação ao volume da embalagem e reduzem as trocas de massa por osmose entre o produto e a salmoura. Este trabalho de pesquisa teve como objetivo estudar o processamento térmico de fundos de alcachofra (Cynara cardunculus scolymus L.) sob alto vácuo em salmoura convencional (CV) e solid pack (SP). Os objetivos específicos foram: avaliar o efeito de antioxidantes na inibição do escurecimento enzimático e determinar: os parâmetros cinéticos para degradação térmica da textura; perfil de temperatura e pressão, os parâmetros de penetração de calor; letalidade; características físico-químicas e sensoriais. Foi determinado o índice de escurecimento (IE) em amostras pré-tratadas com L-cisteína (LC), ácidos cítrico (AC) e escórbico (AA) e branqueadas em água em ebulição nos tempos 0 a 20 minutos. A textura das amostras tratadas nas temperaturas 80 a 100oC foi determinada em texturômetro (força de penetração) em função do tempo. Os fundos branqueados foram acondicionadas em latas ¿abre-fácil¿, fechadas sob vácuo mecânico (mínimo 20 pol Hg) e processadas termicamente em autoclave por cascata de água a 128 oC por 210 s, sob agitação ¿end over end¿ de 20 rpm. Foi determinado o perfil de temperatura e pressão utilizando termopares e transmissores de pressão. As amostras processadas foram avaliadas sensorialmente quanto à aceitação e intenção de compra. Foi determinada a força de penetração das amostras processadas utilizando o texturômetro. A acidez titulável, pH, sólidos solúveis, composição centesimal, minerais e fenóis totais foram determinados. Na condição mais drástica de tratamento (AA1%, AC1%, LC1%) foi obtido o menor valor de k (0,0283). Foram obtidos os valores de Ea (20,76 kcal.mol-1), z (29,22oC) e Q10 (2,2) para degradação térmica da textura. Os valores de fh obtidos foram, respectivamente 7,01 e 7,82 minutos para CV e SP e o jc e jh variaram em torno de 1. O Fo obtido foi 5,76 e 7,04, para os processos CV e SP. Nos dois processos a degradação da textura foi de 1 ciclo log, sendo considerada sensorialmente aceitável. Os resultados médios dos atributos odor, sabor e aceitação global variaram em torno de 5, correspondendo a ¿não gostei/nem desgostei¿. A amostra in natura apresentou o maior conteúdo de fenóis totais (272 ± 11,74 mg/100 g), seguido pela SP (104 ± 3,79 mg/100g) e CV (85 ± 4,54 mg/100g). As cinzas, minerais, sólidos solúveis e fenóis totais foi significativamente maior (p<0,05) para SP em comparação à CV. O pré-tratamento com antioxidantes é recomendado para retardar o escurecimento antes do branqueamento. Temperaturas mais elevadas de processo por tempo mais curto minimizam a destruição térmica da textura. O tratamento térmico a 116,88 ºC por 6,66 minutos é o limite mínimo de processo capaz de garantir a estabilidade microbiológica do produto sem comprometer a textura dos fundos de alcachofra. A alcachofra in natura apresentou quantidades importantes de cálcio e zinco, além de ser fonte de ferro. O processo solid pack reduziu as trocas osmóticas entre o vegetal e a salmoura / Abstract: Canned foods under high vacuum, also known as solid pack type food contain approximately 10% of the recipient volume in liquid, which reduces the mass transfer by osmosis between the product and brine. This research aimed to study the thermal processing of artichoke (Cynara cardunculus scolymus L.) under high vacuum. The specific objectives were to assess the effect of antioxidants in inhibiting enzymatic browning and determine: the kinetic parameters for the thermal degradation of texture, temperature and pressure profile, the heat penetration parameters, lethality, and physico-chemical and sensorial characteristics of the conventional artichoke processed in brine (CV) and those of the solid pack (SP) one. The browning index (BI) of samples pretreated with solutions of L-cysteine (LC) and citric acid (CA) and ascorbic acid (AA) and blanched in boiling water from 0 up to 20 minutes were determined. The texture of the samples treated at temperatures of 80, 90 and 100oC were measured using the texturometer (penetration force) versus time. The blanched samples were packaged in "easy-open" cans, closed under mechanical vacuum (minimum 20 in Hg), and thermally processed in an water cascade autoclave at 128oC for 210 s with 20 rpm "end-over-end" agitation. The temperature and pressure profiles were determined using thermocouples and pressure transmitters, respectively. The processed samples were evaluated by sensory acceptance and attitude purchase. The penetration force of the processed samples were determined using the texturometer. The acidity, pH, soluble solids content, chemical composition, minerals and phenols were determined in the physical-chemical characterization of samples. The more drastic treatment (AA1% AC1% LC1%) provided the lowest value for k (0.0283). Values of Ea (20.76 kcal.mol-1), z (29.22°C) and Q10 (2.2) were obtained for thermal degradation of the texture. fh values obtained were respectively 7.01 and 7.82 minutes for CV and SP and jc and the jh varied around 1. The Fo obtained was 5.76 and 7.04 for CV and SP processes. In both cases the degradation of texture was 1 log cycle, and it was considered acceptable in sensory aspect. The average scores for odor, flavor and overall acceptability were around 5 corresponding to "neither liked nor disliked¿. The fresh sample showed the highest content of total phenols (272 ± 11.74 mg/100 g), followed by SP (104 ± 3.79 mg/100g) and CV (85 ± 4.54 mg/100g). The ash, minerals, phenols and total soluble solids were significantly higher (p <0.05) for the SP as compared to CV. Pre-treatment with antioxidants is recommended to control the browning before the heat blanching. Higher temperatures for shorter procedures minimize the thermal destruction of the texture. The thermal treatment at 116.88°C for 6.66 minutes is the minimum process capable of ensuring the microbiological stability of the product without compromising the texture of the artichoke hearts. The artichoke is a fresh source of copper and iron, and presents significant amounts of calcium and zinc. The physical-chemical results showed that the solid pack process reduced osmotic exchanges between the plant and brine / Doutorado / Tecnologia de Alimentos / Doutor em Tecnologia de Alimentos

In this study, a number of experiments were undertaken to investigate possible methods for effective improvement of the texture and flavour of canned late-run chum salmon. These included removal of the skin and bones from the fish, processing of the boneless-skinless steaks in retort pouches, brine treatment using two washes with an 8% salt solution for one hour each time, and a precanning treatment in which the boneless-skinless steaks were soaked in a solution of 10% tripolyphosphate and 2% brine for two minutes. Only fish of advanced sexual maturity were used. The canned salmon was steam processed at 120°C for 65 minutes in an FMC laboratory retort. This was based on a known commercial process for 307 x 115 cans. Heat penetration studies were carried out to design the process schedules for the pouched samples. It was found that the pouched product required 48% less thermal processing time than the canned product to achieve similar lethality. Sensory results showed that the removal of the skin and bones did not produce any significant improvement in the flavour and acceptability of the fish. There was no significant difference between the polyphosphate/brine samples and the untreated (control) samples for all attributes tested. The brine treatment also did not improve the texture of the samples. However, there was less detection of late-run flavour in the brine treated samples when compared to the control. Comments offered by panelists described these samples as having a salty/briny flavour. Pouched samples had a firmer, drier and more fibrous texture than the canned product. They also scored better in terms of late-run flavour. Acceptance of the fish however was only moderate. As a consequence, although this study demonstrated an improvement in the texture and flavour of the pouched late-run chum in comparison to the canned product, it was concluded that a more acceptable pouched product could probably be obtained by using late-run salmon of less advanced sexual maturity. Results of linear regression analysis showed that significant relationships were obtained between sensory firmness, fibrousness and chewiness and instrumental hardness, maximum slope and chewiness. However, none of the sensory parameters were well predicted by the instrumental results. / Land and Food Systems, Faculty of / Graduate

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M.S.