Maria Madalena Rinaldi

Estabilidade de repolho minimamente processado sob diferentes sistemas de embalagem

Stability of fresh-cut cabbage packed in low density polyethylene under active modified atmosphere and in expanded polyestyrene trays wrapped with PVC was evaluated. The fresh-cut product was stored for 16 days in a cold room at 5 ± 1 °C and 95 ± 5% RH and in a refrigerated display case similar to those found in grocery stores. The following variables were analyzed: content of oxygen and carbon dioxide inside the package headspace; browning, luminosity, polyphenoloxidase and peroxidase activities, pH, titratable acidity; soluble solids, fresh mass loss, and ascorbic acid content. The stability of fresh-cut cabbage was higher at the temperature of 5 °C compared to those stored in the refrigerated displays. The active modified atmosphere was not effective in extending the shelf life of fresh-cut cabbage compared to other treatments. LDPE packaging was more adequate for fresh-cut cabbage storage. However, PVC wrapping also presented satisfactory effects.

Stability and microbiological quality of rice bran subjected to different heat treatments

Rice bran is a byproduct commonly used for animal feeding; however its nutritional value and potential application in human diet have attracted market interest. Its preservation for safe use is still a challenge, so the objective of this study was to determine the quality of commercially available rice bran samples subjected to different heat treatments (extruding, parboiling, toasting, and microwave oven heating) in order to promote stabilization during storage under room temperature. Rice bran samples were collected from two industries, and each treatment was divided in three parts, each corresponding to three repetitions. All samples were evaluated for moisture content, total microorganisms, mold and yeast counting, hydrolytic rancidity, and lipase activity during 90 days of storage. Most of the heat treatments, including domestic and thermoplastic extrusion, generated products which may be used for human consumption under the tested conditions in terms of physicochemical and microbiological quality. The domestic treatments were more efficient in eliminating microorganisms or keeping them within acceptable limits. The toasted rice bran showed satisfactory results in terms of moisture, hydrolytic rancidity control, and lipase activity.

Atividade respiratória, produção de etileno e vida útil de repolho (Brassica oleracea, var. capitata) minimamente processado em atmosfera controlada

Com o objetivo de avaliar a atividade respiratoria e a producao de etileno do repolho inteiro e minimamente processado e a vida util do repolho mimimamente processado em atmosfera controlada, realizaram-se dois experimentos em etapas sequenciais. Na primeira etapa, avaliaram-se a atividade respiratoria e a producao de etileno do repolho inteiro e minimamente processado, em sistema fechado, nas temperaturas de 5 oC e 10 oC. Na segunda etapa, avaliou-se a vida util do repolho minimamente processado em atmosfera controlada. O produto foi submetido a fluxo continuo de misturas gasosas ternarias, com concentracoes de 2% a 10% de O2 e de 3% a 10% de CO2, previamente umidificadas, na temperatura de 5 oC por 10 dias. Como controle, foi utilizado o ar atmosferico. A atividade respiratoria do repolho inteiro e minimamente processado, armazenado a 5 oC, foi significativamente menor que a do armazenado a 10 oC, sendo que, em ambas as temperaturas, o repolho minimamente processado foi o que obteve a maior atividade respiratoria com relacao ao repolho inteiro. Nao foi detectada a producao de etileno pelo metodo de analise utilizado. A atmosfera controlada nao prolongou a vida util do repolho minimamente processado nas concentracoes de 2% a 10% de oxigenio e de 3% a 10% de dioxido de carbono.

Efeito de diferentes formas de congelamento sobre raízes de mandioca

The physical-chemical, sensory and microbiological characteristics during storage of cassava roots subjected to different freezing methods were evaluated. The roots were physically characterized, processed, packaged in LDPE packages with 100 µm of thickness and subjected to different treatments: freezing and storage at –18°C; freezing and storage at –80°C; and freezing with liquid nitrogen and storage at –80°C. The storage period was 31 days. The product subjected to all treatments had acceptable levels of pH, titratable acidity, soluble solids, ratio, ascorbic acid and time for cooking as well as the counting of evaluated microorganisms. In treatments freezing and storage at –18°C, freezing with liquid nitrogen and storage at –80°C cassava roots were sensory accepted throughout the storage. Despite the good results presented in storage of cassava roots subjected to freezing with liquid nitrogen and storage at –80°C, further studies are suggested regarding requirements and costs for the use of this technology at the producer level. The temperature of –18°C is sufficient to keep the product with appropriate characteristics for at least 31 days.

Utilização de ácido cítrico para a conservação pós-colheita de raízes de mandioca

Minimally processed table cassava roots have emerged as an alternative to increase the post-harvest life of the product, and make a more practical, safer food available for consumers. The Brazilian Federal District and surroundings are becoming a major cassava producer and consumer. Thus the objective of this study was to determine the effects of different concentrations of citric acid (0.5%, 1.0%, 1.5%, 2.0%, 2.5%) in the conservation of minimally processed IAC 576-70 cassava roots immersed in water. The product was maintained at a temperature of 3 °C for 35 days. The following analyses were carried out on the raw material and on the product during storage: pH, titratable acidity, soluble solids, ratio, cooking time, colour and texture of the roots. The action of the citric acid on the shelf life of the product was positive for all concentrations throughout storage. There were significant reductions in pH and increases in titratable acidity of the product for all the citric acid concentrations evaluated, being less pronounced in the product subjected to a concentration of 0.5%. Visually the presence of microorganisms was not observed in any of the minimally processed cassava roots or in the water in which they were submerged.

Conservação pós-colheita de frutos de Passiflora setacea DC. submetidos a diferentes sanitizantes e temperaturas de armazenamento

A Passiflora setacea DC. e uma especie silvestre de maracujazeiro que ocorre nos biomas Cerrado e Caatinga, e em areas de transicao, como o Semiarido norte-mineiro do Brasil. A alta perecibilidade dos frutos de P. setacea reduz sua vida util, limitando sua comercializacao. Objetivou-se determinar a melhor temperatura e o melhor sanitizante para a conservacao pos-colheita de frutos de P. setacea. Os frutos foram submetidos a dois sanitizantes quimicos e armazenados por 21 dias, sob condicao ambiente (21,3 °C e 77,8% de umidade relativa) e nas temperaturas de 6 °C, 10 °C, 15 °C e 20 °C e 90% de umidade relativa. No inicio do armazenamento e aos 4, 7, 14 e 21 dias, realizaram-se analises de perda de massa fresca, cor, acidez titulavel, solidos soluveis, ratio e pH dos frutos. A temperatura de 10 °C e 90% de umidade relativa e a condicao mais recomendada para o armazenamento dos frutos. Os sanitizantes nao aumentaram a vida util dos frutos, nao sendo recomendados para utilizacao nas concentracoes estudadas, uma vez que os mesmos nao auxiliaram na reducao da perda de massa fresca e na conservacao dos mesmos. De acordo com as condicoes experimentais do presente trabalho, a vida util pos-colheita dos frutos foi inferior a quatro dias de armazenamento, mesmo sob refrigeracao; observou-se que, assim como o maracujazeiro azedo comercial, frutos de P. setacea perdem massa fresca e apresentam o enrugamento da casca apos quatro dias de armazenamento. No entanto, de acordo com os valores de acidez titulavel, solidos soluveis e pH, essas caracteristicas nao inviabilizam o consumo da polpa apos sete dias de armazenamento.