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Doctoral Thesis
DOI
10.11606/T.11.2003.tde-03042003-155537
Document
Author
Full name
José Maria Monteiro Sigrist
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2002
Supervisor
Committee
Minami, Keigo (President)
Chitarra, Maria Isabel Fernandes
Durigan, Jose Fernando
Jacomino, Angelo Pedro
Kluge, Ricardo Alfredo
Title in Portuguese
Estudos fisiológicos e tecnológicos de couve-flor e rúcula minimamente processadas.
Keywords in Portuguese
couve-flor – qualidade
efeito da temperatura
fisiologia pós-colheita
metabolismo vegetal
processamento de alimentos
respiração vegetal
rúcula – qualidade
Abstract in Portuguese
Este trabalho teve por finalidade avaliar os efeitos de temperatura nos metabolismos de couves-flores e rúculas inteiras e minimamente processadas e diferentes materiais de embalagem na sua qualidade. No primeiro experimento, couves-flores, seus floretes, rúculas e suas folhas foram mantidos a 1º, 5º e 11ºC e determinados suas taxas de respiração, produção de etileno e quocientes de temperatura (Q10). No segundo, os floretes foram colocados em embalagens de filmes de polietileno de baixa densidade (PEBD), poliolefínicos coextrusados (PD - 941 e Clysar) e de policloreto de vinila, PVC esticável de 12 e 20 mm, envolvendo bandejas de poliestireno expandido mantidos a 5ºC. Análises físicas, químicas, físico-químicas, microbiológicas e sensoriais foram realizadas. No terceiro, folhas de rúculas foram colocadas em embalagens de filme de polietileno de baixa densidade (PEBD), laminado de polipropileno/polietileno (PP/PE), poliolefínicos coextrusados (PD - 900 e Clysar) e de policloreto de vinila, PVC esticável de 20 mm, envolvendo bandejas de poliestireno expandido e armazenados a 5ºC. Análises físicas, químicas, físico-químicas, microbiológicas e sensoriais foram realizadas. As taxas respiratórias das couves-flores inteiras e minimamente processadas foram iguais em quaisquer das temperaturas estudadas e sempre decrescentes até o 16º dia. A 1º e a 5ºC, tiveram a mesma taxa respiratória, diferindo das mantidas a 11ºC. Na faixa de 1º a 11ºC, o Q10 foi o mesmo para floretes e couves-flores; 2,1 e 2,2, respectivamente. Comportamento distinto tiveram as rúculas inteiras e as folhas soltas, pois, a 1ºC e a 5ºC, as taxas respiratórias foram significativamente iguais. A 11ºC, a partir do 4º dia, as folhas soltas começaram a apresentar taxas de respiração superiores às das inteiras, chegando a ser o dobro nos 14º e 16º dias de armazenamento. O Q10 médio para as rúculas inteiras situou-se ao redor de 3,54 e para as folhas soltas, 5,74, na faixa de 1º a 11ºC. Não foi detectada produção de etileno. As embalagens para floretes de couves-flores tiveram pouca ou nenhuma influência em seu pH, acidez, ºBrix, luminosidade, croma, Hue e firmeza. A embalagem PD - 941 foi a melhor por manter uma atmosfera modificada próxima à da recomendada para couves-flores (2-3% O2 e CO2 < 5%) e permitir menores perdas de vitamina C e melhores notas para vários atributos sensoriais de qualidade. Todas as embalagens mantiveram níveis de coliformes totais, bolores e leveduras bem abaixo dos limites permitidos pela Legislação Brasileira. As folhas de rúculas apresentaram níveis de coliformes totais ao redor de 10 5 UFC/g de produto no 10º dia a 5ºC, tornando-as impróprias para o consumo. Nestes 10 dias, as embalagens de PEBD e PP/PE se destacaram em relação às outras por reterem melhor a vitamina C e a coloração verde das folhas, por alcançarem melhores valores para sólidos solúveis, firmeza, presença de odor estranho, qualidade geral das folhas, deterioração e murchamento. As atmosferas modificadas desenvolvidas no interior destas embalagens, 5 a 7% O2 e 10 a 15% CO2, talvez sejam as mais indicadas para a conservação de rúculas minimamente processadas a 5ºC.
Title in English
Physiological and technological studies of fresh-cut cauliflower and salad rocket.
Keywords in English
cauliflower-quality
food processing
plant metabolism
plant respiration
post-harvest physiology
rocket & quality
temperature effect
Abstract in English
This work aimed at evaluating the effects of temperature on the metabolism of minimally processed and intact cauliflowers and salad rockets, and of different packaging materials on the quality of cauliflower florets and loose salad rocket minimally processed leaves. In the first experiment, intact cauliflowers, florets, intact salad rockets and loose salad rocket leaves were held at 1º, 5º and 11ºC and their respiration rates, ethylene production and temperature quotients (Q10) determined. In the second experiment, the florets were packed in low density polyethylene film (PEBD), co-extruded polyolefins (PD - 941 and Clysar AFG) and in 12 and 20 mm polyvinyl chloride (PVC) overwrapping expanded polystyrene trays, and maintained at 5ºC/85-95% relative humidity for 14 days. In the third experiment, loose salad rocket leaves were held under the same conditions in bags of low density polyethylene film (PEBD), laminated polypropylene/polyethylene film (PP/PE), co-extruded polyolefins, PD - 900 and Clysar HP and in expanded polystyrene trays overwrapped with 20 mm polyvinyl chloride (PVC). In the second and third experiments, physical, chemical, physical-chemical, microbiological and sensory analyses were performed. The respiration rates of both intact and fresh-cut cauliflowers declined over the 16-day period and were significantly the same at all temperatures studied. At 1º and 5ºC the respiration rates were the same but differed from those (cauliflower and florets) at 11ºC. From 1º to 11ºC, the Q10 for the cauliflowers was 2.2 and for the florets, 2.1. In contrast, the intact and fresh-cut salad rocket respiration rates were the same at 1º and 5ºC. At 11ºC, the fresh-cut salad rocket showed higher respiration rates than the intact ones as from the 4 th day. By the end of the experiment (14 th and 16 th days) the respiration rates of the fresh-cut salad rockets were twice those of the intact salad rockets, whose Q10 was about 3.45 from 1° to 11°C as compared to 5.74 for the fresh cut product. No ethylene production was detected by any sample at any temperature. The packaging materials had little or no effect on pH, titratable acidity, soluble solids, luminosity, chroma, hue and firmness of the florets at 5ºC. PD - 941 seemed to be the best packaging for florets, maintaining the atmosphere closest to that recommended for intact cauliflower (2-3%O2, CO2 < 5%), showing the lowest vitamin C losses and the best scores for several of the quality attributes. In general, all the packaging materials kept the yeast and mold counts low and the total coliform counts far below the maximum values permitted by the Brazilian Legislation, during 14 days at 5ºC, except for fresh-cut salad rocket leaves, which presented 10 5 CFU/g total coliforms by the 10 th day, being inappropriate for consumption. For 10 day periods, PEBD and PP/PE were the best packaging materials for green color and vitamin C retention, higher soluble solids, firmness, lack of off-odors, overall quality, decay and shriveling. The modified atmosphere generated inside these packaging materials (5-7% O2, 10-15% CO2) seemed the best for maintaining the quality of fresh-cut salad rockets held at 5ºC.
 
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Publishing Date
2003-05-09
 
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