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Achieving modified atmosphere (MA) effects on fruit through the use of surface coatings relies upon a suitable degree of internal atmosphere modification, which is strongly dependent upon both respiration rate and skin permeance to gases. In this study, skin porosity, skin permeance, internal partial pressures of oxygen and carbon dioxide, and respiration rate were measured at 0°C, 10°C, 20°C and 30°C in non-coated 'Braeburn' apples. Variation in respiration rate, internal partial pressures of oxygen and carbon dioxide, skin permeance to oxygen and carbon dioxide, and the extent to which all of these gas exchange characteristics affected by temperatures of 0°C, 5°C, 10°C, 15°C, 20°C were characterised in both non-coated and coated 'Braebum' apples. Coating treatments were 0, 0.2, 0.4, 0.6, 0.8 and 1.0 times either a 2% (w/w) solution of hydroxypropylcellulose (HPC) in distilled water, or a commercial formulation of carnauba wax and shellac coating, achieved by mixing the full strength solutions with distilled water. There was a 6- or 10-fold difference in respiration rate between fruit kept at 0°C and 20°C, or 0°C and 30°C, whilst the relative permeance to both O 2 and CO 2 differed only a factor of 1.7 or 1.5 in non-coated fruit. The differing effects of temperature upon these two variables were responsible for the depression of internal O 2 and elevation of internal CO 2 associated with increase in temperature from 0°C to 20°C or 30°C. There was no evidence that porosity was dependent on temperature, suggesting that the increasing permeance with higher temperatures may have resulted from increasing permeance of the cuticle. The modification of internal atmosphere composition in carnauba-coated fruit depended upon coating concentration and temperature. The effects of HPC coating on internal atmosphere, especially on internal CO 2 were less marked than those of temperature. In non-coated fruit, the magnitude of decline in internal O 2 was slightly greater than the i

The objective of the study described in this thesis was to explore the potentials of NMR for the study of water relations in harvested mushrooms ( Agaricus bisporus ). Since harvested mushrooms tend to continue their growth after harvest, their morphogenesis is heavily influenced by the external climatic conditions. Their respirative resources as well as their internal water can not be replenished after harvest and has therefore to be present in the mushroom before harvest.The main metabolic pools and changes in these pools were studied in Chapter 2. Extracts of the cap, gill and stipe of the fruiting body of the mushroom ( Agaricus biporus ) were studied by 13 C-NMR spectroscopy. This technique enables changes in the main metabolite pools to be studied simultaneously as a function of storage time, temperature and postharvest development. An earlier reported reduction in dry weight of the stipe could be explained by a decrease in mannitol content. At 274 K storage temperature no postharvest development occurred, yet mannitol content decreased. It was concluded that mannitol is probably used as a respiratory substrate in gill tissue. Proteolytic breakdown was apparent, even during storage at 274 K, but occurred preferentially in the stipe. The products were most probably used by the gill and to a lesser extent by the cap to maintain metabolic activity as demonstrated by urea-cycle activity. Changes in the content of four amino acid pools (glutamate, glutamine, alanine and aspartate) proved to be tissue-specific, as were changes in the content of mannitol, fumarate and malate.In Chapter 3, multi-echo imaging together with mono-exponential T 2 decay fitting was applied to determine reliable proton density and T 2 distributions over a mushroom. This was done at three magnetic fields strengths (9.4, 4.7 and 0.47 T) because susceptibility inhomogeneities were suspected to influence the T 2 relaxation times negatively and because the influence of susceptibility inhomogenei

This study was carried out to characterize the physiological developement and maturity of maraco fruit in arder to determine an adequate harvest and postharvest handling of the fruit. It was measured the physiological and physicochemical changes during the reproductive stage of the plant. It was determined a respiratory curve of either pH, acidity, brix, reduced and total sugars, vitamin C and maturity index variations. The commercial ripening stage was considered from 83 day, where the respiratory intensity showed the lowest value to the day 113. At this point it was observed an increase of the respiratory intensity, indicative of the climateric condition of maraco's fruit. This behavior was also accompanied with an increase in pH, brix and total and reduced sugars., El presente estudio tuvo como objetivo caracterizar fisiológicamente el desarrollo y la maduración del fruto de maraca y encontrar parámetros que permitan su adecuado manejo en pre y poscosecha. Las muestras de los frutos requeridos para el trabajo procedieron del Centro Experimental El Trueno del Instituto Amazónico de Investigaciones Científicas SINCHI. Los análisis de laboratorio se llevaron a cabo en el Laboratorio de Postcosecha de la Planta de Vegetales del ICTA de la Universidad Nacional. Para alcanzar los objetivos se determinaron los cambios fisiológicos y fisicoquímicos más importantes durante la fase reproductiva del cultivo, estableciéndose la curva del patrón respiratorio y las variaciones de pH, acidez (% Acido cítrico), grados brix (%), azúcares reductores y totales (mg glu/100 g pulpa), vitamina C (mg Acido ascórbico/100g pulpa) e índice de madurez. La fase de madurez comercial se contempló desde los 83 días, donde la respiración mostró valores muy bajos; sólo a los 113 días, al finalizar el estudio se observó un incremento de la intensidad respiratoria, condición característica de los frutos clirnatéricos. Este comportamiento estuvo acompañado de un ascenso del pH y descenso de la acidez; hubo un aumento significativo de los grados brix y azúcares reductores y totales.

A study has been conducted to compare different methods to measure bruise susceptibility of fruit. In order to compare measured values with actual commercial bruising, an appropriate test method to simulate impact damage during handling was developed, employing a revolving tumbler. From the analysis of bruise damage produced by the tumbler on four apple cultivars under different storage treatments, it was found that a large percentage of bruises were less than 1.5 cm in area, and the number of bruises above 1.5 cm did not change between treatments. It was concluded that laboratory measurements involving high impact energy levels may be insensitive as indicators of bruising levels on fruit during commercial operations. The impact loads produced by this method was very similar to those incurred by a practical grader, as indicated by Instrumented Sphere measurements. The tumbler test permitted examination of actual grader damage relationships with standard tests. Three standard impact tests (vertical drop test, double and single pendulum test) were conducted on four cultivar apples: Splendour, Granny Smith, Pacific Rose, and Braeburn. Four different shapes of impact surface were used for each impact test. It was found that bruise susceptibility varied with different impact tests. Regression analysis was made on the data obtained from standard impact tests and tumbler test to find the correlation between the bruise susceptibility and the bruise area/apple. Bruise susceptibility obtained from the vertical drop test using the hockey ball was closely related to the bruise area per apple produced by the tumbler test (R = 0.72). The bruise factor obtained from the single pendulum test using the flat indenter also showed a correlation with the bruise area per apple produced by the tumbler test (R = 0.78). However, the bruise susceptibility produced by the double pendulum test and single pendulum test was not well correlated with the bruise area/apple and bruise number/apple p

Después de la cosecha, gran número de frutas llamadas climatéricas sufren profundas transformaciones bioquímicas que influyen directamente la calidad de esos productos. La respiración medida como la cantidad de CO2 producido por Kg de producto por hora, es el proceso metabólico mas importante entre los demás que ocurren en las frutas después de la cosecha, siendo que su intensidad se refleja en la mayor o menor deterioración del producto, para una determinada condición de almacenamiento. La importancia del conocimiento de la intensidad respiratoria de un producto, hace posible relacionar algunas de las transformaciones físicas y bioquímicas tales como la variación del peso, volumen, firmeza, desarrollo de azucares, ácidos, etc., que en conjunto son responsables por la buena calidad y conservación posterior. En el presente trabajo se tuvo como objetivo principal el estudio de la tasa respiratoria del banano, variedad NANICA (MUSA Cavendishii), en dos condiciones diferentes de almacenamiento: 26° C y 60% de humedad relativa y 15°C y 90% de humedad relativa. Se estudió paralelamente su incidencia en los parámetros físicos, de peso, peso específico, volumen, firmeza y químicos en solidos solubles, pH, acidez, azucares reductores y azucares totales. Los resultados obtenidos pueden considerarse de gran utilidad para el estudio de los parámetros que intervienen en procesos de almacenamiento, empaque, transporte y conservación de este producto., Después de la cosecha, gran número de frutas llamadas climatéricas sufren profundas transformaciones bioquímicas que influyen directamente la calidad de esos productos. La respiración medida como la cantidad de CO2 producido por Kg de producto por hora, es el proceso metabólico mas importante entre los demás que ocurren en las frutas después de la cosecha, siendo que su intensidad se refleja en la mayor o menor deterioración del producto, para una determinada condición de almacenamiento. La importancia del conocimiento de la intensidad respiratoria de un producto, hace posible relacionar algunas de las transformaciones físicas y bioquímicas tales como la variación del peso, volumen, firmeza, desarrollo de azucares, ácidos, etc., que en conjunto son responsables por la buena calidad y conservación posterior. En el presente trabajo se tuvo como objetivo principal el estudio de la tasa respiratoria del banano, variedad NANICA (MUSA Cavendishii), en dos condiciones diferentes de almacenamiento: 26° C y 60% de humedad relativa y 15°C y 90% de humedad relativa. Se estudió paralelamente su incidencia en los parámetros físicos, de peso, peso específico, volumen, firmeza y químicos en solidos solubles, pH, acidez, azucares reductores y azucares totales. Los resultados obtenidos pueden considerarse de gran utilidad para el estudio de los parámetros que intervienen en procesos de almacenamiento, empaque, transporte y conservación de este producto.

Door middel van chemisch onderzoek is nagegaan of er kwaliteitsverschillen bestaan tussen alternatief en gangbaar geteelde winterwortelen na de oogst en na enige tijd bewaren.

Homepage of the journal Postharvest Biology and Technology an international scholarly journal covering biological and technological research in the area of postharvest systems for agronomic and horticultural crops. It is published in 3 volumes of 3 issues per year by Elsevier Science. The website provides information about the scope of the journal and information for authors. Contents and abstracts are available for browsing by date, keyword or author, and they can also be searched by keyword from volume 1 onwards. Full-text articles are only available to subscribers..

Poster met resultaten uit onderzoek naar mogelijkheden tot verlenging van de bewaartijd van biologisch geteelde appel, cultivar Topaz.