25 research outputs found
Measurement of Water Vapor Condensation on Apple Surfaces during Controlled Atmosphere Storage
Apples are stored at temperatures close to 0 °C and high relative humidity (up to 95%) under controlled atmosphere conditions. Under these conditions, the cyclic operation of the refrigeration machine and the associated temperature fluctuations can lead to localized undershoots of the dew point on fruit surfaces. The primary question for the present study was to prove that such condensation processes can be measured under practical conditions during apple storage. Using the example of a measuring point in the upper apple layer of a large bin in the supply air area, this evidence was provided. Using two independent measuring methods, a wetness sensor attached to the apple surface and determination of climatic conditions near the fruit, the phases of condensation, namely active condensation and evaporation, were measured over three weeks as a function of the operating time of the cooling system components (refrigeration machine, fans, defrosting regime). The system for measurement and continuous data acquisition in the case of an airtight CA-storage room is presented and the influence of the operation of the cooling system components in relation to condensation phenomena was evaluated. Depending on the set point specifications for ventilation and defrost control, condensed water was present on the apple surface between 33.4% and 100% of the duration of the varying cooling/re-warming cycles
Tetrahymena Metallothioneins Fall into Two Discrete Subfamilies
BACKGROUND: Metallothioneins are ubiquitous small, cysteine-rich, multifunctional proteins which can bind heavy metals. METHODOLOGY/PRINCIPAL FINDINGS: We report the results of phylogenetic and gene expression analyses that include two new Tetrahymena thermophila metallothionein genes (MTT3 and MTT5). Sequence alignments of all known Tetrahymena metallothioneins have allowed us to rationalize the structure of these proteins. We now formally subdivide the known metallothioneins from the ciliate genus Tetrahymena into two well defined subfamilies, 7a and 7b, based on phylogenetic analysis, on the pattern of clustering of Cys residues, and on the pattern of inducibility by the heavy metals Cd and Cu. Sequence alignment also reveals a remarkably regular, conserved and hierarchical modular structure of all five subfamily 7a MTs, which include MTT3 and MTT5. The former has three modules, while the latter has only two. Induction levels of the three T. thermophila genes were determined using quantitative real time RT-PCR. Various stressors (including heavy metals) brought about dramatically different fold-inductions for each gene; MTT5 showed the highest fold-induction. Conserved DNA motifs with potential regulatory significance were identified, in an unbiased way, upstream of the start codons of subfamily 7a MTs. EST evidence for alternative splicing in the 3ⲠUTR of the MTT5 mRNA with potential regulatory activity is reported. CONCLUSION/SIGNIFICANCE: The small number and remarkably regular structure of Tetrahymena MTs, coupled with the experimental tractability of this model organism for studies of in vivo function, make it an attractive system for the experimental dissection of the roles, structure/function relationships, regulation of gene expression, and adaptive evolution of these proteins, as well as for the development of biotechnological applications for the environmental monitoring of toxic substances
Watercore dissipation in âfujiâ apples at different holding temperatures
Proceedings of the International Conference âEnvironmentally friendly and safe
technologies for quality of fruit and vegetablesâ, held in Universidade do Algarve, Faro,
Portugal, on January 14-16, 2009. This Conference was a join activity with COST Action 924.Fruit with high levels of watercore are rejected during market quality control inspections because affected
apples can develop alcoholic off-flavours and internal browning symptoms. In 2007 and 2008 late harvest
âFujiâ apples with a high incidence of watercore were kept at 1 °C (2008), 3 °C (2007), 6 °C and 10 °C in air.
Some fruit at 10 °C were also treated with 1-MCP and Ethephon. Changes in flesh firmness and watercore
were followed during 51 d storage. Fruit at 1, 3 °C and 1-MCP treated fruit at 10 °C showed no clear
change in flesh firmness during 51 d storage while fruit at 6 °C softened between 0.7 and 0.9 kg/cm-2
and untreated fruit at 10 °C lost around 1.0 kg/cm-2. Watercore in âFujiâ apples with or without 1-MCP or
Ethephon treatments at 10 °C dissipated to acceptable levels after around 16 to 22 d, while apples at 6, 3
and 1 °C showed acceptable watercore at 26, 29 and 51 d respectively. When âFujiâ apples have high levels
of watercore at-harvest, one option is to treat them with 1-MCP and store at 10 °C. The watercore will
reduce rapidly but fruit flesh firmness will generally be maintained at acceptable levels
Measurement of Water Vapor Condensation on Apple Surfaces during Controlled Atmosphere Storage
Apples are stored at temperatures close to 0 °C and high relative humidity (up to 95%) under controlled atmosphere conditions. Under these conditions, the cyclic operation of the refrigeration machine and the associated temperature fluctuations can lead to localized undershoots of the dew point on fruit surfaces. The primary question for the present study was to prove that such condensation processes can be measured under practical conditions during apple storage. Using the example of a measuring point in the upper apple layer of a large bin in the supply air area, this evidence was provided. Using two independent measuring methods, a wetness sensor attached to the apple surface and determination of climatic conditions near the fruit, the phases of condensation, namely active condensation and evaporation, were measured over three weeks as a function of the operating time of the cooling system components (refrigeration machine, fans, defrosting regime). The system for measurement and continuous data acquisition in the case of an airtight CA-storage room is presented and the influence of the operation of the cooling system components in relation to condensation phenomena was evaluated. Depending on the set point specifications for ventilation and defrost control, condensed water was present on the apple surface between 33.4% and 100% of the duration of the varying cooling/re-warming cycles
Measurement of Water Vapor Condensation on Apple Surfaces during Controlled Atmosphere Storage
Apples are stored at temperatures close to 0 °C and high relative humidity (up to 95%) under controlled atmosphere conditions. Under these conditions, the cyclic operation of the refrigeration machine and the associated temperature fluctuations can lead to localized undershoots of the dew point on fruit surfaces. The primary question for the present study was to prove that such condensation processes can be measured under practical conditions during apple storage. Using the example of a measuring point in the upper apple layer of a large bin in the supply air area, this evidence was provided. Using two independent measuring methods, a wetness sensor attached to the apple surface and determination of climatic conditions near the fruit, the phases of condensation, namely active condensation and evaporation, were measured over three weeks as a function of the operating time of the cooling system components (refrigeration machine, fans, defrosting regime). The system for measurement and continuous data acquisition in the case of an airtight CA-storage room is presented and the influence of the operation of the cooling system components in relation to condensation phenomena was evaluated. Depending on the set point specifications for ventilation and defrost control, condensed water was present on the apple surface between 33.4% and 100% of the duration of the varying cooling/re-warming cycles