Assessment of changes in optical properties of fresh-cut tomato using video image analysis
Moreira Lana, M. ; Tijskens, L.M.M. ; Theije, A. ; Hogenkamp, M. ; Kooten, O. van - \ 2006
Postharvest Biology and Technology 41 (2006)3. - ISSN 0925-5214 - p. 296 - 306.
keeping quality - storage - color - fruit - cantaloupe - honeydew - pericarp - temperature - appearance - physiology
Tomato fruit (Lycopersicon esculentum cv. Belissimo) at different stages of maturity were sliced in 7-mm thick transverse slices and stored at 5 °C. In a second experiment, slices obtained from fruit at the light-red stage were stored at temperatures from 5 to 13 °C. Intact control fruit were stored under the same conditions. Digital images were taken immediately after processing, before cooling, and at regular intervals during storage, after placing the slice in a double (half white, half black) background. The data were expressed as the average intensities per pixel of red (R), green (G) and blue (B) separately for the white background and for the black background. Additional indices were obtained by algebraic calculations from the original RGB values and through the conversion of RGB into L*a*b* values. The development of translucency in the pericarp was the main change in appearance of cut tomato. This process was strongly affected by the stage of maturity of the fruit and independent of storage temperature. The more mature the fruit the faster and more intense was the development of translucency. Using video image analysis, an increase in translucency could be assessed by a decrease in the amount of red pixels when the sample was measured against a black background. Changes in colour due to maturation could be measured both by a decrease in the amount of green pixels or by an increase in the proportion of red pixels (R/(R + G + B)), when the sample was placed on a white background. Using the L*a*b* colour space, an increase in translucency corresponded to a decrease in lightness and changes in colour due to maturation resulted in an increase in a*-value.
A xylogalacturonan epitope is specifically associated with plant cell detachment.
Willats, W.G.T. ; McCartney, L. ; Steele-King, C.G. ; Marcus, S.E. ; Mort, A.J. ; Huisman, M.M.H. ; Alebeek, G.J.W.M. van; Schols, H.A. ; Voragen, A.G.J. ; Goff, A. le; Bonnin, E. ; Thibault, J.F. ; Knox, J.P. - \ 2004
Planta 218 (2004)4. - ISSN 0032-0935 - p. 673 - 681.
pectic polysaccharides - spatial regulation - hairy regions - pea hulls - walls - homogalacturonan - tomato - cotyledons - separation - pericarp
A monoclonal antibody (LM8) was generated with specificity for xyloglacturonan (XGA) isolated from pea (Pisum sativum L.) testae. Characterization of the LM8 epitope indicates that it is a region of XGA that is highly substituted with xylose. Immunocytochemical analysis indicates that this epitope is restricted to loosely attached inner parenchyma cells at the inner face of the pea testa and does not occur in other cells of the testa. Elsewhere in the pea seedling, the LM8 epitope was found only in association with root cap cell development at the root apex. Furthermore, the LM8 epitope is specifically associated with root cap cells in a range of angiosperm species. In embryogenic carrot suspension cell cultures the epitope is abundant at the surface of cell walls of loosely attached cells in both induced and non-induced cultures. The LM8 epitope is the first cell wall epitope to be identified that is specifically associated with a plant cell separation process that results in complete cell detachment.