Textural, histological and biochemical changes in cucumber (Cucumber sativus L.) due to immersion and variations in turgor pressure.

SAJNÍN C., GAMBA G., GERSCHENSON L.N. Y ROJAS A.M.

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE

John Wiley & Sons Ltd., publica para The Society of Chemical Industry (SCI).

Lugar: Baffins Lane, Chichester, Sussex PO19 1UD, England.; Año: 2003 vol. 83 p. 731 - 740

0022-5142

Abstract: Textural, histological and biochemical characteristics of cucumber (Cucumber sativus L.) under different tissue turgor pressures were studied after equilibration of mesocarp tissue cylinders in varous polyethylene glycol 400 (PEG) solutions. Tissue swelling was observed for all hypotonic solutions. Cell membrane vitality was detected in all cucumber tissues where significant values of initial firmness (fi) and residual relaxation force (FR) were found. Good turgor status was also associated with higher values of these parameters, observing higher values of the textural parameters for higher turgor. Cell wall integrity was observed through calcofluor fluorescence assay in tissue equilibrated in hypotonic, isotonic and hypertonic solutions, although a lower fluorescence intensity was observed in tissue equilibrated with 0 mol m-3 PEG solution, probably owing to some cell bursting. Calcium bridges between pectic polymers were proven to be responsible for cell-cell adhesion and tissue integrity of cucumber mesocarp tissue. Compresion curves obtained for raw tissue showed a stage of fracture, and its loss after immersion might be attributed to cell-cell adhesion weakness due to immersion in calcium-free PEG solutions. Peroxidase and polygalacturonase increased after cucumber equilibration in the solutions, probably expressing tissue injury. Cucumber textural behaviour was very much affected by immersion in calcium-free solutions, determining the loss of fracture stage and a great influence of turgor pressure on the textural response of soaked tissue.