Effects of temperature and water relations on carrots and radish tuber texture

• Tissue firmness and stiffness are functions of tissue and cell wall structure, water status and temperature, and their interactions. This investigation elaborates the physiological basics of temperature and water status effects on firmness of fresh intact carrots and radish tubers. The results can add to a better understanding of the mechanical properties at least of these succulent plant storage organs. Water potential of intact carrot roots and radish tubers was measured with a pressure bomb, firmness was determined as the force necessary to cut the entire tuber perpendicularly to the length axis with a microtome knife adapted to a universal testing machine, and osmotic potential psychrometrically in expressed tissue sap. Hence, volume averaged pressure potential or turgor could be calculated from water potential and osmotic potential data. Water potential and turgor were positively correlated with cutting force in both species. Beyond wilting, the variation of cutting force with declining water potential was less pronounced. In carrot but not in radish tubers, cutting force and turgor were higher at lower tissue temperature (ca 10degreesC compared to ca 20degreesC). On the other hand, temperature did not influence the relationship between water status and texture in radish. In contrast, tuber development led to an increase in cutting force. From the presented results it seems obvious that the temperature effect on cutting force in carrots is mediated by affecting cell wall properties and not water status.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Annan teknik -- Livsmedelsteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Other Engineering and Technologies -- Food Engineering (hsv//eng)

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