Stress in Harvested Products

Different postharvest dehydration rates affect quality characteristics and volatile compounds of Malvasia, Trebbiano and Sangiovese grapes for wine production

“…In a fast dehydration process such as the tunnel type the increase in airflow around the grape berry surface sweeps the boundary layer (the layer of unstirred air surrounding the tissue), removing this diffusional resistance and accelerating water loss. Although under normal conditions the resistance to gas diffusion presented by the intercellular air channels is small, in extreme conditions such as that of the tunnel the lack of continuity, due to the altered cellular structure or leakage of cell fluid as a result of strong water removal, increases the resistance, thus reducing the permeability of gas diffusion,29 and an anaerobic condition can occur 1. Thus high acidity and low oxygen diffusion can provoke an anaerobic situation leading to the formation of ethanol in tunnel‐treated grapes but not the oxidation of ethanol, since ADH requires a very high pH 28.…”

“…Although this aspect is not important or is less important for the production of raisins, in the case of wine the technology or practice of dehydrating grapes can play an important role in modulating the production and release of volatile compounds. Water loss is responsible for large and significant changes in the metabolism of fruits and vegetables 1. With 0.5% water loss, cell wall enzyme activity is already increased, and a further increase in the rate of water loss accelerates respiration and ethylene production together with the loss of volatiles.…”

“…High temperature can modify the structure of the epicuticular wax platelets in fruits, preventing water loss and attack by pathogens,3, 4 but in the case of a thin wax layer it accelerates water evaporation. Higher ventilation can facilitate water loss from fruits, even from grapes, owing to the removal of the boundary layer 1. The reduction in relative humidity around the grapes accelerates the water loss even when the cluster is wrapped in paper or other water vapour‐absorbing materials 5.…”

Influence of combined hot air and UV-C treatment on the antioxidant system of minimally processed broccoli (Brassica oleracea L. var. Italica)

“…Plants modify their phenolic metabolism and antioxidant capacity as a mechanism to protect against mentioned stresses (Dixon & Paiva, 1995). Several studies have shown that UV light affects the physiology of fresh produce by triggering responses that could induce the accumulation of phenolic compounds or other secondary metabolites (Kays, 1997;Saltveit, 1997).…”

Biochemical and Anatomical Characters of Snap Bean (Phaseolus vulgaris L.) Pods under Furrow and Drip Irrigation System at Harvest and during Postharvest

“…Also, Kays (1991) found that, exposure of snap beans to chilling temperatures (at 0 or 5ºC) might have resulted in loss of cell membrane integrity and leakage of solutes and water, which often leads to manifest of CI symptoms such as pitting and wilting. In addition, weight loss was significantly decreased in all periods of storage for all treatments under study, due to reduction of transpiration and respiration rate under cooling (Taiz and Ziger, 2002).…”