Studies On Physiological Properties Of Fresh-cut Pumpkins And Antioxidant Activity Of Pumpkin Powders

Fresh-cut vegetables and fruits are that vegetables and fruits are processed before distribution, including selecting, washing, centrifugation, grading and package, sometimes peeling and sliceing are needed. Comsumer trends in fresh-cut vegetables and fruits are dramatic increased, and further research and development in the area are expected. Pumpkin (Cucurbita moschata) is a familiar vegetable in person's daily life, which is high not only in nutrient values, but also in medicinal values. Usually, one single pumpkin is as large as several kilogrammes, which is an amount exceeding the capacity of ordinary families to consume in a relatively short period of time. Fresh-cut pumpkin is just what comsumer trends of pumpkin are. And as we all known, pumpkin, not like tomatoes, strawberries, and so on, is really suitable for fresh-cut processing.The physiological reactions of pumpkin after cut was: the production of ethylene and respiration were induced rapidly in a relatively short time, and during the period of storage, weight loss and whiteness index were also increased, but there were no significant effect in firmness, relative conductivity. The cut degree had a positive correlation with weight loss, respiration, ethylene production. Higher cut degree, more enhancement in weight loss, respiration, ethylene production. We deemed that the key factor that stopped the distribution of pumpkin was whitness.We chose CaCl₂ as the way to inhibit white discoloration of pumpkin, which may be due to dehydration of absent surfaces, and/or formation of a wound barrier such as lignin. By a orthogonal test, we got a optimum treatment parameter: treatment time was 20min, the concentration of CaCl₂ was 3%, the temperature for treatment was 55 ℃. Control, 3% CaCl₂ treated in room-temperature (20℃) for 20min, and the optimum treatment were emploied for validating. We found that: improving the temperature of treatment liquid (from 20℃ to 55℃) can effective enhance the inhibition effect of white discoloration of pumpkin by CaCl2, the optimum treatment had notable effect on delaying the peak-productiong of ethylene, inhibiting the generation of ligin, restraining the formation of whitness. The samples treated in optimum parameter keep the acceptable quality in appearance in a relatively longer time than others. Because pumpkins are regarded as health and functional foods, it is feasible to develop a stable...