Retardation of Chilling Injury Symptoms and Reducing Quality Loss of Cactus Pear Fruits During Cold Storage by Heat Treatments

Document Type : Original Article

Authors

1 Mamouraa Botanical Garden, Alex., Hort. Res. Center, Giza. Egypt.

2 Dep. Plant Prod. (Pomology), Institute of Efficient Productivity, Zagazig Nniv.

Abstract

Cactus pear fruits had three ripening stages of light green (G), yellowish green (YG) and yellow (Y) were
exposed to water steam (WS) at approximately 78 ?C for one min or dipped into hot water (HW) at 55 ?C for two min or washed with regular tap water(control). Each of the above nine (3 stages x 3 treatments) groups was divided into two sections, the first one was stored at 5 ?C and the other was stored at 10 ?C. Heat treatments prolonged the storage period of all ripening stages of fruits. At 5 and 10?C, respectively, the treated fruits were stored for 32 and 40 days compared with 28 and 32 days for the untreated one. Control fruits were the first to decay due to the chilling injury incidence specially the green stage at 5 ?C and became unattractive as a result of loss of its brightness. On the other hand, heated fruits kept its good appearance, free from decay and wrinkles for longer time. Heat treatments retard the appearance of chilling injury symptoms for the stored fruits at 5 ?C and the best appearance with less chilling symptoms was for
the yellow fruits. The fruits stored at 10 ?C were free from chilling symptoms except of small red spots appeared on the control fruits. WS treatment reduced weight loss of cactus pear fruits and the differences were significant for the yellowish green fruits except of those stored at 5 ?C in the first season. On the other side, HW treatment increased the weight loss of all treatments with insignificant differences compared with the control fruits with exception of yellowish green fruits in the second season which reduced it. Green fruits had the highest initial color index (CI) and the heat treatments did not affect CI of all ripening stages of fruits stored at 5 and 10 ?C in the two seasons and there were no differences between heat treatments. Heat treatments had no significant effect on pulp weight percent, but generally heated fruits had lower percentages and the fruits stored at 10 ?C had higher percentages with significant increase by the duration of cold storage. At harvest in the two experimental seasons, yellow fruits had the highest contents of juice. Heat treatments had no significant effect on pulp juice weight at 5 and 10 ?C but generally the WS
treated fruits had the highest juice weight which may be due to the water loss reduction. Except the green cactus pear fruits which lost its juiciness with the progress of the storage time. At harvest, yellow fruits had the highest values of SSC, V.C, water soluble pectin (WSP) and polyphenoloxidase (PPO) activity and the lowest percentages of acidity. Heat treatments had no significant effect on the SSC of cactus pear fruits except the higher significant content of heated fruits in some intervals. Heat treatments had significant effect on acidity and V.C especially the WS treatment which had the highest values at the two storage temperatures and in two seasons. Heat treatments had significant effect on reducing WSP pulp < /strong>
content and the activity of PPO. In both seasons, SSC of all treatments decreased by the advancing of cold storage and the highest values were obtained from yellow fruits. Fruit acidity increased by the end of the cold storage at 5?C and after the same period at 10 ?C (32 days), then decreased at the last two intervals at 10 ?C. WSP content increased with the loss of fruit firmness and the lowest changes were obtained with the yellow fruits and the fruits stored at 5 ?C. PPO activity increased, then decreased after 24 days at 5 and 10C.

Main Subjects

Files

Share

How to cite

Statistics