The Quality of Fresh-Cut Green Onions Treated with Different Application Times of Ultrasound

Abstract

This study was conducted to determine the effect of ultrasound treated at different duration on posharvest quality of onions. In the study, the onions were pulled, cleaned, sorted and washed. Then they are divided into two part as green and white. After this, they were subjected to 52
dB ultrasound in water at the temperature of 24±1oC for 2, 5, 10 and 15 minutes . Onions not applied were evaluated as control. In addition, as the application was made in water, it was used as a second control in onions kept in water for 5 minutes. After the applications, the onions
were dried and placed in the foam dishes (200 g onion per dish), and is wrapped polyethylene stretch film, and then were stored in a cold room containing 4 ± 1 °C temperature and 85-90% relative humidity. At the beginning of the research and at the five days intervals; color (L*, a*,
b*), total soluble solids (%), chlorophyll (SPAD), axle length (mm), axle diameter (mm) and weight loss measurements were performed in white and green parts of onion. According to the results of the experiment, 5 minutes of ultrasound application was decreased the amount of
elongation and weight loss, increased brightness of white part (L * value), reduce yellowing (b * value), and slowed the progression of TSS in the white part. However, the amount of chlorophyll (SPAD) in the green part was reduced in all ultrasound applications. For this reason, 5
minutes of ultrasound application may be recommended as the best practice for quality preservation.