Abstract:
In this study, the changes in the quality of fresh-cut water chestnut caused by the soaking in aqueous ethanol were examined.The changes of polyphenol oxidase activity, respiration rate, hardness, appearance color, odor, total number of colonies and number of coliforms of fresh cut mites during storage were analyzed. The effects of the ethanol concentration on the quality of fresh-cut water chestnut was evaluated through analyzing the activity of polyphenol oxidase, respiratory rate, hardness, color, flavor, total number of colonies and the number of coliforms of the fresh-cut water chestnut. The results showed that the ethanol concentration during soaking did not cause significant changes in the polyphenol oxidase activity and hardness of fresh-cut water chestnuts, but had significant effects on their respiratory rate, flavour and color.During 1 d storage, the respiration rate of fresh-cut water chestnut increased from 74 μg/(kg·h) to 134 μg/(kg·h) when the concentration of ethanol was elevated from 15% to 75%; The respiration rate of fresh-cut water chestnut treated with ethanol exhibited a downward trend over the storage . There was no significant change in the color of fresh-cut water chestnut within the first 4 d. With the prolongation of storage time, a high concentration of ethanol (≥35%) could prevent the change in the color of fresh-cut water chestnut from white to yellow. Analysis with an electronic nose showed that the higher the concentration of ethanol, the more the methyl groups and alcohols, aldehydes, ketones and other substances formed during storage. The response values of the sensors R(6) and R(8) corresponding to the methyl groups, alcohols, aldehydes,ketones increased from 111.13 and 37.10 to 270.65 and 121.70, respectively, when fresh-cut water chestnut treated with 75% ethanol. In addition,the ethanol treatment could reduce the total number of colonies and the number of coliforms in fresh-cut water chestnut. When the concentration of ethanol increased from 15% to 35%, the soaking led to the total number of colonies and the number of coliform in fresh-cut water chestnut(stored for 13 d) decreased to a countable range. When the ethanol concentration was greater than 55%, no colonies and coliforms were detected during the storage period. Thus, the shelf life of the fresh-cut water chestnut could be prolonged if they were soaked in 35%～55% aqueous ethanol and stored at 4 ℃ for 13 d.
