Effect of Different Drying Methods on Nutritional and Functional Properties of Onion Powder

Abstract

Onion is one of the most important vegetables used as a food ingredient and spice due to its flavor, aroma and pungency. Chemical composition of onion revealed that it contains vitamins, carbohydrates, proteins, minerals, dietary fiber, some cysteine derivatives and phenolic compounds. It has many medicinal benefits like wound healing, growth-inhibition of microbial and tumor cells, reduction of cancer risk, protection against cardiovascular diseases and diabetes and anti-inflammatory properties. However, post harvest loss during storage remains a major challenge for food researchers. To prevent price hikes and increase the shelf life of onion, preservation is a crucial step. The present study was conducted to evaluate the effect of the sun, tray, vacuum and freeze-drying treatment on the nutritional, functional and sensory acceptability of onion powders. The result indicates that the nutritional, color, texture, rheological and rehydration ratio of freezedried onion powder were better than other drying processes. Volatile compounds retain in lyophilized onion powder. However, they may be readily lost during other drying processes. Based on the micro-structure analysis of onion powder, the freeze-dried powder was found intact and porous cell. There was no leak of solute concentration. It can be concluded that among all drying methods, freeze-drying is considered the best method to preserve onions in various form like powder, flakes and was well accepted by the sensory panel.