Effect of gamma radiation on the shelf life, physiological and nutritional value of onion (Allium cepa L.)

Onion is one of the most important and perhaps one of the oldest cultivated vegetable crop in all continents. In Pakistan, it is grown in different volumes and harvesting periods. Based on the latest United Nation's report, Pakistan ranks as the 8th country that produces the most onion. Onion is widely used for culinary purposes particularly in savory dishes to improve the gastronomic properties of most recipes. Apart from its culinary characteristics, onion has a remarkable medicinal powers and antifungal, antibacterial, antihypertensive, anti-inflammatory, and antioxidant properties. However, post-harvest losses reduce these benefits. Post-harvest losses occur due to mishandling, rotting sprouting, and dehydration. Reduction of these post-harvest losses would maintain and enhance onion quality. Thus, this study aimed to enhance the shelf life and the removal of micro flora without affecting the nutritional value of onion through gamma irradiation. The onion sample used during the experiment was collected from a wholesale market in Lahore, Pakistan. The main objective for treating harvested onions with different doses of gamma radiation was to prevent the physiological processes leading to sprouting during extended storage. The samples were sent to Pakistan Radiation Services (PARAS) Lahore for irradiation at doses of 0.05 kGy, 0.10 kGy, and 0.15 kGy then these were stored at room temperatures. Various physiological and nutritional parameters were assessed during the various storage time. The parameters include the percent of weight loss, ash content, moisture content, fat, crude fiber, crude protein, and carbohydrates. By measuring these parameters, before and after gamma irradiation, it was concluded that the dose of 0.10n kGy is optimum for enhancing onion shelf life without any significant change in its physiological as well as nutritional value.