Technical Notes: Detecting Impact Damage of Sweet Onions Using Muriatic Acid and X-rays

Abstract

Damage received by Granex-Grano type sweet onion bulbs may not be clearly evident with the naked eye because the effect of damage may be internal rather than on the surface of the onion. Damage may result from disease, insects, or mechanical means. Considering mechanical damage, layers of dry skin on the surface of an onion may shield the surface while transmitting an impact force to within the onion bulb. Methods of nondestructively examining sweet onions are being sought. Both a muriatic acid dip test and an X-ray CT have been found to provide some indication of damage under certain conditions. For freshly harvested sweet onions, muriatic acid has been found to cause the flesh of a sweet onion to appear yellow and become a sticky gel in the vicinity of damage, thus enhancing the visibility of damage. X-rays have been found to aid in viewing the internal structure of a sweet onion and thus damage that may have occurred. These techniques may lead to a further understanding of how sweet onions should be cared for in order to keep damage to a minimum.