Low-Dose X-ray Irradiation Extends Shelf Life of Asparagus

MENOMONIE, Wis.Researchers at the University of WisconsinStout have successfully used low-dose X-ray irradiation to significantly reduce bacteria and extend the shelf life of minimally processed foods like pre-cut and packaged fruit and vegetables such as asparagus, according to a study published in the journal HortScience.

The researchers tested their theory on fresh asparagus, which is one of the most popular minimally processed vegetables in the United States. Asparagus has a limited shelf life, due in part to the vegetables high respiration rate, which makes packing and storing asparagus especially challenging for food processors. Asparagus tendency toward rapid moisture loss and its susceptibility to bacteria invasion also create additional food safety concerns for producers.

For the study, fresh-cut asparagus grown in Peru was sorted, cut, washed, immersed in sanitizer solution, and rinsed. The asparagus was then divided into three groups: a control group, vacuum skin-packaged (VSP) group, and vacuum skin-packaged plus X-ray irradiation (I-VSP) group. Asparagus in the I-VSP group were irradiated using a low-energy X-ray food irradiator. During a 24-day period the researchers measured headspace gas content, microbial growth, water soluble sugar content, and enzyme activity in all groups of asparagus.

They found low-dose X-ray irradiation treatment significantly reduced aerobic bacteria and mold/yeast populations and helped to maintain sugar (glucose and fructose) levels in asparagus.