Gamma-ray sanitization of Argentinean dehydrated garlic ( Allium sativum L.) and onion ( Allium cepa L.) products

Abstract

The contaminating microflora of 12 dehydrated garlic and onion products was investigated. The products were presented in powder, chops and flakes, both packed and unpacked, as sold in the Argentinean retail market. Also, the efficacy of gamma rays doses between 5 and 25 kGy to reduce microbial population was investigated. The prevailing microflora were the spores of mesophilic aerobic bacteria (between 1.4 × 10 3–2.7 × 10 5 in garlic and 3.5 × 10 4–4.6 × 10 5 CFU/g in onion). A dose of 10 kGy for onion was required to reduce the spore counts up to non-detectable levels. Sulfite-reducing clostridia and their spores were detected only in garlic at levels below 30 CFU/g. In all products, Bacillus cereus and their spores, moulds and yeasts did not exceed 266 and 6.0 × 10 3 CFU/g, respectively. Total coliforms predominated in onion with a MPN maximum of 1.1 × 10 3/g. A dose of 5 kGy was enough to reduce this non-prevailing microflora up to non-detectable limits. As regards public health, the treatment with gamma rays is suggested for garlic and onion products used by Argentinean consumers.