Antibacterial Effect of a Copper Surface in the Germination of Alfalfa Seeds (Medicago sativa L.)

Abstract

Copper metal as a contact surface was studied during the germination of alfalfa seeds (Medicago sativa L.) inside a rotating drum on a laboratory scale and compared with a plastic surface of food-grade. A system of three rotating drums was used inside a thermo-regulated chamber to germinate seeds. Alfalfa seeds were inoculated with 4.2 log cfu g-1 of Escherichia coli and after 84 h of germination sprouts were evaluated for E. coli, mesophilic aerobic bacteria, the content of copper and other minerals (potassium, calcium, magnesium, sodium, iron, manganese, and zinc), total mass, unit mass and length, and color. The contact of alfalfa sprouts with copper sheets allowed to reduce the E. coli load from 6.54 to <0.1 log cfu g-1. However, all sprouts exceeded in copper (> 10 ppm) according to Food Sanitary Regulations. Germinated mass and length decreased after copper treatments. No statistically significant differences were observed between treatments for the remaining quality parameters. Finally, it is concluded that copper was very efficient in reducing the microbial load of E. coli in alfalfa sprouts, complying with the regulations established by the Chilean Ministry of Health.