Wrinkled Alfalfa Seeds Harbor More Aerobic Bacteria and Are More Difficult to Sanitize Than Smooth Seeds

WrinkledAlfalfa Seeds Harbor More Aerobic Bacteria and Are More Difficult To Sanitizethan Smooth Seeds

Journalof Food Protection: Vol. 64, No. 9, pp. 1292-1298.

AmyO. Charkowski, Chester Z. Sarreal, and Robert E. Mandrell
Food Safety and Health, USDA, ARS, WRRC, 800 Buchanan Street, Albany, California94710, USA

Abstract-At least 14 separate outbreaks of food poisoningattributed to either Salmonella enterica or Escherichia coliO157:H7 have been traced to sprouts in the past decade. Seeds contaminated withhuman pathogens caused most of these outbreaks, thus many sprout growers are nowtreating alfalfa seeds with the sanitizing agent, calcium hypochlorite (Ca[OCl]2),prior to sprouting. The efficacy of alfalfa seed sanitation varies between seedlots and between seeds within each lot. Alfalfa seeds from different seed lotswere sorted by type in an effort to determine if certain seed types carry moreaerobic bacteria than other seed types. Seeds with a wrinkled type,characteristic of lygus bug damage, had significantly higher levels ofculturable aerobic bacteria and were more difficult to sanitize than smooth,healthy seeds. After sanitation, wrinkled alfalfa seeds that had been inoculatedwith S. enterica ser. Newport carried significantly higher levels of SalmonellaNewport than smooth seeds. If S. enterica is present on wrinkled seeds innaturally contaminated seed lots, it may be difficult to chemically sanitize theseed lot. Removal of the wrinkled alfalfa seeds from the seed lots, perhaps byadapting color sorting equipment similar to that used to sort rice grains andother seeds, should reduce the level of aerobic bacteria in seed lots and mayresult in lower levels of human pathogens on contaminated alfalfa seeds.