Heat treatments control extension growth and enhance microbial disinfection of minimally processed green onions

Extension growth of minimally processed (removal of roots and compressed st em) green onions (Allium cepa L. x A. fistulosum L.) was greatly reduced by storage in air at 0 degreesC, while growth of 10-20 min occurred at 5 degr eesC over 10 days. Heat treatments of 52.5 and 55 degreesC water for 4 and 2 min, respectively, were especially effective in reducing growth to less t han 5 min during 12-14 days at 5 degreesC. Growth was inhibited irrespectiv e of whether the heat treatments were applied before or after cutting. Heat treatments resulted in higher average respiration rates during 12 days at 5 degreesC, but did not affect the overall visual quality or shelf life. Tr eatments with 52.5 degreesC water alone or in combination with different ch lorine concentrations (50 to 400 mg.L-1 NaOCl, pH 7.0) were more effective than use of water or chlorine solutions at 20 degreesC for initial microbia l disinfection.