Evaluation of Volatile Chemical Treatments for Lethality to Salmonella OnAlfalfa Seeds and Sprouts

Evaluationof Volatile Chemical Treatments for Lethality to Salmonella on Alfalfa Seeds andSprouts

Journalof Food Protection: 2001, Vol. 64, No. 4, pp. 442-450.

W.R. Weissiner, K. H. McWatters, and L. R. Beuchat, Center for Food Safety,Department of Food Science and Technology, University of Georgia,

Abstract-A study was done to evaluate natural volatile compounds for theirability to kill Salmonella on alfalfa seeds and sprouts. Acetic acid, allylisothiocyanate (AIT), trans-anethole, carvacrol, cinnamic aldehyde, eugenol,linalool, methyl jasmonate, and thymol were examined for inhibitory and lethalactivity against Salmonella by exposing inoculated alfalfa seeds to compounds(1,000 mg/liter of air) for 1, 3, and 7 h at 60°C. Only acetic acid, cinnamicaldehyde, and thymol caused significant reductions in Salmonella populations(>3 log₁₀ CFU/g) compared with the control (1.9 log₁₀CFU/g) after treatment for 7 h. Treatment of seeds at 50°C for 12 h with aceticacid (100 and 300 mg/liter of air) and thymol or cinnamic aldehyde (600 mg/literof air) significantly reduced Salmonella populations on seeds (>1.7 log₁₀CFU/g) without affecting germination percentage. Treatment of seeds at 50°Cwith AIT (100 and 300 mg/liter of air) and cinnamic aldehyde or thymol (200mg/liter of air) did not significantly reduce populations compared with thecontrol. Seed germination percentage was largely unaffected by treatment withgaseous acetic acid, AIT, cinnamic aldehyde, or thymol for up to 12 h at 50°C.The number of Salmonella on seeds treated at 70°C for 80 min with acetic acid(100 and 300 mg/liter of air), AIT (100 mg/liter of air), and cinnamic aldehydeand thymol (600 mg/liter of air) at water activity (a_w) 0.66 was notsignificantly different than the number inactivated on seeds at a_w0.49. Acetic acid at 200 and 500 mg/liter of air reduced an initial populationof 7.50 log₁₀ CFU/g of alfalfa sprouts by 2.33 and 5.72 log₁₀CFU/g, respectively, within 4 days at 10°C, whereas AIT at 200 and 500 mg/literof air reduced populations to undetectable levels; however, both treatmentscaused deterioration in sensory quality. Treatment of sprouts with 1 or 2 mg ofAIT per liter of air adversely affected sensory quality but did not reduceSalmonella populations after 11 days of exposure at 10°C.