Dimethyl dicarbonate and potassium sorbates effects on microbial growth and color of fresh salsa

Fresh salsa produced from tomatoes, onions, oil, vinegar, lemon juice and Jalapeno peppers was adjusted to pH 3.7-3.8 with citric acid. Six antimicrobial treatments were tested in salsa by combining dimethyl dicarbonate (DMDC) at 0, 100 or 200 ppm with potassium sorbate (PS) at 0 or 1% to determine effects of DMDC and PS, individually and in combination. Aerobic plate counts (APC), mold and yeast counts (MYC), lactic acid bacteria counts (LAB) and coliform counts of salsa stored for up to 28 days at 4°C or 20°C were determined. Color, pH and titratable acidity as citric acid (TA) were also determined. The salsa initially contained an average aerobic plate count (APC) of approximately 6.8 log cfu/mL, yeast and mold count (YM) of 1.4 log cfu/mL, lactic acid bacteria count (LAB) of 4.2 log cfu/mL and a coliform count of 1.4 log cfu/mL. The APC in salsa stored at 25°C increased when 0% PS was added but decreased 3-4 log cfu/mL if only 1% PS was added. APC for salsa containing 100 or 200 ppm DMDC plus 1% PS decreased 5-6 log cfu/mL after 8 days. Salsa stored at 4°C had nondetectable APC by 8 to 24 days, depending on the treatment. Yeast and mold growth in salsa stored at 25°C was controlled by PS but not DMDC. No yeast or mold growth was detected in salsa stored at 4°C. LAB were controlled by 1% PS at 25°C but reached log 9 cfu/mL in salsa with 0% PS. LAB did not grow at 4°C. Conforms were not detectable at either temperature after storage. The pH increased from 3.9 to 4.6 with the addition of 1% PS. The pH decreased and TA increased following the growth of LAB in salsa containing 0% PS, stored at 25°C. There was a reduced red color measured in the salsa containing 0% PS. Microbial growth was not detected in salsa stored for 28 days at 4°C. PS (1%) was effective in controlling spoilage for salsa stored at 25°C. DMDC did not control microbial growth at 25°C.