QUALITY LOSS OF DOUBLE CONCENTRATED TOMATO PASTE - EVOLUTION OF THE MICROBIAL-FLORA AND MAIN ANALYTICAL PARAMETERS DURING STORAGE AT DIFFERENT TEMPERATURES

This study deals with nonsterile canning of double concentrate tomatoe s (almost-equal-to 30-degrees Brix) stored for 210 days at three diffe rent temperatures (4, 10 and 25C) in 200 kg drums. The evolving analyt ical composition (soluble solids, total solids, glucose, fructose, pH, total acidity, volatile acidity, citric acid, malic acid, succinic ac id, hydroxymethylfurfural (HMF) and color parameters) that the product underwent during storage was dependent both on storage temperature an d on different aerobic levels within the drum (top and bottom sections ). The microbial profile (yeast, lactic acid bacilli and molds) was co rrelated with many important metabolites (D- and L-lactic acids, ethan ol, acetic acid and diacetyl). The results indicate that the increase of these substances is dependent both on storage temperature as well a s the oxygen tension within the drums. Taken all together, the analyti cal findings offer a great help in evaluating the quality of semifinis hed tomatoes. We also found that lactic bacteria grow rapidly at 25C a nd after 15 days their number from both sampling areas in the drums (i .e., 10 cm below the sample surface and 15 cm above the bottom of each drum) is already greater than 10(5) cfu/ml. At 10C, 30 days were need ed to reach such a cell concentration, and after 45 days the level rea ches 10(7)-10(8) cfu/ml. By contrast, at 4C there were differences bet ween top and bottom sampling areas. In the top area, 10(5) cfu/ml was reached after 60 days, while for the bottom area this was reached afte r 120 days. Regarding yeast at 25C, the cfu/ml values were 10(5)-10(6) in both areas of the drum after the 60th storage day. At 10C the beha vior was the same: about 10(5) cfu/ml had been found after 30 days. Fi nally, at 4C the yeast reached 10(5) cfu/ml after 45 days in both samp ling areas. Regarding mold, no growh in the sampling areas was seen.