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Dairy, Food and Environmental Sanitation Abstracts - April, 2001 Occurrence of Listeria monocytogenes in Vegetables Summary The occurrence of L. monocytogenes in lettuce, cabbage, parsley, and watercress was studied at various times during the year. Quantification of L. monocytogenes was carried out only in lettuce. One-hundred samples of lettuce and fifty samples of each of the other vegetables were examined, giving a total of 250 samples. The vegetables, purchased in the local market in the cities of Campinas and Piracicaba in the state of São Paulo, Brazil, were aqcuired in the same way as the consumer buys them. The incidence of the bacterium was determined with enrichment in Listeria enrichment broth, and incubation at 4°C for 30 days, followed by isolation on Palcam and Oxford agars. For the L. monocytogenes count in lettuce, the multiple tube technique in tryptic soy broth with 0.6% added yeast extract was used, in addition to incubation at 4°C for 30 days and isolation on Palcam and Oxford agars as mentioned before. The total incidence of L. monocytogenes in the vegetables examined was 3.2%. The bacterium was not found in any of the cabbage samples analyzed. The average population of L. monocytogenes in lettuce was 1.2 MPN/g. Isolation of the organism occurred in the months of January (62.5%), June (12.5%) and July (25%), the wettest and coldest months of the year. Maximizing Microbiological Quality
of Fresh Orange Juice by Processing Sanitation and Fruit Surface Treatments Summary This study was designed to evaluate the individual and combined effects of processing sanitation and fruit surface treatments on the microbial quality of fresh-squeezed, unpasteurized ‘Valencia’ orange juice. The average initial total microorganism count of fresh juice extracted with a non-sanitized juice extractor was 4.0 ± 0.7 log CFU/ml, and this figure was significantly reduced, to 2.5 ± 1.0 log CFU/ml, by cleaning and sanitizing the extractors with quaternary ammonia. Juice initial yeast and mold counts were about 2.5 ± 0.2 log CFU/ml when non-washed fruit were extracted by use of a thermally sanitized extractor. When fruit were washed prior to extraction, however, the yeast and mold counts were lowered to < 1.0 ± 0.0 log CFU/ml. The best result was obtained with treatment of both fruit and equipment surfaces with hot water (80°C), which yielded juice with low values (<1.0 ± 0.0 log CFU/ml) for both total microorganism counts and yeast-and-mold counts. Further, fresh juice produced with surface thermal treatment of both fruit and equipment had superior microbial stability during both refrigerated (4°C) and abused (25°C) storage. |