ABSTRACT
The effect of calcium lactate on osmodehydrated guavas in sucrose and maltose solutions was monitored during storage under passive modified atmosphere for 24 d at 5 °C. Sample texture and color characteristics, microbial spoilage, sensory acceptance, structural changes, and gas composition inside the packages were periodically evaluated. Calcium lactate inhibited microbial growth on guavas, with yeast and mold counts in the order of 10(2) CFU/g throughout storage. The calcium salt reduced respiration rate of guava products, showing O(2) and CO(2) concentrations around 18% and 3% inside the packages. A firming effect on fruit texture, with up to 5 and 2 times higher stress and strain at failure values and tissue structure preservation could also be attributed to calcium lactate use. However, fruits treated with calcium lactate, osmodehydrated in maltose and sucrose solutions, showed sensory acceptance scores below the acceptability limit (4.5) after 13 and 17 d of storage, respectively.
Subject(s)
Anti-Infective Agents/pharmacology , Calcium Compounds/pharmacology , Food Microbiology , Food Preservation , Fruit/drug effects , Lactates/pharmacology , Psidium/drug effects , Carbon Dioxide/analysis , Colony Count, Microbial , Food Contamination/analysis , Food Packaging , Fruit/microbiology , Hydrogen-Ion Concentration , Oxygen/analysis , Pigmentation/drug effects , Psidium/microbiology , Salmonella/growth & development , Salmonella/pathogenicityABSTRACT
The possibility of the survival, germination, and multiplication of Bacillus cereus in extended-shelf-life milk prompted research into the occurrence of the bacteria in refrigerated milk submitted to different heat treatments. Samples were submitted to ultrapasteurization (138 degrees C for 2 s), "superpasteurization" (96 degrees C for 13 s), and pasteurization (74 degrees C for 15 s) and stored under refrigeration at 4 +/- 2 degrees C for up to 6 weeks. The milk was analyzed for its sensory quality and for the quantitative determination of mesophilic and psychrotrophic B. cereus in the vegetative form at incubation temperatures of 7 and 30 degrees C, in addition to standard plate counts and psychrotrophic counts. In the three experimental trials, the psychrotrophic B. cereus counts were below the detection limit of the methodology (<10 CFU/ml) in all of the samples analyzed, independent of the heat treatment and storage period. The count of mesophilic B. cereus was restricted to samples of superpasteurized and pasteurized milk from a single trial, reaching 4.0 x 10(1) and 7.0 x 10(5) CFU/ml, respectively. Although the pasteurized milk had higher populations of mesophilic B. cereus after the second week of storage, flavor defects resulting in sensory rejection of the product did not appear before the fourth week of storage. The results of this research indicate that superpasteurization and ultrapasteurization are adequate for maintaining the product at refrigeration temperatures for 6 weeks. Pasteurized milk produced under clean conditions should have a shelf life limited to less than 2 weeks.
Subject(s)
Bacillus cereus/growth & development , Food Contamination/analysis , Food Handling/methods , Milk/microbiology , Animals , Bacillus cereus/isolation & purification , Colony Count, Microbial , Consumer Behavior , Consumer Product Safety , Food Microbiology , Hot Temperature , Humans , Milk/standards , Refrigeration , Spores, Bacterial/growth & development , Taste , Time FactorsABSTRACT
As indústrias de leite de coco no Brasil utilizam como método de conservaçäo deste produto a pasteurizaçäo acompanhada da adiçäo de conservadores químicos do tipo metabissulfito de sódio, sorbato de potássio e benzoato de sódio. Devido às características do produto (pH 6,0 e atividade de água maior que 0,85), esse tratamento näo é efetivo para garantir sua estabilidade microbiológica. Estudou-se entäo a estabilidade microbiológica do leite de coco, comercializado à temperatura ambiente, através da avaliaçäo da eficiência dos processos termoquímicos mais comumente empregados pelas indústrias, comparando-os ao processo de esterilizaçäo em autocalve rotativa. O leite de coco foi previamente formulado e acrescido de esporos de Clostridium sporogenes (PA 3679). Para cada processo utilizaram-se dois níveis de inoculaçäo, um de 2x dez ao quadrado e outro de 2x dez a sexta esporos/200ml. Os resultados obtidos demonstraram que existe a possibilidade do desenvolvimento de clostrídios anaeróbicos putrefativos, indicando inclusive o risco de desenvolvimento de Clostridium botulinum quando näo se utiliza a esterilizaçäo do leite de coco em autoclave rotativa. Portanto, o tratamento térmico à pressäo atmosférica praticado pela indústria implica em risco potencial à saúde pública