Atividade microbiana em couve (Brassica oleraceae c.v. acephala) minimamente processada
Alterações nas características químicas, sensoriais e na microbiota contaminante de couve minimamente processada e estocada em embalagem com modificação passiva da atmosfera foram avaliadas durante a estocagem a 1 o C, 5 o C e 10 o C. Estabeleceu-se que a seqüência das etapas do processamento mínimo...
|Nível de Acesso:||openAccess|
Universidade Federal de Viçosa
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|Citação:||BITTENCOURT, Márcia Teixeira. Atividade microbiana em couve (Brassica oleraceae c.v. acephala) minimamente processada. 2000. 5 f. Dissertação (Mestrado em Microbiologia Agrícola) - Universidade Federal de Viçosa, Viçosa. 2000.|
|Resumo inglês:||Alterations in chemical and sensorial characteristics and microbial contamination of minimally processed collarc greens stored in packaging with passive atmospheric modification were evaluated during storage at 1, 5 and 10 o C. The sequence of steps established for minimum processing of the collard greens, based on the results of reduction of aerobic mesophilic contamination, residual chlorine levels, sanitizing solution pH and product acceptance testing, consisted of sanitization, slicing and rinsing. Sanitization of collard greens in a solution with 200 ppm of active chlorine for 10 min at approximately 10 o C resulted in a significant reduction (P≤0,05) of 1.2 to 2 log cycles in the number of aerobic bacteria. Concentrations of O 2 and CO 2 within the packaging of minimally processed collard greens wrapped in PD 941 film (Cryovac ® ) varied significantly (P1≤0,01) during storage. The results indicated that greater O 2 consumption and CO 2 accumulation were registered for the product maintained at 10 o C than at 5 and 1 o C. Collard green pH increased significantly when maintained at 5 and 10 o C while glucose and fructose levels decreased in the product maintained at the three temperatures evaluated. Acceptance testing xresults permitted estimating that the appearance and aroma of minimally processed collard greens were acceptable on the 21 st day of storage at 1 o C and for a period of less than 18 days at 5 o C. Although product appearance was acceptable until the tenth day at 10 o C, it was estimated that its aroma would be sufficiently strong to provoke the prduct ́s rejection on the eighth day of storage. The population of mesophiles and psychrophiles predominated over the populations of lactic acid bacteria, mesophilic anaerobes, coliforms, filamentous fungi and yeast in all samples analyzed and increased the equivalent of 1.5 and 2.8 log cycles after 20 days of storage at 1 and 5 o C, respectively. At 10 o C, microbial populations varied between 4.0 and 4.6 log cycles after 15 days. Although they were not the predominant microbes present, anaerobic and lactic acid bacteria exhibited the greatest growth during storage of minimally processed collard greens, increasing 2.4 to 6.0 log cycles. Yeast were present in the product analyzed, and, although their growth was significant during storage, numbers observed did not surpass 10 5 CFU g -1 . Fecal coliforms were not present in any of the samples analyzed. Isolation and characterization of fifty one colonies representative of the psychrotrophic population indicated that approximately 91% of the psychrotrophic microbes were Gram negative rods, including representatives of the genera Pseudomonas, Flavobacterium, Chromobacterium, Enterobacter and Cedecea. Four psychrotrophic isolates were cultured in collard green and TSB broths at temperatures between 1 o C and 15 o C and their specific growth rates were determined as a function of temperature from the exponential phase of the growth curves obtained. The data were adjusted and a square root equation was the mathematical model that best described the isolates behavior under the growth conditions studied.|