RESUMO
Novel processing technologies can be used to improve both the microbiological safety and quality of food products. The application of high pressure processing (HPP) in combination with dimethyl dicarbonate (DMDC) represents a promising alternative to classical thermal technologies. This research work was undertaken to investigate the combined effect of HPP and DMDC, which was aimed at reaching over 5-log reduction in the reference pathogens Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes inoculated in apple juice. Different strains of each species were tested. The pressure (ranging from 100 to 600 MPa), dwell time (from 26 to 194 s), and DMDC (from 116 to 250 mg/L) were tested based on a central composite rotatable design. The dwell time, in the studied range, did not have a significant effect (p > 0.1) on the pathogens´ reduction. All treatments achieved a greater than 5-log reduction for E. coli O157:H7 and L. monocytogenes. The reductions for S. enterica were also greater than 5-log for almost all tested combinations. The results for S. enterica suggested that it is more resistant to HPP and DMDC compared with E. coli O157:H7 and L. monocytogenes. The findings of this study showed that DMDC at low concentrations can be added to apple juice to reduce the parameters conventionally applied in HPP. The combined use of HPP and DMDC was highly effective under the conditions of this study.
Assuntos
Pressão Atmosférica , Bactérias/efeitos dos fármacos , Dietil Pirocarbonato/análogos & derivados , Sucos de Frutas e Vegetais/microbiologia , Malus/microbiologia , Viabilidade Microbiana/efeitos dos fármacos , Bactérias/patogenicidade , Contagem de Colônia Microbiana , Dietil Pirocarbonato/farmacologia , Escherichia coli O157/efeitos dos fármacos , Microbiologia de Alimentos/métodos , Listeria monocytogenes/efeitos dos fármacos , Salmonella enterica/efeitos dos fármacosRESUMO
Quality and safety of fresh produce are important to public health and maintaining commerce between Mexico and USA. While preventive practices can reduce risks of contamination and are generally successful, the variable environment of the supply chain of fresh produce can be suitable for introduction or proliferation of pathogenic microorganisms. As routine surveillance of these pathogens is not practical, indicator microorganisms are used to assess the sanitary conditions of production and handling environments. An opportunity exists to use indicators on fresh produce to measure how handling and transport from field to market may affect microbial populations that contribute to their quality or safety. The objective was to quantify indicator microorganisms on tomatoes sampled along the supply chain during the harvest year, in order to observe the levels and changes of populations at different locations. Roma tomatoes (n=475) were taken from the same lots (n=28) at four locations of the postharvest supply chain over five months: at arrival to and departure from the packinghouse in México, at the distribution center in Texas, and at retail in USA. Samples were analyzed individually for four microbial populations: aerobic plate count (APC), total coliforms (TC), generic Escherichia coli, and yeasts and molds (YM). APC population differed (p<0.05) from 1.9±1.1, 1.7±1.1, 2.3±1.1 and 3.5±1.4logCFU/g at postharvest, packing, distribution center and supermarket, respectively. TC populations were <1logCFU/g at postharvest, increased at packing (0.7±1.0logCFU/g), decreased in distribution (0.4±0.8logCFU/g) and increased in supermarkets (1.4±1.5logCFU/g). Generic E. coli was not identified from coliform populations in this supply chain. YM populations remained <1logCFU/g, with the exception of 1.1±1.3logCFU/g at supermarkets and tomatoes were not visibly spoiled. The levels reported from this pilot study demonstrated the dynamics within populations as influenced by time and conditions in one supply chain during a harvest year, while the large variances in some locations indicate opportunities for improvement. Overall, packinghouse and supermarket locations were identified as crucial points to control microbial safety risks.
Assuntos
Bactérias/isolamento & purificação , Contaminação de Alimentos/análise , Frutas/microbiologia , Solanum lycopersicum/microbiologia , Bactérias/classificação , Bactérias/genética , Contagem de Colônia Microbiana , Contaminação de Alimentos/economia , Microbiologia de Alimentos/economia , Frutas/economia , Humanos , México , Projetos PilotoRESUMO
Apples and apple products are excellent substrates for Penicillium expansum to produce patulin. In an attempt to avoid excessive levels of patulin, limiting or reducing P. expansum contamination levels on apples designated for storage in packinghouses and/or during apple juice processing is critical. The aim of this work was (i) to determine the thermal resistance of P. expansum spores in apple juice, comparing the abilities of the Bigelow and Weibull models to describe the survival curves and (ii) to determine the inactivation of P. expansum spores in aqueous chlorine solutions at varying concentrations of chlorine solutions, comparing the abilities of the biphasic and Weibull models to fit the survival curves. The results showed that the Bigelow and Weibull models were similar for describing the heat inactivation data, because the survival curves were almost linear. In this case, the concept of D- and z-values could be used, and the D-values obtained were 10.68, 6.64, 3.32, 1.14, and 0.61 min at 50, 52, 54, 56, and 60 degrees C, respectively, while the z-value was determined to be 7.57 degrees C. For the chlorine treatments, although the biphasic model gave a slightly superior performance, the Weibull model was selected, considering the parsimony principle, because it has fewer parameters than the biphasic model has. In conclusion, the typical pasteurization regimen used for refrigerated apple juice (71 degrees C for 6 s) is capable of achieving a 6-log reduction of P. expansum spores.
Assuntos
Cloro/farmacologia , Desinfetantes/farmacologia , Temperatura Alta , Penicillium/efeitos dos fármacos , Penicillium/fisiologia , Malus , Penicillium/metabolismoRESUMO
This study examined the potential for patulin production in six different varieties of apples (Red Delicious, Golden Supreme, Gala, Fuji, Empire, and McIntosh) inoculated with Penicillium expansum spores and stored at two different temperatures (11 and 20.5 degrees C). Samples for patulin analysis were randomly taken from apples stored at different times, ranging from 21 to 93 days. While patulin was produced at both storage temperatures, apples incubated at 20.5 degrees C yielded significantly higher patulin concentrations than did those incubated at 11 degrees C. All apple varieties showed mold spoilage at both temperatures, except Red Delicious and Empire. A total of 44% of the samples analyzed showed patulin concentrations above the U.S. Food and Drug Administration regulatory limit (50 ppb). The highest patulin productions occurred in Golden Supreme (54,221 ppb) and McIntosh (52,131 and 48,457 ppb) varieties. Our results showed that careful culling of apples is essential for high juice quality, since high patulin levels in some apples varieties could result in a level greater than 50 ppb of this mycotoxin in the finished juice or cider, even when only one contaminated apple occurs in 1,000 apples.
Assuntos
Conservação de Alimentos/métodos , Malus/microbiologia , Patulina/biossíntese , Penicillium/metabolismo , Qualidade de Produtos para o Consumidor , Contaminação de Alimentos/análise , Contaminação de Alimentos/prevenção & controle , Manipulação de Alimentos/métodos , Microbiologia de Alimentos , Malus/química , Esporos Fúngicos , Temperatura , Fatores de TempoRESUMO
The effectiveness of several wash treatments was evaluated against spores of Penicillium expansum inoculated on six varieties of apples (Red Delicious, Golden Supreme, Empire, Macintosh, Fuji, and Gala). The wash treatments were water, acidified water (pH 6.5), acidified sodium hypochlorite (pH 6.5), nonacidified sodium hypochlorite (pH 8.8, 9.3, and 9.7; 50, 100, and 200 ppm, respectively), and peracetic acid (50 and 80 ppm). Spores of P. expansum were dried on the surface of the apples for 2 h before exposure to the different sanitizer solutions. Each apple was submerged in 100 ml of each treatment solution for 30 s, and the number of spores remaining were recovered and enumerated. The efficacy of chlorine solutions was enhanced by decreasing the pH to 6.5 (up to 5-log reduction, depending on apple variety). Peracetic acid solutions (50 and 80 ppm) resulted in a reduction of less than 2 log spores per g and had the same efficacy (P < or = 0.05) as nonacidified chlorine solutions (50, 100, and 200 ppm). Control water solutions produced a reduction of 1.34 log spores per g. Chlorine solutions at pH 6.5 resulted in the largest reduction of P. expansum spores for all apple varieties tested.