Microbial modeling of Alicyclobacillus acidoterrestris CRA 7152 growth in orange juice with nisin added

The adaptation time of Alicyclobacillus acidoterrestris CRA 7152 in orange juice was determined as a response to pH (3 to 5.8), temperature (20 to 54 degrees C), soluble solids concentration (degrees Brix; 11 to 19 degrees Brix), and nisin concentration (0 to 70 IU/ml) effects. A four-factor central composite rotational design was used. Viable microorganisms were enumerated by plating on K medium (pH 3.7). Two primary models were used to represent growth and adaptation time. A second-order polynomial model was applied to analyze the effects of factors. Results showed that the Baranyi and Roberts model was better than the modified Gompertz model, considering the determination coefficient (R-2) for experimental data description. Inhibition of bacteria can be obtained through several studied combinations for at least 47 days of storage. The shortest period of adaptation was observed between 37 to 45 degrees C, with pHs between 4 and 5, yet the longest periods of adaptation could be obtained around 20 degrees C with pHs close to 3.0. Statistical analysis of the quadratic model showed that the adaptation time increased as temperature or pH decreased, and as nisin concentration or soluble solids increased. The model showed that adaptation time has a minimum value for juice without nisin added, with 13.5% soluble solids, pH 5.0, and incubated at 43.8 degrees C. The statistical parameters that validated this model were an R-2 of 0.816, a bias factor of 0.96, and an accuracy factor of 1.14. Manipulation of more than one factor, as well as the use of an antimicrobial agent, can be an alternative to preventing the development of A. acidoterrestris in orange juice, thus contributing to increased orange juice shelf life.6981904191

Thermal process evaluation of retortable pouches filled with conduction heated food

Two models using the finite element technique (FE) and another using an analytical solution to solve the 3-dimensional heat conduction equation for a finite plate were built. FE models were built considering the actual pouch shape and retort temperature profile. Chi-square and regression lines were obtained for each set of temperatures generated by the models against experimental data. A mass average sterilizing value of 9.9 min was estimated when a critical point sterilizing value was at 8.7 min using the 3-Dimensional FE model. Close agreement was found among the three models for heating phase. Using actual retort temperature profile made FE models more accurate than the one using analytical solution, especially for cooling phase.25539540

Thermal death kinetics of B-Stearothermophilus spores in sugarcane must

Thermal death kinetic parameters for Bacillus stearothermophilusspores were evaluated in sugarcane must (21.5 degrees Brix, pH = 6.14) at temperatures ranging from 98 to 130C, using the thermal-death-time tube method and survivors count. Resulting survival curves showed strong nonlinearity and different shapes according to heating temperature. The 98 and 110C curves showed an initial shoulder or thermal lag and were adjusted to the logistic model. At the temperature range of 120-125C, the two-term exponential model for population with heterogeneous heat resistance was fitted, and at 130C, the classic linear model was suitable. It was shown that rate constants are influenced by temperature according to two irreconcilable methods: the Arrhenius and the Bigelow methods. Activation energy (E-a) obtained was 249.52 kJ/mol while thermal resistance parameter (z-value) calculated from E-a and the Bigelow method were 11.48 and 9.19C, respectively. Thermal death kinetic constant, k values, varied from 0.019 to 13.63/min.30562563

Biological validation of tomato pulp continuous heat process

This research validated the commercial process applied to tomato pulp (pH 4.3 and 8 Brix) packed in Tetra Brik packages. Spores of Bacillus coagulans and Neosartorya fischeri were selected as targets. The heat resistance of both microorganisms, tested independently, was compared. The redesigned thermal processes were carried out in a aseptic processing and tested by indirect inoculation and retrieval with spores immobilized in alginate/tomato balls. The results showed that processes for 30 s at 115C or greater did not allow the survival of heat-resistant molds. For bacterial spores, processes for 30 s at 109C or greater showed no survivors. Although, 30 s at 115C will control both types of spoilage spores, concern for possible C. botulinum growth attributed to metabiosis in product with varying initial populations of molds and residual oxygen content dictated, a process recommendation of 60 s at 126C for safety reasons.27644946

Thermal degradation kinetics of sucrose, glucose and fructose in sugarcane must for bioethanol production

Thermal degradation of sugars contained in sugarcane must (21.5 degrees Brix, pH 6.14) was evaluated at temperatures of 110, 120, 130 and 140C, using the thermal-death-time tube method, determining remaining sugars by high-pressure liquid chromatography. The study analyzed thermal degradation kinetics of both the total reducing sugars (TRS) and glucose and fructose individually. All curves of remaining sugars presented strong nonlinearity, with initial shoulder and final tail adjusted by an extended logistic model that was adapted for two species for TRS, and a simple logistic model for the monosaccharides. It was shown that rate constants are influenced by temperature according to two irreconcilable methods: the Arrhenius and the Bigelow methods. Obtained activation energies for fructose and glucose were quite coincident, 140.37 and 140.23 kJ/mol, respectively. Thermal resistance parameters were 21.59 and 21.61C, respectively. Comparison of the rate constants revealed that fructose degraded approximately 9-10 times faster than glucose.29546247

Heat resistance and the effects of continuous pasteurization on the inactivation of Byssochlamys fulva ascospores in clarified apple juice

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)To determine thermal resistance, the effect of pasteurization temperature variations (c. 2 degrees C) in a continuous system in the number of decimal reductions (n) of a Byssochlamys strain in clarified apple juice (CAJ). Thermal destruction kinetics of Byssochlamys fulva IOC 4518 in thermal death tubes were determined at 85 degrees, 90 degrees, 92 degrees and 95 degrees C by using Weibull distribution frequency model. Three processes with different heating and holding temperatures (A: 94 degrees, 92 degrees C; B: 95 degrees, 93 degrees C; C: 96 degrees, 94 degrees C, respectively) were performed in a continuous system. Process time was 30 s. delta (time of first decimal reduction) values were: 42.98, 8.10, 3.62 and 1.81 min. Variable n ranged from 0.16 to > 4.78 for process B (equivalent to industrial). Variable n (0.95-2.66 log CFU ml(-1)) were obtained in CAJ bottles processed under condition B, while process A resulted in total heat-resistant mould (HRM) survival and process C in total HRM destruction. This study demonstrates that small variations in temperature during the CAJ pasteurization could result in elimination or survival of HRM due to its nonlogarithmic behaviour. This was the first study to use Weibull frequency method to model inactivation of HRM in fruit juices. Temperature variations could culminate in the presence of HRM in pasteurized juices even when low counts (< 10 spores per 100 ml) were present in the raw materials.1071197209Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundo de Apoio ao EnsaioPesquisa e a Extensao (Faepex) [282/06, 129/07]Prodetab (Embrapa) [042-01/01]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Pesquisa e a Extensao (Faepex) [282/06, 129/07]Prodetab (Embrapa) [042-01/01

Modelling the lag time and growth rate of Aspergillus section Nigri IOC 4573 in mango nectar as a function of temperature and pH

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Aims: To assess the behaviour of Aspergillus section Nigri IOC 4573 in mango nectar as affected by temperature and pH. Methods and Results: A central composite design (22 + 2*2 + 3) was used to estimate the influence of temperature (17 center dot 2-22 center dot 8 degrees C) and pH (3 center dot 28-4 center dot 7) on A. section Nigri growth (lambda, lag time; mu, growth rate). Secondary models (polynomial and Arrhenius-Davey) describing the effects of temperature and pH on lambda and mu were constructed. A decrease in temperature from 22 center dot 8 degrees C to 17 center dot 2 degrees C resulted in an a 16-fold increase in lambda. The increase in temperature from 20 degrees C to 22 center dot 8 degrees C at pH = 4 center dot 0 led to a fourfold increase in mu. The polynomial model was the best in fitting the data and the pH (linear), temperature (linear and quadratic terms) significantly influenced lambda. For mu, there was a significant influence by the pH (linear), temperature and pH (quadratic terms). Conclusions: The storage of mango nectar at < 15 degrees C and reduced pH could completely inhibit the growth of A. section Nigri. Significance and Impact of the Study: This is the first study to show how storage temperature and seasonal variability (pH) between harvests may affect mould growth in mango nectar.109311051116PRODETAB-EMBRAPA (Brazilian Agricultural Research Corporation)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

EPIDEMIOLOGICAL AND MICROBIOLOGICAL STUDIES OF AN OUTBREAK OF FOODBORNE INTOXICATION

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Alicyclobacillus acidoterrestris in pasteurized exotic Brazilian fruit juices: Isolation, genotypic characterization and heat resistance

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In this study, the population of Alicyclobacillus spp. was estimated in pasteurized exotic Brazilian fruit juices using the most probable number (MPN) technique followed by biochemical tests. Pasteurized passion fruit (n = 57) and pineapple (n = 50) juices were taken directly from Brazilian manufacturers. While Alicyclobacillus spp. was isolated from passion fruit juice, the microorganism was not found in any pineapple juice samples. A higher incidence of Alicyclobacillus was observed in samples taken in June and July (dry months in Brazil) in comparison to the other months (March, April, May and August), and the highest Alicyclobacillus counts were recovered from these samples(>23 MNP/100 mL). Sixteen (n = 16) Alicyclobacillus strains were typed using the randomly amplified polymorphic DNA method (RAPD-PCR). RAPD-PCR revealed great genetic similarity between the passion fruit juice strains and Alicyclobacillus acidoterrestris DSM 2498. The heat resistance of three isolates was determined, and the mean D(95)degrees. (1.7 min) and z (7.6 degrees C) values in the passion fruit juice were not significantly different (p > 0.05) from those obtained for the DSM 2498 strain (D(95)degrees = 1.5 min and z = 7.1 degrees C). This is the first report on the isolation of A. acidoterrestris from exotic fruit juices such as passion fruit juice. It is worth pointing out the importance of applying good agricultural practices in the field and applying controls for the fruit selection and washing steps, as well as controlling the time/temperature conditions for pasteurization so as to reduce the incidence and chances of A. acidoterrestris spoilage in these juices. (C) 2010 Elsevier Ltd. All rights reserved.27810161022Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq