Pilar Rodriguez de Massaguer

Review: Microbiological quality and safety of fruit juices--past, present and future perspectives.

In this review paper, several aspects of fruit juice microbiology, from past to future perspectives, are considered. An overview of the most relevant outbreaks involving foodborne pathogens and spoilage microorganisms associated with fruit juices is provided. One of the sections provides data on the sources of fruit juice contamination, followed by perspectives on preservation methods. Furthermore, considerations on the role of international guidelines about exotic fruit juices in respect to public health, and of the microbiological status of fruit juices used as food/beverage ingredients are discussed. Issues and challenges highlight how the microbiology of fruit juices has evolved over the years, when aspects of stability or microbiological safety are under consideration.In this review paper, several aspects of fruit juice microbiology, from past to future perspectives, are considered. An overview of the most relevant outbreaks involving foodborne pathogens and spoilage microorganisms associated with fruit juices is provided. One of the sections provides data on the sources of fruit juice contamination, followed by perspectives on preservation methods. Furthermore, considerations on the role of international guidelines about exotic fruit juices in respect to public health, and of the microbiological status of fruit juices used as food/beverage ingredients are discussed. Issues and challenges highlight how the microbiology of fruit juices has evolved over the years, when aspects of stability or microbiological safety are under consideration.

Quality of Mango Nectar Processed by High‐Pressure Homogenization with Optimized Heat Treatment

UNLABELLED This work aimed to evaluate the effect of high-pressure homogenization (HPH) with heat shock on Aspergillus niger, vitamin C, and color of mango nectar. The nectar was processed at 200 MPa followed by heat shock, which was optimized by response surface methodology by using mango nectar ratio (45 to 70), heat time (10 to 20), and temperature (60 to 85 °C) as variables. The color of mango nectar and vitamin C retention were evaluated at the optimized treatments, that is, 200 MPa + 61.5 °C/20 min or 73.5 °C/10 min. The mathematical model indicates that heat shock time and temperature showed a positive effect in the mould inactivation, whereas increasing ratio resulted in a protective effect on A. niger. The optimized treatments did not increase the retention of vitamin C, but had positive effect for the nectar color, in particular for samples treated at 200 MPa + 61.5 °C/20 min. PRACTICAL APPLICATION The results obtained in this study show that the conidia can be inactivated by applying HPH with heat shock, particularly to apply HPH as an option to pasteurize fruit nectar for industries.

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 ((o)Brix; 11 to 19 (o)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 (R2) 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 R2 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.

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

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°) (1.7 min) and z (7.6 °C) values in the passion fruit juice were not significantly different (p > 0.05) from those obtained for the DSM 2498 strain (D(95°) = 1.5 min and z = 7.1 °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.

Microbial modeling of thermal resistance of Alicyclobacillus acidoterrestris CRA7152 spores in concentrated orange juice with nisin addition

Estudou-se o efeito da nisina na inativacao termica dos esporos de Alicyclobacillus acidoterrestris CRA 7152 em suco de laranja concentrado (64 oBrix). Foram avaliadas as concentracoes de 0, 50, 75 e 100 UI de nisina/ml de suco nas temperaturas de 92, 95, 98 e 102 oC. Foi utilizado o modelo polinomial quadratico para analisar os efeitos dos fatores e suas interacoes. A contagem dos esporos sobreviventes foi feita atraves de plaqueamento em meio K (pH = 3,7). De acordo com os resultados obtidos encontrouse um valor de D sem adicao de nisina de 25,5; 12,9; 6,1 e 2,3 min para as temperaturas de 92, 95, 98 e 102 oC respectivamente. Quando a nisina foi adicionada ao suco observouse uma queda na resistencia termica em funcao do aumento da concentracao de nisina para os mesmos valores de temperatura. Ao utilizar as concentracoes de 30, 50, 75 e 150 IU/ml a 95 oC, o valor de D obtido foi de 12,34; 11,38; 10,49; 9,49; e 9,42 min respectivamente demonstrando que a adicao de nisina provoca um decrescimo de ate 27 % no valor de D. O modelo polinomial de segunda ordem ajustado com r2 = 0,995 mostrou que a resistencia do microorganismo foi afetada pela temperatura seguida da concentracao de nisina. A adicao de nisina e, portanto, uma alternativa para reduzir o rigor do tratamento termico em A. acidoterrestris CRA 7152.The nisin effect on thermal death of Alicyclobacillus acidoterrestris CRA 7152 spores in concentrated orange juice (64oBrix) was studied. Concentrations of 0, 50, 75 and 100 IU of nisin/ml juice, at temperatures of 92, 95, 98 and 102oC were evaluated. The quadratic polynomial model was used to analyze the effects of the factors and their interaction. Verification of surviving spores was carried out through plating in K medium (pH 3.7). The results showed that the D values without nisin addition were 25.5, 12.9, 6.1 and 2.3 min for 92, 95, 98 and 102oC respectively. With addition of nisin into the juice there was a drop of heat resistance as the concentration was increased at a same temperature. With 30, 50, 75, 100 and 150 IU/ml at 95oC, the D values were 12.34, 11.38, 10.49, 9.49 and 9.42 min respectively, showing that a decrease in the D value up to 27% can be obtained. The second order polynomial model established with r2 = 0.995 showed that the microorganism resistance was affected by the action of temperature followed by the nisin concentration. Nisin therefore is an alternative for reducing the rigor of the A. acidoterrestris CRA 7152 thermal treatment.

Use of a logistic model to assess spoilage by Byssochlamys fulva in clarified apple juice

The percentage P (%) of spoiled bottles (n=40) of clarified apple juice due to Byssochlamys fulva, was modeled by using a logistic model: P = P(max)/1 + exp (k(tau-t)) where P(max) (%) the maximum percentage of spoiled bottles, k (h(-1)) a slope parameter and tau (h) the time for P=P(max)/2. Bottles of pasteurized apple juice were inoculated with B. fulva IOC 4518 ascospores for low and high initial loads, 4.8+/-2.3 ascospores/100mL and 19.3+/-4.6 ascospores/100mL respectively and incubated at 21 degrees C and 30 degrees C. P(max) was not significantly different from 100% except for a low initial load at 21 degrees C. Model parameters were estimated with a good accuracy, RMSE in the range 3.89-7.50. Then the model was used to determine the time for 10% bottles spoiled, t(10%). This time was greater at low initial loads, 57.4 and 104 h at 30 and 21 degrees C respectively, than at high initial loads 23.9 and 75.1h at 30 and 21 degrees C respectively. This study demonstrated that even at a very low initial contamination, clarified apple juice can be easily spoiled by B. fulva highlighting the importance of controlling critical control steps of fruit juice processing (i.e., fruit washing, juice filtration and pasteurization).

Ocorrência de fungos filamentosos termo-resistentes em polpa de tomate envasada assepticamente

This work aimed at determining the occurrence of heat resistant molds during the aseptic processing of tomato pulp (8° BRIX). During tomato harvest, 9 lots were sampled (3 at the beginning, 3 at the apex and 3 at the end of harvest) and other 5 lots were sampled between harvest. For each lot, the enumeration of heat resistant molds was carried out in samples collected during the aseptic process. The mean count of heat resistant molds was relatively low, ranging from <1 to 8CFU/100mL of sample. The higher counts were observed in the raw material and the pre-wash and transportation water. Fifty strains of heat resistant molds detected in the enumeration procedure were isolated, codified and stocked. One-month-old spores of each isolate were submitted to different heat shocks to select the most heat resistant mold. The most heat resistant isolated strain (survived 100° C/25 minutes) was identified as Neosartorya fischeri.

Isolamento e seleção de fungos filamentosos termorresistentes em etapas do processo produtivo de néctar de maçã

Heat resistant molds are able to survive the pasteurization process applied to apple products. This study aimed at detecting and identifying heat resistant molds during the processing of apple nectar (pH 3.4; 11.6 °Brix) in order to select the most heat resistant mold. The isolation was carried out after heat shock at 70 °C, during 2 hours, and incubation at 30 °C, in PDA (3% agar), where rose bengal was added. The identification of macro and microscopic structures was carried out after incubation in three different media (G25N, CYA, MEA) and temperatures. Different heat shocks, from 80 °C/20 minutes to 97 °C/15 minutes, were applied to select the most heat resistant mold. Eleven strains were selected, of which five were heat-resistant: three strains were isolated from apple and concentrated apple juice and were identified as Neosartorya fischeri ; one strain, isolated from apple, was identified as Byssochlamys fulva and one strain, isolated from the product after the first pasteurization, was identified as Eupenicillium sp. The most heat-resistant strains belong to N. fischeri and B. fulva, which were able to survive at 95 °C/20 minutes. Among the six remaining, one was identified as Aspergillus sp., however, none of them was heat resistant.

Growth of Byssochlamys nivea in pineapple juice under the effect of water activity and ascospore age

The study of thermal resistant mould, including Byssochlamys nivea, is of extreme importance since it has been associated with fruit and fruit products. The aim of this work is to analyze the influence of water activity (aw) and ascospore age (I) on the growth of Byssochlamys nivea in pineapple juice. Mold growth was carried out under different conditions of water activity (aw) (0.99, 0.96, 0.95, 0.93, 0.90) and ascospore age (I) (30, 51, 60, 69, 90 days). Growth parameters as length of adaptation phase (λ), maximum specific growth rate (µmax) and maximum diameter reached by the colony (A) were obtained through the fit of the Modified Gompertz model to experimental data (measuring radial colony diameter). Statistica 6.0 was used for statistical analyses (significance level α = 0.05). The results obtained clearly showed that water activity is statistically significant and that it influences all growth parameters, while ascospore age does not have any statistically significant influence on growth parameters. Also, these data showed that by increasing aw from 0.90 to 0.99, the λ value substantially decreased, while µmax and A values rose. The data contributed for the understanding of the behavior of B. nivea in pineapple juice. Therefore, it provided mathematical models that can well predict growth parameters, also helping on microbiological control and products’ shelf life determination.

Metodologia para limpeza no local em equipamento de alta pressão dinâmica

Summary Cleaning-in-place (CIP) is an important procedure for the correct cleaning and sanitization of equipment, thus avoiding contamination amongst batches and the formation of biofilms. The purpose of this research was to determine CIP methodology for dynamic high pressure equipment contaminated with Aspergillus niger conidia. In vitro tests were carried out with aqueous suspensions of conidia to determine the minimum inhibitory concentration (MIC), and sporicidal tests of the surface to determine the efficiency of the alkaline detergent and sanitation agent (based on peracetic acid) against A. niger conidia. The efficiency of the peracetic acid was tested at concentrations of 0.0025 to 0.2% (v/v) for 20 and 30 min contact time in the in vitro MIC trials,, and at 0.01 to 0.03% (v/v) for 30 min in the sporicidal trials. The detergent was tested at concentrations of 1.5 to 2.5% (v/v) for 30 and 40 min in both trials. The pilot test was carried out in an ultra-high pressure homogenizer after treatment with mango nectar that had been previously contaminated with 10