Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
Mais filtros











Base de dados
Intervalo de ano de publicação
1.
Foods ; 11(15)2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35954012

RESUMO

The study investigated the effect of active modified atmosphere packaging (20% CO2-60% N2-20% O2) with CO2 emitters (MAP-PAD) and conventional MAP (MAP) on the quality and shelf-life of gilthead seabream fillets during chill storage, while the most appropriate enzymatic Time Temperature Integrators (TTI) were selected for monitoring their shelf-life at isothermal and variable temperature storage conditions (Teff = 4.8 °C). The concentration of CO2 and O2 in the headspace of the package, volatile compounds and of the microbial population were monitored during storage. The kinetic parameters for bacterial growth were estimated at 0-10 °C using the Baranyi growth model. The MAP-PAD samples presented significantly lower microbial growth rates and longer lag phases compared to the MAP samples, leading to significant shelf-life extension: 2 days of extension at 2.5 °C and 5 °C, while 50% extension at variable conditions (Teff = 4.8 °C). CO2 emitters in the package improved the chemical freshness (K-values) and volatile compounds (characterizing freshness). The responses of different enzymatic TTI were modeled as the function of enzyme concentration, temperature and storage time. The activation energy (Ea) ranged from 97 to 148 kJ mol-1, allowing the selection of appropriate TTIs for the shelf-life monitoring of each fish product: LP-150U for the MAP and M-25U for the MAP-PAD samples. The validation experiment at Teff = 4.8 °C confirmed the applicability of Arrhenius-type models, as well as the use of TTIs as effective chill chain management tools during distribution and storage.

2.
Food Microbiol ; 63: 72-83, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28040184

RESUMO

This study examined the effect of osmotic dehydration of Kalamata natural black olives as pre-fermentation treatment in combination with partial substitution of NaCl by monosodium glutamate (MSG) on the fermentation profile of olives. Osmotic dehydration was undertaken by immersing the olives in 70% (w/w) glucose syrup overnight at room temperature. Further on, three different mixtures of NaCl and MSG with/without prior osmotic dehydration of olives were investigated, namely (i) 6.65% NaCl - 0.35% MSG (5% substitution), (ii) 6.30% NaCl - 0.70% MSG (10% substitution), (iii) 5.95% NaCl - 1.05% MSG (15% substitution), and (iv) 7% NaCl without osmotic dehydration (control treatment). Changes in the microbial association (lactic acid bacteria [LAB], yeasts, Enterobacteriaceae), pH, titratable acidity, organic acids, sugars, and volatile compounds in the brine were analyzed for a period of 4 months. The final product was subjected to sensory analysis and the content of MSG in olives was determined. Results demonstrated that osmotic dehydration of olives prior to brining led to vigorous lactic acid processes as indicated by the obtained values of pH (3.7-4.1) and acidity (0.7-0.8%) regardless of the amount of MSG used. However, in non-osmotically dehydrated olives, the highest substitution level of MSG resulted in a final pH (4.5) that was beyond specification for this type of olives. MSG was degraded in the brines being almost completely converted to γ-aminobutyric acid (GABA) at the end of fermentation. Finally, the sensory assessment of fermented olives with/without osmotic dehydration and at all levels of MSG did not show any deviation compared to the control treatment.


Assuntos
Dessecação , Fermentação , Olea , Cloreto de Sódio/farmacologia , Glutamato de Sódio/farmacologia , Contagem de Colônia Microbiana , Enterobacteriaceae/fisiologia , Microbiologia de Alimentos/métodos , Conservação de Alimentos/métodos , Glucose/metabolismo , Glucose/farmacologia , Concentração de Íons de Hidrogênio , Lactobacillaceae/fisiologia , Olea/química , Olea/efeitos dos fármacos , Olea/microbiologia , Osmose , Sais , Cloreto de Sódio/metabolismo , Glutamato de Sódio/metabolismo , Paladar , Leveduras/fisiologia
3.
Int J Food Microbiol ; 240: 131-140, 2017 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-27745710

RESUMO

The aim of the study was to develop and test the applicability of predictive models for shelf-life estimation of ready-to-eat (RTE) fresh cut salads in realistic distribution temperature conditions in the food supply chain. A systematic kinetic study of quality loss of RTE mixed salad (lollo rosso lettuce-40%, lollo verde lettuce-45%, rocket-15%) packed under modified atmospheres (3% O2, 10% CO2, 87% N2) was conducted. Microbial population (total viable count, Pseudomonas spp., lactic acid bacteria), vitamin C, colour and texture were the measured quality parameters. Kinetic models for these indices were developed to determine the quality loss and calculate product remaining shelf-life (SLR). Storage experiments were conducted at isothermal (2.5-15°C) and non-isothermal temperature conditions (Teff=7.8°C defined as the constant temperature that results in the same quality value as the variable temperature distribution) for validation purposes. Pseudomonas dominated spoilage, followed by browning and chemical changes. The end of shelf-life correlated with a Pseudomonas spp. level of 8 log(cfu/g), and 20% loss of the initial vitamin C content. The effect of temperature on these quality parameters was expressed by the Arrhenius equation; activation energy (Ea) value was 69.1 and 122.6kJ/mol for Pseudomonas spp. growth and vitamin C loss rates, respectively. Shelf-life prediction models were also validated in real cold chain conditions (including the stages of transport to and storage at retail distribution center, transport to and display at 7 retail stores, transport to and storage in domestic refrigerators). The quality level and SLR estimated after 2-3days of domestic storage (time of consumption) ranged between 1 and 8days at 4°C and was predicted within satisfactory statistical error by the kinetic models. Teff in the cold chain ranged between 3.7 and 8.3°C. Using the validated models, SLR of RTE fresh cut salad can be estimated at any point of the cold chain if the temperature history is known. Shelf-life models of validated applicability can serve as an effective tool for shelf-life assessment and the development of new products in the fresh produce food sector.


Assuntos
Conservação de Alimentos/métodos , Armazenamento de Alimentos/métodos , Lactobacillaceae/crescimento & desenvolvimento , Lactuca/microbiologia , Pseudomonas/crescimento & desenvolvimento , Refrigeração , Verduras/microbiologia , Temperatura Baixa , Contagem de Colônia Microbiana , Microbiologia de Alimentos/métodos , Cinética , Modelos Biológicos
4.
J Food Sci ; 75(6): E379-86, 2010 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-20722923

RESUMO

The potential use of Thermomyces lanuginosus xylanase to develop a pressure-temperature-time integrator (PTTI) for high pressure processing was investigated. The combined effect of pressure and temperature on the inactivation of xylanase was studied in the pressure range of 100 to 600 MPa and temperature range of 50 to 70 degrees C. A synergistic effect of pressure and temperature was observed. Xylanase inactivation at the studied processing conditions followed first-order kinetics and was found to be very sensitive to changes in pressure and temperature. The values of activation energy and activation volume were estimated as 92.8 kJ/mol and -23.3 mL/mol at a reference pressure of 450 MPa and a reference temperature of 60 degrees C, respectively. A mathematical model of xylanase inactivation, having as variables time, pressure, and temperature allows the calculation of remaining enzyme activity at any combination of processing conditions within the studied domain. Practical Application: To ensure the optimization and control of high pressure processing, evaluation of the process impact on both safety and quality attributes of foods is essential. Enzymes can serve as effective tools in evaluating the impact of high pressure processes of foods.


Assuntos
Ascomicetos/enzimologia , Desinfecção/métodos , Endo-1,4-beta-Xilanases/metabolismo , Conservação de Alimentos , Tecnologia de Alimentos/métodos , Proteínas Fúngicas/metabolismo , Ascomicetos/metabolismo , Bebidas/microbiologia , Simulação por Computador , Endo-1,4-beta-Xilanases/biossíntese , Manipulação de Alimentos , Microbiologia de Alimentos , Proteínas Fúngicas/biossíntese , Temperatura Alta , Pressão Hidrostática , Cinética , Modelos Teóricos
5.
Int J Food Microbiol ; 128(1): 108-15, 2008 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-18783843

RESUMO

The objective of the study was to establish a validated kinetic model for growth of spoilage bacteria on vacuum packed tuna slices in the temperature range of 0 to 15 degrees C and to evaluate the applicability of the TTI (Time Temperature Integrators) based SMAS (Safety Monitoring and Assurance System) system to improve tuna product quality at the time of consumption in comparison to the conventional First In First Out (FIFO) approach. The overall measurements of total flora and lactic acid bacteria (LAB) on the tuna samples used in a laboratory simulated field test were in close agreement with the predictions of the developed kinetic model. The spoilage profile of the TTI bearing products, handled with SMAS, was improved. Three out of the thirty products that were handled randomly, according to the FIFO approach, were already spoiled at the time of consumption (logN(LAB)>6.5) compared to no spoiled products when handled with the SMAS approach.


Assuntos
Contaminação de Alimentos/análise , Embalagem de Alimentos/métodos , Conservação de Alimentos/métodos , Modelos Biológicos , Alimentos Marinhos/normas , Atum/microbiologia , Animais , Temperatura Baixa , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Contaminação de Alimentos/prevenção & controle , Microbiologia de Alimentos , Conservação de Alimentos/normas , Humanos , Cinética , Alimentos Marinhos/microbiologia , Sensibilidade e Especificidade , Fatores de Tempo , Vácuo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA