Modeling the effect of storage temperature on the respiration rate and texture of fresh cut pineapple

The effect of temperature on the respiration rate and texture of fresh cut pineapple was studied over the course of 10 days of storage. The thermal exchange between the pineapple trays and the cooling environment was simulated using the finite element method and tested at 6 °C. The temperatures on pineapple wedges differed between the cold point and points near the surface, indicating that the respiration rate may be affected in pineapple subjected to temperature abuse. The experimental respiration rates obtained were used to develop a model relating respiration to O₂ and CO₂ concentrations at different temperatures using the closed system method. The O₂ consumption and CO₂ production of pineapple wedges was accurately modeled using Michaelis–Menten kinetics. The texture degradation of pineapple wedges follows a zero-order kinetic reaction at different temperatures and the thermal dependence of the model’s parameters for both respiration rate and texture degradation was described by Arrhenius-type equations.     

Modelling the respiration rate of fresh-cut Annurca apples to develop modified atmosphere packaging

In this work, the effect of temperature, oxygen, red coloration process and post-harvest storage time on the respiration rate of fresh-cut Annurca apples was studied to properly develop modified atmosphere packaging. Our results showed that the red coloration process and the post-harvest storage time did not affect the respiration rate or the respiratory quotient of fresh-cut Annurca apples in the range of temperature studied (5–20 °C). A Michaelis–Menten-type equation, with the model constants described by means of an Arrhenius-type relationship, was used for predicting respiration rate on varying the temperature and O₂ concentration in the head space. The maximal respiration rate (mL kg h⁻¹) (RR_max) and the O₂% corresponding to     values estimated at the reference temperature (12.5 °C), i.e. the average of the experimental temperature ranges, were, respectively, 6.77 ± 0.1 mL kg⁻¹ h⁻¹ and 0.68 ± 0.07% v/v, and the activation energy of the aerobic respiration rate of fresh-cut Annurca apples was estimated at 51 ± 1 kJ mol⁻¹. The model works well to develop a modified atmosphere for fresh-cut Annurca apples.     

Ethylene production,respiration and gas exchange modelling in modified atmosphere packaging for banana fruits

A mathematical model was developed from experimental measurements to describe the evolution of the O₂, CO₂ and ethylene in a modified atmosphere packaging system for Cavendish bananas. The respiration and ethylene production in the fruits were experimentally obtained from a closed system method and then represented by Michaelis–Menten equations of enzyme kinetics. The gas transfer through the packaging was described by a Fick's diffusion equation, and the temperature dependence was represented based on the Arrhenius law. The model was validated by packaging the fruit in perforated bags of polypropylene and low density polyethylene at 12 °C for a period of 8 days. With the developed model it was possible to satisfactorily describe the experimental evolution of the gas content in the headspace of the packages, obtaining coefficients of determination (R²) of 0.93 for the O₂ levels, 0.90–0.91 for the CO₂ levels, and 0.89–0.93 for the ethylene levels.     

Modelling the respiration rate of minimally processed broccoli (Brassica rapa var. sylvestris) for modified atmosphere package design

In this work, the effect of temperature, oxygen and carbon dioxide on the respiration rate of minimally processed broccoli was studied to develop suitable modified atmosphere packaging. Respiration rate was measured at 3, 5, 7, 10, 15 and 20 °C under different gas compositions of O₂ and CO₂ (1%, 5%, 10%, 15% and 21% of O₂ with the balance N₂, a mixture of 10% and 20% of carbon dioxide with the balance air and a mixture at 3% of O₂ and 15% of CO₂ with the balance N₂). As expected, temperature was the most influential factor on respiration rate, for all atmospheres tested: increasing the temperature from 3 to 20 °C resulted, for air‐stored samples, in a 84% change in oxygen respiration rate, whereas at constant temperature, the respiration rate decreased by 35% with lowering the O₂ concentration from 21% to 1% and by 44% with increasing the CO₂ concentration from 0% to 20%. The Michaelis and Menten competitive model with maximum respiration rate varying against temperature with an Arrhenius equation accurately described the influence of gas composition and temperature on the respiration rate of minimally processed broccoli, and it was used to design a suitable package.     

Modelling the gas exchange rate in perforation-mediated modified atmosphere packaging: Effect of the external air movement and tube dimensions

Perforation-mediated modified atmosphere packages control the gas exchange rate and thus the internal atmosphere composition by judicious choice of dimensions of small tubes in perforations in an otherwise hermetic container. The aims of this work were (i) to study the effect of external turbulence on the gas exchange rate through small perforations, (ii) to develop a mathematical model to predict the effect of tube dimensions and hydrodynamic conditions on gas exchange coefficients, and (iii) validate the model developed during the storage of shredded carrots. Different hydrodynamic conditions in the controlled temperature room due to the storage temperature settings (5, 10 and 15 °C) and PVC tubes dimensions (diameter from 1.5 to 4.5 mm length from 2.0 to 6.0 mm) were tested. Results showed that, as expected, hydrodynamic conditions (induced turbulence) and tube diameter had a significantly positive effect on the mass transfer values, whereas tube length had a negative effect. The permeability ratio between CO₂ and O₂ was 0.83 ± 0.01 and did not show any pattern with the factors tested. The gas exchange coefficients increased with decreasing temperature, as the establishment of lower temperatures implied a frequent air movement. A mathematical model to estimate changes of gas composition over time as a function of tube dimensions and hydrodynamic conditions was developed and found to have good predictive abilities. The model was validated during the storage of shredded carrots at 5 °C in PM-MAP, showing a good agreement between the experimental and predicted gas exchange of O₂ and CO₂. The results obtained in this work showed that hydrodynamic conditions of the cold storage room affected the gas exchange rate in PM-MAP.     

Evaluation and predictive modeling of shelf life of minced beef stored in high-oxygen modified atmosphere packaging at different temperatures

The aims were: (1) to follow the freshness decay of minced beef stored in high-oxygen modified atmosphere packaging at different temperatures (4.3, 8.1 and 15.5 °C) by applying traditional methods (microbiological counts, color evaluation, thiobarbituric acid assay TBA, headspace gas composition) and e-nose; (2) to model the decay kinetics to obtain information about the maximum shelf life as function of storage conditions. The minced beef, packaged in modified atmosphere was supplied by a manufacturer at the beginning of its commercial life. The study demonstrated the ability of the traditional methods to describe the kinetics of freshness decay. The modeling of the experimental data and the comparison with microbiological or chemical thresholds allowed the setting, for each index, of a stability time above which the meat was no longer acceptable. The quality decay of meat was also evaluated by the headspace fingerprint of the same set of samples by means of a commercial e-nose. A clear discrimination between “fresh” and “old” samples was obtained using PCA and CA, determining at each temperature a specific range of stability time. The mean value of the stability times calculated for each index was 9 days at 4.3 °C (recommended storage temperature), 3–4 days at 8.1 °C (usual temperature in household refrigerators) and 2 days at 15.5 °C (abuse temperature). Resolution of the stability times allowed calculation of mean Q₁₀ values, i.e. the increase in rate for a 10 °C increase in temperature.The results show that the Q₁₀ values from the traditional methods (3.6–4.0 range) overlapped with those estimated with e-nose and color indexes (3.4 and 3.9, respectively).     

Respiration Rate of a Dry Coleslaw Mix Affected by Storage Temperature and Respiratory Gas Concentrations

The respiration rate of dry coleslaw mix at different concentrations of O₂ and CO₂ was determined in an open flow-through respirometer at 5°C. Product O₂ consumption rate fitted an enzyme kinetics model. V_m and K_m values of 22.72 mlkg^-1h^-1 and 1.083 %O₂, respectively were calculated. CO₂ had an inhibitory effect on respiration rate. The effect of CO₂ on respiration gave a good fit with an uncompetitive inhibition enzyme kinetics model (E = 5.11%). Product respiration rate increased with temperature by an Arrhenius type relationship. Activation energies for O₂ consumption and CO₂ evolution were 74.8 kJ/kg and 84.2 kJ/kg respectively. These results provide information essential for the design and optimization of modified atmosphere packs for this product.     

Effects of lactate and modified atmospheric packaging on premature browning in cooked ground beef patties

Our objectives were to determine the effects of lactate and modified atmosphere packaging on raw surface color, lipid oxidation, and internal cooked color of ground beef patties. Eight chubs (85% lean) were divided in half and each half was either assigned to the control (no lactate) or mixed with 2.5% lactate (w/w). Following treatment, patties were prepared and packaged in either vacuum, PVC (atmospheric oxygen level), high-oxygen (80% O₂ + 20% CO₂), or 0.4% CO (30% CO₂ + 69.6% N₂) and stored for 0, 2, or 4 days at 2 °C. After storage, raw surface color and lipid oxidation were measured and patties were cooked to either 66 °C or 71 °C. Lactate improved (p < 0.05) color stability of PVC, high-oxygen, and vacuum packaged raw patties, but had no effect (p > 0.05) on the a∗ values and visual color scores of patties in 0.4% CO. Lactate decreased (p < 0.05) lipid oxidation in all packaging atmospheres. Nevertheless, high-oxygen and PVC-packaged patties had more (p < 0.05) lipid oxidation than patties in CO and vacuum. Lactate had no effect (p > 0.05) on premature browning, whereas patties packaged in high-oxygen demonstrated premature browning. Conversely, cooked patties in 0.4% CO and vacuum were more red (p < 0.05) than both high-oxygen and PVC-packaged patties. Although lactate improved raw color stability, it did not minimize premature browning in cooked ground beef patties.     

The effect of harvest date on the responses of Discovery apples to modified atmosphere retail packaging

In order to study effects of physiological maturity on responses of Discovery apples to modified atmosphere (MA) retail packaging, samples of fruit were picked at 3–4 day intervals over a 3-week period spanning the development of the climacteric rise in respiration and the normal marketing season for the variety. The apples were packed in MA (301∼.ethylene vinyl acetate) or perforated control packs and held under simulated marketing conditions at 10 or 20°C. The degree of modification of the pack atmospheres and the effects of MA packaging on fruit ripening changes were influenced by harvest date and related to the respiration rate of fruit when packed. MA packs were effective in retarding softening and skin colour changes in immediately pre-climacteric and early climacteric fruit. There was little risk of taint development, except during 14-day simulated marketing periods at 20°C. Little beneficial effect of MA packaging was found in apples harvested 4 days before the onset of the climacteric; relatively little deterioration occurred in such fruit in perforated control packs. Beneficial effects of MA packaging on ripening changes and quality attributes were reduced, and taint risk enhanced, when the technique was used for late picked fruit with much higher rates of respiration. Possible causes for the observed relationship between the different stages of physiological maturity of Discovery apples and their responses to MA packaging are discussed.     

Characterization of vapor-induced and liquid-induced moisture migration through fractionated palm kernel (PKO) based multiphase systems

Moisture migration through PKO based films under vapor-induced and liquid-induced conditions were investigated through measurements of unsteady state diffusivity, steady state permeability, and characterization of structure. A model was developed to describe changes in diffusivity through fat-based films containing hydrophilic components. At water activity gradients of 0.80 and 0.90, there were no significant differences in diffusivity and permeability values of PKO based films containing sucrose under vapor-induced and liquid-induced conditions. Addition of sucrose decreased both diffusivity and permeability of the films at a water activity gradient of 0.80. However, at a water activity gradient of 0.90, addition of sucrose increased permeability. At a water activity gradient of 1.0, diffusivity and permeability were significantly higher in sucrose containing films at liquid-induced condition than at vapor-induced condition. Addition of sucrose at a water activity gradient of 1.0 significantly reduced diffusivity but increased permeability under both vapor-induced and liquid-induced conditions. There were no significant differences in diffusivity and permeability of the film containing lecithin or cellulose under liquid-induced and vapor-induced conditions at a water activity gradient of 1.0. Addition of lecithin or cellulose significantly reduced diffusivity but increased permeability.     

Modelling the evolution of oxidative browning during storage of white wines: effects of packaging and closures

Shelf life of products is a key parameter for any company at local and international level that wish to improve their competitiveness; thus, there is a need to search for methods that allow one to predict the shelf life of bottled wines. In this view, the progress of chemical oxidative reactions of six Italian white wines during storage (10 months after bottling), in different packaging, was monitored by means of selected oenological parameters. The optical density at 420 nm, an index of browning, showed a progressive increase that fitted the zero‐order kinetic rate. The onset of wine browning was further tested by means of accelerated ageing in controlled temperature conditions which results, modelled using the rate constants approach, showed an Arrhenius‐like dependence from temperature, allowing to estimate apparent activation energies of oxidative chemical browning (range: 46.8–88.3 kJ mol^?1). Kinetic and thermodynamic approach provided a useful tool to predict quality changes of white wines during storage with respect to packaging conditions.     

硅窗气调包装保鲜贮藏茶树菇呼吸特性与贮藏品质的研究

以乙醇作为厌氧呼吸的指标，评估气调包装贮藏茶树菇时厌氧呼吸产生的条件，探讨硅窗对茶树菇的呼吸特性与贮藏品质变化的影响。结果表明：与普通气调相比较，硅窗气调能明显改善茶树菇贮藏的气体环境。贮藏温度为3℃，硅窗面积0．9cm。以上和贮藏温度为7℃，硅窗面积1．2cm。以上，都能避免厌氧呼吸的发生，茶树菇有更好的贮藏品质。     

Protein and lipid oxidative stability of fresh ostrich M. Iliofibularis packaged under different modified atmospheric packaging conditions

This study investigated the aptness of modified atmospheric packaging (70:30, O₂:CO₂ (O_MAP); 70:30, N₂:CO₂ (N_MAP)) and traditional overwrap (control) for fresh ostrich steaks, stored at 4 ± 1 °C for 10 days. N_MAP showed the least oxidation, O_MAP the highest and the control moderate. Myoglobin (CIE a^∗) was gradually oxidised in all packaging atmospheres, but the O_MAP oxidised at the slowest rate, remaining significantly more bloomed from day 0 (17.86 ± 1.17) to 8 (9.78 ± 1.12). Free carbonyls were constant in all packaging environments. TBARS remained constant for the N_MAP (2.39 ± 0.21 mg MDA/kg meat) and the overwrap (3.06 ± 0.29 mg MDA/kg meat), but the O_MAP increased significantly (9.96 ± 1.02 mg MDA/kg meat) to day 10. The pH increased in the control but remained constant in the MAP treatments. The control also showed the greatest drip loss (>5%). The success of MAP application to ostrich will depend on the ability of the consumer to detect the by-products of lipid oxidation.     

Modelling heat-disinfestation of dried fruits on “biological model” larvae Ephestia kuehniella (Zeller)

The effects of heat treatment on the survival of isolated Ephestia kuehniella Zeller larvae were examined. Larvae were treated in a specific device at a temperature range of 46 to 70 °C. Statistical analysis of the data demonstrated that the thermal survival kinetics was best represented by a 2-parameter Weibull model above 50 °C. The mortality of larvae only occurs beyond a critical temperature of 41.6 °C ± 2.5 °C. A 2D axial-symmetric model of heat transfer (convection, microwave at 915 MHz) was developed for cocoa bean and date palm. It was combined with the survival rate of larvae (Weibull model) and some z-values (from literature) are used for calculating a “food quality index” degradation kinetics. The intensive heating/convection process may not be adaptable for food products at low water activity due to high surface product temperatures. The use of microwave heating for date fruits and conventional hot air treatments for cocoa beans is recommended.     

Modelling the effect of temperature and lipid content on anchovy (Engraulis anchoita) salting kinetics

The effect of initial lipid content and temperature on the salting behaviour of anchovy (Engraulis anchoita) was studied. For this purpose brining of anchovy with variable initial lipid content (2.69–7.76 g 100 g⁻¹) was performed at temperatures between 5 and 35 °C. The obtained results indicate that initial mass transfer rate increased with brining temperature. Moreover, mass transfer rate was inversely related to the initial lipid content. In order to explain the dependence of the mass transfer rate on these variables two novel mathematical models were proposed. It was determined that both, salt gain and water loss rate constants depend on initial lipid content, whereas temperature only affects constants for salt transfer. In addition, salt gain constants depend linearly with initial lipid content and inversely with brining temperature. On the other hand, water loss rate constant was a function of the initial lipid content, fitting to a quadratic equation.     

Modelling the respiration rate of guava (Psidium guajava L.) fruit using enzyme kinetics, chemical kinetics and artificial neural network

The respiration rate prediction of fresh produce is crucial for designing and operating postharvest storage systems. This paper constructs and evaluates respiration models of guava fruit by using not only the enzyme, chemical kinetics but also artificial neural network (ANN) with the experimental data obtained from 5, 10, 15, 20, 25 and 30 °C (for constructing) as well as 12 and 22 °C (for evaluating) by closed system method. All of the developed models showed good agreement with actual observations. As regards fidelity the ANN model with topologic structure of 3 × 9×1 trained by the Levenberg–Marquardt algorithm, evaluation results were such that the mean absolute percentage error (MAPE) and the two-tailed Pearson correlation coefficient (r) were 5.31 and 0.997 for 12 °C, 4.85 and 0.995 for 22 °C, had superiority over the two other models. The results indicate that the ANN approach is a more precise method, and can be used for predicting the respiration rate of guava fruit.     

Synergistic effect of tannic acid and modified atmospheric packaging on the prevention of lipid oxidation and quality losses of refrigerated striped catfish slices

Chemical, microbiological and sensorial changes of striped catfish (Pangasius hypophthalmus) slices treated without and with tannic acid (100 and 200 mg/kg) were determined during 15 days of storage at 4 °C in air and under modified atmospheric packaging (MAP, 60% N₂/35% CO₂/5% O₂). The slices consisted of 9.2 g lipid/100 g and the lipid contained 64.55% unsaturated fatty acids and 33.87% saturated fatty acids. During the storage, the sample treated with 200 mg/kg tannic acid and stored under MAP (M₂) had the lowest peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) with the coincidental lowest non-haem iron content, indicating the retarded lipid oxidation. Fourier transform infrared (FTIR) spectra indicated the formation of primary oxidation products and free fatty acids in M₂ sample after 15 days. Conversely, these compounds were found at lower contents in the control samples kept in air without tannic acid treatment (A₀), suggesting that the deterioration was more advanced. Myosin heavy chain of A₀ was degraded by 17.85% after 15 days of storage, whereas no change was noticeable in M_2, compared with the fresh sample (F). Based on microbiological acceptability limit (10⁷ cfu/g), the shelf-life of A₀ and M₂ was estimated to be 3 and 15 days, respectively. M₂ had the acceptable scores for all sensory attributes up to 15 days, while A₀ was acceptable when stored for 9 days. Therefore, tannic acid exhibited a synergistic effect with MAP on retarding lipid oxidation and microbial growth, thereby increasing the shelf-life of striped catfish slices during refrigerated storage.     

Water vapor and oxygen-barrier performance of corn–zein coated polypropylene films

A novel corn–zein coating structure on polypropylene (PP) films was developed to examine its feasibility as an alternative water vapor and oxygen-barrier for flexible packaging industry. The barrier properties of the resulting films were evaluated as affected by coating formulation (solvent, corn–zein, plasticizer concentration and plasticizer type). Corn–zein with different amounts (5% and 15%) was dissolved in 70% and 95% aqueous ethanol solution at 50 °C, respectively. Solutions of corn–zein plasticized by polyethylene glycol (PEG) and glycerol (GLY) with various levels (20% and 50%) were applied on corona-discharged-treated PP by using solvent-casting method. The significant improvements in water vapor and oxygen-barrier properties of uncoated PP films were obtained with corn–zein coating. Water vapor permeability (WVP) of the coated films decreased significantly with increasing corn–zein concentration. The application of plasticized corn–zein coating on PP films showed nearly more than three order of reduction in oxygen permeability (OP). The high water vapor and oxygen-barriers were obtained for films coated with coating formulation consisting of higher amounts of corn–zein plasticized by GLY. The statistical analysis defined the key parameters of coating formulation that had major effect on the final properties of coated PP films as corn–zein, plasticizer concentration, and plasticizer type.