Measurement and Modeling of Respiration Rate of Guava (CV. Baruipur) for Modified Atmosphere Packaging

Several experiments were conducted at different storage temperatures for generating respiration data using close system method for respiration. A respiration rate model, based on enzyme kinetics and the Arrhenius equation was proposed for predicting the respiration rates of Guava as a function of O₂ and CO₂ concentrations and storage temperature. Temperature was found to influence the model parameters. In this model, the dependence of respiration rate on O₂ and CO₂ was found to follow the uncompetitive inhibition. The enzyme kinetic model parameters, calculated from the respiration rate at different O₂ and CO₂ concentration were used to fit the Arrhenius equation against different storage temperature. The activation energy and respiration pre-exponential factor were used to predict the model parameters of enzyme kinetics at any storage temperature between 0–30°C. The developed models were tested for its validity at 12°C and it was found to be in good agreement (the mean relative deviation moduli between the predicted and experimental respiration rates were found to be 8.95% and 8.02% for O₂ consumption and CO₂ evolution, respectively) with the experimentally estimated respiration rates.     

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.     

Development and comparison of multivariate respiration models for fresh papaya (Carica papaya L.) based on regression method and artificial neural network

Respiration modelling is the fundamental of the packaging and storage of fresh fruit and vegetables. Previous model of respiration rate accounted for external forcing from temperature and modified atmosphere but did not attempt to predict internally generated natural variability such as maturity. We present two types of respiration models here that predict the respiration rate of fresh papaya in response to changes of temperature, CO₂/O₂ concentrations and maturity as well. These two models were separately developed using a quadratic polynomial with four parameters and fifteen coefficients and using an artificial neural network (ANN) model with 4-15-2 architecture trained by Levenberg–Marquardt algorithm, in which the maturity of papaya covers skin yellowing from 10 to 90% and the temperatures vary over 10–30 °C. Comparison between the two types of respiration models shows a predictive superiority of the ANN-based model over the regressive one, demonstrating that the use of ANN technique can provide a reliable and effective approach to describe papaya’s respiration rate as a function of multivariate influencing factors.     

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.     

Modeling Respiration Rate of Strawberry (cv. San Andreas) for Modified Atmosphere Packaging Design

A model for strawberry (Fragaria × ananassa cv. San Andreas) respiration rate was determined as a function of O₂ and CO₂ concentrations and temperature. Strawberries were enclosed in containers under different gaseous compositions (0–24% O₂ and 0–15% CO₂) and temperatures (10, 19, 23°C). Respiration rate was determined as O₂ consumption and CO₂ production. Respiration rate data was fitted to Michaelis-Menten models, with temperature dependence according to Arrhenius type equation. Non–linear regression was applied to calculate model parameters. No CO₂ inhibition was verified, so a simple Michaelis–Menten model was selected (R² = 0.91).     

Sensory and microbiological quality of shiitake mushrooms in modified‐atmosphere packages

The aim of the present work was to study the influence of modified‐atmosphere packaging on the microbiological and sensory quality of shiitake mushrooms (Lentinula edodes). Mushrooms were packaged under atmospheric air (passive modified atmosphere) and an initial gas mixture of 5% O₂ and 2.5% CO₂ (active modified atmosphere), in bags of two different films: low‐density polyethylene (PE) and polypropylene (PP). As control, mushrooms were packaged in macroperforated PP films. Bags were stored at 5 °C for 20 days. Package atmosphere composition, mushroom respiration rate, weight loss, microbiological counts and sensory quality were determined during storage. Risk assays were also performed. Under the studied conditions, shiitake mushroom deterioration was not due to microorganism growth, and therefore the shelf‐life of this product might be defined by changes in its sensory characteristics. Sensory analysis showed that mushrooms stored under modified atmosphere (active and passive) had a higher deterioration rate than those stored in PP macroperforated films, and lower sensory quality values during the entire storage time. These results suggest that mushroom deterioration was probably due to shiitake mushrooms' sensitivity to high CO₂ concentrations. Copyright © 2007 Society of Chemical Industry     

Evaluation of Models for Spinach Respiratory Metabolism Under Low Oxygen Atmospheres

Anaerobic respiration is a major problem that causes the deterioration of fresh produce packaged under low O₂ atmospheres. The problem becomes more severe and causes high losses in the packages handling at ambient conditions, especially in developing countries. In designing modified atmosphere packaging, the risk of anaerobic development greatly depends upon the accuracy of respiration rate prediction; therefore, the respiration rate model for a particular produce has to be identified. In this study, different atmospheric storage conditions in a closed system were realized to examine the adaptability of respiration rate models for spinach storage under low O₂ at an expected ambient temperature of 25 °C. Six models were applied and it was found that, for aerobic conditions, the respiration rate could be described with a constant respiratory quotient by three models, viz., (a) Michaelis–Menten model without inhibition, (b) Michaelis–Menten model with uncompetitive inhibition, and (c) Langmuir adsorption model, whereas three other models, viz. (d) Michaelis–Menten model with competitive inhibition, (e) Michaelis–Menten model with noncompetitive inhibition, and (f) Michaelis–Menten with mixed inhibition could not be fitted. Among the three successful models, the Michaelis–Menten with uncompetitive inhibition was found to be the most suitable model for practical applications in developing countries where cold-chain systems are lacking. This model can be applied for the prediction of gas composition and optimize the packages, particularly to ensure the aerobic respiration.     

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 respiration rate of soybean seeds (Glycine max (L.)) in hermetic storage

The dynamic of oxygen (O₂) and carbon dioxide (CO₂) concentration was characterized in soybean (Glycine max (L.)) samples hermetically stored in glass jars at 15, 25 and 35 °C and 13, 15 and 17% moisture content (m.c., wet base). Two correlations were used for smoothing gas concentration in time: linear and exponential. Then, the respiration rate at each temperature and m.c. combination was calculated as storage time progressed and oxygen was consumed and two predictive models for respiration were proposed: Model I (temperature and m.c. dependent) and Model II (temperature, m.c. and oxygen dependent). It was observed that respiration rate increased with storage m.c. and temperature. However, respiration rate was not mainly affected by O₂ until a critical concentration limit of about 2% was reached. Respiration rates were from 0.341 to 22.684 mg O₂/(kgDM d) and from 0.130 to 20.272 mg CO₂/(kgDM d) for a range of storage condition of 13–17% m.c. and 15–35 °C temperature. The respiration rate of soybean seeds obtained in this study resulted significantly lower than the rates reported in the literature for other grains at similar temperature and a_w (water activity) storage condition. For hermetic storage simulations in which O₂ concentration is not expected to drop below 2%, the simplest model (Model I) could be used, but if the O₂ concentration of the hermetic system is expected to be depleted, Model I would under estimate the time at which O₂ is consumed, and thus a model with O₂ dependency is recommended instead (Model II).     

APPLICATION of an ENZYME KINETICS BASED RESPIRATION MODEL to CLOSED SYSTEM EXPERIMENTS FOR FRESH PRODUCE

An approach was developed to use a respiration model, based on enzyme kinetics principle, along with the closed system method for generating respiration rates of fresh produce as a function of O₂ and CO₂ concentrations. to verify this approach, experiments were conducted to measure the respiration rates of cut broccoli contained in closed jars at 0, 7, 13 and 24C. the respiration model was found to fit the experimental data very well, and the model parameters were estimated using multiple linear regression analysis. Another experiment was also conducted with a permeable package containing cut broccoli at 13C, and the experimental respiration rates were found to compare well with those predicted using the model parameter values estimated above.     

Effects of packaging type, gas atmosphere and storage temperature on survival and growth of Listeria spp. in shredded dry coleslaw and its components

The survival and growth of Listeria populations inoculated on to dry coleslaw mix and its components were investigated, focusing on effects of storage temperatures and gas atmospheres within packaging films or storage chambers. There were few significant effects of packaging film at 3 °C, but at 8 °C the elevated CO₂/low O₂ atmospheres generated within orientated polypropylene (OPP) packages and used in controlled atmosphere chambers were inhibitory. Although two strains of Listeria monocytogenes had survival characteristics comparable with Listeria innocua, L. monocytogenes ATCC 19114 survived better at 3 °C and also in the elevated CO₂/low O₂ atmospheres within OPP at 8 °C. The effects of product components on the survival of L. innocua were linked to storage temperature. Shredded carrot reduced initial counts and at 8 °C inhibited survival of L. innocua in comparison with shredded cabbage.     

Assessment of Relationships between Sensory and Instrumental Quality of Controlled-atmosphere-stored 'Fuji' Apples by Multivariate Analysis

ABSTRACT: Physicochemical parameters, sensory attributes, and total aroma emission of ‘Fuji’ apples (Malus×domestica Borkh.) were studied in relation to storage conditions, storage duration, and shelf life period. Commercially ripe fruit were analyzed after 3, 5, and 7 mo of cold storage in normal atmosphere (AIR) (210 L/m³ O₂+ 0.3 L/m³ CO₂) or under 3 different controlled atmosphere (CA) treatments (10 L/m³ O₂+ 10 L/m³ CO₂, 20 L/m³ O₂+ 20 L/m³ CO₂, or 10 L/m³ O₂+ 30 L/m³ CO₂), after which apples were kept at 20 °C for 1, 5, and 10 d. Data were subjected to partial least square regression (PLSR) analysis. Physicochemical parameters were well preserved throughout storage, especially in CA‐stored apples; however, these apples showed lower total aroma emission. Sensory acceptability was also higher for CA‐stored fruit after 7 mo of storage, whereas no significant differences were found for shorter storage periods. Accordingly, greater scores in sensory firmness, sensory flavor, sensory acidity, and appearance were observed for fruit stored in 10 L/m³ O₂+ 10 L/m³ CO₂ after long storage. Two PLSR models were established, 1 for relating physicochemical parameters to overall acceptability, and another for assessing the correlation between sensory acidity and instrumentally measured titratable acidity. The 1st PLSR model indicated that soluble solids concentration, titratable acidity, flesh firmness, and background color of the shaded side have a positive influence on acceptability. The 2nd model indicated that sensory acidity also showed an excellent correlation to instrumentally measured titratable acidity.     

Impact of Mixtures of Different Fresh‐Cut Fruits on Respiration and Ethylene Production Rates

Packaging and storage of fresh‐cut fruits and vegetables are a challenging task, since fresh produce continue to respire and senesce after harvest and processing accelerates the physiological processes. The response on respiration and ethylene production rates of fresh produce to changes in O₂ and CO₂ concentrations and temperature has been extensively studied for whole fruits but literature is limited on processed and mixed fresh‐cut fruits. This study aimed to investigate the effects of mixing various proportions of fresh‐cut fruits (melon chunks, apple slices, and pineapples cubes) on respiration and ethylene production rates and to develop predictive models for modified atmosphere packaging. The experiment was designed according to a simplex lattice method and respiration and ethylene production rates were measured at 10 °C. Results showed that single component pineapple cubes, apple slices, and melon chunks, in this order, had significant constant coefficients (P = 0.05) and the greatest impact on respiration rate while the interactive binary and tertiary coefficients were insignificant. For ethylene production rates, single component apple slices, melon chunks, and pineapple cubes, and their 3‐component mixtures, in this order, had significant constant coefficients (P = 0.05) while binary coefficients were insignificant. Mathematical models were developed and validated; the cubical model was the best to describe the influence of proportion of fruit on respiration and ethylene production rates, however, considering simplicity the linear part of the model is recommended to quantify respiration and ethylene production rates of mixed fresh‐cut fruits.     

Oxygen and Carbon Dioxide Solubility and Diffusivity in Solid Food Matrices: A Review of Past and Current Knowledge

Oxygen and carbon dioxide solubility and diffusivity are 2 key parameters to understand gas transfer in food matrices. Knowledge of these parameters could help to predict gas concentration in modified atmosphere packaging and, consequently, to predict shelf?life of the product through the development of appropriate mathematical models. The aim of this review is to present the existing methodologies to quantify O₂ and CO₂ contents in food, especially in solid food matrices which is very challenging. There is a focus on how these methodologies could be used to determine gas transfers kinetics. Data of O₂/CO₂ solubilities and diffusivities in food are collected and compared with a specific emphasis on the food characteristics and factors impacting them. An analysis of the current state of knowledge in solid food matrices is carried out to tentatively build a general predictive model of the O₂ and CO₂ solubility and diffusivity extendable to any kind of food matrix.     

Model for Fresh Produce Respiration in Modified Atmospheres Based on Principles of Enzyme Kinetics

A respiration model, based on enzyme kinetics, was proposed for predicting respiration rates of fresh produce as a function of O₂ and CO₂ concentrations. In this model, the dependence of respiration on O₂ was assumed to follow a Michaelis-Menten type equation (r = V_m[O₂]/{K_m+ [O₂]}), and the effect of CO₂ on respiration to follow an uncompetitive inhibition model (r = V_m[O₂]/{Km + (1 + [CO₂]/ Ki) [O₂]}). The model predictions agreed well with published data for a variety of commodities and with experimental data for cut broccoli. Fresh produce respiration rates (O₂ consumption or CO₂ evolution) at various O₂ and CO₂ concentrations, as well as transient and equilibrium gas concentrations within permeable packages, could be accurately predicted with the model equations.     

Antioxidant properties and shelf‐life extension of fresh‐cut tomatoes stored at different temperatures

BACKGROUND: The feasibility of using modified atmosphere packaging (5 kPa O₂ + 5 kPa CO₂) to maintain the antioxidant properties of fresh‐cut tomatoes during shelf‐life was assessed through storage at different temperatures (5, 10, 15 and 20 °C). Health‐related compounds, antioxidant capacity, microbiological counts, physicochemical parameters and in‐package atmosphere of tomato slices were determined. RESULTS: Initial lycopene, vitamin C and phenolic contents and physicochemical parameters of tomato slices were well maintained for 14 days at 5 °C. Lycopene and total phenolic contents were enhanced over time in tomato slices stored at 15 and 20 °C. However, this increase in antioxidant compounds of fresh‐cut tomatoes during storage may be associated with excessive amounts of CO₂ (R² = 0.5679–0.7328) in the packages due to microbial growth. Although keeping tomato slices at temperatures above 10 °C increased their antioxidant content, the shelf‐life of the product was reduced by up 4 days. CONCLUSIONS: A storage temperature of 5 °C is appropriate for maintaining the microbiological shelf‐life of fresh‐cut tomatoes for up to 14 days and also allows the antioxidant properties of tomato slices to be retained over this period, thus reducing wounding stress and deteriorative changes. Copyright © 2008 Society of Chemical Industry     

Effect of initial oxygen concentration and film oxygen transmission rate on the quality of fresh‐cut romaine lettuce

Modified atmosphere packaging (MAP) is widely used to maintain the quality of fresh‐cut produce by matching the oxygen transmission rate (OTR) of the packaging film to the respiration rate of the packaged product. The effect of the interaction between film OTR and the initial headspace O₂ on quality of fresh‐cut vegetables has not previously been reported. Romaine lettuce leaves were sliced, washed, dried and packaged with film OTRs of 8.0 and 16.6 pmol s^?1 m^?2 Pa^?1, and with initial headspace O₂ of 0, 1, 2.5, 10 and 21 kPa. Packages were hermetically sealed and stored at 5 °C for up to 14 days. For samples packaged in 16.6 OTR film, increasing the initial headspace O₂ concentration delayed O₂ depletion within the packages, hastened the onset and increased the intensity of discoloration, and inhibited the development of CO₂ injury, acetaldehyde and ethanol accumulation, off‐odors and electrolyte leakage. With 8.0 OTR‐packaged lettuce pieces, ≤1 kPa initial headspace O₂ treatments induced an essentially anaerobic environment within the packages and increased acetaldehyde and ethanol accumulation and off‐odor development. Increasing the initial O₂ concentration above 1 kPa in 8.0 OTR packages transiently increased O₂ concentrations and reduced fermentative volatile production, off‐odors, electrolyte leakage and CO₂ injury. Regardless of initial headspace O₂ concentration, all 16.6 OTR‐packaged samples had severe discoloration after 14 days of storage. Quality was better maintained in 8.0 OTR‐packaged lettuce pieces as the initial headspace O₂ concentration was increased. A 21 kPa initial O₂ treatment of 8.0 OTR‐packaged lettuce maintained good quality throughout storage and had the best overall quality score. Copyright © 2005 Society of Chemical Industry     

Shelf‐Life Extension of Chill‐Stored Beef Longissimus Steaks Packaged under Modified Atmospheres with 50% O2 and 40% CO2

This study was conducted to compare the shelf‐life of beef steaks stored in different packaging conditions: overwrapped (OW) packaging and 2 modified atmosphere packaging systems (MAP): 80% O₂ MAP (80% O₂/20% CO₂) and 50% O₂ MAP (50% O₂/40% CO₂/10% N₂). Steaks were stored at 2 °C for 20 d. Headspace gas composition, microbial counts, color stability, pH, purge loss, and lipid oxidation were monitored. Among the packaging types, 50% O₂ MAP was superior to OW packaging and 80% O₂ MAP in delaying bacterial growth and extending shelf‐life to 20 d. 50% O₂ MAP also gave steaks an acceptable color during storage. No significant differences were observed in color stability of steaks packaged in both 50% O₂ MAP and 80% O₂ MAP. This study reveals 50% O₂ MAP is a realistic alternative to preserve beef steaks efficiently.     

Modelling the effect of temperature on respiration rate of fresh cut papaya (Carica papaya L.) fruits

A respiration rate (RR) model based on Peleg’s equation was developed for predicting RRs of fresh cut papaya. Respiration data for fresh cut papaya at 3/4 maturity were generated at temperatures 5, 10, 15, 20, 25 and 30°C using a closed system. RRs was found to be significantly influenced by storage temperature and increased from 0.021 to 0.289 mL[O₂]/kg·h and 0.063 to 0.393 mL[CO₂]/kg·h as a function of O₂ and CO₂ gas concentrations, respectively. Peleg’s constant K ₁ and K ₂ were obtained from linear regression analysis using GraphPad Prism 5.0 software and regression coefficients have good fit with values close to unity. The model was verified to assess the capability of its predictability of the RRs over the temperatures. There was good agreement with the experimentally estimated RRs. Information derived from the model can contribute in the design of successful modified atmospheric systems for storage of fresh cut papaya.