Kinetic modelling of vitamin C loss in frozen green vegetables under variable storage conditions.

Abstract A systematic kinetic study of l-ascorbic acid loss of four green vegetables was conducted in the temperature range of freezing storage. The temperature-dependence of vitamin C loss in the À3 to À20 C range was adequately modelled by the Arrhenius equation and activation energy ranged from 98 to 112 kJ/mol for the four frozen green vegetables. The developed models were validated in fluctuating time-temperature conditions, in order to establish their applicability in the real marketing path of the commercial products. Based on the models, the nutritional level can be estimated, at any point of the freezing chain, when the full time-temperature history is available. Comparison among different green vegetables showed that the type of plant tissue significantly affects the rate of vitamin C loss. Frozen spinach was found to be the most susceptible to vitamin C degradation, peas and green beans demonstrated a moderate retention, whereas okra exhibited a substantially lower loss rate.

A quality, energy and environmental assessment tool for the European cold chain

According to 5th Informatory Note on Refrigeration and Food published by the International Institute of Refrigeration, 20% of the global losses in perishable products was due to lack of refrigeration. It is expected that increased use of refrigeration to reduce these losses will help meet the increasing food demands of the growing world population. However, the use of refrigeration already accounts for about 15% of world’s electricity usage. In addition, the use of refrigeration significantly contributes to global warming via emission of CO2. In this paper, a software tool was developed to assess food quality and safety evolution, energy usage and CO2 emission of different refrigeration technologies along the European cold chain. A reference product was chosen for the main different food categories in the European cold chain. Software code to predict the products temperature using the room temperature as input, based on validated heat and mass transfer models, were written in Matlab (The Mathworks Inc., Natick, USA). Also, based on validated kinetic models for the different quality indicators of the reference products, a software code was written to calculate the quality and safety evolutions of the food product, using the predicted product temperature as input. Finally, software code to calculate the energy usage and Total Equivalent Warming Impact (TEWI) value of different refrigeration technologies was also written in Matlab. All three software codes were integrated, and a graphical user interface was developed. Using the graphical user interface, a user can tailor a cold chain scenario by adding different cold chain blocks. Each cold chain block has properties that can be modified. The tool can be used to compare different cold chains with respect to quality, safety, energy usage, and environmental impact

Towards sustainability in cold chains: Development of a quality, energy and environmental assessment tool (QEEAT)

Quantification of the impact of refrigeration technologies in terms of the quality of refrigerated food, energy usage, and environmental impact is essential to assess cold chain sustainability. In this paper, we present a software tool QEEAT (Quality, Energy and Environmental Assessment Tool) for evaluating refrigeration technologies. As a starting point, a reference product was chosen for the different main food categories in the European cold chain. Software code to predict the products temperature, based on validated heat and mass transfer models, were written in Matlab (The Mathworks Inc., Natick, USA). Also, based on validated kinetic models for the different quality indicators of the reference products, (including fruit, meat, fish, vegetables and dairy products) a software code was written to calculate the quality and safety evolutions of the food product, using the predicted product temperature as input. Finally, software code to calculate the energy usage and Total Equivalent Warming Impact (TEWI) value of different refrigeration technologies was also written in Matlab. All three software codes were integrated, and a graphical user interface was developed. Using the QEEAT, a user can tailor a cold chain scenario by adding cold chain blocks (different steps of a cold chain) and simulating the quality evolution, energy use and emission throughout the chain. Also, the user can modify properties of a cold chain block, by selecting different technologies, or changing set point values. Defaults are provided for input values, and are based on the current practice, and obtained by extensive literature studies and consultation with different experts of the cold chain. Furthermore, the user can build and simulate several chains simultaneously, allowing him/her to compare different chains with respect to quality, energy and emission

Kinetics of food deterioration and shelf-life prediction

Quality is an attribute of food, on which understandably a lot of consideration is focused. Food quality can be defined as the assemblage of properties which differentiate individual units and influence the degree of acceptability of the food by th

Applicability of an Arrhenius Model for the Combined Effect of Temperature and CO(2) Packaging on the Spoilage Microflora of Fish

The temperature behavior of the natural microflora on the Mediterranean fish red mullet (Mullus barbatus) was examined as a case study. The growth of the spoilage bacteria Pseudomonas spp., Shewanella putrefaciens, Brochothrix thermosphacta, and lactic acid bacteria was modeled as a function of temperature and the concentration of carbon dioxide in modified atmosphere packaging. Combined models were developed and comparatively assessed based on polynomial, Belehradek, and Arrhenius equations. The activation energy parameter of the Arrhenius model, E(A), was independent of the packaging atmosphere and ranged from 75 to 85 kJ/mol for the different bacteria, whereas the preexponential constant decreased exponentially with the packaging CO(2) concentration. We evaluated the applicability of the models developed by using experimental bacterial growth rates obtained from 42 independent experiments performed with three Mediterranean fish species and growth rates predicted from the models under the same temperature and packaging conditions. The accuracy factor and bias factor were used as statistical tools for evaluation, and the developed Arrhenius model and the Belehradek model were judged satisfactory overall