Modeling moisture migration in a multi-domain food system: Application to storage of a sandwich system

Delayed Quality Deterioration of Low-Moisture Cereal-Based Snack by Storing in an Active Filler-Embedded LDPE Zipper Bag

This study focused on controlling the vapor permeability of an active zipper bag and preserving the quality of cereal-based snacks during the storage period at home. The active zipper bag was prepared by extruding low-density polyethylene with active fillers obtained from natural mineral materials. The active zipper bag showed the same transparent appearance as the existing one but showed 21% lower water vapor capability. As a result, during a 20-day storage period, three types of grain-based snacks (biscuits, shortbread cookies, and puffed snacks) showed delayed increases in weight, moisture content, and moisture activity when stored in an active zipper bag. In addition, this also affected the texture of the biscuits and shortbread cookies, in which the area under the curve was reduced significantly after appearing at a peak during the hardness measurement. On the other hand, the decrease in the number of air cell fracture events in puffed snacks was remarkable. This result suggests that the inner microstructure is preserved better when stored in an active zipper bag. In conclusion, the active zipper bag showed poor water vapor permeability, suggesting that the prepared zipper bag can be developed as snack packaging.

Numerical Investigation of the Deformable Porous Media Treated by the Intermittent Microwave

A 2D axi-symmetric theoretical model of dielectric porous media in intermittent microwave (IMW) thermal process was developed, and the electromagnetic energy, multiphase transport, phase change, large deformation, and glass transition were taken into consideration. From the simulation results, the mass was mainly carried by the liquid water, and the heat was mainly carried by liquid water and solid. The diffusion was the dominant mechanism of the mass transport during the whole process, whereas for the heat transport, the convection dominated the heat transport near the surface areas during the heating stage. The von Mises stress reached local maxima at different locations at different stages, and all were lower than the fracture stress. A material treated by a longer intermittent cycle length with the same pulse ratio (PR) tended to trigger the phenomena of overheat and fracture due to the more intense fluctuation of moisture content, temperature, deformation, and von Mises stress. The model can be extended to simulate the intermittent radio frequency (IRF) process on the basis of which one can select a suitable energy source for a specific process.

Chemical and optical characterization of white efflorescences on dry fermented sausages under modified atmosphere packaging

BACKGROUND

Dry fermented sausages that are packed under modified atmosphere are often affected by the formation of white crystals on the surface. These so called efflorescences are rejected by consumers and lead to high financial losses for the meat processing industry. In this study, the distribution of efflorescence-causing components was investigated over the sausage profile during 8 weeks of storage under modified atmosphere at 4 °C. In addition, two visual methods (image and sensory analyses) were compared regarding the ability to quantify the efflorescence content.

RESULTS

The initial formation of efflorescences was observed after 2 weeks (7%). After 4 weeks of storage, 23.4% of the sausage surface was covered with efflorescences, and the amount of efflorescences did not change significantly by the end of storage. Furthermore, chemical analyses revealed that magnesium (increased by 98.1%), lactate (increased by 54.2%) and creatine (increased by 51.8%) are enriched on the sausage surface during storage.

CONCLUSION

Sensory and image analyses lead to comparable results (r = 0.992) and therefore both are suitable to quantify the amount of efflorescences. The moisture gradient in the interior of the sausages which is built upon drying is supposed to be the driving force for the movement of efflorescence-causing compounds. © 2017 Society of Chemical Industry.

Toward predictive food process models: A protocol for parameter estimation

Mathematical models, in particular, physics-based models, are essential tools to food product and process design, optimization and control. The success of mathematical models relies on their predictive capabilities. However, describing physical, chemical and biological changes in food processing requires the values of some, typically unknown, parameters. Therefore, parameter estimation from experimental data is critical to achieving desired model predictive properties. This work takes a new look into the parameter estimation (or identification) problem in food process modeling. First, we examine common pitfalls such as lack of identifiability and multimodality. Second, we present the theoretical background of a parameter identification protocol intended to deal with those challenges. And, to finish, we illustrate the performance of the proposed protocol with an example related to the thermal processing of packaged foods.