Journal of Food Engineering最新文献

Carbon dioxide (CO₂) is the most common gas used in modified atmosphere packaging (MAP) to protect packaged foods from spoilage and pathogenic microorganisms and thus extend the shelf life of food products. Non-destructive measurement of CO₂ concentration of the packaging headspace is of great interest as it could be used at various stages of the value chain, from outgoing goods inspection to storage tests and possible monitoring of the modified atmosphere at retail. Therefore, the aim of this work was to develop a measuring device operating non-destructively on closed MAP trays. Absorption measurement in the mid-infrared range at four different wavelengths proved to be a suitable principle for determining the CO₂ gas concentration in a closed packaging system: 4.26 μm (2347 cm⁻¹) and 4.27 μm (2342 cm⁻¹) in the range of the antisymmetric stretching vibration, as well as 4.45 μm (2247 cm⁻¹) at the edge of the antisymmetric stretching vibration, and 3.95 μm (2532 cm⁻¹) as a reference measurement outside the absorption band with a thermal infrared source. Measurement principle and setup - the measurement in the absorbing and non-absorbing range and the guiding of the thermal infrared (IR) emitter at a 45° angle through the corner of the tray - allows a measurement largely independent of tray shape, height, and packaged product. The measurement can also be used for pigmented and printed trays - except for carbon black pigments. Optical impairments of the packaging and labeled areas of the lidding film appeared to have the greatest influence on the measurement accuracy. The applicability of the measurement system was evaluated and successfully demonstrated using commercially available food packaging from a local supermarket by comparing the CO₂ gas concentrations yielded with those obtained using a destructive measurement device.

This study examined the mechanical glass transition and dynamical transition of bacteria (Cronobacter sakazakii)-solute (glycerol and glucose) systems. From the effect of water activity (a_w) on the mechanical relaxation, the a_w at which mechanical glass transition occurs at 25 °C (a typical ambient temperature) was determined as 0.225 for the glycerol-added sample and 0.540 for the glucose-added sample. These values were lower than that (0.667) reported previously for non-added sample. The effect of temperature on the mean square displacement of atoms within the samples was investigated by incoherent elastic neutron scattering. The a_w at which dynamical transition occurs at 25 °C was determined as 0.156 for the glycerol-added sample and 0.475 for the glucose-added sample. These values were lower than that (0.675) reported previously for non-added sample. According to the Couchman-Karasz model, the T_g for the bacteria plasticized by the additive and that for the bulk additive were obtained.

In this study, we constructed a thermal insulation interface layer for O/W emulsion using composite nanoparticles formed through the aggregation of CaCO₃ particles, which was mediated by sodium casein (SC) and chitosan oligosaccharide (CHO). As a representative of hydrophilic thermo-sensitive active ingredients, the (−)-epigallocatechin gallate (EGCG) was dispersed in a blended oil comprising peppermint essential oil (PEO) and sunflower seed oil (SO). The retention rate of EGCG in the emulsion, which had a thermal insulation protective layer, increased by 34.37% after heating, compared to the control emulsion. Furthermore, our research findings indicate that the thermal degradation process of EGCG in emulsified oil droplets involves initial isomerization into (−)-gallocatechin gallate (GCG), followed by subsequent degradation. Notably, the presence of the thermal insulation interface layer effectively suppresses the thermal degradation of GCG. This can be primarily attributed to the numerous mesopores in SC&CHO&CaCO₃ particles and low thermal diffusivity of the thermal insulation interface layer. This study provides a reliable solution for the stable encapsulation of thermo-sensitive active ingredients in emulsified oil droplets of O/W emulsion through the design of a thermal insulation interface layer, thus effectively improving their stability.

The objective of this work was to quantify the effect of atmospheric pressure changes on gas transmission through microperforations, in order to understand the role of fluctuations in the atmospheric pressure on the headspace composition of microperforated modified atmosphere packages. A 3D numerical model that considers the spatial-time and pressure dependence of the gas composition was adapted to simulate the gas exchange through microperforations at different fixed pressures and at variable pressure due to atmospheric pressure fluctuations (such as those caused by atmospheric tides or by the development of high and low-pressure systems) or to changes in altitude during land or air transport. The model results were successfully verified with experimental data recorded in an experimental system built to measure the CO₂ exchange through microperforations affected by pressure changes due to weather conditions (the root mean squared error of the CO₂ composition was 0.01%). The results reveal the importance of contemplating the convective flow generated by a change in pressure outside the package. In the simulated routes, the difference in CO₂ concentration between considering the pressure-driven flow and neglecting it is one order of magnitude in a 10-h land transport through a medium mountain route, for a 1250 mL container with a single microperforation of 7420.6 μm² area and initial CO₂ concentrations on both sides of the hole of 0.05% and 20.95%. The air transport simulations showed that it is not enough to consider the difference in altitude between the cities of origin and destination, but rather all the pressure fluctuations along the route must be included in the model.

The non-uniformity of radio frequency (RF) heating is a major obstacle to develop successful large-scale disinfestation processes for agricultural products with large particles. To effectively improve the RF heating uniformity in red jujubes, the chemical material of BaTiO₃ (BT) with different volume percentages was added into food-grade silicone (FGS) to form FGS/BT composite particles with various dielectric properties. The various FGS/BT composite particles were filled inside the rectangular container of red jujubes and used to evaluate the effect of matching degree of their dielectric constants on the RF heating uniformity. The results showed that the dielectric constant of the composite increased from 3.41 ± 0.14 to 8.31 ± 0.15 as the BT volume percentage increased from 0% to 20% at 25 °C and 27.12 MHz. Compared with FGS, the filled FGS/BT composite with a BT volume percentage of 20% not only improved the heat conduction but also optimized the temperature distributions among red jujube particles, which reduced the heating uniformity index in the top, middle, and bottom layers by 40%, 32%, and 27%, respectively. As the electrode gap increased from 160 mm to 180 mm, the heating rate and uniformity index in FGS/BT filled samples decreased significantly (p < 0.05). There was no significant (p > 0.05) difference in color and textural properties between the treated and control samples. This study provided the effective filling materials with matched dielectric constant in the RF treatment of red jujubes and a feasible method to further improve the RF heating uniformity in large-size agricultural products.

The incorporation of advanced technologies in agricultural industry procedures has boosted operational efficiency, enabling more effective data collection and analysis. In this study, we developed an ”optical tongue” using fiber-optic Mach–Zehnder interferometers (MZIs) built from micro tapered long-period fiber gratings (MT-LPFGs). This tool was employed to collect data related to milk quality, with results indicating a high potential to improve the quality control of dairy products. These advances demonstrate the potential of optical fiber sensor technologies in the agricultural industry and quality control.

This article described the low-cost hibiscus flower based colorimetric paper sensor to monitor the quality and freshness of raw fish. The extract of hibiscus flower was used to develop pH sensing paper strips for qualitative analysis. The sensitivity of paper sensor was checked by colorimetric detection of ammonia gas and then it was implemented to monitor the freshness of fish visually. The extract of hibiscus flower containing anthocyanin molecules are the key molecule for visual detection of spoiled food. The above molecule was spectroscopically analyzed with change in pH of the solution before and after the interaction of food products. We also studied the variation of both color and shade of paper sensor with change in pH at natural and artificial light conditions. The color information extracted from images and their relationship with pH was explored in red, green, blue (RGB) and hue, saturation, and value (HSV) color spaces by the image-J software for qualitative monitoring of food. Anthocyanin based paper sensor is used as a convenient and real time smart food sensor in packaging application.

Drying is one of the most energy-intensive food processing technologies and can contribute to greenhouse gas (GHG) emissions. Therefore, novel nonthermal pretreatment methods can be used to affect the plant tissue and decrease the drying time. A pulsed electric field (PEF), direct current electric field (DCEF), and electromagnetic field (EMF) were applied to black garlic cloves which were subsequently subjected to convective pre-drying followed by a vacuum-microwave finishing drying. The effect of these pretreatments on the physical properties, energy consumption, attributes of texture profile analysis (TPA), as well as microstructure determined by the use of X-ray computed tomography is presented. The application of pretreatments reduced the porosity of the material and resulted in an increased hardness compared to the unpretreated sample. Overall, nonthermal pretreatments proved beneficial in reducing the drying time and minimizing the energy consumption as well as greenhouse gas emissions during processing while maintaining a high quality of dried black garlic.

This study aimed to investigate the effect of protease hydrolysis pretreatment (PHP) on extruder response and the structural characteristics of high-moisture plant-protein extrudates. The results showed that specific mechanical energy of the extruder decreased from 147.06 kJ/kg to 116.14 kJ/kg, which reduced the energy consumption of the extruder and was beneficial for the application of hydrated wheat gluten with strong viscoelasticity during the extrusion process. Texturization degree that characterized the fibrous structure formation of high-moisture plant-protein extrudates reduced from 1.70 to 1.05. The hardness and chewiness decreased, while the springiness of the extrudates increased. Moderate PHP weakened the cross-linking strength and viscoelasticity of the extrudates, which can improve the problem of the excessively dense texture of high-moisture plant-protein extrudates. Meanwhile, PHP improved protein extractability and increased immobilized water and free water content in the extrudates.