Microstructure–texture relationships of aerated sugar gels: Novel measurement techniques for analysis and control

The Effect of Composition, Pre-Treatment on the Mechanical and Acoustic Properties of Apple Gels and Freeze-Dried Materials

This study aimed to determine the effect of the addition of apple juice concentrate (AJC) on the properties of agar gel and dried materials. Agar gels with the addition of apple juice concentrate in the range of 5–20% were prepared with or without the addition of maltodextrin. The gels were also soaked in the solution of AJC. The water content, water activity, densities, some mechanical and acoustic descriptors of gels, and the freeze-dried gels were analysed. The porosity and shrinkage of dried products were also investigated. The addition of AJC significantly changed mechanical and acoustic properties of gels. The hardness of gels decreased with a higher addition of concentrate. Dried samples with a lower concentration of sugars (the lower addition of AJC) were characterised by lower shrinkage and higher porosity, as well as crispness and glass transition temperature. The investigated mechanical and acoustic properties of dried gels showed the addition of apple concentrate at the level of 5% to agar solution was optimal.

Effect of Addition of Chokeberry Juice Concentrate and Foaming Agent on the Physical Properties of Agar Gel

This study aimed to determine the effect of the addition of chokeberry juice concentrate (CJC) and foaming agent (egg albumin) with different percentages on the selected physical properties of agar gel. The agar gels with the addition of 5, 10, and 20% concentrations of chokeberry juice concentrate and with fructose addition were prepared. In addition, the foamed gels with different concentrations of egg albumin (in the range 0.5–2.0%) and CJC were produced. The water content, colour, density, hold-up and some mechanical and TPA (Texture Profile Analysis) descriptors as well some structural and acoustic emission parameters of non-aerated and foamed gels were analysed. The addition of CJC changed the colour of agar gel with fructose, the attractive appearance of the aerated gel was also linked with the addition of concentrate. The addition of 20% of CJC and foaming agent created samples with very low hardness, cohesiveness, and gumminess, and the structure of the aerated samples was characterised by the larger bubble diameter and the wider distribution of their size. The more promising texture and structure properties were obtained for samples with aerated gels with 5 and 10% addition of chokeberry juice concentrate.

Designing Mechanical Properties of 3D Printed Cookies through Computer Aided Engineering

Additive manufacturing or 3D printing can be applied in the food sector to create food products with personalized properties such as shape, texture, and composition. In this article, we introduce a computer aided engineering (CAE) methodology to design 3D printed food products with tunable mechanical properties. The focus was on the Young modulus as a proxy of texture. Finite element modelling was used to establish the relationship between the Young modulus of 3D printed cookies with a honeycomb structure and their structure parameters. Wall thickness, cell size, and overall porosity were found to influence the Young modulus of the cookies and were, therefore, identified as tunable design parameters. Next, in experimental tests, it was observed that geometry deformations arose during and after 3D printing, affecting cookie structure and texture. The 3D printed cookie porosity was found to be lower than the designed one, strongly influencing the Young modulus. After identifying the changes in porosity through X-ray micro-computed tomography, a good match was observed between computational and experimental Young’s modulus values. These results showed that changes in the geometry have to be quantified and considered to obtain a reliable prediction of the Young modulus of the 3D printed cookies.

Nondestructive determination of optical properties of a pear using spatial frequency domain imaging combined with phase-measuring profilometry

Spatial frequency domain imaging (SFDI), as a rapid, noncontact, and scan-free method, can realize wide-field, quantitative optical property mapping and tomographic imaging for a biological sample. Phase-measuring profilometry (PMP) is a surface profile characterization method. Since the projection of structured light onto an object is the basis for PMP and SFDI, the SFDI system is capable of performing both techniques. In this work, we present the results of a feasibility study with the developed SFDI system to realize acquisition of the optical property information and the surface profile information. The surface profile information was used to correct the absorption (μ_a) maps and reduced scattering (μs') maps. The evaluation of correction effect of the PMP and the calibration and calculation of detection accuracy of the SFDI system were realized by using a series of self-made hemispheric and homogeneous solid phantoms covering a wide range of absorption and reduced scattering coefficients. The results show that the μ_a and μs' maps become more uniform after using profilometry correction. The maximum relative errors of the system after profilometry correction and calibration were 8.74% for μ_a and 4.97% for μs' at the wavelength of 527 nm, respectively. A case study was carried out on a pear to verify the application prospect of the method in the field of agricultural products quality inspection. Results indicate that μ_a and μs' maps of a pear after profilometry correction and calibration were more uniform and more comparable with the reported values.

Potential of vis-NIR spectroscopy to monitor the silica precipitation reaction

Controlling production online is an important issue for chemical companies. Visible and near-infrared (NIR) spectroscopy offers a number of important advantages for process monitoring, and has been used since the 1980s. For complex media such as silica precipitation samples, it is interesting to be able to study independently the scattering and absorption effects. From the scattering coefficient it is possible to extract information on the physical structure of the medium. In this work, the physical changes were monitored during a silica precipitation reaction by simple measurement of collimated transmittance NIR spectra. It is shown that it is possible to differentiate samples before and after the gel point, which is a key parameter for monitoring the process. From these NIR spectra the scattering coefficients were simply extracted, allowing a global vision of the physical changes in the medium. Then principal component analysis of the spectra allowed refinement of the understanding of the scattering effects, in combination with particle size monitoring.

Newer Approaches to Identify Potential Untoward Effects in Functional Foods

Globalization has greatly accelerated the numbers and variety of food and beverage products available worldwide. The exchange among greater numbers of countries, manufacturers, and products in the United States and worldwide has necessitated enhanced quality measures for nutritional products for larger populations increasingly reliant on functionality. These functional foods, those that provide benefit beyond basic nutrition, are increasingly being used for their potential to alleviate food insufficiency while enhancing quality and longevity of life. In the United States alone, a steady import increase of greater than 15% per year or 24 million shipments, over 70% products of which are food related, is regulated under the Food and Drug Administration (FDA). This unparalleled growth has resulted in the need for faster, cheaper, and better safety and efficacy screening methods in the form of harmonized guidelines and recommendations for product standardization. In an effort to meet this need, the in vitro toxicology testing market has similarly grown with an anticipatory 15% increase between 2010 and 2015 of US$1.3 to US$2.7 billion. Although traditionally occupying a small fraction of the market behind pharmaceuticals and cosmetic/household products, the scope of functional food testing, including additives/supplements, ingredients, residues, contact/processing, and contaminants, is potentially expansive. Similarly, as functional food testing has progressed, so has the need to identify potential adverse factors that threaten the safety and quality of these products.

Automatic analysis of the 3-D microstructure of fruit parenchyma tissue using X-ray micro-CT explains differences in aeration

BACKGROUND

3D high-resolution X-ray imaging methods have emerged over the last years for visualising the anatomy of tissue samples without substantial sample preparation. Quantitative analysis of cells and intercellular spaces in these images has, however, been difficult and was largely based on manual image processing. We present here an automated procedure for processing high-resolution X-ray images of parenchyma tissues of apple (Malus × domestica Borkh.) and pear (Pyrus communis L.) as a rapid objective method for characterizing 3D plant tissue anatomy at the level of single cells and intercellular spaces.

RESULTS

We isolated neighboring cells in 3D images of apple and pear cortex tissues, and constructed a virtual sieve to discard incorrectly segmented cell particles or unseparated clumps of cells. Void networks were stripped down until their essential connectivity features remained. Statistical analysis of structural parameters showed significant differences between genotypes in the void and cell networks that relate to differences in aeration properties of the tissues.

CONCLUSIONS

A new model for effective oxygen diffusivity of parenchyma tissue is proposed that not only accounts for the tortuosity of interconnected voids, but also for significant diffusion across cells where the void network is not connected. This will significantly aid interpretation and analysis of future tissue aeration studies. The automated image analysis methodology will also support pheno- and genotyping studies where the 3D tissue anatomy plays a role.