Characterization of the 3-D microstructure of mango (Mangifera indica L. cv. Carabao) during ripening using X-ray computed microtomography

Virtualization and digital twins of the food supply chain for enhanced food safety

Meeting food safety requirements without jeopardizing quality attributes or sustainability involves adopting a holistic perspective of food products, their manufacturing processes and their storage and distribution practices. The virtualization of the food supply chain offers opportunities to evaluate, simulate, and predict challenges and mishaps potentially contributing to present and future food safety risks. Food systems virtualization poses several requirements: (1) a comprehensive framework composed of instrumental, digital, and computational methods to evaluate internal and external factors that impact food safety; (2) nondestructive and real-time sensing methods, such as spectroscopic-based techniques, to facilitate mapping and tracking food safety and quality indicators; (3) a dynamic platform supported by the Internet of Things (IoT) interconnectivity to integrate information, perform online data analysis and exchange information on product history, outbreaks, exposure to risky situations, etc.; and (4) comprehensive and complementary mathematical modeling techniques (including but not limited to chemical reactions and microbial inactivation and growth kinetics) based on extensive data sets to make realistic simulations and predictions possible. Despite current limitations in data integration and technical skills for virtualization to reach its full potential, its increasing adoption as an interactive and dynamic tool for food systems evaluation can improve resource utilization and rational design of products, processes and logistics for enhanced food safety. Virtualization offers affordable and reliable options to assist stakeholders in decision-making and personnel training. This chapter focuses on definitions and requirements for developing and applying virtual food systems, including digital twins, and their role and future trends in enhancing food safety.

Observation and Measurement of Ice Morphology in Foods: A Review

Freezing is an effective technology with which to maintain food quality. However, the formation of ice crystals during this process can cause damage to the cellular structure, leading to food deterioration. A good understanding of the relationship between food microstructure and ice morphology, as well as the ability to effectively measure and control ice crystals, is very useful to achieve high-quality frozen foods. Hence, a brief discussion is presented on the fundamentals/principles of optical microscopic techniques (light microscopy), electronic microscopic techniques (transmission electron microscopy (TEM) and scanning electron microscopy (SEM)), as well as other non-invasive techniques (X-rays, spectroscopy, and magnetic resonance) and their application to measuring ice formation rates and characterizing ice crystals, providing insight into the freezing mechanisms as well as direct monitoring of the entire process. And, in addition, this review compares (the negative and positive aspects of) the use of simple and cheap but destructive technologies (optical microscopy) with detailed microscopic technologies at the micro/nanometer scale but with pretreatments that alter the original sample (SEM and TEM), and non-destructive technologies that do not require sample preparation but which have high acquisition and operational costs. Also included are images and examples which demonstrate how useful an analysis using these techniques can be.

Fruit growth and development in apple: a molecular, genomics and epigenetics perspective

Fruit growth and development are physiological processes controlled by several internal and external factors. This complex regulatory mechanism comprises a series of events occurring in a chronological order over a growing season. Understanding the underlying mechanism of fruit development events, however, requires consideration of the events occurring prior to fruit development such as flowering, pollination, fertilization, and fruit set. Such events are interrelated and occur in a sequential order. Recent advances in high-throughput sequencing technology in conjunction with improved statistical and computational methods have empowered science to identify some of the major molecular components and mechanisms involved in the regulation of fruit growth and have supplied encouraging successes in associating genotypic differentiation with phenotypic observations. As a result, multiple approaches have been developed to dissect such complex regulatory machinery and understand the genetic basis controlling these processes. These methods include transcriptomic analysis, quantitative trait loci (QTLs) mapping, whole-genome approach, and epigenetics analyses. This review offers a comprehensive overview of the molecular, genomic and epigenetics perspective of apple fruit growth and development that defines the final fruit size and provides a detailed analysis of the mechanisms by which fruit growth and development are controlled. Though the main emphasis of this article is on the molecular, genomic and epigenetics aspects of fruit growth and development, we will also deliver a brief overview on events occurring prior to fruit growth.

Hypolipidemic Activity of Olive Oil-Based Nanostructured Lipid Carrier Containing Atorvastatin

Currently, hyperlipidemia is a growing health issue that is considered a risk factor for obesity. Controlling body weight and modifying life style in most of cases are not adequate and the condition requires medical treatment. Statin drugs (mainly Atorvastatin (ATO)), have been used broadly and for long time as medications for handling higher levels of lipid, especially bad cholesterol, which accordingly controls the prevalence of obesity. Still, the obstacle that stands in front of any formulation is the poor solubility of the drug. Low solubility of ATO came up with poor absorption as well as poor bioavailability. This paved the way for the present study, which aimed to exploit nanotechnology and develop certain nanolipid carriers that could accommodate hydrophobic drugs, such as ATO. Nanostructured lipid carrier (NLC) containing ATO was fabricated using olive oil. Olive oil is natural plant oil possessing confirmed hypolipidemic activity that would help in improving the efficacy of the formulation. Via applying the Quality by Design (QbD) approach, one NLC formula was selected to be optimized based on appropriate size and higher entrapment. Optimized ATO-NLC was scrutinized for zeta potential, in vitro study and kinetic profile. Moreover, stability testing and in vivo hypolipidemic behavior was conducted. The optimized NLC formulation seemed to show particle size (254.23 nm) with neutral zeta potential (−1.77 mV) and entrapment efficiency (69.56%). The formulation could be prolonged for 12 h and provided higher % of release (97.17%). Stability testing confirmed the role of modifying the surface of the formulation with PEG-DSPE in providing a highly stable formulation that could withstand three months storage in two altered conditions. Ultimately, optimized ATO-NLC could successfully lower total cholesterol level in rats induced with obesity and fed a high-fat diet. Remarkably, ATO-NLC prepared with olive oil, in addition to shielding its surface, would provide a stable formulation that holds up the synergistic action between olive oil and ATO.

Microstructural changes enhance oxygen transport in tomato (Solanum lycopersicum) fruit during maturation and ripening

Climacteric ripening of tomato fruit is initiated by a characteristic surge of the production rate of ethylene, accompanied by an increase in respiration rate. As both activities consume O₂ and produce CO₂ , gas concentration gradients develop in the fruit that cause diffusive transport. This may, in turn, affect respiration and ethylene biosynthesis. Gas diffusion in fruit depends on the amount and connectivity of cells and intercellular spaces in 3D. We investigated micromorphological changes in different tomato tissues during development and ripening by visualizing cells and pores based on high-resolution micro-computed tomography, and computed effective O₂ diffusivity coefficients based on microstructural features of the tissues. We demonstrated that mesocarp and septa tissues have larger cells but small and more disconnected pores than the placenta and columella, resulting in relatively lower effective O₂ diffusivity coefficients. Cell disintegration occurred in the mesocarp and septa during ripening, indicating lysigenous air pore formation and resulting in a gradual increase of the effective O₂ diffusivity. The results suggest that hypoxic conditions caused by the increasing size and, hence, diffusion resistance of the growing fruit may induce an increase of tissue porosity that results in a greatly enhanced O₂ diffusivity and, thus, helps to alleviate them.

Numerical simulation and microtomography study for drying a deformable isodiametric-cellular food

The aim of this work is the simulation of volumetric strain of tuberous crop during drying. We propose a poroelastic model for predicting the drying kinetics and volume loss of potato cubes during convective drying. The Biot’s theory of poroelasticity was used, which considers the Lamé parameters, Young’s modulus and Poisson’s ratio. Drying kinetics and volumetric strain were modeled and compared versus experimental data. An X-ray microtomograph coupled with image analysis was used to visualize the shape and size of the samples during drying. Drying experiments were conducted at 50, 60 and 70 °C, 20% RH, with an air velocity of 1 and 2 m/s. The drying process was interrupted several times to perform tomographic acquisitions. We found a period of ideal shrinkage, nevertheless, the volumetric strain reveals a kinetic behavior over time. The model computes the volumetric strain, which describes correctly the experimental data obtained by microtomography.

High-Resolution Microstructure Analysis of Cork Spot Disordered Pear Fruit "Akizuki" (Pyrus pyrifolia Nakai) Using X-Ray CT

Cork spot is one of the most damaging physiological disorders in pear fruit, causing considerable economic loss every year. However, the mechanism of cork spot occurrence requires further examination. In this study, X-ray CT scanning was applied to analyze the microstructure of pear fruit "Akizuki" (Pyrus pyrifolia), a cultivar susceptible to cork spot disorder, to elucidate the fruit texture alteration between healthy and cork spotted fruit. Results showed that cork spotted fruit had much higher porosity (9.37%) than healthy fruit (3.52%). Reconstructed three-dimensional (3D) network skeleton models showed highly branched pore channels in cork spotted fruit and a low degree of pore connectivity in healthy fruit. Even in areas of disordered fruit without cork spot, the pore throat diameter, pore length, and coordinated core number (i.e., 77, 160, and 16, respectively) were much higher than that of healthy fruit. The structure analysis of fruit core showed that core deformation only occurred in cork spotted fruit. A much more highly branched network was observed in cork spotted fruit cores compared with healthy fruit cores. High-resolution observation of flesh tissue directly demonstrated that pore size in cork spotted fruit (87 μm) was four times larger than that of healthy fruit (22 μm). Altered expression of genes related to Ca²⁺ transport and the uneven distribution of intracellular Ca²⁺ were also shown to associate with the development of cork spot disorder. Our results suggest that flesh tissue damage likely occurred prior to the initiation of cork spot. The dysfunction of long-distance and transmembrane Ca²⁺ transport channels could be responsible for the imbalanced distribution of Ca²⁺ inside the fruit, thus resulting in the development of cork spot.

Microstructure-Property Relationship of Polyurethane Foams Modified with Baltic Sea Biomass: Microcomputed Tomography vs. Scanning Electron Microscopy

In this paper, novel rigid polyurethane foams modified with Baltic Sea biomass were compared with traditional petro-based polyurethane foam as reference sample. A special attention was focused on complex studies of microstructure, which was visualized and measured in 3D with high-resolution microcomputed tomography (microCT) and, as commonly applied for this purpose, scanning electron microscopy (SEM). The impact of pore volume, area, shape and orientation on appearance density and thermal insulation properties of polyurethane foams was determined. The results presented in the paper confirm that microcomputed tomography is a useful tool for relatively quick estimation of polyurethane foams’ microstructure, what is crucial especially in the case of thermal insulation materials.

3-D microstructural changes in relation to the evolution of quality during ripening of mango (Mangifera indica L. cv. Carabao)

BACKGROUND

The ripening of mango involves changes in texture, flavor, and color, affecting the quality of the fruit. Previous studies have investigated the physiology on the evolution of quality during ripening but only a few have looked at microstructural changes during ripening. None of them has provided an insight into the relationhip between 3-D microstructure and the evolution of quality during ripening. As the 3-D microstructure of fruit tissue determines its mechanical and gas-transport properties, it is likely to affect fruit texture, respiratory metabolism, and other ripening processes.

RESULTS

The present study focuses on the role of 3-D microstructural changes in relation to quality changes during mango ripening. Microstructural imaging using X-ray micro-computed tomography suggested the incidence of cell leakage, which was confirmed by the measurement of electrolyte leakage from the fruit peel. Due to cell leakage, porosity, pore connectivity, and pore local diameter were decreased whereas the tissue local diameter and pore specific area were increased. The decline in respiration and respiratory quotient during ripening followed the microstructural changes observed. Meanwhile, changes in aroma were observed such as a decrease in monoterpenes and an increase in esters and other fermentative metabolites.

CONCLUSION

Overall, the results provide a complete, integrated picture of microstructural changes during ripening accompanying the evolution of fruit quality, suggesting functional relationships between the two. © 2020 Society of Chemical Industry.

Fundamental Understanding of Cellular Water Transport Process in Bio-Food Material during Drying

Bio-food materials are heterogeneous in structure with cellular diversity, where the majority of the water is located in the intracellular spaces. Understanding of the nature of the microscopic behaviour of water transport is crucial to enhance the energy efficiency in food processing and obtain the better quality of processed food. In this research, apoplastic and symplastic transport of cellular water in the bio-food material during drying was investigated using 1H-NMR-T2 relaxometry. We found that intracellular water (ICW) migrates from intracellular spaces to the intercellular spaces by progressive rupturing the cell membranes while drying at a higher temperatures (60 °C-70 °C). In this case, apoplastic process dominates the transport process. However, at lower temperature (45 °C), cell membranes do not rupture and therefore ICW migrates from cell to the neighbouring cell through micro-capillaries, where the symplastic process dominates the mass transfer at different stages of drying.

Multilacunarity as a spatial multiscale multi-mass morphometric of change in the meso-architecture of plant parenchyma tissue

The lacunarity index (monolacunarity) averages the behavior of variable size structures in a binary image. The generalized lacunarity concept (multilacunarity) on the basis of generalized distribution moments is an appealing model that can account for differences in the mass content at different scales. The model was tested previously on natural images [J. Vernon-Carter et al., Physica A 388, 4305 (2009)]. Here, the computational aspects of multilacunarity are validated using synthetic binary images that consist of random maps, spatial stochastic patterns, patterns with circular or polygonal elements, and a plane fractal. Furthermore, monolacunarity and detrended fluctuation analysis were employed to quantify the mesostructural changes in the intercellular air spaces of frozen-thawed parenchymatous tissue of pome fruit [N. A. Valous et al., J. Appl. Phys. 115, 064901 (2014)]. Here, the aim is to further examine the coherence of the multilacunarity model for quantifying the mesostructural changes in the intercellular air spaces of parenchymatous tissue of pome and stone fruit, acquired with X-ray microcomputed tomography, after storage and ripening, respectively. The multilacunarity morphometric is a multiscale multi-mass fingerprint of spatial pattern composition, assisting the exploration of the effects of metabolic and physiological activity on the pore space of plant parenchyma tissue.

Multiscale Modeling for Food Drying: State of the Art

Plant-based food materials are mostly porous in nature and heterogeneous in structure with huge diversity in cellular orientation. Different cellular environments of plant-based food materials, such as intercellular, intracellular, and cell wall environments, hold different proportions of water with different characteristics. Due to this structural heterogeneity, it is very difficult to understand the drying process and associated morphological changes during drying. Transport processes and morphological changes that take place during drying are mainly governed by the characteristics of and the changes in the cells. Therefore, to predict the actual heat and mass transfer process that occurs in the drying process and associated morphological changes, development of multiscale modeling is crucial. Multiscale modeling is a powerful approach with the ability to incorporate this cellular structural heterogeneity with microscale heat and mass transfer during drying. However, due to the huge complexity involved in developing such a model for plant-based food materials, the studies regarding this issue are very limited. Therefore, we aim in this article to develop a critical conceptual understanding of multiscale modeling frameworks for heterogeneous food materials through an extensive literature review. We present a critical review on the multiscale model formulation and solution techniques with their spatial and temporal coupling options. Food structure, scale definition, and the current status of multiscale modeling are also presented, along with other key factors that are critical to understanding and developing an accurate multiscale framework. We conclude by presenting the main challenges for developing an accurate multiscale modeling framework for food drying.

Spatial development of transport structures in apple (Malus × domestica Borkh.) fruit

The void network and vascular system are important pathways for the transport of gases, water and solutes in apple fruit (Malus × domestica Borkh). Here we used X-ray micro-tomography at various spatial resolutions to investigate the growth of these transport structures in 3D during fruit development of "Jonagold" apple. The size of the void space and porosity in the cortex tissue increased considerably. In the core tissue, the porosity was consistently lower, and seemed to decrease toward the end of the maturation period. The voids in the core were more narrow and fragmented than the voids in the cortex. Both the void network in the core and in the cortex changed significantly in terms of void morphology. An automated segmentation protocol underestimated the total vasculature length by 9-12% in comparison to manually processed images. Vascular networks increased in length from a total of 5 m at 9 weeks after full bloom, to more than 20 m corresponding to 5 cm of vascular tissue per cubic centimeter of apple tissue. A high degree of branching in both the void network and vascular system and a complex three-dimensional pattern was observed across the whole fruit. The 3D visualizations of the transport structures may be useful for numerical modeling of organ growth and transport processes in fruit.