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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 [ABSTRACT FROM AUTHOR]

Chilling injury (CI) presents a major problem in postharvest preservation and marketing potential of mango. In this study, tissue breakdown caused by chilling injury was investigated using X-ray computed microtomography (X-ray μCT). This provided a unique insight in 3-D changes in tissue structure and pore networks during chilling injury development. Evidence of cell collapse and cavity formation in severely chill injured fruit was apparent. In addition, microstructural evidence supporting the occurrence of intracellular water leakage was found. Quantitative analysis revealed that chilling injury was associated with, first, a decrease in porosity, pore size and pore connectivity due to cell leakage and tissue breakdown, which was followed by an increase in pore size due to cavity formation. Multivariate statistics identified pore connectivity and Euler number as the most important parameter in relation to chilling injury. The results support the hypothesis that changes in tissue and pore structure in mango fruit contribute significantly to the development of postharvest tissue disorders by drastic changes in tissue aeration and water movement, identical to what has been observed in other fruit species. [ABSTRACT FROM AUTHOR]

In this study, X-ray computed microtomography (X-ray μCT) was applied to investigate the changes in the 3-D microstructure of mango during ripening at 20 °C. X-ray μCT provided a unique insight of the undamaged tissue and pore network during ripening. Analysis of the pore and tissue network revealed differences in the microstructure along the radial axis of the fruit and microstructural changes during ripening. Multivariate statistical analysis unveiled that ripening was associated with a decrease in pore size, and increase in pore fragmentation and pore specific surface area. These structural parameters have the highest discriminating ability, correctly classifying unripe from ripe fruit samples. The study concludes that ripening can be successfully characterized on the basis of its 3-D microstructure using X-ray microtomography. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fruit microstructural differences were found among kiwifruit cultivars. [•] Differences in raphide bundles were found among kiwifruit cultivars. [•] Orchard manipulation caused macro, but not microstructural, quality differences. [ABSTRACT FROM AUTHOR]

Vacuum impregnation is used in the food industry to facilitate the impregnation of porous products with, e.g. firming, antioxidant, antimicrobial or cryoprotective agents. X-ray micro-tomography (μCT) was used to study the process of vacuum impregnation in spinach leaves. Low (300 mbar absolute pressure) and mild vacuum (150 mbar absolute pressure) impregnation protocols were used to impregnate an isotonic solution of trehalose in the leaves and μCT was used to make observations of the cross section of the impregnated samples and quantify their porosity. Results revealed that the free volume in the spongy mesophyll is easier to impregnate than the spaces around the palisade mesophyll. The low vacuum impregnation protocol provoked less impregnation close to the edge of the leaf than in its centre, probably accounting for an influence of the tissue structure on impregnation. The vacuum impregnation protocols tested in this investigation drastically decreased the proportion of large pores (>100 μm) and increased the proportion of small pores (<50 μm). The mild vacuum impregnation protocol, which was designed on the basis of measured apparent porosity, did not achieve full impregnation of the tissue. [ABSTRACT FROM AUTHOR]

The impregnation of leafy vegetables with cryoprotectants using a combination of vacuum impregnation (VI) and pulsed electric fields (PEF) has been proposed by our research group as a method of improving their freezing tolerance and consequently their general quality after thawing. In this study, we have investigated the metabolic consequences of the combination of these unit operations on spinach. The vacuum impregnated spinach leaves showed a drastic decrease in the porosity of the extracellular space. However, at maximum weight gain, randomly located air pockets remained, which may account for oxygen-consuming pathways in the cells being active after VI. The metabolic activity of the impregnated leaves showed a drastic increase that was further enhanced by the application of PEF to the impregnated tissue. Impregnating the leaves with trehalose by VI led to a significant accumulation of trehalose-6-phosphate (T6P), however, this was not further enhanced by PEF. It is suggested that the accumulation of T6P in the leaves may increase metabolic activity, and increase tissue resistance to abiotic stress. [ABSTRACT FROM AUTHOR]

Pre-harvest growing conditions during the development of fruit have impacts on fruit quality at the time of harvest and during storage. These impacts may result in differences in the skin properties of the fruit and some sub-surface cellular structural changes, which have potential effects on postharvest fruit quality and storability. Optical coherence tomography (OCT) is a non-destructive imaging method that enables acquisition of three-dimensional (3D) images of sub-surface structures of semi-transparent and turbid objects. This technology is a potential tool to provide new information about the structural nature of horticulture products. This work used five commercial kiwifruit cultivars, ‘G3’, ‘G9’, ‘G14’, ‘Hort16A’ and ‘Hayward’, where ‘Hayward’ was also manipulated with different orchard management practices (crop load and girdling), to investigate the properties of the layers of structures immediately underneath the periderm. Fruit samples were harvested at commercial maturity and then 3D OCT images of the skins were captured prior to fruit quality assessment. An automated image processing protocol was established to enable visualisation and characterisation of larger near skin cellular structures in the outer parenchyma tissue. There was no obvious differentiation between the observed large cells and the stone cells that are present in Actinidia chinensis cultivars. Significant differences in the microstructures of the sub-surface cells were found amongst five commercial kiwifruit cultivars. In general ‘G3’, ‘G14’ and ‘Hayward’ had larger and greater numbers of large sub-surface cells than ‘G9’ and ‘Hort16A’. The volume fraction of large cells in the near skin tissue was lower for the yellow-fleshed cultivars (‘G3’, ‘G9’ and ‘Hort16A’) in comparison to the green-fleshed cultivars (‘G14’ and ‘Hayward’). Low crop load increased maximum large cell length. However, no other effects of crop load and girdling were observed on the microstructures of the large cells in ‘Hayward’. Overall, OCT was an efficient non-destructive technique that can be utilised to reveal the structures of skin and sub-surface cellular layers with high resolution. The developed image processing protocol was suitable for the processing of large data sets with acceptable accuracy. However, more work should be carried out to overcome image artefacts caused by surface lenticels and trichomes. Limitations caused by low penetration depth should also be improved to allow better representation of the whole fruit structure. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Crop seeds are often treated with pesticides before planting. Pesticide-laden dust particles can be abraded from the seed coating during planting and expelled into the environment, damaging nontarget organisms. Drift of these dust particles depends on their size, shape and density. In this work, we used X-ray micro-CT to examine the size, shape (sphericity) and porosity of dust particles from treated seeds of various crops. The dust properties quantified in this work were very variable in different crops. This variability may be a result of seed morphology, seed batch, treatment composition, treatment technology, seed cleaning or an interaction of these factors. The intraparticle porosity of seed treatment dust particles varied from 0.02 to 0.51 according to the crop and generally increased with particle size. Calculated settling velocities demonstrated that accounting for particle shape and porosity is important in drift studies. For example, the settling velocity of dust particles with an equivalent diameter of 200 μm may vary between 0.1 and 1.2 m s-1, depending on their shape and density. Our analysis shows that in a wind velocity of 5 m s-1, such particles ejected at 1 m height may travel between 4 and 50 m from the source before settling. Although micro-CT is a valuable tool to characterize dust particles, the current image processing methodology limits the number of particles that can be analyzed. [ABSTRACT FROM AUTHOR]

Waxy, low-amylose and high-amylose rice starches were chosen to separate inner blocklets and outer shell from their granules under incomplete gelatinization. Isolated outer shells and swollen or merged inner blocklets, based on morphological structure of broken granules, were used as a probe to study the mechanism of differences between outer and inner blocklets formation, through molecular characteristics and starch granule-associated proteins (SGAPs) analyses. On the basis of molecular composition, it was concluded that shorter branched-chain amylopectin and some amylose chains were involved in the formation of inner blocklets (shells). While the stronger interaction occurred among outer blocklets (shell), those are composed of longer branched-chains amylopectin and few amylose molecules. SGAPs types and content of inner shells (blocklets) were higher than outer shell (blocklets). SGAPs not only interacted with amylose chains but also with amylopectin chains. The enzymatic machinery for biosynthesis, such as starch branching enzyme, plays a critical role in blocklet architecture. [Display omitted] • Inner blocklets and outer shell were successfully separated from rice starch granules. • Inner blocklets are mainly composed of shorter amylopectin and some amylose chains. • Longer amylopectin and few amylose chains are involved in formation of outer shell. • SGAP types and content of inner blocklets were higher than for outer shell. • Starch synthesis enzymes play a critical role in blocklet architecture. [ABSTRACT FROM AUTHOR]

This study aims to explore diversity in rheological properties, structure and digestibility of starches isolated from 16 common bean (Phaseolus vulgaris L.) varieties from Europe and Asia. All common bean starches showed C A -type (closer to A-type) crystallinities. Relative crystallinity varied from 27.8% to 32.9% with a similar coefficient of variation (CV: 5.0%–6.0%) to 1045/1014 cm−1 ratio (varied from 0.429 to 0.508). A peak position shift occurred at 989 and 1014 cm−1. The peak intensity at 989, 1014 and 1045 cm−1 varied greatly and the variation followed the order: at 989 > 1014 > 1045 cm−1. A great variation was also observed for the presence of hydroxyl group and the C–O bond stretching. Rapidly digestible starch, slowly digestible starch and resistant starch contents varied from 61.5% to 73.0% (CV: 4.7%), 0.3% to 7.2% (CV: 53.7%) and 23.9% to 35.4% (CV: 11.4%), respectively. CV of storage modulus (G′) and loss tangent (tan δ) were 29.4%–39.4% and 11.9%–36.1%, respectively. G′ max (maximum G′ during heating) varied from 2.52 to 10.32 kPa. These starches showed high G′. This study indicates extensive variation in starch properties among these common bean varieties, which may be useful for selecting varieties for processing, or selecting genotypes for plant breeding. [Display omitted] • Relative crystallinity of common bean starches varied from 27.8% to 32.9%. • ATR-FTIR indicated that a peak position shift occurred at 989 and 1014 cm−1. • The peak intensity variation followed the order: at 989 > 1014 > 1045 cm−1. • The maximum storage modulus of starches during heating varied from 2.52 to 10.32 kPa. • Resistant starch content varied from 23.9% to 35.4%. [ABSTRACT FROM AUTHOR]