Mechanical damages and packaging methods along the fresh fruit supply chain: A review.

Mechanical damage of fresh fruit occurs throughout the postharvest supply chain leading to poor consumer acceptance and marketability. In this review, the mechanisms of damage development are discussed first. Mathematical modeling provides advanced ways to describe and predict the deformation of fruit with arbitrary geometry, which is important to understand their mechanical responses to external forces. Also, the effects of damage at the cellular and molecular levels are discussed as this provides insight into fruit physiological responses to damage. Next, direct measurement methods for damage including manual evaluation, optical detection, magnetic resonance imaging, and X-ray computed tomography are examined, as well as indirect methods based on physiochemical indexes. Also, methods to measure fruit susceptibility to mechanical damage based on the bruise threshold and the amount of damage per unit of impact energy are reviewed. Further, commonly used external and interior packaging and their applications in reducing damage are summarized, and a recent biomimetic approach for designing novel lightweight packaging inspired by the fruit pericarp. Finally, future research directions are provided.HIGHLIGHTSMathematical modeling has been increasingly used to calculate damage to fruit.Cell and molecular mechanisms response to fruit damage is an under-explored area.Susceptibility measurement of different mechanical forces has received attention.Customized design of reusable and biodegradable packaging is a hot topic of research.

Non-Destructive Detection of Damaged Strawberries after Impact Based on Analyzing Volatile Organic Compounds.

Strawberries are susceptible to mechanical damage. The detection of damaged strawberries by their volatile organic compounds (VOCs) can avoid the deficiencies of manual observation and spectral imaging technologies that cannot detect packaged fruits. In the present study, the detection of strawberries with impact damage is investigated using electronic nose (e-nose) technology. The results show that the e-nose technology can be used to detect strawberries that have suffered impact damage. The best model for detecting the extent of impact damage had a residual predictive deviation (RPD) value of 2.730, and the correct rate of the best model for identifying the damaged strawberries was 97.5%. However, the accuracy of the prediction of the occurrence time of impact was poor, and the RPD value of the best model was only 1.969. In addition, the gas chromatography-mass spectrophotometry analysis further shows that the VOCs of the strawberries changed after suffering impact damage, which was the reason why the e-nose technology could detect the damaged fruit. The above results show that the mechanical force of impact caused changes in the VOCs of strawberries and that it is possible to detect strawberries that have suffered impact damage using e-nose technology.

Profiling the Bioactive Compounds in Broccoli Heads with Varying Organ Sizes and Growing Seasons.

Broccoli is a rich source of diverse bioactive compounds, but how their contents are influenced by different growing seasons and variations in broccoli head sizes remains elusive. To address this question, we quantified sixteen known bioactive compounds and seven minerals in broccoli with varying head sizes obtained in two different growing seasons. Our results suggest that the contents of vitamin C, total phenols, carotenoids, and glucoraphanin were significantly higher in samples from the summer-autumn season, showing increases of 157.46%, 34.74%, 51.80%, and 17.78%, respectively, compared with those from the winter-spring season. Moreover, chlorogenic acid is a phenolic compound with relatively high contents among the six detected, while beta-sitosterol is the sterol with relatively high contents. Further, principal component analysis was conducted to rank the comprehensive scores of the profiles of phenolic compounds, phytosterols, and minerals, demonstrating that the broccoli samples grown during the summer-autumn season achieved the highest composite scores. Our results indicate that broccoli heads from the summer-autumn season are richer in a combination of bioactive compounds and minerals than those from the winter-spring season based on the composite score. This study extends our understanding of the nutrition profiles in broccoli and also lays the foundation for breeding broccoli varieties with improved nutrition quality.

Activation of mitophagy improves cognitive dysfunction in diabetic mice with recurrent non-severe hypoglycemia.

Recurrent non-severe hypoglycemia (RH) in patients with diabetes might be associated with cognitive impairment. Previously, we found that mitochondrial dysfunction plays an important role in this pathological process; however, the mechanism remains unclear. The objective of this study was to determine the molecular mechanisms of mitochondrial damage associated with RH in diabetes mellitus (DM). We found that RH is associated with reduced hippocampal mitophagy in diabetic mice, mainly manifested by reduced autophagosome formation and impaired recognition of impaired mitochondria, mediated by the PINK1/Parkin pathway. The same impaired mitophagy initiation was observed in an in vitro high-glucose cultured astrocyte model with recurrent low-glucose interventions. Promoting autophagosome formation and activating PINK1/Parkin-mediated mitophagy protected mitochondrial function and cognitive function in mice. The results showed that impaired mitophagy is involved in the occurrence of mitochondrial dysfunction, mediating the neurological impairment associated with recurrent low glucose under high glucose conditions.

Comprehensive analysis of transcriptome and metabolome provides insights into the stress response mechanisms of apple fruit to postharvest impact damage.

An integrated analysis of the transcriptome and metabolome was conducted to investigate the underlying mechanisms of apple fruit response to impact damage stress. During the post-damage storage, a total of 124 differentially expressed genes (DEGs) were identified, which were mainly annotated in 13 pathways, including phenylpropanoid biosynthesis. Besides, 175 differentially expressed metabolites (DEMs), including 142 up-regulated and 33 down-regulated metabolites, exhibited significant alteration after impact damage. The DEGs and DEMs were simultaneously annotated in 7 metabolic pathways, including flavonoid biosynthesis. Key genes in the volatile esters and flavonoid biosynthesis pathways were revealed, which may play a crucial role in the coping mechanisms of apple fruit under impact damage stress. Moreover, 13 ABC transporters were significantly upregulated, indicating that ABC transporters may contribute to the transportation of secondary metabolites associated with response to impact damage stress. The results may elucidate the comprehension of metabolic networks and molecular mechanisms in apple fruits that have undergone impact damage.

Mechanisms of the response of apple fruit to postharvest compression damage analyzed by integrated transcriptome and metabolome.

Apple fruit is susceptible to compression damage within the postharvest supply chain given its thin peels and brittle texture, which can result in decay and deterioration and have a substantial impact on its marketability and competitiveness. Thorough bioinformatics investigations are lacking on postharvest compression damage stress-induced alterations in genes and metabolic regulatory networks in fruits. In the present study, a comprehensive analysis of both the transcriptome and metabolome was conducted on 'Red Fuji' apples experiencing compression-induced damage. During the storage after damage has occurred, the gene expression of MdOFUT19, MdWRKY48, MdCBP60E, MdCYP450 and MdSM-like of the damaged apples was consistently higher than that of the control group. The damaged apples also had higher contents of some metabolites such as procyanidin A1, Dl-2-Aminooctanoic acid, 5-O-p-Coumaroyl shikimic acid and 5,7-Dihydroxy-3',4',5'-trimethoxyflavone. Analysis of genes and metabolites with distinct expressions on the common annotation pathway suggested that the fruit may respond to compression stress by promoting volatile ester and lignin synthesis. The above results can deepen the comprehension of the response mechanisms in apple fruits undergoing compression-induced damage.

Volatile Profile and Biosynthesis of Post-harvest Apples are Affected by the Mechanical Damage.

Mechanical damage to fruit causes flavor changes during post-harvest supply chains. It is important to identify the main volatiles and explore their biosynthesis mechanism. In this study, the volatile changes in apples caused by mechanical damage were analyzed by gas chromatography-ion mobility spectrometry. Hexanal and ethyl acetate were accumulated and identified as potential volatile biomarkers to detect damaged apples. The study on the lipoxygenase (LOX) pathway and transcription factors (TFs) shows that mechanical damage up-regulated the expression of MdLOX-like, MdLOX3b, MdLOX7b, MdLOX7c, MdLOX2a, and MdAAT in the LOX pathway and that of one MYB TF (MdMYB-like), five ERF TFs (MdERF073, MdERF003, MdERF114, MdERF15, and MdERF2), and five WRKY TFs (MdWRKY23, MdWRKY17, MdWRKY46, MdWRKY48, and MdWRKY71). Notably, MdAAT was significantly correlated to MdMYB-like, MdWRKY23, MdWRKY71, MdERF15, and MdERF2. Thus, TFs may attribute to the accumulation of hexanal and ethyl acetate by regulating the expression of LOX pathway-related genes.