Effect of post-harvest storage on the chemical and microstructural characteristics of the common bean (Phaseolus vulgaris L.).

Hard to cook is a textural defect that affects the nutritional quality of beans stored under adverse temperature and humidity conditions. This defect is related to intrinsic characteristics such as seed coat thickness, composition and microstructure. The aim of the present study was to evaluate the chemical and microstructural characteristics of common bean (Phaseolus vulgaris L.) during 270 days of post-harvest storage at 30 °C and 70% relative humidity. Microstructural analysis revealed alteration of the cotyledon cell wall and seed coat affecting seed viability and restricting seedling emergence. The seed coat thickness contraction from 105.79 µm to 97.35 µm (270 days). Changes are related with the protein bodies migration from cotyledons to seed coat. An increase in neutral detergent fiber and the presence of CaOx crystals were observed, which confer rigidity to the seed coat and affect water diffusion after 150 days causing permeability changes that contributed to seed hardening.

Transcriptome analysis reveals the effect of cold storage time on the expression of genes related to oxidative metabolism in Chinese black truffle.

Chinese black truffle (Tuber indicum) is a hypogenous fungus of great value due to its distinctive aroma. In this study, both transcriptome and physicochemical analyses were performed to investigate the changes of nutrients and gene expression in truffle fruiting bodies during cold storage. The results of physicochemical analysis revealed the active metabolism of fruiting bodies in cold storage, showing the decreased contents of protein and soluble sugar, the variations in both polyphenol oxidase activity and total phenol content, and the detrimental effect of reactive oxygen species production caused by heavy metals (cadmium and lead) in truffles. Transcriptome analysis identified a total of 139,489 unigenes. Down-regulated expression of genes encoding the catalase-like domain-containing protein (katE), glutaredoxin protein (GRX), a copper/zinc superoxide dismutase (Sod_Cu), and aspartate aminotransferase (AAT) affected the degradation metabolism of intracellular oxides. Ribulose-5-phosphate-3-epimerase (RPE) was a key enzyme in response to oxidative stress in truffle cells through the pentose phosphate pathway (PPP). A total of 51,612 simple sequence repeats were identified, providing valuable resources for further genetic diversity analysis, molecular breeding, and genetic map-ping in T. indicum. Transcription factors GAL4 and SUF4-like protein were involved in glucose metabolism and histone methylation processes, respectively. Our study provided a fundamental characterization of the physicochemical and molecular variations in T. indicum during the cold storage at 4°C, providing strong experimental evidence to support the improvement of storage quality of T. indicum.

Carotenoid retention during post-harvest storage of Capsicum annuum: the role of the fruit surface structure.

In this study, a chilli pepper (Capsicum annuum) panel for post-harvest carotenoid retention was studied to elucidate underlying mechanisms associated with this commercial trait of interest. Following drying and storage, some lines within the panel had an increase in carotenoids approaching 50% compared with the initial content at the fresh fruit stage. Other lines displayed a 25% loss of carotenoids. The quantitative determination of carotenoid pigments with concurrent cellular analysis indicated that in most cases, pepper fruit with thicker (up to 4-fold) lipid exocarp layers and smooth surfaces exhibit improved carotenoid retention properties. Total cutin monomer content increased in medium/high carotenoid retention fruits and subepidermal cutin deposits were responsible for the difference in exocarp thickness. Cutin biosynthesis and cuticle precursor transport genes were differentially expressed between medium/high and low carotenoid retention genotypes, and this supports the hypothesis that the fruit cuticle can contribute to carotenoid retention. Enzymatic degradation of the cuticle and cell wall suggests that in Capsicum the carotenoids (capsanthin and its esters) are embedded in the lipidic exocarp layer. This was not the case in tomato. Collectively, the data suggest that the fruit cuticle could provide an exploitable resource for the enhancement of fruit quality.

Mapping biochemical and nutritional changes in durum wheat due to spoilage during storage.

Synchrotron X-ray imaging and spectroscopy techniques were used for studying changes during post-harvest storage of food grains. Three varieties (AAC Spitfire, CDC Defy, and AAC Stronghold) of the Canada Western Amber Durum (CWAD) wheat class were stored for five weeks at 17 % moisture content (wb). Control (dry) and stored moistened seeds were analyzed for biochemical and nutritional changes using synchrotron bulk X-ray fluorescence spectroscopy (SR-XRF), X-ray fluorescence imaging (SR-XFI), and mid-infrared (mid-IR) spectroscopy at the Canadian Light Source (CLS), Saskatoon, SK. All varieties of durum wheat were spoiled at the end of five week, and AAC Spitfire and CDC Defy varieties were most affected in nutritional composition and their distribution than AAC Stronghold. Variable response to changes in biochemical and nutrition were found in all three spoiled varieties of the same durum wheat class.

Low expression of lipoxygenase 3 (LOX3) enhances the retention of kernel tocopherols in maize during storage.

BACKGROUND: Deficiency of vitamin E results in several neurological and age-related disorders in humans. Utilization of maize mutants with favourable vte4-allele led to the development of several α-tocopherol (vitamin E) rich (16-19 µg/g) maize hybrids worldwide. However, the degradation of tocopherols during post-harvest storage substantially affects the efficacy of these genotypes. METHODS AND RESULTS: We studied the role of lipoxygenase enzyme and Lipoxygenase 3 (LOX3) gene on the degradation of tocopherols at monthly intervals under traditional storage up to six months in two vte4-based contrasting-tocopherol retention maize inbreds viz. HKI323-PVE and HKI193-1-PVE. The analysis revealed significant degradation of tocopherols across storage intervals in both the inbreds. Lower retention of α-tocopherol was noticed in HKI193-1-PVE. HKI323-PVE with the higher retention of α-tocopherol showed lower lipoxygenase activity throughout the storage intervals. LOX3 gene expression was higher (~ 1.5-fold) in HKI193-1-PVE compared to HKI323-PVE across the storage intervals. Both lipoxygenase activity and LOX3 expression peaked at 120 days after storage (DAS) in both genotypes. Further, a similar trend was observed for LOX3 expression and lipoxygenase activity. The α-tocopherol exhibited a significantly negative correlation with lipoxygenase enzyme and expression of LOX3 across the storage intervals. CONCLUSIONS: HKI323-PVE with high tocopherol retention, low -lipoxygenase activity, and -LOX3 gene expression can act as a potential donor in the vitamin E biofortification program. Protein-protein association network analysis also indicated the independent effect of vte4 and LOX genes. This is the first comprehensive report analyzing the expression of the LOX3 gene and deciphering its vital role in the retention of α-tocopherol in biofortified maize varieties under traditional storage.

Phenolic profiles and their responses to pre- and post-harvest factors in small fruits: a review.

The consumption of small fruits has increased in recent years. Besides their appealing flavor, the commercial success of small fruits has been partially attributed to their high contents of phenolic compounds with multiple health benefits. The phenolic profiles and contents in small fruits vary based on the genetic background, climate, growing conditions, and post-harvest handling techniques. In this review, we critically compare the profiles and contents of phenolics such as anthocyanins, flavonols, flavan-3-ols, and phenolic acids that have been reported in bilberries, blackberries, blueberries, cranberries, black and red currants, raspberries, and strawberries during fruit development and post-harvest storage. This review offers researchers and breeders a general guideline for the improvement of phenolic composition in small fruits while considering the critical factors that affect berry phenolics from cultivation to harvest and to final consumption.

Research progress on the relationship between leaf senescence and quality, yield and stress resistance in horticultural plants.

Leaf senescence, the final stage of leaf development, is one of the adaptive mechanisms formed by plants over a long period of evolution. Leaf senescence is accompanied by various changes in cell structure, physiological metabolism, and gene expressions. This process is controlled by a variety of internal and external factors. Meanwhile, the genes and plant hormones involved in leaf aging affect the quality, yield and stress resistance in horticultural plants. Leaf senescence mediated by plant hormones affected plant quality at both pre-harvest and post-harvest stages. Exogenous plant growth regulators or plant hormone inhibitors has been applied to delay leaf senescence. Modification of related gene expression by over-expression or antisense inhibition could delay or accelerate leaf senescence, and thus influence quality. Environmental factors such as light, temperature and water status also trigger or delay leaf senescence. Delaying leaf senescence could increase chloroplast lifespan and photosynthesis and thus improve source strength, leading to enhanced yield. Accelerating leaf senescence promotes nutrient redistribution from old leaves into young leaves, and may raise yield under certain circumstances. Many genes and transcriptional factors involved in leaf senescence are associated with responses to abiotic and biotic stresses. WRKY transcriptional factors play a vital role in this process and they could interact with JA signalling. This review summarized how genes, plant hormones and environmental factors affect the quality, yield. Besides, the regulation of leaf senescence holds great promise to improving the resistance to plant biotic and abiotic stresses.

Effect of 60Co γ-rays on dried figs adsorption isotherms and thermodynamic properties.

Irradiation is one of the promising food preservation techniques, but few are known about its impact on foods' water vapor change. In this research, the impact of gamma irradiation on moisture adsorption isotherms of dried figs, one of the most emblematic foods of the Mediterranean diet, at increasing doses (0, 1, 1.5, and 2 kGy) was investigated. The isotherms data of equilibrium points displayed a sigmoid-shaped curve of the type II pattern for both controlled and irradiated dried figs, with a notable effect of irradiation on equilibrium moisture content, which revealed a decreasing pattern as irradiation dose and temperature increase. This effect was also seen in data fitting, where GAB model showed the best prediction statistics for control samples, while Peleg model displayed the most suitable samples irradiated at 1 and 1.5 kGy, then the Enderby model for those treated with 2 kGy. Results of Net isosteric heat of adsorption suggested that high irradiation dose increases the spontaneity of moisture adsorption. Hence, gamma irradiation exhibited a significant effect on the water-specific surface area of which the magnitude was proportional to the increasingly applied doses. This effect was also visibly significant on the optimum water activity [aw (op)] for proper dried fig storage. Indeed, aw was about 0.4243 for control samples, which is much higher compared to irradiated ones (aw = 0.2). Information from this research suggests that gamma irradiation at a dose up to 2 kGy extended the dried figs' shelf life. Since many aspects related to the impact of gamma irradiation on the moisture adsorption isotherms and thermodynamic properties of dried figs as well as in other foods have yet to be further investigated, this study provides interesting results that may be a useful reference for future research direction.

Phenolic compounds profile by UPLC-ESI-MS in black beans and its distribution in the seed coat during storage.

Hard to cook phenomenon results from inadequate post-harvest storage of the bean associated with the microstructure and changes in seed color and texture. The aim of this study was to evaluate the physical and chemical properties, identify the phenolic compounds and their relationship with the black bean seed coat microstructure during 270 days at 30 °C and 70% r. h. The water absorption capacity decrease to 12.19% that induced changes in seed texture observed by increasing the hardness from 5.42 to 19.96 N. A total of 37 compounds were identified by UPLC-ESI-MS and the changes in phenolic profile during storage period contribute to the seed coat color saturation. The identification of flavonoids, hydroxybenzoic and hydroxycinnamic acids, as well as distribution of condensed tannins in the seed coat, the changes in physical properties evidenced by seed darkening and hardening contribute to the seed coat impermeability.

Green grain warehousing: bibliometric analysis and systematic literature review.

Grain warehousing contributes persistent environmental effects in the food supply chain because of its long-term storage feature and distribution requirements. Thus, it has attracted a number of interdisciplinary researchers to the investigations of green grain warehousing (GGW) over the past decades. This paper presents a valuable comprehensive literature review on the existing publications on this topic via bibliometric analysis and systematic review based on 37 papers obtained from three common international academic databases, namely Web of Science, Scopus, and EBSCOhost. We concluded a framework of existing literature with proposing three macro-themes (energy-saving in transporting, environmental harmony, and green deinsectization) as well as a classification of commonly used methods. The results revealed that (1) the increase in research interests over years was found; (2) there are differences in the attention of GGW among countries. Most of the scholars from developing countries focused more on the green operational technologies or strategies, while most of the scholars from developed countries placed their research focuses on keeping grain quality and developing environment-friendly deinsectization approaches with low emission or chemical alternatives; (3) grain quality started to become the most popular hotspot in recent years; (4) the researchers tended to use more comprehensive methodologies or combined methods to conduct their works. Accordingly, we proposed potential research directions. The contribution of this work is to extend current literature and to offer reference to scholars and practitioners for future research and operation in GGW.

Post-Harvest Quality Evaluation of "Soreli" Kiwifruit at Two Ripening °Brix Values from Vineyards of Different Age Under Hail Nets.

The application of anti-hail nets is a practice that has been employed for a long time on different fruit and vegetable cultivations and in different fields of the world. In this work, we checked the effects of shading with white anti-hail nets on the post-harvest quality of "Soreli" kiwifruit collected at two different °Brix (7-8 and 8-9) from vineyards of two different ages (8 and 9 years) and stored at 1 °C for 90 days. It was observed that during the storage, the firmness and color parameters (L*, a*, b*, and Chroma) and the SSC content were generally higher in kiwifruit samples harvested in open field than in those under the nets. Regarding the bioactive compounds, the open field samples showed higher values in total flavonoids content during storage, and the content of carotenoids and chlorophylls in fruits grown in open fields was higher from 30-45 days up to the end of the storage. In contrast, the polyphenols and ascorbic acid values of fruits in open fields and under the nets showed a similar evolution of the values from 45 to 60 days. In general, the early and late harvest time based on the °Brix values and the different ages of the kiwifruit plants under the nets did not affect the quality parameters.

Assessment of factors affecting the decision of smallholder farmers to use alternative maize storage technologies in Gatsibo District-Rwanda.

Storage is an important aspect of food security in developing countries. Therefore, it is crucial for farmers to have access to sustainable storage technologies to cope with storage losses. Maize is an important staple and commercial food in Rwanda, but maize farmers are still being challenged by storage losses because of the lack of proper storage facilities. It is in that regard that advanced maize storage technology, notably hermetic maize storage technology, has been introduced in Rwanda in 2012. However, since its introduction, the adoption rate is low among smallholder maize farmers. Understanding the factors influencing farmers' choice of alternative maize storage technology could provide Rwandan policymakers with important information for designing policies and programs aimed at reducing maize post-harvest losses to enhance household food security. This study used a multivariate probit model on a randomly selected cross-sectional sample of 301 smallholder maize farmers from the Gatsibo District of Rwanda to take part. The results revealed that the common maize storage technologies used among smallholder farmers were polypropylene sacks with and without chemicals, hermetic bags, and silos. Only 41% of respondents used hermetic maize storage technology. The model results showed that membership in a farmer group, access to credit, the quantity of maize produced, access to training, and selling maize soon after it dries, were the major factors influencing the decision of smallholder farmers to use alternative maize storage technologies. The study recommends that the policymakers and other stakeholders in post-harvest loss reduction should support the dissemination of advanced storage technologies to facilitate access. The government should support farmer acquisition of post-harvest maize loss reduction technologies either through subsidization of hermetic bags or provision of cheap credit.

Effect of light on sensory quality, health-promoting phytochemicals and antioxidant capacity in post-harvest baby mustard.

The effect of light exposure on sensory quality, health-promoting phytochemical contents, and antioxidant capacity in the lateral buds of baby mustard plants was investigated at ambient storage temperature (20 °C). The results showed that light exposure (36 µmol m-2 s-1) during post-harvest storage significantly prolonged shelf life (more than 1.75-fold), delayed the weight loss and the decrease of firmness. Light treatments also enhanced chlorophyll and carotenoid contents, and retarded declines in contents of soluble sugars, ascorbic acid, flavonoids and glucosinolates, as well as antioxidant capacity. The quality of baby mustard plants receiving 24 h daily light treatment was superior to those in plants receiving 12 h treatment and constant darkness at 20 °C. These findings indicate that light exposure, especially 24 h treatment, is an effective method of prolonging shelf life and maintaining sensory and nutritional qualities in baby mustard plants stored at ambient temperature.

Comparative Analysis of Cuticular Wax in Various Grape Cultivars During Berry Development and After Storage.

Cuticular wax covering the surface of fleshy fruit is closely related to fruit glossiness, development, and post-harvest storage quality. However, the information about formation characteristics and molecular mechanisms of cuticular wax in grape berry is limited. In this study, crystal morphology, chemical composition, and gene expression of cuticular wax in grape berry were comprehensively investigated. Morphological analysis revealed high density of irregular lamellar crystal structures, which were correlated with the glaucous appearances of grape berry. Compositional analysis showed that the dominant wax compounds were triterpenoids, while the most diverse were alkanes. The amounts of triterpenoids declined sharply after véraison, while those of other compounds maintained nearly constant throughout the berry development. The amounts of each wax compounds varied among different cultivars and showed no correlation with berry skin colors. Moreover, the expression profiles of related genes were in accordance with the accumulation of wax compounds. Further investigation revealed the contribution of cuticular wax to the water preservation capacity during storage. These findings not only facilitate a better understanding of the characteristics of cuticular wax, but also shed light on the molecular basis of wax biosynthesis in grape.

Understanding colour retention in red chilli pepper fruit using a metabolite profiling approach.

Carotenoids are the pigments responsible for conferring the characteristic deep red colour to chilli pepper. The post-harvest retention of this colour is a key trait that governs the price of the produce. Determining colour retention and the associated underlying biochemical mechanisms are important issues that require investigation. In this present study, the ability of image analysis to determine colour change in ground chilli fruit was evaluated. This method enabled differentiation of extreme retention phenotypes whilst also reducing the duration of storage required to make accurate determinations. The analysis of volatiles indicated different levels of lipid and carotenoid derived volatiles in lines with different retention properties. Metabolite profiling of intermediary metabolism supported these findings, with increased levels of unsaturated fatty acids present in lines with low retention properties. Collectively, these data have led us to propose that in chilli fruit lipid peroxidation is one of the progenitors of carotenoid degradation.

Integrative transcriptomics reveals genotypic impact on sugar beet storability.

KEY MESSAGE: An integrative comparative transcriptomic approach on six sugar beet varieties showing different amount of sucrose loss during storage revealed genotype-specific main driver genes and pathways characterizing storability. Sugar beet is next to sugar cane one of the most important sugar crops accounting for about 15% of the sucrose produced worldwide. Since its processing is increasingly centralized, storage of beet roots over an extended time has become necessary. Sucrose loss during storage is a major concern for the sugar industry because the accumulation of invert sugar and byproducts severely affect sucrose manufacturing. This loss is mainly due to ongoing respiration, but changes in cell wall composition and pathogen infestation also contribute. While some varieties can cope better during storage, the underlying molecular mechanisms are currently undiscovered. We applied integrative transcriptomics on six varieties exhibiting different levels of sucrose loss during storage. Already prior to storage, well storable varieties were characterized by a higher number of parenchyma cells, a smaller cell area, and a thinner periderm. Supporting these findings, transcriptomics identified changes in genes involved in cell wall modifications. After 13 weeks of storage, over 900 differentially expressed genes were detected between well and badly storable varieties, mainly in the category of defense response but also in carbohydrate metabolism and the phenylpropanoid pathway. These findings were confirmed by gene co-expression network analysis where hub genes were identified as main drivers of invert sugar accumulation and sucrose loss. Our data provide insight into transcriptional changes in sugar beet roots during storage resulting in the characterization of key pathways and hub genes that might be further used as markers to improve pathogen resistance and storage properties.

Transient heat stress during tuber development alters post-harvest carbohydrate composition and decreases processing quality of chipping potatoes.

BACKGROUND: Adverse air and soil temperatures are abiotic stresses that occur frequently and vary widely in duration and magnitude. Heat stress limits productivity of cool-weather crops such as potato (Solanum tuberosum) and may degrade crop quality. Stem-end chip defect is a localized discoloration of potato chips that adversely affects finished chip quality. The causes of stem-end chip defects are poorly understood. RESULTS: Chipping potatoes were grown under controlled environmental conditions to test the hypothesis that stem-end chip defect is caused by transient heat stress during the growing season. Heat stress periods with 35 °C days and 29 °C nights were imposed approximately 3 months after planting and lasted for 3, 7 or 14 days. At harvest and after 1, 2 and 3 months of storage at 13 °C, potato tubers were evaluated for glucose, fructose, sucrose and dry matter contents at the basal and apical ends. Chips were fried and rated for defects at the same sampling times. Differences in responses to heat stress were observed among four varieties of chipping potatoes. Heat stress periods of 7 and 14 days increased reducing sugar content in the tuber basal and apical ends, decreased dry matter content, and increased the severity of stem-end chip defects. CONCLUSION: Transient heat stress during the growing season decreased post-harvest chipping potato quality. Tuber reducing sugars and stem-end chip defects increased while dry matter content decreased. Planting varieties with tolerance to transient heat stress may be an effective way to mitigate these detrimental effects on chipping potato quality. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Dynamic proteomic changes in soft wheat seeds during accelerated ageing.

Previous research demonstrated that soft wheat cultivars have better post-harvest storage tolerance than harder cultivars during accelerated ageing. To better understand this phenomenon, a tandem mass tag-based quantitative proteomic analysis of soft wheat seeds was performed at different storage times during accelerated ageing (germination ratios of 97%, 45%, 28%, and 6%). A total of 1,010 proteins were differentially regulated, of which 519 and 491 were up- and downregulated, respectively. Most of the differentially expressed proteins were predicted to be involved in nutrient reservoir, enzyme activity and regulation, energy and metabolism, and response to stimulus functions, consistent with processes occurring in hard wheat during artificial ageing. Notably, defense-associated proteins including wheatwin-2, pathogenesis-related proteins protecting against fungal invasion, and glutathione S-transferase and glutathione synthetase participating in reactive oxygen species (ROS) detoxification, were upregulated compared to levels in hard wheat during accelerated ageing. These upregulated proteins might be responsible for the superior post-harvest storage-tolerance of soft wheat cultivars during accelerated ageing compared with hard wheat. Although accelerated ageing could not fully mimic natural ageing, our findings provided novel dynamic proteomic insight into soft wheat seeds during seed deterioration.

Does improved storage technology promote modern input use and food security? Evidence from a randomized trial in Uganda.

We use panel data from a randomized controlled trial (RCT) administered among 1200 smallholders in Uganda to evaluate input use and food security impacts of an improved maize storage technology. After two seasons, households who received the technology were 10 percentage points more likely to plant hybrid maize varieties that are more susceptible to insect pests in storage than traditional lower-yielding varieties. Treated smallholders also stored maize for a longer period, reported a substantial drop in storage losses, and were less likely to use storage chemicals than untreated cohorts. Our results indicate that policies to promote soft kernel high-yielding hybrid maize varieties in sub-Saharan Africa should consider an improvement in post-harvest storage as a complementary intervention to increase adoption of these varieties.

Multitrait analysis of fresh-cut cantaloupe melon enables discrimination between storage times and temperatures and identifies potential markers for quality assessments.

Fresh-cut cantaloupe melon is valued for its aroma but is highly perishable. Temperature of storage (typically 0-5°C) is critical for maintaining fresh-cut melon quality, but often reaches 10°C during transportation and in retail outlets. A comparison amongst 0, 5 and 10°C storage temperatures for fresh-cut melon over 14days reveals that storage at 0°C is optimal for avoiding increases in microbial load and loss of vitamin C especially at later time points. However, higher temperatures maintain better the balance of esters (acetate versus non-acetate) and phenolic content. The whole volatile organic compound (VOC) profile can be used to discriminate both time and temperature effects especially at earlier time points. Potential VOC markers for changes in vitamin C from day 0 to day 6 of storage (3-methyl butane nitrile) and temperature (limonene) are identified through a multi-trait analysis.