Postharvest Deterioration Research Articles

Post Harvest Management of Vegetables: A Review

Horticulture is backbone of our country and greater population about 60-65% is directly or indirectly hooked in to it. In the export earnings for the country the role of horticultural produce is vital. In Indiaabout 20-40% of total horticulture produce wasted due to lack of post-harvest management of vegetables which resulted in huge financial loss.Most poor horticulture producers cannot meet the expense of modern technologies.Many metabolic changes occur in vegetables after harvesting that are influenced by disruption of supply of nutrients, water and growth regulators from the parent plant to the harvested vegetables. The overall process leads to postharvest deterioration of the produce. However, the losses are often reduced with adoption of postharvest management and use of processing technology of vegetable crops.

ANTIFUNGAL ACTIVITY OF SELECTED CHEMICAL AGENTS AGAINST PHYTOPATHOGENIC ISOLATED FUNGI SPORES.

Postharvest deterioration has been a major problem associated with yam storage for both famers and traders and it is caused mostly by micro-organisms especially fungi. During the storage of yam, many organisms such as Aspergillus flavus, Aspergillus niger, Penicillium citrinum and Rhizopus stolonifer are often reported to cause rotting of the stored yams. The aim of this research is to find out the antifungal effect of some commonly used anti-dermatophytic agents,(Fluconazole, Terbinafine Hcl, Ketoconazole, Sodium propionate and Griseofulvin) on the above named isolated fungi spores. This was carried out using zone of inhibition, MICs, MFCs, FICs and FFCs to measure the antifungal activities of the test antifungal agents against the isolated phytopathogenic fungi spores. These agents were found to have fungitoxic effects on the test organisms in the order of: Terbinafine Hcl > Fluconazole > Ketoconazole > Sodium propionate > Griseofulvin. This work indicated that the test antifungal agents were able to inhibit the fungi spores that are widely reported to be associated with yams rot when stored. The observation in this study showed that a good and efficient fungicide against the test organisms that are known to cause yam rot during storage can be effectively arrested with combination of these fungicides.

Silicon Nanoparticles Enhance Ginger Rhizomes Tolerance to Postharvest Deterioration and Resistance to Fusarium solani.

Postharvest deterioration of ginger rhizome caused by microorganisms or wound infections causes significant economic losses. Fusarium solani is one of the important causal agents of prevalent ginger disease soft rot across the world. The massive and continuous use of chemical fungicides in postharvest preservation pose risks to human health and produce environmental contamination. Hence, new alternative tools are required to reduce postharvest deterioration and extend the postharvest life of ginger. In this study, the use of silicon nanoparticles (SiNPs) on the storability of ginger rhizomes during postharvest storage and their resistance to Fusarium solani was investigated. The results showed that 50, 100, and 150 mg L−1 of SiNPs increased the firmness of the ginger rhizome during storage but decreased the decay severity, water loss, total color difference, and the reactive oxygen species (ROS; H2O2 and superoxide anion) accumulation. Specifically, 100 mg L−1 (SiNP100) demonstrated the best effect in the extension of postharvest life and improved the quality of the ginger rhizomes. SiNP100 application increased the activities of antioxidant enzymes (SOD and CAT) and the total phenolics and flavonoid contents, thereby reducing the ROS accumulation and malondialdehyde (MDA) content. Meanwhile, SiNP100 treatment negatively impacts the peroxidase (POD) and polyphenol oxidase (PPO) activities, which may have contributed to the lower level of lignin and decreased total color difference. SiNP100 likely decreased water loss and the transfer of water by altering the expression of aquaporin genes. Moreover, SiNP100 modulated the expression of lignin synthesis and phytopathogenic responses genes including MYB and LysM genes. Furthermore, SiNP100 inhibited Fusarium solani by preventing the penetration of hyphae into cells, thus decreasing the severity of postharvest pathogenic decay. In summary, this study revealed the physiology and molecular mechanisms of SiNPs-induced tolerance to postharvest deterioration and resistance to disease, which provides a foundation for using SiNPs resources as a promising alternative tool to maintain ginger quality and control postharvest diseases.

Control of fruit softening and Ascorbic acid accumulation by manipulation of SlIMP3 in tomato.

SummaryPostharvest deterioration is among the major challenges for the fruit industry. Regulation of the fruit softening rate is an effective strategy for extending shelf‐life and reducing the economic losses due postharvest deterioration. The tomato myoinositol monophosphatase 3 gene SlIMP3, which showed highest expression level in fruit, was expressed and purified. SlIMP3 demonstrated high affinity with the L‐Gal 1‐P and D‐Ins 3‐P, and acted as a bifunctional enzyme in the biosynthesis of AsA and myoinositol. Overexpression of SlIMP3 not only improved AsA and myoinositol content, but also increased cell wall thickness, improved fruit firmness, delayed fruit softening, decreased water loss, and extended shelf‐life. Overexpression of SlIMP3 also increased uronic acid, rhamnose, xylose, mannose, and galactose content in cell wall of fruit. Treating fruit with myoinositol obtained similar fruit phenotypes of SlIMP3‐overexpressed fruit, with increased cell wall thickness and delayed fruit softening. Meanwhile, overexpression of SlIMP3 conferred tomato fruit tolerance to Botrytis cinerea. The function of SlIMP3 in cell wall biogenesis and fruit softening were also verified using another tomato species, Ailsa Craig (AC). Overexpression of SlDHAR in fruit increased AsA content, but did not affect the cell wall thickness or fruit firmness and softening. The results support a critical role for SlIMP3 in AsA biosynthesis and cell wall biogenesis, and provide a new method of delaying tomato fruit softening, and insight into the link between AsA and cell wall metabolism.

Calcium Chloride Efficacy on Physicochemical Properties and Microbial Count of Chrysophyllum albidum- Linn Fruit during Storage

Chrysophyllum albidum fruits are underutilized because they are seasonal and perishable in nature due to physiological, biochemical and microbial alteration. This study investigated the potency of calcium chloride (CaCl2) in suppressing postharvest deterioration of Chrysophyllum albidum fruits. Ripe wholesome fruits of Chrysophyllum albidum were harvested and treated with different concentrations of CaCl2 (1, 2, and 3%) at three different dip times (5, 10, and 15 min). The goal was to use established analytical methods to investigate the influence of CaCl2 on the firmness, weight loss, pH, titratable acidity, total sugar (TS), pectin, color, microbial (fungi and bacteria) loads of Chrysophyllum albidum fruits. All the treated fruits were stored at ambient temperature 28 ± 2°C and 90± 5% relative humidity for 15 days. The obtained results indicated that treating Chrysophyllum albidum fruits with 3% CaCl2 for 15 min was found the most effective in controlling weight loss, microbial load, color, firmness, and other compositional changes such as pH, titratable acidity, pectin and total sugar. It was observed that CaCl2 treated samples showed reduced fungal loads from 6.00 × 103 SFU/g at harvest to 0.02 × 103 SFU/g after 15 d of storage as compared to untreated samples. No record of bacterial load was detected on Chrysophyllum albidum fruits treated with 3% CaCl2 for 15 min. The shelf life of Chrysophyllum albidum fruits could be extended for 15 d without excessive deterioration in quality by treating the fruits with 3% CaCl2 for 15 min with a minimum quality loss, as compared to the control sample which had greater compositional changes with maximum quality loss during storage at ambient temperature.

Exploring Farmers’ Knowledge and Approaches for Reducing Post-Harvest Physiological Deterioration of Cassava Roots in Malawi

Cassava utilisation in Malawi is negatively affected by rapid deterioration of fresh roots, primarily caused by postharvest physiological deterioration (PPD). A study was conducted to assess farmers’ knowledge and approaches used to minimize losses from PPD. Multi-stage sampling was used to identify districts, Extension Planning Areas (EPA’s) and farmers. Data were collected from 519 farmers using a structured questionnaire. Results revealed that PPD (74.0%) was the major post-harvest constraint followed by pests and diseases (62.1%). Farmers had varying knowledge levels on signs and causes of PPD. They were knowledgeable on PPD signs with 91.5% ably identifying PPD through change of pulp colour. The farmers also had moderate knowledge on causes of PPD, citing high temperature (57.6%) and over-staying of roots (56.2%) as main causes of PPD. Key methods for preventing PPD are: storage (43.0%) and piece-meal harvesting (40.4%). Only 2.6% of the farmers exploited varietal difference in dealing with PPD as some varieties (Sauti, Mpuma, Ching’amba, and Kalasa) take three to five days before showing PPD signs. Farmers’ knowledge levels and PPD preventive methods could be strengthened through: provision of training on post-harvest handling, improvement in storage and processing technologies; and application of advanced breeding techniques to exploit genetic variation in cassava germplasm.

Effectiveness of Ozonated Water for Preserving Quality and Extending Storability of Star Ruby Grapefruit

The aim of this study was to explore the impact of aqueous ozone technology on maintaining grapefruit flavor and freshness by minimizing the occurrence of postharvest deterioration. During the 2018 and 2019 seasons, Star Ruby grapefruit fruits were treated with 0.3 and 0.6 ppm aqueous ozone for 5 and 10 min after harvest at water temperatures of 5 °C and 15 °C, respectively. The fruits were stored for 40 days at 8 ± 1 °C with 85–90% relative humidity. The results revealed that all the ozonated water treatments reduced physiological weight loss, disease infection, and decay, as well as providing long-term protection to the fruits throughout storage. The best treatment for preserving the postharvest quality was 0.6 ppm ozonated water at 5 °C for 5 min, which successfully delayed ripening while concurrently preserving the TSS/acid ratios, total phenolics, and antioxidant activity. Overall, aqueous ozone treatment is a promising example of a treatment that is beginning to be utilized on a commercial scale. In accordance with the findings of this study, it can be deduced that aqueous ozone can be used to maintain fruit quality, reduce postharvest diseases, and extend storage life.

Kurthia gibsonii Mb126 immobilised chitinase against Aspergillus flavus, a fungal pathogen linked to lemon postharvest deterioration

Background of the study: As fungi become resistant to commonly used pesticides, fungicides are becoming not only more expensive, but also less effective in controlling postharvest infections. New chitinase immobilisation techniques are urgently needed to minimize enzyme costs while enhancing bio catalytic performance, antifungal activity, enzyme stability, and reusability. Objectives: The objective of this study was to immobilise chitinase of Kurthia gibsonii Mb126 by entrapping it in calcium alginate beads and to analyse its antifungal activities against Aspergillus flavus. Methods: The optimal parameters influencing the immobilization process and the characteristics of soluble and immobilised chitinase of K. gibsonii Mb126 were analysed. The antifungal activities of immobilised and free chitinase of K. gibsonii Mb126 against A. flavus, which was isolated from decayed lemon fruit, were performed using the agar-disk diffusion method. Free chitinase 25.0 mL (0.8 U/mL) and immobilised chitinase 0.06 g (specific activity 124–192 U/mg) were treated on separate lemon fruits for testing antifungal activity against A. flavus. Findings: K. gibsonii Mb126 chitinase was immobilised perfectly in calcium alginate beads. After optimising process parameters of immobilisation (sodium alginate concentration 3%, calcium chloride 0.2 M, 120 min. curing time), the specific activity of K. gibsonii Mb126 immobilised chitinase improved to 11.9-fold greater than the free form of chitinase and the immobilisation yield increased to 84%. It was observed that the thermal stability and storage stability of immobilised chitinase were better than those of free enzymes. The immobilised chitinase could be reused, and it retained 78% activity even after 16 cycles. The surface morphology of immobilised chitinase was observed in a scanning electron microscope at different magnification powers. Enzyme kinetics was studied and compared with that of its chitinase soluble counterpart. An in vitro study demonstrated that immobilised chitinase of K. gibsonii Mb126 has higher antifungal activity against A. flavus. In vivo experimental study of theantifungal nature of chitinase in lemon fruits infected by A. flavus indicated that immobilised chitinase significantly decreased the incidence of postharvest decay. Conclusion: The immobilised chitinase of K. gibsonii Mb126 can be utilised as an important source of sustainable and environmentally friendly fungicides to prevent pathogens and saprophytic fungi from food. Novelty: To the best of our knowledge, this is the one and only study report about the antifungal nature of immobilised chitinase against a fungus that causes postharvest decay in lemon fruits. Keywords: Kurthia gibsonii Mb126; Aspergillus flavus; immobilised chitinase; postharvest decay of lemon; sodium alginate

The Combined Effect of Hot Water Treatment and Chitosan Coating on Mango (Mangifera indica L. cv. Kent) Fruits to Control Postharvest Deterioration and Increase Fruit Quality

The synergistic effect of dipping in 55 °C for 5 min of hot water (HW) and 1% chitosan coating during the storage of mango at 13 ± 0.5 °C and 85%–90% relative humidity for 28 days was investigated. The combined treatment significantly suppressed the fruit decay percentage compared with both the single treatment and the control. In addition, the specific activities of key plant defense-related enzymes, including peroxidase (POD) and catalase (CAT), markedly increased. The increase occurred in the pulp of the fruits treated with the combined treatment compared to those treated with HW or chitosan alone. While the control fruits showed the lowest values, the combination of pre-storage HW treatment and chitosan coating maintained higher values of flesh hue angle (h°), vitamin C content, membrane stability index (MSI) percentage, as well as lower weight loss compared with the untreated mango fruits. The combined treatment and chitosan treatment alone delayed fruit ripening by keeping fruit firmness, lessening the continuous increase of total soluble solids (TSS), and slowing the decrease in titratable acidity (TA). The results showed that the combined application of HW treatment and chitosan coating can be used as an effective strategy to suppress postharvest decay and improve the quality of mango fruits.

Ergothioneine: a potential antioxidative and antimelanosis agent for food quality preservation.

The global population increase has increased the demand for food products. However, post-harvest deterioration because of oxidation and discoloration results in a drastic loss of food quality and supply. Thus, research has focused on developing strategies to minimize such losses. One of those strategies includes the application of ergothioneine (ET), a potent hydrophilic antioxidant, to several food products to overcome their short shelf-life. ET can be synthetic or derived from several species of edible mushrooms and their extracts, which are known sources of natural ET. Given the reported potential of ET in food quality preservation, this review compiles the recent applications of ET as a preservative for maintaining the quality of food commodities.

The Effect of Melanthera Scandens and Mimosa Pudica on Fungi Causing Postharvest Deterioration of Cassava Root Tubers

Fresh cassava (<i>Manihot esculenta</i>) tubers unlike most other tubers of root crops are highly perishable. This study, therefore, investigated the antifungal activities of ethanol and hot water extract of <i>Melanthera scandens</i> (vine) and <i>Mimosa pudica</i> (touch me not) on rot fungi of cassava. Rotten cassava tuber samples were inoculated into Potato Dextrose Agar (PDA) for isolation of rot fungi causing postharvest deterioration of cassava tubers. The fungi obtained were identified using macroscopic and microscopic characteristics. The establishment of the pathogenicity of the fungal isolates was carried out by inoculating freshly harvested cassava tubers with the isolated fungi. The ethanol and hot water extract of the selected plants were tested against the isolated fungi both <i>in vitro and in vivo</i>. The isolates were identified as <i>Aspergillus niger, Aspergillus flavus, Penicillium notatum, Penicillium sp, and Fusarium verticillioides. A. flavus</i> being the most virulent with a percentage in severity of (27.15) on day 7 as compared with <i>Aspergillus niger, Fusarium verticillioides, Penicillium sp, and Penicillium notatum</i> which had (25.22, 17.17, 15.76 and 14.71) respectively. In the <i>in vitro</i> test the plants exhibited a high degree of fungicidal activity by inhibiting the mycelia growth of the rot fungi and <i>Mimosa pudica</i> was more effective in the suppression of fungal growth than <i>Melanthera scandens</i>. In the <i>in vivo</i> test there was a higher percentage reduction in diameter of rot when the plant extract was applied after twenty four hours of microbial inoculation directly to the cassava tuber. The extracts of <i>Melanthera scandens</i> and <i>Mimosa pudica</i> can therefore be used as a bio fungicide to extend the shelf-life of freshly harvested cassava tubers.

Cassava Roots Wound Healing Prevents Postharvest Deterioration to Ensure Quality of Postharvest Roots

Cassava Roots Wound Healing Prevents Postharvest Deterioration to Ensure Quality of Postharvest Roots

Roselle anthocyanin stability profile and its potential role in post-harvest deterioration: A review

The conversion of roselle calyx into a dried extract without decreasing its consistency is a challenge, given the perishability of the calyx and instability of anthocyanin, which can quickly degrade and develop colored or unwanted brown colors because of its high reactivity. The most critical factors influencing anthocyanins' stability are pH, temperature, light and post-harvest-related enzymes. Besides, the calyx suffered wound injury when removing seed from the calyx, causing stress and eventually, microbial degradation. Nonetheless, mature anthocyanins stimulate plants by responding to stress, especially drought, high salinity, excess light and injury; it is also correlated with improved stress resistance as the genes of individual plants are triggered under these conditions modulate anthocyanin biosynthesis. This work investigates the stability and potential role of roselle anthocyanin in post harvest deterioration. Anthocyanin stability can, therefore, be achieved by maintaining low pH and temperature, acylation, glycosylation, copigmentation and encapsulation. In the quest for roselle deterioration biomarkers, the detection of critical enzymes, such as Chalcone synthase CHS and FH3 Flavanone 3 hydroxylase, would offer insight into the genetic modification of anthocyanin.

Molecular Characterization of Post Harvest Fungus Associated with Spoilt Broccoli

Broccoli (Brassica oleracea var. italica) is a nutritional vegetable that looks like a small tree. Despite the fact that it is extensively loaded with arrays of vitamins, minerals, fiber and antioxidants, it has been observed that it has a short lifespan of not more than 2-5 days due to post-harvest deterioration. A study was conducted to isolate and identify the common fungal pathogens causing post-harvest deterioration of broccoli crown. Diseased broccoli crowns were collected from Ogunabali Fruit Garden Market in D-Line, Port Harcourt Local Government Area of Rivers State. Fungal isolates were collected and morphologically identified. The DNA of the most common fungal isolate, BC-3B was molecularly characterized using Internal Transcribed Spacer 4 and 5 (ITS-4 and 5) molecular markers. The morphological studies revealed that the BC-3B isolate was an Aspergillus niger. The BC-3B isolate DNA sequence was aligned using Basic Local Alignment Search Tool for Nucleotide (BLASTN) 2.8.0 version of National Center for Biotechnology Information (NCBI) database. The molecular weight of the DNA of the isolates was over 600base pairs. Based on sequence similarity, it was observed that the broccoli isolate BC-3B was 93% identical to Aspergillus niger. From the above results, these findings showed that Aspergillus niger is the causal fungal pathogen of post-harvest rot of broccoli. Phylogenetic tree was constructed to access the relationship between the isolates obtained from this study. This study has provided information on some of the fungal organisms found in broccoli. It is anticipated that this result will provide information for disease control approach for alleviating the post-harvest losses of broccoli caused by Aspergillus niger and provide a foundation for further study of possible harm of consuming diseased broccoli.

Seaweed products for the future: Using current tools to develop a sustainable food industry

BackgroundAlthough commonly consumed in Asia, seaweeds are a largely underutilized food source in the Western world. However, interest is rising, and seaweeds have a major potential as both main and functional ingredients in European markets. The current barriers for seaweeds as food products relate to food safety, quality preservation and optimization, and food neophobia. Scope and approachThis commentary provides an overview of current challenges to providing seaweed in the European market and proposed solutions to tackle these obstacles, taking inspiration from other food sectors. Processing and packaging concepts for future manufacturing of seaweeds as food are explored and insight into market research and strategies for overcoming the barrier of consumer skepticism are given. Key findings and conclusionsTackling safety issues related to human consumption of seaweeds is required for their widespread use in food applications. Sustainable, multi-target mitigation strategies towards microbiological and chemical (excessive iodine, heavy metals, allergens) hazards are driving the improvement of food safety of seaweeds and derived products. Rapid post-harvest deterioration of seaweeds can be avoided through stabilization techniques, for instance through temporary storage solutions before final processing, direct utilization into food items, and packaging. Innovative drying and alternative processing strategies may reduce energy consumption and processing time, while at the same time improving the safety as well as the nutritional and sensory qualities of the product. Despite the rising popularity of Asian cuisine and the Western-consumers’ perception of seaweeds as a “healthy superfood”, understanding consumer behavior in relation to new foods and facilitating information-based decisions could reduce potential consumer skepticism. In conclusion, innovation tools discussed in this work can be exploited for further development of a sustainable seaweed food industry.

Untargeted Metabolomics Profiling of High Beta Carotene Cassava with respect to Postharvest Physiological Deterioration

Cassava roots undergo postharvest physiological deterioration (PPD), and for most varieties it sets in within 72 hours of harvest. An untargeted metabolomics approach combined with a data-driven approach for statistical analysis was used to characterize and profile high beta-carotene cassava varieties with the aim of identifying any relevant metabolite changes that occur during PPD. Sixteen cassava root samples from four cassava lines were planted in a greenhouse and harvested after four months. The samples included four of 2 conventionally bred beta carotene cassava varieties &amp;ndash; UMUCASS 38, UMUCASS 45 and four of 2 transgenic high beta carotene cultivars - EC20-7 and EC20-8 cassava lines. Extracts of fresh cassava roots from 20-100 mg tissues were used for the analyses and data were processed using Elements for Metabolomics software. Starch and lipid metabolites were the major constituents which may help explain the observed differences in starch and dry matter content among the varieties. The results provide further insight in the understanding of PPD and suggestions on controlling this deterioration in cassava are made.

Effects of exogenous melatonin on ripening and decay incidence in plums (Prunus salicina L. cv. Taoxingli) during storage at room temperature

The effects of exogenous melatonin on ripening and decay incidence of plum fruit (Prunus salicina L. cv. Taoxingli) were investigated after the plums at green mature stage were dipped in 0 (as the control), 0.05, or 0.1 mmol•L−1 melatonin solution for 1 h, and then stored at room temperature (25 ± 1 °C) and 75–80% relative humidity (RH) for 14 d. The results showed that melatonin treatments could slow the ripening process as indicated by the firmness, respiration rate, and ethylene production, and decreased the weight loss and decay incidence of plum fruit during storage. Moreover, the melatonin treatments activated the phenylpropanoid pathway by increasing the activities of phenylalanine ammonia-lyase (PAL), 4-coumarate-coenzyme A ligase (4CL), cinnamate-4-hydroxylase (4CH) and peroxidase (POD), and accompanied by higher contents of total phenols and lignin, which might be contributed to enhancing the disease resistance in plum fruit during storage. Therefore, it was suggested that melatonin application could be a promising method to suppress postharvest deterioration, maintain fruit quality and extend the shelf-life of plum fruit.

Metabolomics reveals dopa melanin involved in the enzymatic browning of the yellow cultivars of East Asian golden needle mushroom (Flammulina filiformis)

Browning seriously causes postharvest deterioration of the yellow cultivars of Flammulina filiformis, yet the browning process and its mechanism have not been described. Changes of L*, a*, b* values, the browning and whiteness index during air contacted storage were evaluated, uncovering the great loss of brightness and meanwhile the accumulation of yellowness and redness. Browning tissue showed an increase of malondialdehyde, total phenolics, and browning-related enzyme activities of polyphenol oxidase and peroxidase, in contrast to the decrease of bioprotective catalase, superoxide, and dismutase. Non-targeted metabolomics revealed an upregulation of melanin synthesis under oxidation stress, and targeted LC-MS/MS verified the upregulation of l-dopa (3,4-dihydroxy-l-phenylalanine) during browning. Pyrrole-2,3,5-tricarboxylic acid was identified in the degradation products of browning pigments after alkaline hydrogen peroxide by LC-MS/MS, suggesting the existence of 5,6-dihydroxyindole-2-carboxylic acid derived units of eumelanin. Therefore, the biosynthesis of eumelanin via l-dopa pathway could participate in the enzymatic browning of postharvest F. filiformis.

Metabolite changes of apple Penicillium expansum infection based on a UPLC-Q-TOF metabonomics approach

The Penicillium expansum (P. expansum) infection causes apple postharvest deterioration and declines the quality of apple derived products. Investigation into the metabolic process of apple P. expansum infection will help to illustrate the mechanism of pathology and discover the biomarkers for quality control. Here, the changes of metabolite during the apple P. expansum infection were explored by ultra performance liquid chromatography and the quadrupole-time of flight mass spectrometry (UPLC-Q-TOF/MS) based metabonomics. Between four group of 32 samples, average 1720 positive and 1761 negative peaks were obtained, which aligned into comparable peaks of 5048 and 4945. Significantly metabonomic differences were observed between the control and P. expansum infected samples. A total of 485 differential metabolites were screened. In these different metabolites, the majority of sugars were decreased during P. expansum infection, whereas the majority of organic acids, amino acids and peptides were increased. Changes in the profile of phenolics and fatty acids were diverse, and major of them were increased for disease resistance. Disturbed metabolic pathways in early infection were mainly secondary metabolite biosynthesis, ATP-binding cassette transporters, amino acid and carbon metabolism. The intergroup comparison obtained 140 differential metabolites to represent the core metabolic changes during infection. And 27 metabolites were strongly increased along with the disease process, which could aid the biomarker discovery. This study highlights the differential metabolites during the apple P. expansum infection, and provide a basis for further investigation.

Effect of Scopoletin and Carotenoids on Postharvest Physiological Deterioration (PPD) of Transgenic High Beta Carotene Cassava

Cassava tubers suffer from postharvest physiological deterioration (PPD) which normally sets in within 72 hours of harvest. This study examines the role of scopoletin and carotenoids in the onset or delay in PPD in two transgenic varieties EC20-7 and EC20-8 compared to a wild variety TME-7. Scopoletin and carotenoids were quantified by liquid chromatography-mass spectrometry. The scopoletin content (0.10 &amp;ndash; 0.20 nmol/g) in the fresh varieties was not significantly (P&amp;gt;0.05) different from the amount in stored cassava roots (12.58 &amp;ndash; 14.90 nmol/g). The carotenoid content values in EC20-7 variety were 6.66 &amp;micro;g/g (&amp;alpha;-carotene), 80.45 &amp;micro;g/g (&amp;beta;-carotene) and 5.98 &amp;micro;g/g (lutein). As for EC20-8, &amp;alpha;-carotene, &amp;beta;-carotene and lutein values were 6.19 &amp;micro;g/g, 69.11 &amp;micro;g/g and 3.12 &amp;micro;g/g, respectively. There was no significant (P&amp;gt;0.05) difference between the varieties in &amp;alpha;-carotene content but in their lutein content. The results indicate that carotenoids are more relevant in the delay of PPD and scopoletin content is not a major factor in PPD vascular streaking or discolouration. Hence scopoletin content of cassava varieties may not be considered as a chemical marker for determining the potential of PPD in cassava tubers.