Postharvest Application Research Articles

Development of EVA and LLDPE polymer-based carvone and spearmint essential oil release systems for citrus postharvest diseases applications

Carvone and spearmint essential oil vapours are suitable candidates for the control of citrus postharvest pathogens due to their strong antifungal activity. However, the high volatility of essential oils remains a hurdle that needs to be overcome before it can be applied as an alternative fungicide. This work investigates the antifungal activity of 20 and 30 wt-% spearmint essential oil or carvone, incorporated into ethylene–vinyl acetate (EVA) and linear low-density polyethylene (LLDPE) strands postharvest pathogens affecting kumquats. Following the melt-extrusion process, an average yield of 16–29 % and 15–28 % of the total carvone and spearmint essential oil, respectively, was determined in the polymer strands. Morphological studies using scanning electron microscopy (SEM) revealed the presence of microporous structures in the internal structure of the strands. The membrane-like skin that covers the polymer strand was also confirmed by SEM. Variations in the release rates were observed between carvone and spearmint essential oils, which was attributed to the difference in the vapour pressure of the neat essential oils. Furthermore, in this study, the results demonstrated that the diffusion exponent ‘n’ of the Korsmeyer–Peppas, Weibull and Log-logistic models exceeded 1.0. In most cases, the Super Case II mechanism was observed. In the case of the Mapossa model, as k2 was ˃> 1, it implies that the outer skin-like membrane covering the polymer strand fully controlled the carvone release. The application of the essential oil-loaded polymer strands resulted in a significant reduction in deterioration, caused by citrus postharvest pathogens, of kumquats kept at room temperature for 21 days. This study indicates that the incorporation of spearmint essential oil or carvone into LLDPE or EVA polymer strands promoted the preservation of kumquat over a 21-day period.

Phenylalanine induces mango fruit resistance against chilling injuries during storage at suboptimal temperature

Cold is the best means of prolonging fruit storage. However, tropical fruit are susceptible to cold storage. The mode of action of mango fruit tolerance to suboptimal cold temperature of 7 or 10 °C after postharvest application of 8 mM phenylalanine was investigated using transcriptomic and metabolomic analyses of mango fruit during suboptimal cold storage. Phenylalanine-treated fruit had less chilling injuries—black spot and pitting electrolyte leakage,—and reduced decay after suboptimal cold storage. Phenylalanine treatment induced genes related to plant–pathogen interactions, plant hormone signal transduction, and the phenylpropanoid pathway, increasing the levels of the flavonoids quercetin and kaempferol glycosides and anthocyanins, and antioxidant content. Reduced oxidation led to lower lipid peroxidation, and a reduction in fatty acid-degradation products, e.g., volatile aldehydes. Treatment with phenylalanine, therefore, enhances chilling tolerance of mango fruit through regulation of metabolic and defense-related pathways, maintaining high levels of flavonoids, and antioxidants enzyme activity, and reducing H2O2 content, lipid peroxidation, and volatile aldehydes.

Postharvest physiology and biochemistry of Valencia orange after coatings with chitosan nanoparticles as edible for green mold protection under room storage conditions.

Because of their unique features, nanomaterials have been proposed and have gained acceptance in postharvest applications in fruit. Increasing the storage life and improving the quality of Valencia oranges was investigated using nano-chitosan. A chitosan nanoparticle was prepared by using high-energy ball milling. Chitosan nanoparticles were characterized by Dynamic light scattering, FTIR spectroscopy and Surface morphology by transmission electron microscopy. Fully mature Valencia oranges were harvested and then coated with one of these concentrations (0.2, 0.4, and 0.8% nano-chitosan) and control. The fruits were stored under room storage conditions for 75 days. The quality parameters (fruit weight losses, fruit decay percentage, fruit firmness, total acidity, total soluble solids percentage and T.S.S./acid ratio, ascorbic acid content) were taken in biweekly intervals after 0, 15, 30, 45, 60, and 75 days. Beside the in vitro testing of antifungal activity of chitosan nanoparticles. According to the findings of the two succeeding seasons, the nano-chitosan 0.8% treatment showed the best effects and had the lowest rate of fruit weight loss, fruit deterioration, and T.S.S./acid ratio in comparison to the other treatments in both seasons. Furthermore, the 0.8% nano-chitosan reveled the highest levels of fruit hardness and fruit pulp firmness. Fruit weight loss, fruit deterioration, TSS, and TSS/acid ratio, as well as other metrics, were steadily elevated prior to the storage time. The best results were obtained when Valencia oranges fruits were treated with 0.8% nano-chitosan for 75 days at room temperature.

Optimized Alternating Current Electric Field and Light Irradiance for Caulerpa lentillifera Biomass Sustainability—An Innovative Approach for Potential Postharvest Applications

Recently published preliminary data proposed alternating current electric field (ACEF) as a promising technique for the postharvest storage of seagrape (Caulerpa lentillifera). The current study suggested a combination of storage light irradiance (SLI) and ACEF (intensity and time) to enhance seagrape physicochemical quality (PQ). It utilized Taguchi orthogonal array design (OAD) to optimize the processing conditions. Results showed all the processing parameters had significant (p < 0.05) effects on seagrape PQ. This study found that 50 kV/m for 60 min (ACEF) and 9 mol photons m−2 s−1 performed the best inhibition on seagrape PQ deterioration. It revealed that adjusting the processing parameters in the range explored in this study (50, 125, 200 kV/m of ACEF intensity; 30, 60, 90 min of ACEF treatment time; 2, 9, 16 mol photons m−2 s−1 of SLI) can reduce up to 60% of total voltage usage compared to the previous study. With a sufficient SLI and an intermediate treatment time, the finest seagrape PQ can be sustained with a lower electric strength. Therefore, this method can benefit seagrape industries and contribute to realizing sustainable development goals by strengthening resource efficiency and lowering energy consumption.

Antifungal activity of natamycin against kiwifruit soft rot caused by Botryosphaeria dothidea and potential mechanisms

Soft rot caused by Botryosphaeria dothidea leads to massive economic losses in the kiwifruit industry. Natamycin is a natural antimicrobial preservative that effectively prevents postharvest decay and preserves fruit quality. However, the ability to control kiwifruit soft rot and potential antifungal mechanisms have not been explored. In this study, the inhibitory impact of natamycin against soft rot caused by B. dothidea, as well as its putative action mechanisms were investigated. The results indicated that 2 mg L−1 natamycin effectively inhibited mycelial growth and spore germination of B. dothidea in vitro. Natamycin caused B. dothidea hypha to shrink and deform, along with vacuolation and plasmolysis in hypha cells, as observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Likewise, natamycin stimulated the accumulation of reactive oxygen species (ROS) in the hypha. The inhibition effect of natamycin on B. dothidea inoculated in kiwifruit was dose-dependent, with 500 mg L−1 natamycin significantly decreasing the incidence of soft rot to 35%. Furthermore, natamycin induced disease resistance in kiwifruit tissue by activating the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT), increasing the antioxidant compound total phenol, maintaining a low level of malondialdehyde (MDA), and repressing the activity of four cell wall degrading enzymes, as well as gene expression of β-galactosidase (β-Gal) and polygalacturonase (PG). Further field research revealed that pre-harvest treatment combined with the postharvest natamycin application significantly reduced the natural decay incidence of kiwifruit while having no negative effect on soft-ripe quality. In conclusion, our findings proved that natamycin has an antifungal effect on B. dothidea and may be applied as a safe preservative to reduce soft rot.

Salicylic acid and herbal extracts prolong vase life and improve quality of carnation (Dianthus caryophyllus L.) flowers

• Exposure to 50 and 100 mg L − 1 SA resulted in marked increased in vase life of carnation flower. • The bacterial population in flowers exposed to 150 mgL −1 SA vase solution was 83% lower than that of control. • SA treated flowers displayed a dramatic increase in protein, CAT and POD activities compare to untreated control. • Salix and Mentha leaf extracts and SA enhanced the expression of CAT and POD genes, with SA treatment being most superior. The natural limitation of the cut carnation ( Dianthus caryophyllus L.) flower vase-life, led to complications in marketing and long-distance transportation. Different chemical preservatives and growth regulators are currently in use to extend the shelf and postharvest life of cut flowers. This research was aimed to evaluate the impacts of Salix and Mentha leaf extracts (SE and ME) and salicylic acid (SA) on post-harvest quality and vase life status of cut carnations flowers. Cut carnations were exposed to the various concentrations of SE and ME (25, 50 and 100 mg L − 1 ) and SA (50, 100 and 150 mg L − 1 ) vase solutions. All concentrations of SE, ME and SA considerably prolonged the vase life and increased membrane stability index (MSI), protein and antioxidant enzyme activity of catalase (CAT) and peroxidase (POD). Exposure to 50 and 100 mg L − 1 SA resulted in marked increase in vase life. In flowers treated with 150 mgL −1 SA vase solution, the bacterial population was 83% lower than control. The SA treated flowers displayed a dramatic increase in protein, CAT and POD activities compared to untreated control. Furthermore, ME, SE and SA treatments enhanced the expression of CAT and POD genes, but this increase was much greater with SA treatment. In general, post-harvest application of SA in comparison with ME and SE and control improved longevity in cut carnation flowers by enhancing the scavenging ability related to CAT and POD activity and improving the water balance.

Postharvest application of 1-methylcyclopropene delays chloroplast degradation in Gynura bicolor DC under sugar scarcity conditions

• 1-MCP fumigation effectively delayed sugar scarcity. • 1-MCP fumigation delayed RuBisCo and chlorophyll degradation. • 1-MCP fumigation blocked the expression of GbATGs and GbSAG101 . • Sugar scarcity induced ROS burst in chloroplasts. • RuBisCo was preferentially degraded over chlorophyll. During postharvest transport and storage stage , Gynura bicolor DC ( G. bicolor ) is commonly handled in the darkness. However, long-term storage in the dark exacerbates postharvest sugar scarcity. 1-methylcyclopropene (1-MCP) was showing effective in inhibiting postharvest physiological metabolism of fruits and vegetables. The aim of this research was to uncover the mechanism underlying the effects of 1-MCP on the chloroplasts of G. bicolor under postharvest sugar scarcity conditions. The status of carbon sources, the enzymes and genes involved in chloroplast degradation were investigated. Furthermore, reactive oxygen species (ROS), chloroplast function, and chloroplast structure were also investigated to examine the physiological changes that occur in chloroplasts during storage. Degradations of starch, soluble sugar, and soluble protein were effectively retarded by 1-MCP. The increase of free amino acid content and decay rate were markedly inhibited by 1-MCP. 1-MCP not only inhibited the ROS burst, structural disintegration, and function (maximum photochemical efficiency Fv/Fm, effective quantum yield of PSII photochemistry QY, and relative electron transfer rate ETR) decreased in chloroplast, but also delayed the increased activities of chlorophyll degraded-related enzymes (chlorophyllase CHL, pheophytin pheophorbide hydrolase PPH and Mg-dechelatase), and proteinases (cysteine proteinase CP, serine proteinase SP and total proteinases TP), which retarding the ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCo), and chlorophyll degradation. The upregulated expressions of GbCHL, GbPPH, Gb-proteinases, GbATGs , and GbSAG101 were markedly blocked by 1-MCP. Correlation analysis showed that ROS burst was associated with sugar scarcity, the upregulated expressions of GbATGs , and GbSAG101 were associated with sugar scarcity and ROS burst, chlorophyll degradation was associated with the RuBisCo level. In conclusion, 1-MCP effectively delayed chloroplast degradation in G. bicolor by retarding sugar scarcity, inhibiting ROS burst in chloroplast, blocking the upregulated expressions of genes involved chloroplast degradation, and delaying the activities increase in proteases and chlorophyll degraded-related enzymes.

Cell wall composition and enzyme-related activities in eggplant as affected by hot water, 1-MCP and calcium chloride treatments.

The effects of postharvest applications of hot water (HWT) (45, 50, and 55 °C), 1-MCP (1, 5, and 10 μL/L), and CaCl2 (1, 2, and 3%) on polygalacturonase (PG), pectin methylesterase (PME), α-galactosidase (α-Gal), β-galactosidase (β-Gal) and β-1,4-glucanase (β-1,4-Glu) activities, and the fruit firmness and cell wall composition of eggplant fruit were investigated. The results showed that the decrease in the eggplants firmness was delayed by HWT, 1-MCP, and CaCl2 treatments during storage compared with the control. However, HWTs were less effective than the 1-MCP and CaCl2 treatments. The results show that 1-MCP and CaCl2 treatments inhibited the depolymerization of water (WSP), CDTA (CSP), and sodium carbonate (SSP) soluble polyuronides. The results suggest that 1-MCP (5 and 10 μL/L) and CaCl2 (1, 2, and 3%) could prevent eggplant softening by inhibiting hydrolase enzymes and reducing the disintegration of the polysaccharides. In addition, 1-MCP and CaCl2 were more effective than hot water treatment in extending postharvest storage life. There is a significantly high correlation between firmness, polyuronide content and cell wall enzyme activity.

Effect of exogenous melatonin in fruit postharvest, crosstalk with hormones, and defense mechanism for oxidative stress management

AbstractDerived from tryptophan, melatonin (MT; N‐acetyl‐5‐methoxytryptamine) is a ubiquitous indoleamine that is widely distributed in species ranging from microorganisms to mammals. It has been associated to play vital roles in the human body like cardiac rhythms, immunological enhancement, and antioxidant activity. In plants, it is a pleiotropic molecule with multiple roles, as it not only performs extensive functions like delaying senescence, growth and development regulation, exerting antioxidant effects, and facilitating adaption of plants to certain biotic and abiotic stress responses but also provides resistance to chilling injury and disease development. This paper reviews the latest progress in the multiple roles of MT in fruits, summarizes the pathways for its biosynthesis, and presents the relation of MT with plant hormones, like auxin, cytokinin, ethylene, gibberellins, abscisic acid, jasmonic, and salicylic acid, and highlights the effect of postharvest application of MT on physiology and quality of fruits, action mechanisms, and safety regulations of MT. Recent trends focus on using alternatives that are safe for postharvest produce and do not have major side effects. MT is a better alternative to hazardous chemicals being commercially used in the postharvest management of fruits and providing future directions for its utilization.

Changes of the microbial community in kiwifruit during storage after postharvest application of Wickerhamomyces anomalus

High-throughput sequencing techniques can provide important information for understanding the interaction between exogenous microbial agents and fruit microbial communities, and explain how it controls postharvest fungal diseases. In this study, we found that Wickerhamomyces anomalus could control the postharvest disease of kiwifruit. Meanwhile, high-throughput sequencing technology results showed that the composition and structure changes of the fungal community in microbial flora were significantly greater than those of bacteria after W. anomalus treated. W. anomalus could colonize inside the fruit and regulate the community composition of bacteria to reduce the abundance of pathogens and eventually maintain the healthy state of the fruit. The dominant genus in the microbiota of kiwifruit after application of W. anomalus showed an increased ability to interact. Some fungi or bacteria are positively associated with yeast in the epiphytic and endophytic sample communities, guiding the synthesis of compound biocontrol strains for kiwifruit postharvest diseases.

Effect of exogenous postharvest application with thyme and cinnamon oils on quality and storability of cherry tomato

Cherry tomato are classified as perishable fruits that deteriorate vastly after harvest. The use of natural and eco-friendly products, such as essential oils, for preserving the quality of fresh fruits and vegetables is highly demands for the consumers. Thus, the aim of this study was to evaluate the efficiency of exogenous postharvest application with thyme oil (1%), cinnamon oil (1%), and their combination on quality and shelf-life of cherry tomato stored for 28 days at 10°C and 90% RH. The results indicated that both essential oils were able to preserve the quality of cherry tomato by reducing weight loss, decay, appearance, and firmness. Additionally, essential oils application conserved total soluble solids, total carbohydrates, and total phenolic compounds. Lycopene and carotene contents were decreased by essential oils application. In conclusion, the application of both essential oils could be effective in maintain the quality and increase the shelf-life of cherry tomato during refrigerated storage.

Postharvest Exogenous Melatonin Treatment of Table Grape Berry Enhances Quality and Maintains Bioactive Compounds during Refrigerated Storage

Table grape berries are classified as a perishable crop that deteriorates quickly after harvest. The application of melatonin after harvest was found to be effective for retarding senescence and slowing ripening. In the current study, we tested the influence of two melatonin concentrations (50 and 100 µmol) as a postharvest application on quality, bioactive compounds, and enzyme activities of grape berries cv “Crimson” stored at 0 ± 1 °C and 90% relative humidity (RH) for 35 days. Our results indicated that melatonin application extends the shelf-life of berries by reducing weight loss and maintaining total soluble solids (TSS), titratable acidity (TA), berry adherence strength, and firmness. Melatonin treatment also reduced pectin methyl esterase (PME) and polygalactouranase (PG) enzyme activities compared to the control. Moreover, O2•− and H2O2 rates in berries were reduced by high melatonin concentration. Moreover, peroxidase (POD) and catalase (CAT) enzyme activities were increased by melatonin application. Our findings suggested using melatonin postharvest to increase shelf life and maintain quality attributes during refrigerated storage, which could be advantageous on a large scale.

Role of Post-harvest Treatment of Polyamines on Physico-physiological Qualities of Papaya (Carica papaya L.) Fruits Var. Red Lady during Ambient Storage

Polyamines are the natural compound, act as anti-senescent agents, reduce rate of respiration, delay ethylene production, retard colour change, maintain fruit firmness. Show that plays a pivotal role in postharvest life of fruits and vegetables. The objective of this study was to investigate the effect of post-harvest application of polyamines in different concentration on physico-physiological quality parameters of papaya fruits during ambient storage (33-36oC). Papaya fruits are treated with different concentration of polyamines i.e., T2-0.50mM Spermine, T3- 1.0mM Spermine,T4- 1.5mM Spermine,T5- 0.50 mMSpermidine, T6- 1 mM Spermidine,T7- 1.5mM Spermidine,T8- 2 mM Putrescine,T9- 3 mM Putrescine,T10- 4 mM Putrescine and T1-Control. Among the treatments, papaya fruits treated with 4 mM of Putrescine (T10) recorded significantly minimum physiological loss in weight, respiration rate and colourvalues (L*, a*, b*) of peel and pulp, fruit disease index and maximum firmness, shelf life compared to control (T1). Hence it is confirmed from the study that Putrescine at 4mM (T10) was found to be effective in delaying the physico-chemical and physiological process of papaya fruit cv. Red Lady.

ADAPTABILITY OF APPLE VARIETES TO FUNGAL DISEASES AND PHYSIOLOGICAL DISORDERS, DEPENDING ON THE STORAGE TECHNOLOGY APPLIED

A special feature of apple fruits is that they can be kept for a longer period of time. However, during storage, the fruits are affected by certain diseases, which can cause considerable losses. As a result of research, it has been established that the technology used is one of the main factors in the storage period, able to regulate the intensity of ripening senescence processes in apple fruits, and as a result their degree of resistance to fungal diseases and physiological disorders. Fitomag has had a significant influence not only on the fruit ripening process, but also on the quality and resistance to fungal diseases and physiological disorders. The investigated fruits had an attractive appearance, high firmness, juiciness and a more pleasant taste, compared to the control fruits. The storage technology by post-harvest application of Fitomag can compete with that of storage under controlled atmosphere (AC) conditions, the advantages of the researched preparation being: simplicity in application, low electricity consumption during storage and minimal equipment investments.

Effect of methyl jasmonate on the quality and antioxidant capacity by modulating ascorbate-glutathione cycle in peach fruit

We investigated the effect of methyl jasmonate (MeJA) on the quality and antioxidant capacity in ‘Xiahui 8’ peach fruit during storage at 20°C and 90–95% relative humidity (RH) for 7 days. Exogenous MeJA maintained better fruit quality during storage, as indicated by reduced weight loss, respiration rate, ethylene production and total soluble solids, as well as maintained appearance and firmness. MeJA treatment significantly improved the activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) in peach fruit, therefore, reducing the accumulation of superoxide anion (O2−), hydrogen peroxide (H2O2) and malondialdehyde (MDA). Additionally, MeJA treatment enhanced the metabolic intensity of AsA-GSH cycle, as key enzyme activities involved in AsA-GSH cycle were markedly increased. These MeJA-promoting effect increased the content of reduced ascorbate (AsA) and glutathione (GSH), and the ratios of reduced to oxidized forms of AsA and GSH, contributing to higher redox status in peach fruit. Collectively, these results suggest that MeJA can maintain better fruit quality and improve antioxidant ability through enhancing AsA-GSH cycle, thus suitable for postharvest application.

Postharvest Application of Aloe Vera Gel Improved Shelf Life and Quality of Strawberry (Fragaria x ananassa Duch.)

Strawberry is highly appreciated for its aroma and texture, but rapid detrimental changes lead to decay and loss of quality in strawberries, which are the main reasons for huge economic losses. To tackle this major concern, this research focused on assessing the efficacy of edible coatings based on aloe vera (AV) gel to maintain quality parameters and postharvest storage of strawberries. Fruits were coated with gel containing one of five different concentrations of AV gel (0%, 20%, 40%, 60% and 80%) and stored at 1 °C and 95% relative humidity (RH) for up to 20 days. The weight loss, total soluble solids and malondialdehyde content was higher in untreated fruits, whilst these parameters were reduced in treated fruits. The AV gel treated fruits also maintained firmness, titratable acidity, ascorbic acid and total antioxidant activity, whereas, a significant decrease in these parameters was observed in untreated fruits. Furthermore, AV gel coated fruits had better superoxide dismutase, catalase and ascorbate peroxidase activities than uncoated fruits. Additionally, AV gel coatings reduced the rate of loss of total phenolic and flavonoid contents during storage. Consequently, it is concluded that AV gel edible coating is recommended for improving postharvest life and for maintaining maximum quality characteristics of strawberry stored for 20 days stored at 1 °C and 95% RH. Among all treatments, 80% AV gel revealed the best results in maintaining the overall fruit quality and delaying ripening throughout the storage period

Methyl jasmonate encapsulated in protein-based nanoparticles to enhance water dispersibility and used as coatings to improve cherry tomato storage

Exogenous methyl jasmonate (MeJA) has been demonstrated to improve plant resistance to environmental stresses and fruit storability, but its poor aqueous solubility limits its application. This work fabricated colloidal-stable MeJA loaded gliadin-casein nanoparticles (MeJA/G-C NPs) to increase its water dispersibility and applied it as edible coatings to improve storability of cherry tomato. The NPs could increase the dispersibility of MeJA by 30-fold to 20 mmol L−1 with a mean particle diameter of 218 ± 2 nm, and zeta-potential of 13.7 ± 0.2 mV. The multiple light scattering test showed that MeJA as cargo could hinder the flocculation/coalescence of the nanocarrier system. Molecular docking showed that the interactions between MeJA with gliadin were stronger than that with casein. The MeJA is encapsulated in gliadin via hydrophobic interactions of alkyl groups augmented by three hydrogen bonds between the CO groups of MeJA and the Leu149, Val148, and Ile109 of gliadin. The MeJA/G-C NPs could effectively delay the ripening process and maintain the quality of cherry tomato during room temperature storage. It also alleviated chilling injury (CI) in cherry tomatoes during long-term cold storage. This study is beneficial for the development of edible nano-coatings and MeJA in postharvest applications.

Nano-clay, layered-double hydroxide (LDH), improves the efficacy of double‐stranded RNA in controlling postharvest decay

Major losses in postharvest fruit and vegetables are due to rotting caused by pathogenic fungi. The environmental impact of fungicides requires new eco-friendly strategies to control postharvest pathogens. B. cinerea, a major postharvest pathogen, was controlled by dsRNA targeting three key genes in ergosterol biosynthesis. However, due to the limited stability of dsRNA, we incorporated the dsRNA in layered-double hydroxide (LDH) nano-clays to protect the dsRNA from degradation and serve as a long-term controlled-release mechanism. Our results show that either in-vitro and in-planta, the hyphae and conidia emergence zone of the germination tube of B. cinerea can uptake free dsRNA or when it was complexed with LDH. The fungal inhibition provided by either form of dsRNA was selective to B. cinerea and not for other pathogens. Notably, the LDH-dsRNA complex maintained its potency for at least six weeks of cold storage and reduced gray mold development significantly better when compared to naked dsRNA after long storage. Scanning electron microscopy images implies that LDH by itself forms a mechanical barrier and delays the fungal colonization in the fruit. Furthermore, a modified atmosphere can influence the release of the dsRNA from the LDH complex. Thus, increased levels of CO2 and humidity increase LDH degradation, and the dsRNA release from the complex. Overall, our results suggest that the incorporation of dsRNA in LDH under suitable conditions may serve as a safe alternative to the postharvest application of fungicides.

The effect of post-harvest chitosan applications on some chemical changes of potatoes during storage

Objective: The objective of this study was determination of effects of the chitosan application on changes at some chemical properties of potatoes such as dry matter rate, C vitamin amount, total soluble solids rates, total phenolic compounds and total antioxidant capacity. Material and Method: In this research carried out in cold storage, 4 doses (control, 0.5%, 1% and 2%) of chitosan were applied to potato tubers by spraying method before storage. Results: Among chitosan treatments, 1 % treatment was most effective in terms of preventing the increase dry matter rate (by 50%) and the decrease C vitamin content (by approximately 40%) during the storage. The increase of total phenolic compounds by 20% at the end of storage was prevented with chitosan applications compared to control. Conclusion: Results show that the application of chitosan can reduce some chemical changes that occur in potatoes during storage.

Postharvest application effect of agave fructans on anthracnose disease, defense-related enzyme activities, and quality attributes in avocado fruit.

The postharvest application of high degree of polymerization agave fructans (HDPAF) was tested, evaluating anthracnose disease, defense-related enzyme activities, and quality attributes in avocado fruit. Application of a 20% HDPAF solution showed a reduction in anthracnose severity (60%) and incidence (34%) compared to the other concentrations evaluated and the water-treated control. Polyphenoloxidase activity increased 4.6 times more 24h after treatment. In addition, peroxidase and phenylalanine ammonia-lyase enzyme activity was 4.34 and 1.7 times higher than the control at 0.5h after treatment. HDPAF retrieves the deceleration of both firmness loss and physiological weight loss compared to the control. Regarding quality parameters such as color, pH, total soluble solids, and titratable acidity, no significant differences were observed between treatments compared to the control; therefore, these parameters were not negatively affected by HDPAF treatments, but a positive effect on the induction of the defense system is shown.