बागवानी फसलों के शेल्फ जीवन विस्तार के लिए बायोडिग्रेडेबल नैनो फॉर्म्यूलेशन
Horticulture crops play important role in economic development of the country and it contributes 30.4 per cent to GDP of agriculture. But the post-harvest loss reduced the quality of commodities, in India the estimated loss ranges from 14-36% in fruits and 10-25% in vegetables.
Every year we lost approx 1 lakh crore Rs due to post harvest losses in horticulture crops. Ripened fruits are terribly spoil and prone to transport harm which consequently leads to loss of quality and quantity. This is particularly common in developing countries because of poor post-harvest handling systems, storage facilities and transportation.
Various factors responsible for post-harvest losses can be categorized into two major categories.
First, pre harvest losses because of farmers’ poor agricultural techniques (i.e. varieties with low shelf life, imbalanced use of nutrients, abiotic stresses, insects, pests and disease infestation), old harvesting procedures, non-utilization of pre-harvest suggested methods.
Second, harvest losses due to careless harvesting, harvesting at inappropriate stage, dumping produce without pre-cooling, moisture strengthening that causes pathogen infestation, bulk packaging without grading of produce and reprehensible transportation and storage to distant market distribution. These losses return low profits to growers and processors.
Adverse Effects of Chemicals on fruits and vegetables:
Traditionally, post-harvest management practices/ techniques like pre-cooling after harvest, refrigeration storage, post-harvest uniform heat treatment of tomatoes, modified atmosphere packaging and use of agrochemicals calcium chloride (CaCl2), 1-methylcyclopropene, nitric oxide, H2O2, salicylic acid and sodium selenate are followed to protect/ uphold the quality of fresh fruits and vegetables.
Treatments with synthetic fungicides namely fenhexamid, pyraclostrobin, boscalid etc. has also been the major practice to overcome the postharvest diseases. But, simultaneously, international worries have also been rising over the indiscriminate use of synthetic fungicides on crops because of their harmful effects on human health and the emergence of pathogen resistance against fungicides.
Chemical residues easily distributed in the edible portion of commodities that is responsible for reduced the quality. Toxic organic and inorganic compounds are entering the environment. Long term adverse effects on living organisms.
Why biodegradable Nanoformulation to be used:
Biodegradable nano formulations are effective as compared to other compounds due to high surface-to-volume ratio, small size of the particles (1nm) and high charge density. Chitosan based nano-materials have been explored in agriculture for plant protection and growth.
They are preferably used worldwide for their biodegradability, high permeability, eco-friendly, non-toxicity to human and cost effectiveness. Currently the application of nanomaterials seems to be very attractive in preventing post harvest losses in fruits and vegetable.
Nanoparticles are more effective against microbes at very low dose. It also extends the shelf life of fruits and vegetables by controlling growth and developments of micro organisms. That's why we need to explore newer alternatives to reduce the use of synthetic fungicides.
How it reduce post harvest losses:
Effect of nanoparticles on Fungal decay:
In agriculture, application of nano-based products such as nano-fungicides, nano-bacteriocides, nano-fertilizers and slow release of macro/micro-nutrients are being endorsed from laboratory to field level for crop protection and higher yield.
Because of the efficacy of nano-based materials in crop protection and yield, various nanomaterials have been applied as coating agent, nanolamination, spray, or as enforcement compounds in various fruits and vegetables.
Microbial decay contributes up to ~70% losses in fruits and vegetables and is, therefore, very crucial to control it during storage. Nano materials are more potent in degrading microbial cell wall and inhibiting transcription-and translation by binding with microbial DNA and anionic proteins.
Nanoparticles have also been reported as plant immune booster and enhance the activities of defense antioxidant enzymes. Therefore, nanoparticles more elegantly prevent the microbial infection and act as nano-shield on fruit surface.
Effect of nanoparticle on Physiological parameters:
Physiological parameters of fruits (physiological loss in weight, texture, colour, firmness and respiration rate) change during storage. These changes have severe impact on the quality, nutritional value and subsequent marketability of fruits.
During post-harvest storage, environmental factors adversely affect the cellular homeostasis which crumples the texture and induces quality degradation in fruits and vegetables.
Physiological loss in weight is a primary concern during post-harvest storage of horticulture crops. It is known as a great indicator of fruit freshness and mainly occurs as a result of water loss by transpiration and reserve carbon loss by respiration.
The nanoparticle acts as a semi-permeable barrier for oxygen, carbon dioxide, moisture and other solutes which in turn reduces respiration, moisture loss and oxidation reactions.
Firmness is also an important attribute in post-harvest life of fruit and affects the acceptance by the consumers. Firmness retention by nanoparticles to inhibitory activity against pectate lyase, polygalacturonase and cellulase which are responsible for degradation of cell wall and subsequent loss of firmness.
Similarly, respiration rate increase during storage. Respiration rate in fruits is crucial and affects the overall metabolic activities. Its higher rate severely decreases the shelf-life of fruits. This suppression of respiration rate by nanoparticles due to partial blockage of pores on the surface of fruit.
Previous studies have revealed that nonmaterials acts as a barrier film that creates a modified internal atmosphere by selectively permeating C2H4, CO2 and O2 in and out of fruit leading to a reduced rate of respiration and transpiration.
Effect of nanoparticle on Quality attributes:
Bioactive compounds (titrable acidity, ascorbic acid, total and reducing sugars, lycopene, phenol compounds) are very essential component of fruits and vegetables. Titrable acidity (TA) is one of the important quality parameters to evaluate the sour taste of fruits.
Generally, level of acidity uniformly decreases during storage due to the consumption of organic acids in respiratory processes to maintain the normal activity of fruits. Nanomaterials slow down the physiological processes in fruits by reducing ethylene production, respiration and hence abbreviates the consumption of organic acids.
Ascorbic acid is one of the most important nutritional components in fruits and acts as an antioxidant molecule to resist senescence. Its content decreased with the advancement of fruit ripening. Variability in ascorbic acid content is related to the ripening stage where a green fruit exhibits higher content of ascorbic acid than a ripened fruit.
Nanoparticles have the potential to create a semipermeable film on fruit surface which limits fruit respiratory metabolism and thereby slows the decline of ascorbic acid. Generally, total and reducing sugars in tomato increase during storage periods. Starch degradation during ripening is the cause of glucose production and fruit sweetness.
It is speculated that nanoparticles on fruits abates gaseous exchange and lowers O2 level that reduces the metabolic activity and thus delays conversion of starch into sugars. Lycopene is principally responsible for the characteristic deep-red color of tomato, watermelon and papaya fruits.
Lycopene content in tomato remarkably increased during storage. Nanoparticle reduces the availability of O2 in fruit which in turn inhibits the development of lycopene. Phenolic compounds are responsible for changes in color and flavor, loss of nutritional value and shelf-life of a fruit.
The inhibition of phenol compounds by nanosilica polymer which adsorbs polyphenol oxidase or its substrates and also chelates metal ions at active site and reduces its activity.
Conclusion:
Biodegradable Nanoformulation efficiently used to reduce post harvest losses because of their higher surface to volume ratio that helps to increase the activity of nanoparticles which enhance the quality and shelf life of fruits and vegetables.
Due to the small particle size facilitates its penetration to the plant cells, better absorption, and high reactivity by plant cells. Nanoparticle has charge density, which effectively interact with the negatively charged surfaces of bacterial cells.
It reduces the oxidation reaction as the result it reduce the respiratory activity taking place in fruits and vegetables after harvest, thereby increasing the shelf life of fruits and vegetables.
Nanomaterials effectively prevented microbial decay, physiological loss in weight, maintained fruit firmness and reduced the respiration rate in fruits and vegetables during stored.
It also delayed the loss of titratable acidity, retained the TSS, total sugars, reducing sugars, ascorbic acid, lycopene and phenol content. Nanoparticles are very effective at less concentration and thus exert minimum chemical load on the treated horticulture crops.
The cost can decrease as well as increasing profit by using nano formulations are eco-friendly. Therefore, nanoparticles have potential to be further explored in post-harvest technology. It may be validated in large scale experiments for translation of technology.
Authors:
Mahendra Meena, Heera Lal Atal, Dr. Shalini Pilania and Dr. K.K. Meena
RARI, Durgapura, Jaipur and BCKV, West Bengal and MPUAT, Udaipur
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