Shabiha Nur Khatoon
Indian Agricultural Research Institute scientists have designed a solar cart with a view to increasing the shelf life of vegetables that has come as a boon for thousands of small vendors…
The ministry of food processing industries of India has come up with a new solar-powered vending cart – designed by the Indian Agricultural Research Institute (IARI) – to reduce the wastage of vegetables and fruits by keeping them fresh for up to five days. This surely comes as a boon to thousands of vegetable vendors across the country.
Vegetable vendors are mostly poor people selling their wares in local areas. They procure vegetables from the wholesale markets. During summer, due to considerably less relative humidity, vegetables get spoiled in a day or two at the most. The government needs to take steps to address the income woes of vendors.
A few scientists in New Delhi have designed a solar-powered vending cart that may help increase the shelf life of vegetables and alleviate the vendors’ grind of sprinkling water on their vegetables on hot days.
With the veggie cart, street vendors now can do away with the practice of keeping vegetables and fruits in wet gunny bags and sprinkling water on the vegetables at frequent intervals. While the solar powered cart has a cooling effect, it also contributes to spoilage, with green leafy vegetables, tomatoes and cucumbers among others lasting only two days. The solar power panels atop the cart generate electricity to evaporative cool, a closed chamber just beneath the vending platform, lowering the temperatures inside by 8°C to 11°C, scientists at the Indian Agricultural Research Institute (IARI) said.
In field tests during summer, the evaporative cooled cart – which requires about 20 litres of water a day – was able to keep fruits and vegetables fresh for two to five days compared to conventional carts.
Mahendra Kumar Mohanty of the College of Agriculture, Engineering & Technology, Orissa University of Agriculture and Technology, shared with Sunday POST the nitty-gritty of the solar-powered cart.
Fruits and vegetables account for 92.3 per cent of the total horticultural production of the country. Around 2.1 per cent of the production is used by processing industries; the remaining produce is either consumed soon after harvest or stored for later use in a fresh form. India wastes fruits and vegetables each year equivalent to the annual consumption of the United Kingdom!
Absence of sufficient storage facilities after harvest results in deterioration in the quality of fruits and vegetables that reach the market. This has an immediate impact on the distribution and availability of the required amount for human consumption. The most imperative parameters influencing the post-harvest life and quality of horticultural produce are temperature and relative humidity (RH).
The high cost involved in developing cold storage or controlled atmosphere storage on a movable cart is a pressing problem in India and several developing countries. Evaporative cooling is an efficient and economical means for reducing the temperature and increasing RH in an enclosure.
Evaporative cooled storage has proved to be useful for short-term storage of fruits and vegetables in hot and dry regions. It has been extensively used for enhancing the shelf life of horticultural produce, which is essential for maintaining the freshness of the commodities.
“Evaporative cooling is an environment friendly air-conditioning system that operates using induced processes of heat and mass transfer, where water and air are the working fluids,” said Mohanty.
“It provides an inexpensive, energy-efficient, environmentally benign (not requiring ozone damaging gas as in active systems) and potentially attractive cooling system. A conventional vegetable vending cart does not provide any environmentally controlled storage space for vegetables. One of the alternatives to keep the vegetables safe during summer is the use of a refrigeration system. However, this is expensive and dependent on electric power. The solar-powered cart has already been used by the vendors in Delhi and the response is positive. Scientists are also planning to launch the cart in different states of India so that every street side vendor can avail the benefits of the cart,” he added.
“The vending cart is ideal for hot and dry weather,” said Pramod Sharma, an agricultural engineering researcher who led the field experiments.
He explained in detail the usage of the cart. A solar-powered evaporative cooled mobile vending cart has been developed to store fresh vegetables for a short duration. Suitable modifications in the design have been made to provide an additional storage area of about 8.0 cubic feet below the main platform and between the four wheels of the conventional cart. Provision has been made for making the lower section evaporative cooled so that fruits and vegetables can be kept safely for a longer period of time at the retail vendor’s level. Provision has also been made for cooling pads and channels for application and distribution of water around the additional 8.0 cubic feet storage space for vegetables and fruits. Also, on top of the platform, provision has been made for water dispersal through cotton wicks and two stationary funnel-bucket assemblies. The evaporative cooling system of the cart uses solar power.
The solar-powered vending cart was tested for its performance during summer. The minimum and maximum drop in temperature ranged between 8.1°C and 11.2°C and increase in RH was observed to be up to 15 per cent and 25 per cent in June. This system is an excellent alternative for short duration storage of fresh fruits and vegetables at a low cost. It not only reduces the storage temperature but also increases RH which is essential for maintaining the freshness of the commodities.
Kishore, who has a vegetable stall near Unit I in the state capital, said: “The solar cart is a piece of good news for vendors like us who are expected to deliver fresh vegetables to customers. Earlier, I used to throw away the rotten vegetables and fruits, especially during the summer days. With the solar-powered cart vendors have the option of keeping their products fresh and saleable.”
