Dr. Sanath Kumar H and Dr. Binaya Bhusan Nayak
ICAR-CIFE develops a solar powered cooler for maintaining the shelf-life of fish. It will benefit to both retailers and consumers.
Fish production and consumption is continuously increasing in India making fish an integral part of diet of a large proportion of population. The demand for fish continues to grow in India, and the increase in per capita consumption offers vast opportunities for retail fish business.
Retail fish markets play a very important role in making fish available to consumers at a reasonable price. A large proportion of fish vendors in retail fish markets of India is constituted by individuals operating on a very small scale. The retail markets have tremendous potential to grow and offer great opportunities for startups. As a result, the retail trade has witnessed a shift from traditional ways of selling fish to modern retail businesses.
The highly perishable nature of fish poses a challenge of maintaing quality of fresh fish for selling in retail markets. Icing is the preferred method of storing fresh fish. However, most fish sellers carry limited quantities of fish for sale owing to lack of own transportation facilities. The use of ice increases the bulk of fish and hence is generally avoided. Even when ice is used, a very limited quantity is used for a short period of time as ice is not generally available in the vicinity of fish market for replenishment. Further the prohibitive cost of ice prevents its use by retail fish vendors who are engaged in day-to-day fish sale and lack facilities to cold store the left over fish.
“Substantial quantity of fish is lost due to post harvest spoilage, primarily due to non-availably of cold chain. This accounts for about 25% of fish catch worth more than 15,000 crores.”
Fresh fish sold in retail markets at room temperature undergoes biochemical and microbial changes leading to compromised fish quality, reduced price and issues related to food safety. Fish vendors in Mumbai use bamboo or plastic baskets to display fish meant for sale, usually uncovered, exposing fresh fish to contamination from dust, aerosols and insects.
One of the key interventions that can remediate the loss of quality due to spoilage and unhygienic storage conditions is through providing a cost effective cooling solution to fish vendors. Solar cooling is one such powerful solution, which is not only environment friendly but also economical to implement and operate.
This is also a practical approach in tropical countries like India, where abundant day light is available for almost two-thirds of a year. Solar cooling essentially involves capturing solar energy using photovoltaic cells and converting it into electrical energy to run a cooler. A solar panel is used to capture and generate electric energy from sunlight, which can be stored in a battery so that the stored energy can be used during dark hours.
“This concept of solar-powered cooling facilities can be very useful to retail fish vendors to store their fish in chilled and hygienic conditions.”
The Post-Harvest Technology Department of ICAR-Central Institute of Fisheries Education (CIFE) in Mumbai has developed a solar-powered cooling system that can be used by retail fish vendors. The project to develop a solar fish cooler was funded by “Rajiv Gandhi Science and Technology Commission (RGSTC)”, Maharashtra.
The solar cooler developed under this project can hold about 50 kg of fish. The cooler is powered by two solar panels, which can be rotated in the direction of sunlight. The power generated by solar panels is stored in a battery and supplied to the compressor through a smart converter.
Although the cooler can attain a temperature of -20oC by default, the temperature has been set at 0-5oC using a thermostat. This condition is similar to fish stored in ice, a preferred method for storing fresh fish meant for retail sale. This temperature range reduces the power requirement of the cooler and helps to prolong the cooling and storage time. A small quantity of ice can also be used to keep fish, and the cooler temperature of 0-5oC will retard melting of ice and prolong the chilled storage in the event of less battery power on days of shorter day light.
Since the power supply is automatically cut once set temperature is reached, any additional power generated by the solar panels will be stored in the battery. When fully charged, the battery can support the cooler for approximately 6 hours. Conversion of DC power to AC in this system makes it more efficient in terms of power consumption.
At present, the system makes use of commercial freezers with optimum power requirement for longer cooling hours. A cooler with DC compressor has also been developed which can directly use solar power. This system is currently under evaluation.
To facilitate mobility of solar cooler, a steel cabinet was designed with facilities to mount cooler, battery and other electrical components. The unit has steel surface to clean the fish.A commercial freezer is fitted to the system.
The solar panels are rotatable which also provide shade to the vendor. The entire unit is mounted on wheels so that the fish cooler can be moved around comfortably. This cabinet also helps to protect the cooler and electric components from wear and tear since the unit is meant to keep in the open.
In case of emergency, the cooler can be plugged into electrical grid and can be run with regular alternating current. The system has already been demonstrated to fisherwomen of Versova and exhibited in local fishermen festivals. The cooling system is expected to improve the quality of fish sold in the retail markets and loss of food fish due to spoilage. A better quality fish will also ensure better price for fish sold in the retail markets.
(Dr Kumar is a senior scientist and Dr. Nayak is the Head of the Department of Post-Harvest Technology, ICAR-CIFE. Views expressed are their personal.)