India is one of the leading producers of milk, fruits and vegetables. The cold storage industry is trying to keep pace with the country’s production, in order to exploit its immense potential. Arvind Surange brings a report on the development of the sector in the country, with special reference to modernisation of its infrastructure.
Cold chain is now recognised as an upcoming sector in India. A country which ranks first in milk production in the world, number two in fruit and vegetable (F&V) production and has substantial output of marine, meat and poultry products, warrants a fully developed and efficient cold chain facilities. Given this scenario, there is tremendous scope for the development of a well-streamlined cold chain sector.
Cold stores form the heart of the cold chain sector. Though cold stores made an entry in India at the beginning of the 20th century, its development as a full-fledged segment was rather slow. The units were typically designed for storage of potatoes and were located in states like Uttar Pradesh, West Bengal Punjab and Bihar. It was only in the 1960s that the idea of multi-product and multi-chamber cold stores was introduced, with Maharashtra taking the lead.
At present, the cold storage sector is undergoing a major metamorphosis, with the Government of India focusing on food preservation. Fortunately, the emphasis is also on energy efficiency as the sector is energy intensive.
With the advent of newer materials and equipment, every link of a cold chain renders itself open to improvement. As a result, construction, insulation, refrigeration equipment and controls are witnessing a sea change.
Realising the significance of the cold chain sector, the Government has taken initiatives through bodies like the National Horticulture Board (NHB) to establish standards to regulate all the components of the sector. Efforts are also being made to evolve the concept of a ‘green cold chain’. In short, the cold chain industry is undergoing both an evolution and a revolution.
The present article will cover the development of the cold storage sector in India with changes in the pattern of utilisation, design, construction practices and energy-saving concepts.
When India got Independence in 1947, there were only a few cold stores, mainly located in Uttar Pradesh, Punjab and West Bengal. Most of them were bulk cold stores designed for storage of potatoes. These were mainly based on old technology and design – thermal insulation and refrigeration systems with practically no automation involved. One of the oldest multi-chamber cold stores was located at the Fruit Research Station in Pune, and was said to be installed in 1932, during the British Rule. This was mainly an experimental station, with seven cold rooms, which worked on a common brine chilling plant. The unit was mainly used for studying cold storage parameters for a variety of fruit and vegetables grown in India. This proves that the concept of multi-product cold storage was realised in the 1930s itself. A few cold stores did come up in Mumbai in the 1950s, with a number of small chambers, mainly used for potatoes, some variety of fruits and dry fruits.
During the period between the 1950s and the 1960s, the development of the cold storage industry was mainly confined to Uttar Pradesh, Punjab, Delhi, Bihar, West Bengal, Madhya Pradesh and Gujarat, where cold stores of medium and large sizes were set up. But these were mainly bulk storage units for potatoes.
Major development of the concept of a multipurpose cold storage unit took off between 1965 and 1970, when a few units were established for storage of a variety of products in Bangalore and Pune.
MAFCO (Maharashtra Agro and Fruit Processing Corporation), a Government undertaking in Maharashtra, established around 1970, played a significant role in promoting the concept of multipurpose cold storage, food processing, freezing and the storage of frozen foods. It was followed by a few private promoters setting up units. But it was not an appreciable number. The capacities of multipurpose units generally ranged from 1,000 MT to 20,000 MT. The largest multipurpose unit with a capacity of 22,000 MT is located in the Turbhe Industrial Area in Navi Mumbai (M/s Savla Foods & Cold Storage).
Presently, the multipurpose units store a large number of food products, such as F&V, dry fruits, spices, milk products, confectionery and all types of frozen food.
THE GROWTH OF COLD STORAGE INDUSTRY
The perishable food production is estimated as:
- Milk: 115 Million MT (No. 1 in the world)
- F&V: 200 Million MT (No. 2 in the world)
- Fish: 6.4 Million MT
- Meat: Largest cattle population in the world
The food processing sector in India is growing at a steady pace. From an initial two per cent processing capacity, it has now grown to six per cent of F&V production with a present growth rate of about 14% to 15%. The target rate for the F&V processing segment in the next few years has been set at 20%. This shows that there is a great potential for the sector in India.
The growth of cold storage industry in India from the year 1955 to 2008 is shown in Table 1. Table 2 shows the region-wise breakup of the numbers of cold stores in different regions based on the data available for the year 2007. It is evident from Table 2 that the distribution of cold stores in different regions of India has not been uniform. Figure 1 additionally shows this region-wise distribution. Table 3 indicates the capacities in the MT of cold stores in different regions. Table 4 shows the sector-wise (public, private and cooperative sectors) distribution of cold stores based on the year 2007. Table 5 shows product-wise distribution of the cold storage capacity in 2007.
PRE-COOLING OF F&V
The concept of pre-cooling of grapes was introduced in the 1980s, primarily in Maharashtra, which is the leading grape-growing state in India. This helped the farmers to export grapes to areas like Europe and the Gulf countries. Later, the technology was adopted for other fruits like mango, pomegranate and orange.
Controlled atmosphere storage:
With the onset of the 21st century, the need was felt to set up controlled atmosphere (CA) storage, following trends in Europe, America and other countries. A number of CA stores have now been established in the northern part of the country, at locations which have proximity to the apple-growing regions. The capacities generally range between 1,000 MT and 12,000 MT. A project of 12,000 MT set up by CONCOR (a government body) is the largest in the country so far. A few units of smaller capacities have also been established in western and southern India.
There has been considerable interest in scientific ripening and storage of fruits like banana and mango in recent years, and units are being established at a number of places. A good development in this direction can be seen in southern India, Gujarat and Maharashtra.
With the growth of cold chain in the country, food distribution centres are also being established, with the first such unit constructed in Navi Mumbai. A number of smaller centres have been set up by the food retail sector, and a further growth is expected in the coming years.
COLD STORAGE CLASSIFICATION
As per the present-day practice, cold stores can be classified as follows:
- Bulk cold stores – generally for storage of a single commodity, which mostly operate on a seasonal basis, for example, storage for potatoes, chillies and apples.
- Multipurpose cold stores designed for storage of a variety of commodities, which operate round the year. The products stored in these types of cold stores are fruit, vegetables, dry fruits, spices, pulses and milk products. These units have been mainly located close to consumption centres.
- Small cold stores with pre-cooling facilities for fresh F&V, mainly, for export-oriented items like grapes. The major concentration of these units is in Maharashtra. But the trend is now picking up in other states like Karnataka, Andhra Pradesh and Gujarat.
- Frozen food stores with or without processing and freezing facility for fish, meat, poultry, dairy products and processed F&V. These units have helped the promotion and growth of the frozen food sector, both in the domestic and export markets. However, the percentage of food so processed is extremely low. There is a great potential for the growth in this category.
- Mini units/walk-in cold stores located at hotels restaurants, malls and supermarkets.
- CA stores for certain F&Vs like apples, pears and cherries.
- Ripening chambers mainly set up for bananas and mangoes.
TRENDS IN CONSTRUCTION PRACTICES
While the bulk cold stores have fewer large-sized chambers, the multi-purpose units have a larger number of smaller chambers designed for the simultaneous storage of a variety of items to suit the needs of farmers, traders and customers. The general types of construction followed in the Indian cold storage industry are as under:
- Conventional buildings with RCC frames, brick walls and truss-type sheet roofs or RCC slabs with internal floor structure of RCC or steel frame with wooden or steel grating
- Buildings with a single floor structure designed for mechanised loading and unloading of products
- Pre-engineered building structures designed with cold chambers constructed from sandwich-insulated panel
The latest trend is to have cold chambers in a single-floor construction, with heights varying from five to 12 metres or higher, with mechanised loading/unloading facilities. Some units have racks for stacking the goods.
Recent practices are:
Walls and ceiling: Insulated panel construction
Roof: Sheet metal roofing on trusses
a) Steel structure with steel grille floors for conventional loading
b) Racks for mechanised loading
Construction practices in India vary, depending on the size of the unit, location and pattern of utilisation. Small cold stores usually have sandwich-panel construction.
In case of medium and large cold stores, the facilities involve a) Loading/unloading areas
b) Ante rooms
c) Cold storage chambers
d) Staircases and lifts
e) Machine room
f) Office, toilets and other facilities.
Conventional buildings have multi-floor chambers, where loading and unloading is done manually. The floor height ranges from two to 2.5 metres, and the number of floors from three to six.
The evolution of the cold storage construction practice is shown in the four figures depicted as follows:
TRENDS IN THERMAL INSULATION PRACTICES
Thermal insulation is an extremely important component in a cold chain system. It performs two vital functions:
1. To minimise the flow of heat from the surrounding areas to the inside space
2. To minimise the flow of moisture from surrounding areas to cold chambers
It is, therefore, important to select proper material with the right thickness, vapour barrier, cladding and the method of application to ensure that the basic objectives of providing thermal insulation are fulfilled in the best possible manner. It needs to be kept in mind that while the refrigeration system works for certain number of hours, depending on the load requirement, the insulation is on a continuous 24×7 duty for the entire period of storage.
In some old units, cheaper material, like rice husk, was once used as thermal insulation. Although the insulation itself was very cheap, it necessitated very large insulation thicknesses and also caused maintenance and hygiene problems. This method is almost extinct now.
In cold stores, having conventional construction built after the 1970s, the general practice has been to use insulation materials like Expanded Polystyrene (EPS), fibreglass, Polyurethane Rigid Foam (PUF) or similar materials. Recently, materials like Extruded Polystyrene (XPS) have also been introduced.
The old practice in case of conventional construction was to fix the insulation with bitumen as vapour barrier and using wooden pegs and batten framework, covered with chicken wire mesh and cement and sand plaster. However, the current practice is to avoid the use of wooden battens and use metallic runners instead, to support the sheet metal cladding, which are generally profiled pre-coated sheets.
Sandwich-insulated panel structure
The development of insulated panels has ushered in a revolution in the cold storage construction the world over. Although, these panels have been in use for cold storage construction for over four decades in the developed countries, in India, sandwich panels were introduced only about 25 years ago. Sandwich panels are mainly available in two types:
1. EPS panels, with EPS bonded to the sheet metal skins by using a special type of glue
2. PUF panels using Polyurethane as insulation material foamed between the two metal skins. These panels are structurally strong and have a better insulation value as compared to EPS panels for a given thickness
Insulated panels have been used for making cold stores, right from the small walk-ins to very large cold stores. In fact, the application of panels has gone beyond the cold storage sector, and the panels are being used for construction of processing plants, prefabricated houses, warehouses, clean rooms and the like. The panels have also been used for fabricating doors for cold stores, which are light and simple in construction, compared to the conventional insulated doors.
The panels offer greater flexibility and a faster pace of construction, apart from better thermal efficiency due to better isolation between the outside and the inside areas. The use of panels eliminates brick walls and RCC slabs, thereby increasing the cold store volume for a given footprint. The major advantage is the possibility of modular construction with ease of addition or expansion. Panels are available with different types of skin finish and offer a better hygienic environment to the structure.
TRENDS IN REFRIGERATION SYSTEM
Over 90% of the cold store units built in the northern and the eastern parts of India were based on old technology, involving use of slow-speed ammonia refrigeration compressor, without any capacity control, atmospheric condensers and either bunker-type evaporator coils or floor-mounted air cooling units (diffusers) with ducting for air distribution. These plants were not very energy efficient, due to lack of capacity control, loss of expensive cold storage space for large-sized bunker coils or diffuser units and associated ducting.
The current practices involve energy-efficient designs of equipment and use reciprocating and screw compressors with capacity control, evaporative condensers with MS (hot-dip galvanised) or SS coils and ceiling-suspended finned air- cooling units using MS or SS coils with aluminium fins. The types of fans used in the units have SS/aluminium or FRP blades. The FRP option offers the benefit of lower HP motors for the fans.
Refrigeration systems for cold storage application can be classified as:
- Modular units using HFC/HCFC refrigerant
- Central plants using HFC/HCFC refrigerants with air- cooled/water-cooled machines
- Central plants using ammonia refrigerant
- Vapour-absorption system using ammonia-water combination. This system is now being considered for rural areas due to availability of alternative fuels like biogas and agrofuel.
The flow of products to and from the cold store is an important aspect in cold storage functioning. In conventional cold stores, the loading and unloading of products is still done manually. However, in recent installations, the practice is to use electrical hoists/lifts and/or forklift trucks for handling of products. These storages incorporate rack structures in the chambers for storing products in pallets or boxes. Arrangement for loading of pallets in containers and reefer vans is also provided in the modern cold store units. Use of computers to control loading, unloading operations and to maintain the record of stocks is also in practice in some of the new colds stores.
Cold storage is the heart of the cold chain. Refrigeration is the fundamental process for cooling, pre-cooling, freezing and cold storage. Among the various methods of food preservation, refrigeration is the best one, and there is no substitute for it in terms of quality and extended life. However, refrigeration is an expensive process, both in terms of first cost and energy cost.
Lack of adequate energy supply and rising energy rates are serious problems faced by the cold storage sector. Owners and manufacturers in the sector have increasingly begun to realise the need for adopting various energy-saving methods.
In recent years, the Green Building movement has attracted the attention of planners, designers, builders and contractors the world over. The author has also propagated the concept of ‘green cold chain’ involving green cold stores in India.
An overview of the cold chain system in India over the past five to six decades shows that cold storage construction technology, practices of thermal insulation, refrigeration plant technology, automation and material handling have undergone significant transformation. From the point of view of utilisation, too, the cold stores today offer a much wider scope than in the past. Energy-saving and ‘green cold chain’ concepts are also being seriously looked at by progressive entrepreneurs and designers. However, it must be noted that for a country which is a frontrunner in milk production and in the second position in F&V production, the overall storage capacity of around 25 million MT of cold storage available in the country cannot be considered adequate. Thus, there appears to be a good potential for the development of modern and energy-efficient storage units.
The NHB has taken a big step forward in establishing technical standards for cold chain projects. The following three standards have been developed with the help of experts in the industry, and are available to the promoters and designers of cold chain projects for reference:
(i) Cold storages for storage of fresh horticulture products which do not require pre-cooling
(ii) Multi-commodity cold storages for short-term and long-term storage of fresh horticulture products which require pre-cooling and varying storage requirements
(iii) CA storages
Apart from these, the standards on ripening chambers and refrigerated transport have also been recently released for public review. It is worth mentioning that this is the first attempt by any Government agency to formulate such standards for cold chain projects in India. Efforts are on for establishing standards for ripening chambers and refrigerated transportation. Government agencies like the NHB, National Horticultural Mission and the Ministry of Food Processing have also offered higher financial incentives for new projects as well as for expansion of existing units. However, these projects have to be essentially based on modern and efficient technology so that they are in tune with the new technical standards.
A scientifically developed cold chain, designed to handle and preserve the quality and quantity of food products grown in the country, would turn into a ‘gold chain’ for the country.
The writer is with ACR Project Consultants, Pune, India. He can be contacted at +919822406897