The frozen food market is one of the largest and most dynamic sectors of the food industry. In spite of considerable competition between the frozen food industry and other sectors, extensive quantities of frozen foods are being consumed all over the world. Freezing being one of the best technique for food preservation is widely used for retaining taste, texture, and nutritional value in agricultural products over long storage periods since time immemorial. It provides combination of the beneficial effects of low temperatures preventing microbial growth, reduced chemical reactions, and delayed cellular metabolic reactions.
Freezing, regarded as superior to canning and dehydration, due to its requirement of shortest processing time. During late 1800, frozen storage cabinets were developed which used natural occurring ice and snow for preserving food outside. With the advancement in freezing technology, IQF has evolved as a most promising technology for preserving food and vegetables for longer time in same farm-fresh condition without bringing much alteration in its sensory and physio-chemical attributes. The safety and nutrition quality of frozen products are enhanced when high quality raw materials are used and good manufacturing practices are employed in the preservation process, and the products are kept in accordance with specified required temperatures.
Introduction- IQF Technology:
In Food Processing Industry, IQF stands for Individual Quick Freezing, indicating to each individual piece of food frozen separately from each other’s. Originally developed as a specific solution to block or cluster freezing of small-sized products, to preserve quality and to give unparalleled convenience to end-users. This method of freezing has a unique ability as it freezes all its components individually by keeping them separate from each other. This makes it easy to individually freeze and store products like peaches, berries, grapes, corn, peas, fish, shrimp and poultry products.
The major market segments for IQF are:
- Retail outlets for direct consumption
- Hotels, restaurants, caterers and eateries
- Food industries which use fruits and vegetables as raw material and want to process during the lean season
IQF relies on ultra-quick freezing i.e. freezing the product quickly for which there is requirement of very low temperatures of approx. -30°C to -40°C, for halting the activities of the microorganisms that are responsible for the spoilage of food product. This technology freezes each piece of food individually using fluidization technique, i.e. product is suspended on high velocity air, which leads to freezing of food products in 10 to 12 minutes which otherwise takes at least 3 to 4 hours. Thus, most of the properties of the parent food is preserved, as formation of big crystals does not takes place, which damages the tissues of food material. Moreover, it also presents the advantage of saving energy and time as one does not have to thaw or defrost the whole packet to take out only a portion and the rest shall remain frozen until further requirement.
Types of IQF System
Three extensively used technologies fluidized bed, plate freezing & Cryogenic freezing are very efficient, prevent product stickage, and produce a 100% IQF freezing output.
I. Direct Freezing
1. Fluidized Bed Freezing:
Commercially rapid freezing rates are achieved by introducing food product in an insulated tunnel having vigorous circulation of cold air. Food commodities are passed through this chilled tunnel on trays/ belt. Food is fluidized to form a bed of particles, which is then frozen by forcing cold air upward through the particles. Upward motion of the air through bed partially lift or suspend the particles, which leads to the speedy drying of the particles. This is a direct methord of freezing as cold air comes in direct contact with the product. Here the temperature of the air is approximately -18 to – 34°C and the velocity of the air kept high in the range of 2 – 5 m/sec. This process is economical for producing IQF products as variety of sizes and shapes can be accommodated. The depth of the bed of particles varies with the product. E.g. Solid food particles of the size of pea’s up to strawberries can be frozen with a depth of 1 to 5″ whereas Green beans/French beans are partially fluidizable products, and requires a depth of 8 to 10 inches.
- Cryogenic Freezing:
Few products like mushroom, tomatoes, strawberries and raspberries requires ultrafast freezing which can only be achieved by immersing them either in liquid nitrogen or liquid Carbon Dioxide at low temperature (below -60°C) for freezing the outer surface of the product instantaneously.
II. In Direct Freezing:
1. Plate freezing:
It is an indirect way of freezing food product. Food products are placed in contact with metal plates, which are indirectly cooled using cold brine or vaporizing refrigerants. This process is suitable for unpacked food stuffs e.g. shrimps. It is quite economical as it minimizes the problem of dehydration, defrosting and packet bulging.
- It produces the better quality frozen product possessing similar organoleptic and nutritional attributes as their raw form.
- One of the biggest benefits of individual quick freezing is having small portions of frozen food available at any time. IQF makes it easy to just defrost only the amount you need instead of thawing out an entire bag of frozen chicken breasts.
- It does not require any kind of chemical preservation for increasing shelf life.
Some of the IQF-able products are chopped spinach, chicken breast, peas, corn, shrimp, sliced tomatoes, beans, fruit berries etc. Agriculture produce and meat products are the gold mine of food industry which are considered as the main stay for economy and IQF helps in preserving this treasure efficiently without compromising with its nutritional and sensory qualities.