Applications of RefrigerationFour major areas: a) Food preservation b) Chemical and process industries c) Special Applications d) Comfort / industrial air-conditioning
Food PreservationWhat is food preservation?Retaining food over a period of time without being contaminated by pathogenic organisms or chemicals and without losing its colour, texture, flavour and nutritious value.Why food preservation? Seasonal availability of food Different type of food at different locations
Food Preservation Advantages: Increases the shelf life of food Retain the quality of food – colour, texture, flavour & nutrition value Increases food supply Adds variety to the food decreases wastage of food
Food spoilage Food components: Proteins Carbohydrates Fats Vitamins Minerals Destruction of any of these component is food spoilage.
Cause of food spoilage Spoilage due to physical change impact, bruising and squeezing desiccation or dehydration Spoilage due to chemical change internal spoiling agents : Enzymes external spoiling agents: bacteria, yeast, moulds (fungus)
Methods of food preservation Heat processing Dehydration Chemical preservation Canning Pasteurization Freezing
Freezing for food preservation Slow or sharp freezing Quick freezing smaller ice crystals no separation of minerals, salts Immersion freezing Indirect contact freezing Air blast freezers
Cold stores To store food products after processing Prefabricated insulated panels Air tight door in sandwich construction Safety anti-locking arrangement Temperatures – positive or sub-zero Layout – air lock, sorting-cum-intermediate storage area, store compartments Important points – temperature, RH, air motion, product mix, duration
Methods of Pre-coolingDifferent methods of Pre-Cooling includes:1) Hydrocooling2) Vacuum Cooling3) Forced Air Cooling4) Contact Icing5) Evaporative CoolingCaution. No matter what cooling method is employed, the produceshould never be allowed to re-warm once it has been cooled.