Depending on the quality of milk about 1 Kg of khoa is produced from 4 to 6 Kg of milk and with this assumption the total consumption of this product is estimated to be around 9 million tons / annum ( around 5.5 % of total indigenous milk production). Presently, khoa is made in jacketed kettles or open trays (‘Kadai’) which have a number of disadvantages. The major Disadvantages with the conventional method.

• Batch process and not suitable for large scale production
• Unsanitary operation
• Spillage of the product which makes the floor slippery causing accident
• Bulky equipment due to low heat transfer co-efficient.
• Formation of hard scale of milk protein on heating surface resulting low efficiency
• Long residence time in the equipment causing greater risk of spoilage of the product
• Excessive strain and fatigue on the operator

Keeping in mind the disadvantages, a new machine has been designed by National Dairy Research Institute, Karnal on the basis of heat transfer and hydrodynamics in non-Newtonian mechanically agitated thin film. It is a cascade system comprising of two horizontal straight sided thin film scraped surface heat exchangers. The equipment is fabricated and tested for the manufacture khoa from standardised buffalo milk. In this heat exchanger, milk is concentrated to about 40% total solid which then flows into the second heat exchanger. The newly designed has several advantages like :

• High heat transfer co-efficient
• Total absence of fouling of heat transfer surface
• Short residence time which results in high production capacity
• Product is confined to thin film on the heating surface and consequently hold volume is extremely small
• Adaptable to easy automation and cleaning in place (CIP).
• Hygienic operation
• Uniform product quality

PROCESS

The equipment can be fabricated in a workshop with stainless sheet. The accessories are attached with the equipment.