Mixing - Raw ingredients, such as fresh or powdered milk, water, vegetable oil or butter-fat, sugar, stabilizers and emulsifiers are introduced into the stainless steel tank and blended with rapid agitation. The alternate use of the two tanks ensures a continuous production process.
Pre-heating - The heating system supplies hot water via the circulation pump. Then the mix is heated to 55°C by means of hot water in the jacket. The alternate use of the two tanks ensures a continuous production process. Once the temperature is reached the mix is transferred to the balance tank via a centrifugal pump.
Heating - From balance tank a second feeding pump collects the mix and sends it to the exchanger in the regeneration section. Here the incoming mix is heated to 75°C by outgoing pasteurized mix.
Homogenization - Once the pre-set temperature has been reached, the mix is pumped into the high pressure homogenizer which breaks down and reduces fat globules at working pressure of 200 bar to obtain a great ice cream structure.
Pasteurization and holding - After this the mix is heated further up to 85°C and maintained at this temperature for 30 seconds in a holding tube. The pasteurizing temperature is continuously monitored and recorded. An automatic flow diversion valve at the end of the holding tube returns insufficiently pasteurized mix to the balance tank in case the temperature falls below the limit.
Subsequently the pasteurized mix is fed to the regenerative cooling sections where it is cooled down to 65°C by the incoming mix. The recovery of the thermal energy reduces the energy demand of the unit to a minimum, and it is one of the strong advantages of Mix Plant HTST.
Cooling - In the end, the mix pass through the plate heat exchanger where it is cooled by tower water and cooled further with chilled water to reach 4 - 6°C of final mix temperature. The mix is then stored at 4°C in the ageing tank for at least 4 to 6 hours and usually overnight.