A liquid food with a viscosity of 5cP and a density of 1000 k/m3 is pasteurize. In a first stage and in a tube heat exchanger the product is heats up to a temperature of 85C, in the second stage the product is circulated through a retention tube (stainless steel, diameter internal= 0.02561 m). The product leaves the holding tube at a temperature of 82.2C. In the process if you want to reach a Fo of 12D based on inactivation of Staphylococcus aureus (D= 0.063 min at 82.2C). What should be the length of the holding tube if the feed flow is 19 litres/min?