Electricity + Control August 2016

TEMPERATURE MEASUREMENT

Making ‘cents’ in Pasteurisation Benjamin Mlangeni and Natlee Chetty, Endress+Hauser

Heating processes for the preservation of beverages, pose as one of the most critical points concerning product quality and safety in any beverage production.

T hese processes, therefore, are always part of the HACCP (Hazard Analysis and Critical Control Points) concept of a plant and are usually under special observation in any production audit. Endress+Hauser provides expert solutions guaranteeing consistent production quality, safety and compliance, increased productivity, conservation of resources and lower production costs. Flash pasteurisation ( HTST – H igh T emperature S hort T ime) and UHT treatment – U ltra H igh T emperature) is the most common heat- ing processes for preservation of beverages. The basic mechanism of all processes is to kill spoilage micro-organisms by exposing the product to a certain temperature for a specific amount of time. The higher the temperature, the shorter the necessary exposure time – this is the main difference between the different procedures. As temperature is the critical value, it must be controlled and monitored very accurately to guarantee product safety and quality. Flash pasteurisation or HTST is used for careful preservation of perishable beverages like beer and juices. The name goes back to the French chemist and microbiologist Louis Pasteur, who invented the heat treatment of beverages in 1862. Spoilage microorganisms are inactivated, to increase product safety and to extend shelf life of

the beverage. The product is heated and exposed to temperatures between 68…75°C for a certain time (30…60 seconds). Successful inactivation of micro-organisms is mainly dependent on two factors: Temperature and the time of the heat treatment. This correlation is expressed in Pasteur-Units (PUs) and determines the microbiological effect of the heat treatment (the higher the figure, the higher the effect). Heat treatment time is determined by flow velocity and pipe length. Flash pasteurisation of milk Accurate temperature control is a precondition for product safety and quality as well as for process efficiency. Even an increase of only 0,5°C leads to PU increase of 18%. Typical value for milk (according to stand- ard US protocol from 1993) is 71,7°C and 15 seconds treatment time • 99,999% reduction of harmful bacteria • PU = 0,25 min x 1,393 (71,7°C-60°C) = 12,08 PU Example: Pasteurising time = 15 seconds ≅ constant (determined by

required flow rate and pipe length) • Required temperature ≥ 71,7°C • 0,25 min * 1,393 (72,2°C-60 °C) = 14,26 PU

Electricity+Control August ‘16

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