A comparative analysis of the dairy milk cooling systems in selected farms in the Eastern Cape province of South Africa.

Milk as a raw material is easily perishable since bacteria which contaminate it may multiply rapidly and render it non sanitary for processing and also unacceptable for human consumption. But however, the rate of multiplication of these bacteria can be reduced by refrigeration. This paper presents an overview of the milking process in selected dairy farms in the Eastern Cape Province of South Africa. A comparative analysis of dairy milk cooling systems was done through a survey. The aim of the survey was to establish the best dairy milk cooling technology which best suit the local conditions with special emphasis on the energy consumption during cooling of raw milk from 20 – 35°C to the critical storage temperature of 4 – 4.5°C for preservation before it can be processed. A simple multiple linear regression model was used to predict the cooling savings for a water to milk ratio of 2:1 with input parameters as water inlet temperature and milk outlet temperature for cooling savings as the output. An average cooling savings of 36 - 49% can be achieved using a pre-cooler which also translates to avoided CO2 and water usage. The refrigerant used in these systems was also evaluated on its thermo-physical properties in regards to the heat removal from the milk so as to meet the cooling load demand. The study will also lead to determining crucial parameters in the selection of an effective as well as efficient milk cooling system alongside its feasibility potential.