International. A team of researchers from the University of Hohenheim focused on different ways to cool milk, especially on small dairy farms in African countries.
In these countries, the lack of cooling systems often results in high microbial contamination in a very short time (bacteria levels may exceed the maximum allowed by food safety after 2-5 hours). When the temperature of milk is reduced from 37 ° C to 20 ° C, 10 ° C or 4 ° C, bacterial growth can be partially inhibited, respectively, during the first 8, 16 or 24 hours after milking.
Over the years different cooling methods have been used in these countries: evaporative cooling, absorption (often solar-powered), and steam compression cooling.
The latter system uses ice as a cooling medium, is stored in insulated milk cans, and is provided using a small-scale solar system consisting of a commercially available direct current refrigerator powered by photovoltaic panels and batteries. This system has been tested on seven dairy farms in Tunisia from July 2015 to December 2017. The results of the study showed "the ability of the system to cool milk from 30L to 17°C in less than 90 minutes with 6 kg of ice. using the same can of milk with 20 L and 8 kg of ice, the milk remains below 13 ° C for more than 12 hours at an ambient temperature above 35 ° C. Although the storage temperatures used are above the 6°C recommended by the regulation (853/2004), the cooling temperatures below 20°C and 15°C are low enough to prevent the growth of bacteria for 6 hours and 12 hours, respectively."
Thanks to a partnership between the Kenyan company Davis & Shirtliff and the University of Hohenheim, with the support of the German Agency for International Cooperation (GIZ), small dairy farmers in western Kenya could benefit from this new solar-powered milk cooling system.
Data Source Provider: University of Hohenheim.
