THE EFFECTS OF AGITATION ON THE PASTEURISATION PROCESS OF COW'S MILK AS ASSESSED ON THE CHEMICAL AND MICROBIOLOGICAL ASPECTS

Pasteurization is the initial process that needs to be done for fresh milk before consumption. The application of batch pasteurization is a method that is widely used in small and home industries. Batch pasteurization is low time low temperature (LTLT) pasteurization. In the community, there are differences in batch pasteurization, that is by agitation and without agitation. The application of pasteurization to dairy products needs to be optimized because milk has essential and non-essential nutrients needed by humans. For this reason, this study was conducted to determine the effect of agitation during pasteurization on the chemical and microbiological aspect. This research was carried out through two stages, namely designing pasteurizer and testing the pasteurized milk from pasteurizer. Pasteurization in this study was carried out at 72oC for 15 minutes. This study used three treatments, namely pasteurization without agitation, pasteurization with agitation of 35 rpm, and pasteurization with agitation of 70 rpm. In addition, the samples tested were samples in each treatment at the cold spot and hot spot points. Chemical testing is done on protein, fat, and total solid dissolved in likuid (milk). While microbiological testing was carried out on total plate count (TPC) and coliform. Chemical results showed that there was an increase in protein value after pasteurization, whereas in total solids and fats showed a decrease after pasteurization. The increase in protein in this study can be caused by two things, namely the aggregation of whey protein and protein hydrolysis from the complex to be simpler. On the fat yield which is known to be a fat that does not form a good emulsion, it is described by the presence of fat on the surface of milk. This is caused by a decrease in the amount of phospholipids and MFGM which can form bonds with whey and k-casein. Based on the data obtained, by looking at the difference between cold and hot spots, there was no significant difference in fat values in pasteurized samples without agitation and protein values in pasteurization with agitation of 35 rpm. Based on the data obtained, it is necessary that agitation is needed during pasteurization to obtain good results based on chemical and microbiological testing. The results of panelists' assessment of pasteurized milk showed that panelists were more likely to present pasteurized pasteurized milk with agitation of 35 rpm. Microbiological testing (TPC and coliform) is known that pasteurizers can reduce the number of living microorganisms by 3 logs. However, pasteurizers without agitation can cause pasteurization which is carried out ineffectively. This is indicated by the high total number of contaminant microorganism plates in pasteurized samples without agitation at the cold spot point, which is equal to 5x104. This total plate count exceeds the maximum standard SNI number. 01-3951-1995 concerning pasteurized milk, which is equal to 3x104. In this study, it was known how pasteurization with 35 rpm agitation was the best method based on quality and Safety product. Therefore, agitation needs to be done during pasteurization to optimize the pasteurization. However, pasteurization at 70 rpm can increase heating efficiency during pasteurization.