Comparative Efficiency of KU and ISO Plungers in Mixing Composite Bulk Raw Milk

Abstract

The study was conducted to investigate the best mixing indicators among the milk composition i.e. milk protein, fat and SNF and to determine the efficiency of two plungers, i.e. Kasetsart University (KU) and International organization for standardization (ISO) for raw milk truck. Fat content was found to be the best indicator for mixing milk prior to sampling. Fat content stabilized after 10, 5 and 10 times of stirring raw milk truck’s chamber I, II, and III of 4,700, 3,900 and 7,400 kg capacities respectively; whereas the protein and SNF stabilized after 5 times of stirring irrespective of the chamber sizes in the study. Significant difference (p<0.05) was observed in the efficiency of the two types of plunger in mixing milk. Using milk fat as indicator, the KU designed plunger was found to be more efficient in mixing for the small chambers. However, when compared to ISO plunger there was no difference in mixing efficiency for the larger chamber. Statistically, the milk mixed with KU plunger attained homogeneity after 5 times of stirring in all the chambers; whereas the milk mixed with ISO standard plunger attained homogeneity only after 15 times of stirring for chamber I and II and 10 times of stirring for the chamber III. However, using the criteria of maximum variation of plus or minus 0.1% level between the mixing intervals to obtain representative samples at least 15 times of stirring for chamber I and II, and 20 times of stirring for chamber III for KU plunger would be required prior to sampling. Whereas, 20 times of stirring for ISO plunger would be necessary prior to sampling for all the chambers
with capacity of less than 7,400 kg.