Elimination of Pathogenic Bacteria from Milk Using Membrane Technology: A Review

Abstract

With technological advancements, membrane filtration is becoming increasingly popular in removing harmful microorganisms from milk and this article discusses many such efforts in a detailed manner. Retention of bacteria, vegetative spores and cells, even greater than 99% in most cases, is a clear indication of how efficient membrane technology is in removing these microorganisms from milk. It has been observed that in most of the cases, size exclusion acts as the dominant mechanism for achieving the desired separation. However, there are few studies that also reported about successful retention of bacterial cells from milk through the mechanism of electrostatic and hydrophilic/ hydrophobic interaction. An important aspect of implementing membrane for milk purification is that the presence of proteins and fat globules in milk causes severe membrane fouling and hence, this should be taken care of either by maintaining high cross flow velocity or generating back pulses during filtration. Besides, the microfiltration should also be carried out up to the critical microfiltration time so that the spores cannot germinate and contaminate the milk again. Moreover, an optimum pore size of the membrane is of the utmost importance for a proper balance between the membrane's rejection efficiency and the quantity of permeate produced, without compromising in milk's sensory and organoleptic attributes. It is worth mentioning that the use of third generation membranes with narrow pore size distribution is found to be fruitful in achieving good bacterial rejection from milk. Therefore, it can be inferred that with proper maintenance of all the above-mentioned factors, membrane filtration can definitely become a good alternative to conventional milk pasteurization process.