Investigating the use of lactoperoxidase system in raw milk preservation and its effect on yoghurt processing

Abstract

The lactoperoxidase system (LP-system) is an acceptable chemical method for raw milk preservation, especially in rural areas where refrigeration facilities are not readily available to farmers. The application of the LP-system is a recent preservation method for milk whose efficiency has been proven. The main objective of this study was to investigate the influence of this method on milk preservation as well as its effect on yoghurt processing. The LP-system was activated by adding 10 ppm Potassium thiocyanate and 8.5 ppm Potassium persulphate to fresh milk. The milk quality was analysed using the Alcohol test. Yoghurt was processed separately from treated and untreated (control) milk samples. Yogurt samples were analysed for titratable acidity, susceptibility to syneresis, water holding capacity and protein, fat, ash and moisture content. Activating the LP- System increased the shelf life of the treated milk by 4 hours. The LP- System treatment lowered the titratable acidity, water holding capacity, susceptibility to syneresis, protein and moisture content in the yoghurt from the treated milk and increased the Ash content. The delay in lactic acid formation may lead to longer incubation time during yoghurt processing. Farmers need to be educated on this technology and also to make food grade reagents that are sources of thiocyanate ions and hydrogen peroxide ions available to farmers for use.