Extending the shelf life of pasteurized milk through microfiltration and implementation of a comprehensive safety and quality management system: case study at the farm and dairy plant

This study aimed to implement good hygienic practices and good manufacturing practices programmes, together with the hazard analysis critical control points (HACCP) system, to produce extended shelf-life (ESL) pasteurized milk using crossflow microfiltration. The microbiological quality of raw milk was markedly improved upon implementation of hygienic prerequisites and HACCP, resulting in a reduction of total colony count (TCC), Staphylococcus aureus, psychrotrophs, yeasts and moulds, spore-forming bacteria, Salmonella, coliforms and Escherichia coli. All the milk samples tested negative for antibiotics and aflatoxin M₁. Pasteurized and homogenized milk was microfiltered through a 0.8 or 0.45 μm pore-size membrane to produce ESL whole milk and ESL partly skimmed (2%) milk, respectively, resulting in further improvement of refrigerated shelf life to about 2 weeks and 3 weeks, respectively. ESL 2% milk showed a significantly lower TCC compared to ESL whole milk, and the latter also had a lower TCC than pasteurized whole milk. Both ESL milk products showed negligible denaturation of α-lactalbumin and β-lactoglobulin. The results demonstrate the effectiveness of combining microfiltration with on-farm and in-plant safety management systems for ensuring the safety and quality of ESL pasteurized milk.