SANITARY IMPROVEMENT OF YGGHURT AT A FACTORY LEVEL

Abstract

A total of 180 samples from all ingoing materials in yoghurt manufacture representing raw milk, skim milk powder, yoghurt mix, pasteurized mix, starter and the final product yoghurt (30 of each) were collected from a dairy plant to study their effect on the quality of produced yoghurt. The raw milk samples were examined for absence of any inhibitory substances as well as the starter used was examined by applying "Activity test" to ensure that it is pure, active and phage-free.

Also, a total of 60 environmental plant samples representing the milk receiving tank, workers' hands, pipes, yoghurt machine and storage room (12 of each). The incoming raw materials in yoghurt manufacture were examined chemically and microbiologically and the environmental samples were examined microbiologically. The produced yoghurt was examined organoleptically at the factory level.

The organoleptic evaluation of the produced yoghurt revealed that the mean overall score of all yoghurt samples was 89.06 out of(lOO total overall score points).

Chemical examination of collected samples of raw milk, milk powder and yoghurt, revealed that the mean pH values were 6.66, 6.56 and 4.07, respectively.

The mean values of titratable acidity expressed as lactic acid% of examined raw milk, milk powder and yoghurt were 0.15%, 0.17% and 0.85%, respectively.