Study on Nutrient and Microbial Analysis of Selected Milk Samples from Kottayam District, Kerala, South India

Abstract

This study aimed to evaluate the quality of various milk samples through comprehensive chemical and microbiological analyses. Four distinct sets of data were interpreted, focusing on fat content, solids-not-fat (SNF), water content, adulterants, preservatives, and the presence of pathogenic bacteria. The chemical analyses involved comparing the measured values of fat, SNF, and water in three samples against established permitted levels, while the microbiological analyses assessed the presence of E. coli, Staphylococcus aureus, Brucella spp., and Shigella spp. in three different milk sources: Milma milk, Malanadu milk, Elanadu milk and fresh udder milk.

The initial chemical examination showed that all samples had fat content between 6.33% and 6.43%, well above the 3.2% standard. This high fat was accompanied by low SNF readings (6.48% to 6.57%), below the 8.5% limit, and slightly raised water content (86% to 89%), above the 85% limit. A milk composition mismatch could indicate dilution or an imbalanced milk content. An additional data set showed that three samples had fat concentrations slightly above or below the 3.2% limit. This disparity indicated multiple milk samples were analysed. This second dataset also had low SNF and high water content, suggesting dilution. However, further testing yielded near-perfect results. The third chemical analysis was substantially closer to the limits. Fat content was 3.21–3.31%, close to or above the 3.2% standard. SNF levels were from 8.46% to 8.49%, close to 8.5%. Near-85% water content was also observed. All chemical analyses found no adulterants or preservatives. Fat content was highest in Elanadu milk (3.41 % )and lowest in Malanadu milk(3.05%). SNF level was highest  in fresh udder milk( 8.47%) and lowest in Milma milk( 6.52%). The water content was high in milma milk and lowest in Malanadu milk.

The microbiological investigation showed a clear distinction between processed and unprocessed milk. Milma  Malanadu, and Elanadu milk samples demonstrated excellent bacterial quality, with no detection of E. coli, Staphylococcus aureus, Brucella spp., or Shigella spp. Conversely, the fresh udder milk sample tested positive for E. coli, suggesting fecal contamination.

 This highlights the importance of hygienic milk collection practices for unprocessed milk and validates the efficacy of processing techniques employed in commercial milk production. The absence of Staphylococcus aureus, Brucella spp., and Shigella spp. across all samples indicates a relatively low risk of infection from these specific pathogens.