The use of Glycerol and Propylene glycol as additives during pasteurization reduce the microbial population in colostrum goats

Abstract

The aim of this study was to evaluate the use of Glycerol (Gli) and Propylene Glycol (Pro) at different concentrations as additive during goat colostrum pasteurization. Eleven goats of Majorera breed were milked, using a bucket milker, immediately after partum. After removed the whole available colostrum, that was aliquoted (50 ml) and subsequently frozen at −20°C until treatment. Sampled colostrums were allotted into nine different groups according to treatments with different additives. In control group (CG) 14% of Phosphate Buffer Saline (PBS) was added to colostrum, while in experimental groups colostrum was complemented with different doses of PBS plus diverse percentages of Glycerol or Propylene Glycol. All additions to colostrum were standardized to 14%. After each addition, colostrum samples were heated in a water bath until reach 56ºC; after that, the samples remained for 1 hour more into the water bath at 56ºC. Subsequently samples were transferred to ice water for fast cooling and storage at 4°C until microbiological analyses were performed later on. Colostrum microbiological population was quantified according to standard procedures on Plate Count Agar. No significant differences between Glycerol and Propylene glycol addition were found at any concentration tested. However, colostrum microbial population was significantly higher in CG samples than in all Glycerol and Propylene glycol groups. As Glycerol or Propylene glycol concentration added was increasing a significant reduction of the microbial population was observed, although no significant differences between groups were observed when 10 or 14% of Glycerol or Propylene glycol was added. In conclusion, according to the preliminary results, the addition of Glycerol or Propylene Glycol before goat colostrum pasteurization is an effective method to reduce the colostrum micro biota. Further studies on the effect of these additives on the different microbial populations will be necessary.