Evaluating the effect of storage conditions on milk microbiological quality and composition

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Paludetti, Lizandra F.
Jordan, K.
Kelly, Alan L.
Gleeson, David
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In this study, the effect of storage temperature (2 or 4°C) on the composition of milk and microbiological load was investigated over 96 h. Milk samples were collected from farm bulk milk tanks after one complete milking and stored at 2 or 4°C over 96 h. Total bacterial count (TBC), psychrotrophic bacterial count (PBC) and proteolytic bacterial count (PROT) were affected by storage time and temperature and varied significantly between farms (P < 0.05). The levels of TBC, PBC and PROT bacterial count increased from 4.37 to 6.15 log cfu/mL, 4.34 to 6.44 log cfu/mL and 3.72 to 4.81 log cfu/mL, respectively, when the milk was stored for 96 h at 2°C. The milk samples stored at 4°C had higher increases in these bacterial counts after 72 h in comparison to milk samples stored at 2°C. The casein fraction content was lower in milk samples stored at 4°C, which could be due to high levels of PROT bacteria or enzyme activity in these samples. Milk stored for 96 h at 2°C has less impact on composition or processability parameters compared to milk stored at 4°C.
Cold storage , Dairy microbiology , Proteolysis , Raw milk quality
Paludetti, L.F., Jordan, K., Kelly, A.L. and Gleeson, D. (2018) 'Evaluating the effect of storage conditions on milk microbiological quality and composition,. Irish journal of agricultural and food research, 57(1), pp. 52-62. doi:10.1515/IJAFR-2018-0006
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