Laboratory pasteurization depend (LPC) is used to evaluate uncooked milk high quality; this information is utilized by some dairy producers to designate uncooked milk high quality premiums paid to farmers and can also be used for troubleshooting bacterial contamination points.
LPC usually enumerates thermoduric micro organism – the kind that may face up to pasteurization – but it surely’s not identified the kind of micro organism, e.g. sporeformers or non-sporeformers, could be decided by simply by trying on the LPC stage.
To check if LPC ranges could be an indicator of the kind of micro organism current in uncooked milk, researchers from Cornell College collected 94 natural uncooked milk samples from throughout the US, assessed these through LPC, and characterised the bacterial isolates.
They discovered LPC concentrations that ranged from undetectable to 4.07 log10 cfu/mL, and 380 bacterial isolates had been analyzed, with the thermoduric micro organism remoted from the samples being break up in 3 teams: gram-positive sporeformers (52%), gram-positive non-sporeformers (44%) and gram-negative micro organism (2.4%).
When it comes to the LPC ranges, nearly all of samples (66) had a LPC ≤100 cfu/mL; 6 samples had been with a LPC between 100 and 200 cfu/mL, and 10 samples – with a LPC ≥200 cfu/mL. Extra evaluation confirmed that there was an inverse pattern between the proportion of gram-positive sporeformers and the LPC focus – samples with increased LPC had decrease proportions of gram-positive sporeformers. However that pattern was not vital, in line with the analysis staff.
“LPC stage alone gives no perception into the make-up of the thermoduric inhabitants in uncooked milk and additional characterization is required to elucidate the bacterial drivers of elevated LPC in uncooked milk,” the researchers concluded.
They leveraged a microbial identification device known as MALDI-TOF MS, which is alleged to be extra available to dairy producers than 16S rDNA PCR and sequencing.
“Whereas our information indicated settlement between 16S and MALDI-TOF MS for 66.6% of isolates on the genus stage, 24.2% and 9.2% couldn’t be reliably recognized or had been mischaracterized utilizing MALDI-TOF, respectively,” the researchers mentioned.
“This means that additional optimization of this technique is required to permit for correct characterization of thermoduric organisms generally present in uncooked milk.
“Finally, our research gives a recent perspective on thermoduric micro organism chosen by the LPC technique and establishes that the LPC alone is just not enough for figuring out the bacterial drivers of LPC ranges. Additional growth of fast characterization strategies which might be accessible to producers, cooperatives, and processors will help milk high quality troubleshooting efforts and finally enhance outcomes for dairy business neighborhood members.”
Supply:
Troubleshooting excessive laboratory pasteurization counts in natural uncooked milk requires characterization of dominant thermoduric micro organism, which incorporates non-sporeformers in addition to sporeformers
Authors: Lee, T. R., et al
Revealed: Journal of Dairy Science, 20 January 2024
DOI: 10.3168/jds.2023-24330