Lab pasteurization count (LPC) is utilized to examine raw milk quality; this information is utilized by some dairy manufacturers to designate raw milk quality premiums paid to farmers and might likewise be utilized for repairing bacterial contamination problems.
LPC usually mentions thermoduric germs– the type that can stand up to pasteurization– however it’s not understood the kind of germs, e.g. sporeformers or non-sporeformers, can be identified by simply by taking a look at the LPC level.
To evaluate if LPC levels can be a sign of the kind of germs present in raw milk, scientists from Cornell University gathered 94 natural raw milk samples from throughout the United States, evaluated these by means of LPC, and defined the bacterial isolates.
They discovered LPC concentrations that varied from undetected to 4.07 log10 cfu/mL, and 380 bacterial isolates were examined, with the thermoduric germs separated from the samples being divided in 3 groups: gram-positive sporeformers (52%), gram-positive non-sporeformers (44%) and gram-negative germs (2.4%).
In regards to the LPC levels, most of samples (66) had a LPC ≤ 100 cfu/mL; 6 samples were with a LPC in between 100 and 200 cfu/mL, and 10 samples – with a LPC ≥ 200 cfu/mL. Extra analysis revealed that there was an inverted pattern in between the percentage of gram-positive sporeformers and the LPC concentration– samples with greater LPC had lower percentages of gram-positive sporeformers. That pattern was not substantial, according to the research study group.
“LPC level alone supplies no insight into the makeup of the thermoduric population in raw milk and additional characterization is required to clarify the bacterial motorists of raised LPC in raw milk,” the scientists concluded.
They leveraged a microbial recognition tool called MALDI-TOF MS, which is stated to be quicker offered to dairy manufacturers than 16S rDNA PCR and sequencing.
“While our information suggested arrangement in between 16S and MALDI-TOF MS for 66.6% of isolates at the genus level, 24.2% and 9.2% might not be dependably recognized or were mischaracterized utilizing MALDI-TOF, respectively,” the scientists stated.
“This recommends that additional optimization of this technique is required to permit precise characterization of thermoduric organisms typically discovered in raw milk.
“Ultimately, our research study offers a modern point of view on thermoduric germs picked by the LPC approach and develops that the LPC alone is not enough for determining the bacterial motorists of LPC levels. Additional advancement of fast characterization approaches that are available to manufacturers, cooperatives, and processors will support milk quality fixing efforts and eventually enhance results for dairy market neighborhood members.”
Source:
Repairing high lab pasteurization counts in natural raw milk needs characterization of dominant thermoduric germs, that includes non-sporeformers in addition to sporeformers
Authors: Lee, T. R., et al
Released: Journal of Dairy Science, 20 January 2024
DOI: 10.3168/ jds.2023-24330