For a project, I am trying to figure out if it is possible to determine the acidification of milk without probing, touching, destroying or opening the sample, thus leaving the sample inside the plastic, transparent sample container. I am fairly experienced with machine vision and sensors, but not even a little in biology. I read somewhere that "Milk spoils when bacteria convert the lactose into glucose and galactose, producing lactic acid." I was wondering if there is any way of detecting any of these changes using a special camera or special lighting. Any advice or help will be much appreciated.

  • $\begingroup$ The easiest way would be to use a colored indicator in the milk that changes color with acidity. $\endgroup$
    – Chris
    Commented Sep 22, 2022 at 8:56
  • $\begingroup$ Thank you for your suggestion, but I am looking for a no-probe/contact/destruction way to achieve this goal. I will edit my question to clarify this better. $\endgroup$
    – Malinko
    Commented Sep 22, 2022 at 9:01
  • $\begingroup$ Thanks for the edit, but are we supposed to correct spelling in a quote? $\endgroup$
    – Malinko
    Commented Sep 22, 2022 at 11:06
  • $\begingroup$ Supposed is probably said too much. I would have suspected a typo and corrected it as well. $\endgroup$
    – Chris
    Commented Sep 22, 2022 at 11:07
  • $\begingroup$ If you're going to be using (I assume) a flow cell to do spectroscopy, why not just have a pH meter in the flow? $\endgroup$
    – MattDMo
    Commented Sep 23, 2022 at 15:02

1 Answer 1


Speculation here.

The viscosity may slightly change. Perhaps detectable by vibrating the sample and checking the pattern of standing waves on the surface.

Note that acidification due to lactobacilli may well happen after spoilage due to other bacteria.


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