Determination of the glucose content in hot beverages

[Harini Krishna]

<mentor - moved to Engineering>
Hi,

I would like to know how the glucose content can be measuring in hot beverages using non-intrusive method.

Thankyou

 

[jim mcnamara]

This question would fare better in Engineering. You will probably be asked what you mean by non-intrusive.
Here is a head start:
non-intrusive == you cannot touch the liquid or the container with a probe or device?

 

[berkeman]

<mentor - moved to Engineering>
Hi,

I would like to know how the glucose content can be measuring in hot beverages using non-intrusive method.

Thankyou

Would NMR/MRI do it? Not cheap, though.

 

[anorlunda]

Aroma?

 

[jim mcnamara]

There is no boiling point for glucose. It changes into a liquid from crystalline form at the same temperature, 295 °F, as its decomposition point. So, it can not exist as a stable liquid that can boil. Smelling it in steam does not seem like it would work. The glucose van’t Hoff number is 1.0 - meaning it does not dissociate in solution. So, unless water particles with glucose molecules are in the air around the container (from agitation?) , I do not see a practical way to detect them. I do not think there is a partial pressure for glucose to make it a volatile component.

from -
https://opentextbc.ca/chemistry/chapter/11-4-colligative-properties/
and wikipedia -
https://en.wikipedia.org/wiki/GlucoseThis is why I did not answer to start with - I'm not much help. Just raining on the parade. How about infared sensing? Or refractometry - if the liquid is always optically clear and is the same product, just with +/- glucose levels?

 

[Harini Krishna]

Would NMR/MRI do it? Not cheap, though.

NMR would do it but most of the studies i have read online have maintained a constant temperature during the process.
Does temperature changes effect the measurements through NMR/MRI?

 

[TeethWhitener]

Does temperature changes effect the measurements through NMR/MRI?

The mutarotation equilibrium changes with temperature, which is observable in NMR. This paper might help:
https://www.jstage.jst.go.jp/article/apcche/2004/0/2004_0_110/_pdf

 

[berkeman]

The mutarotation equilibrium changes with temperature, which is observable in NMR. This paper might help:
https://www.jstage.jst.go.jp/article/apcche/2004/0/2004_0_110/_pdf

Very helpful, thanks @TeethWhitener

From your link:

Looks like this is the type of NMR Spectrometer that was used (the picture is from a different university's lab:
https://scs.illinois.edu/sites/default/files/images/ui300-1-small.jpg

 

[tech99]

Maybe weigh the sample and calculate its relative density? Sugar content for brewing is done using a hydrometer to measure SG.
Alternatively, place the sample in a waveguide and measure the electrical characteristics.

 

[Baluncore]

I would like to know how the glucose content can be measuring in hot beverages using non-intrusive method.

How does the glucose get into the beverage?
Do you want something highly specific for glucose only?

The sugar added to a beverage will probably be sucrose = ( glucose + fructose ). Do you want to include the glucose present in sucrose molecules, with or without the fructose?

NMR would have trouble separating the free glucose from the sucrose.
Specific gravity or refractive index are used to estimate crude sugar content = Brix.

 

[Harini Krishna]

How does the glucose get into the beverage?
Do you want something highly specific for glucose only?

The sugar added to a beverage will probably be sucrose = ( glucose + fructose ). Do you want to include the glucose present in sucrose molecules, with or without the fructose?

NMR would have trouble separating the free glucose from the sucrose.
Specific gravity or refractive index are used to estimate crude sugar content = Brix.

I do not want anything specific with glucose.
I wanted to measure the total sugar content in beverages using non-intrusive method. I tried searching online but couldn't fine many methods . Most of the methods were for glucose.
Can sucrose or fructose be measured to determine the total sugar content in the beverages?

 

[Baluncore]

Can sucrose or fructose be measured to determine the total sugar content in the beverages?

"Sucrose is common sugar. It is a disaccharide, a molecule composed of two monosaccharides: glucose and fructose". See; https://en.wikipedia.org/wiki/Sucrose

If you could take a one drop sample from the spoon used to stir a hot beverage, then a Brix measurement of Refractive Index could be done quickly and cheaply.
Search; Sugar Meter, Refractometer, Portable Brix Detector, Handheld Sugar Meter. US$20.

Given your remote measurement requirement, you are forced to stand back. The obvious technique would be to measure the RI through a measurement of Brewster's Angle using the polarisation of reflected light.
https://en.wikipedia.org/wiki/Brewster's_angle

 

[Vigardo]

Hi Harini, if in the beverage there are many different substances, some of the methods above cited will hardly work or be very expensive.

If very tiny quantities would be taken (micro-litres), you would try mass spectrometry. This in not strictly "non-intrusive", but it would do the job for a fraction of the cost of a NMR facility. You have here an example applied to glucose detection in tears. It would even work with nano-drops of beverage.

In addition, there must be elsewhere some enzymatic glucose test that for very small samples and high sensitivity.

 

[Merlin3189]

Polarimetry springs to mind for concentration of sugars, though for mixtures it would be ambiguous.
I don't know how easy it is to find basic reference data, but you could always do your own calibration for the sugars you're interested in. Methods and theory are widely discussed.

I haven't worked out why you want a "non-intrusive method", or really what you mean by that. It might help if you were a little clearer about what you are doing.
If you are making cups of coffee and don't want to rob the customer of even 1ml, then if your production method is standard, just divert one cup every so often to check that the amount of sugar you put in is actually reaching the cup. If you have a continuous flow production, then equally remove a sample occasionally: that won't intrude nor affect the quality of the main flow. The cost of testing is going to be several orders of magnitude more than the value of lost product.
Equally, if it's an automatic beverage machine, it's probably much better to improve the production process, rather than monitor varying quality outputs. "You can't test quality into a product".

 

[chemisttree]

This author correlated the capacitance of ripe fruit with brix. Non contact technique but not proven at elevated temperatures. Also the container would probably need to chosen carefully.