Beer related chemistry experiments?

[KeithMoonsLiver]

I was going to put this in the brew science forum, but it doesn't seem to get much traffic. I need to do a project for a chemistry lab. There is a list of topics we can pick from, but we are encouraged to choose something not on the list and do our own experiment. Naturally my first thought was to do something with beer, but I have no idea what specifically to do.

For some background of the class, it's undergraduate level quantitative analysis- which means we're concerned with determining how much of something there is. I won't be allowed to use any special instruments like a FTIR spectrometer or a gas chromatographer; just basic lab equipment and a spectrophotometer. We only have about 10 hours scheduled in the lab for this, so it can't be too complex of an experiment. Most of the lab work we have done so far has been gravimetric analysis and various types of titrations.

I thought about doing something such as determining the concentration of hop oils or alpha acids in hops, but frankly I'm not quite sure how the real chemists go about doing that, and if it's possible with the equipment I have available. I know spectrophotometers are commonly used to assess beer color, but I can't think of a way to turn that into something more substantial. This isn't biochem or microbiology, so most yeast related stuff is probably off the table.

Anyways, those are my thoughts. It would be awesome if anyone had some ideas about this, because most of the labs we do are so boring I would love to turn it into something I enjoy.

 

[Bonch]

Since you have a spectrometer to us play with some different grains and determine how much of an effect they actually have on changing the color of beer.

For example - have a control grain such as 2-row that you put in all beers and then add speciality grains such as chocolate malt, black patent, carmel, etc. Also you could vary the amounts of each grain and even do several different combinations. You could then plot out the differences based upon your readings.

This would be pretty cheap to do and play around with. Hops are expensive and you dont really have the equipment to actually take the appropriate measurements.

 

[ReverseApacheMaster]

Although the brew science forum doesn't get much traffic, those are definitely the people best equipped to help you out.

I have no idea what you are even talking about. I gather you did something with various types of tit-things. Unless you were judging how awesome they were I'm at a loss. There's a reason why I went to law school instead of anything science/math related...

 

[arover]

I was going to put this in the brew science forum, but it doesn't seem to get much traffic. I need to do a project for a chemistry lab. There is a list of topics we can pick from, but we are encouraged to choose something not on the list and do our own experiment. Naturally my first thought was to do something with beer, but I have no idea what specifically to do.

For some background of the class, it's undergraduate level quantitative analysis- which means we're concerned with determining how much of something there is. I won't be allowed to use any special instruments like a FTIR spectrometer or a gas chromatographer; just basic lab equipment and a spectrophotometer. We only have about 10 hours scheduled in the lab for this, so it can't be too complex of an experiment. Most of the lab work we have done so far has been gravimetric analysis and various types of titrations.

I thought about doing something such as determining the concentration of hop oils or alpha acids in hops, but frankly I'm not quite sure how the real chemists go about doing that, and if it's possible with the equipment I have available. I know spectrophotometers are commonly used to assess beer color, but I can't think of a way to turn that into something more substantial. This isn't biochem or microbiology, so most yeast related stuff is probably off the table.

Anyways, those are my thoughts. It would be awesome if anyone had some ideas about this, because most of the labs we do are so boring I would love to turn it into something I enjoy.

You know what's funny is I'm doing roughly the same thing. I'm taking a quantitative analysis course to finish up my B.S. in Chemistry over here, and our final project is open ended. The course surrounds instrumental analysis of trace metals, so it should surround that aspect, but I wanted to do something beer related as well. Using spectrophotometry (I don't know to what extent you're doing it, we use UV-Vis machines for spectrophotometric analysis), you can actually form complexes with a lot of various metals and, comparing their absorbance to that of prepared standards with known concentrations, gather the concentration of the unknown. Where you want to take this is up to you, perhaps any minerals that are used as yeast nutrients which may be left over in micro-brewed bottles that aren't filtered? There's a whole world of water chemistry going on in there.

If you don't have access to instrumentation, perhaps you can make use of indicators or something of the sort to identify water hardness, and compared water hardness to color of extracted grains. Isn't hardness a factor in determining the depth of black color in stouts? I'm not too sure with that stuff, but just another idea.

 

[The_General]

I guess it depends on what you mean by standard lab equipment.

Just a thought but I remember that alcohol dehydrogenase activity can be measured by UV/Vis based on the fact that it's an NAD dependent reaction.

As an aside, I never realized that there's a science board here. I need to check that out.

 

[devilishprune]

You can measure IBUs in your beer using just a spectrophotometer, I think.

 

[bad coffee]

why not test your water? Lots (and lots) of titration!

 

[mc_eric]

try to figure out how much protein is in a standard sample (like make a wort w/ 100% 2-row @ 1.050 or something) and see how much you can precipitate using various finings. That would be an interesting experiment.

 

[The_General]

try to figure out how much protein is in a standard sample (like make a wort w/ 100% 2-row @ 1.050 or something) and see how much you can precipitate using various finings. That would be an interesting experiment.

That sounds like a great idea! You can also look at the effect of temperature on that too. You can do a quick and dirty protein estimation by measuring absorbance at 280 nm. You'd just need a spectrophotometer, quartz cuvette, and a protein standard to make a standar curve. There are also various colorimetric protein estimations you can do. I prefer the Bradford method.

Of course, this may be getting too much into biochemistry sorts of things but that's what you get for listening to a biochemist!

 

[KeithMoonsLiver]

Thanks for the replies everybody.

try to figure out how much protein is in a standard sample (like make a wort w/ 100% 2-row @ 1.050 or something) and see how much you can precipitate using various finings. That would be an interesting experiment.

That sounds like a great idea! You can also look at the effect of temperature on that too. You can do a quick and dirty protein estimation by measuring absorbance at 280 nm. You'd just need a spectrophotometer, quartz cuvette, and a protein standard to make a standar curve. There are also various colorimetric protein estimations you can do. I prefer the Bradford method.

I really like this idea. Bradford method is a no go, but I think I will be able to do a Kjeldahl digestion. Any suggestions as to what techniques to try as far as precipitating proteins? When I brew I typically do single infusion mashes and toss in some whirlfloc and don't really think about it any more. I was thinking of mashing a single wort and perhaps cooling samples at different rates to see the effect on the cold break. What sort of finings do people typically use aside from whirlfloc/irish moss? Post-fermentation finings like gelatin and isinglass are more for removing yeast, right?

 

[GilaMinumBeer]

Can conversion of starch be quantified by spectrophotometer? And then compared to Iodine Titration color change signifigance?

 

[SpanishCastleAle]

I think it would be a good idea to PM ajdelange (he hangs out in the Science forum). I agree with ReverseApacheMaster though, the ones that could prob help most are in that forum and in at least some cases, don't seem to hang out much in the other forums.

 

[mc_eric]

Post-fermentation finings like gelatin and isinglass are more for removing yeast, right?

I'm pretty sure gelatin drops proteins out of suspension. I don't know about isinglass.

 

[SpanishCastleAle]

Could you do some sort of experiment involving the yeast-induced pH drop?

 

[RogerMcAllen]

I'm pretty sure gelatin drops proteins out of suspension. I don't know about isinglass.

Gelatin is made of protein, so that is a no go. You should be able to get it to fall out of solution with salt or EtOH.

 

[Chemiker]

In growing my own hops, I was thinking it might be nice to test the alpha acid concentration at home with an easy method, so I'm partial to the alpha acid experiment. I found this ASBC method that looks really easy and requires minimal equipment. I was thinking of splurging on an old Spec 20 to see if I could get it going.

Method

1. Place 5.000 +/- .001 gr pulverized hops in an extraction bottle and add 100 mL toluene.
2. Shake for 30 min with vigorous agitation.
3. Let stand until clear or centrifuge (preferred).
4. Dilution A: Dilute 5.0 ml of this extract to 100 mL with methanol.
5. Dilution B: Dilute an aliquot of the dilution A with alkaline methanol (0.2 mL 6M NaOH per 100 mL MeOH) so that the Abs at 325 and 355 falls within the most accurate range of the instrument.
6. Immediately read dilution B (1 cm) at 275, 325 and 355 vs a toluene blank that was prepared and diluted in EXACTLY the same manner.

Notes:

* Hexane may be substituted for toluene

Calculations:
Dilution factor, d= (volume dil A x volume dil B)/ (500 x aliq extract A x aliq dil A)

% alpha acids= d x (-51.56 A355+ 73.79 A325-19.07 A275)

% beta acids= d x (55.57 A355-47.59 A325 + 5.10 A275)

Example:

1. 5 gr hops extracted with 10 mL toluene
2. 5 mL clear extract diluted to 100 mL with methanol=Dilution A
3. 3 mL Dilution A diluted to 50 mL with alkaline methanol
4. Absorbances
* A355=0.615
* A325= 0.596
* A275=0.132

d = (100 x 50) / (500 x 5 x 3) = 0.667

alpha = 0.667 x [ -(51.56 x 0.615) + (73.79 x 0.596) - (19.07 x 0.132) = 6.5

beta = 0.667 x [ (55.57 x 0.615) - (47.59 x 0.596) + (5.10 x 0.132) = 4.3

 

[passedpawn]

Measure dissolved CO2, perhaps through a conditioning bottle. Look up the absorption curve for CO2 and plot over time. I have a nice spectrometer and never do experiments like this. Shame.

 

[jebsterr]

I did an alcohol dehydrogenase experiment in my biochem class, pretty simple, we even used disposable plastic cuvetes in our spectrophotometers. Also could somehow compare the accuracy of our calculations for determining alcohol content from SG by taking measurements with a hydrometer and then what distilling off the alcohol and measuring that.

 

[cklages]

Let me get this straight, you have a spectrophotometer and need to do an experiment, and want to do it on beer. So really you are trying to put the beer into Beer's law. That, good sir, is a noble cause.

mmmmmm....August Beer.....