Mostly just thinking out loud here, but rice fermentation results in what are called "limit dextrins". These are the result of the amylase enzymes only being able to cleave off glucose units in starch down to some terminal length (like 3 or 4) or some minimum distance from a branching point in the starch. Most of these I'd expect to end up in the jigemi, but the smaller ones are probably soluble in water and end up providing some flavor and texture to the chongju. The point being that these dissolved solids probably throw off refraction and density measurements. I'm mostly just theorizing off the cuff here--it will very interesting to learn what you eventually figure out. Excellent video--I do enjoy the more "technical" ones that maybe aren't so rustic. 😏
I agree with Johnathan Corgan on this. I have read that in beer mashing the starch is converted mainly to monosaccharides and maltose, but a proportion (maybe 20%?) is converted only as far as dextrins which are short chain polymers of glucose. The dextrins have a higher refractive index than the sugars and are not fermentable and remain in the fermented product, impacting its RI and SG. There are methods available for using SG + RI to estimate ABV in beer but to be accurate they require calibration for the particular raw materials and mashing procedure. I guess the same would apply for asian rice wines utilizing simultaneous saccharification and fermentation. If this explanation is correct it would explain why the tests with white (grape) wine and with vodka gave significantly more accurate results than with the asian wines.
I've always wanted to know how to measure the ABV for makgeolli. I also have the same tools that you do, but I'm not convinced on my results either. I'm looking forward to the next video on this topic.
This is still useful because if you maintain consistent technique you can at least tell the approximate difference in alcohol content between batches, even if you don't know the real ABV. You should also be able to tell what level you like, and test the brew during fermentation to know when it's done.
I'll do some more tests to see the variation I get in specific gravity and refraction for some other brews. Unfortunately, one thing that I can't do is to test during fermentation, due to sediment and carbonation. Both sediment and carbonation ruin the hydrometer measurement. I have to wait for the sediment to settle and measure only the liquid part, and the liquid part needs to be still, not carbonated. But I'll do what I can!
I suppose you could use the rice and koji hold the temp at 140f for 8 hours so the starches malt, basically make amazake then test the sugar content add yeast and brew.
I have read that while brewing Rice wine it can get higher than you would get with wine brewing. Something about parallel fermentations allows it to get higher. 22% could be accurate.
Thanks for your comment! Well, one way to exceed the yeast's alcohol tolerance is to breed a more alcohol tolerant yeast over time in a multiple-stage brewing process -- for example, with an oyangju recipe. But my cheongju was from a two-stage brew, and it didn't taste like 20%, which is why I doubted my measurement.
@@l0tus4life I would need to test on a cheongju, not on a makgeolli (since any solids suspended in the liquid interfere with measurement). I could just test on white wine... The tolerance allowed on wine labels in the US seems to be +/- 1.5% (for wine under 14% ABV). Which might not be good enough to use as a calibration. But it still would be interesting to do.
I wonder if the kind of residual sugar and compounds matters. Beer is made from mostly maltose, wine is mostly glucose and fructose. For rice wine I think it's mostly glucose (from Amylopectin) and maltotriose and maltose (from Amylose). Makgeolli is also full of Lactic acid and acetic acid, various enzymes, and undigested starches. I'm also wonder if you should retry this again but filter the cheongju through a coffee filter first, to ensure its 100% clear.
I thought any remaining sugar in the final alcohol also threw off the readings from a hydrometer. The yeast eats what it can and leaves some sugar behind, so unless you're positive there is no remaining sugar this process wouldn't work correctly. But I could be wrong, only been into this hobby for a year or so and just have my first sake fermentating. I'm planning on doing the boiling method as it seems more precise.
I’m afraid I don’t know. I haven’t had success with basmati rice. But I know there are many kinds of rice and I also know that rice wine is brewed in many parts of India. You’ll have to try a few kinds. Use a little extra nuruk than usual.
Can u give a suggestion which apparatus is suitable to measure alcohol content and sugar content in rice wine, since u say it is not so accurate in using hydrometer and brixmeter
Some of the other methods are (1) distillation, (2) infrared spectroscopy, and (3) gas chromatography. But I don’t have the equipment for those methods!
Half joking, how about using a breathalyzer? You drink a specific amount of liquor of known alcohol percentage at a specific time of day. Then test your breath 30 minutes later, as a baseline. Next day, at exactly the same time of day, you drink the same amount of your makgeolli, and again, breathalyzer 30 minutes later. A little math, and bam, you have the ABV of your makgeolli! :)
I'm guilty of hounding you about ABV. Thanks for making the info available.
Glad to try it! It's a natural question...
Mostly just thinking out loud here, but rice fermentation results in what are called "limit dextrins". These are the result of the amylase enzymes only being able to cleave off glucose units in starch down to some terminal length (like 3 or 4) or some minimum distance from a branching point in the starch. Most of these I'd expect to end up in the jigemi, but the smaller ones are probably soluble in water and end up providing some flavor and texture to the chongju. The point being that these dissolved solids probably throw off refraction and density measurements. I'm mostly just theorizing off the cuff here--it will very interesting to learn what you eventually figure out. Excellent video--I do enjoy the more "technical" ones that maybe aren't so rustic. 😏
Thanks for the ideas! I'm sure I'm going to try to measure this again in a few different ways.
I agree with Johnathan Corgan on this. I have read that in beer mashing the starch is converted mainly to monosaccharides and maltose, but a proportion (maybe 20%?) is converted only as far as dextrins which are short chain polymers of glucose. The dextrins have a higher refractive index than the sugars and are not fermentable and remain in the fermented product, impacting its RI and SG.
There are methods available for using SG + RI to estimate ABV in beer but to be accurate they require calibration for the particular raw materials and mashing procedure. I guess the same would apply for asian rice wines utilizing simultaneous saccharification and fermentation.
If this explanation is correct it would explain why the tests with white (grape) wine and with vodka gave significantly more accurate results than with the asian wines.
@harveywilson2030 Thanks for your insight on this!
I've always wanted to know how to measure the ABV for makgeolli. I also have the same tools that you do, but I'm not convinced on my results either. I'm looking forward to the next video on this topic.
Thanks for watching!
This is still useful because if you maintain consistent technique you can at least tell the approximate difference in alcohol content between batches, even if you don't know the real ABV. You should also be able to tell what level you like, and test the brew during fermentation to know when it's done.
I'll do some more tests to see the variation I get in specific gravity and refraction for some other brews. Unfortunately, one thing that I can't do is to test during fermentation, due to sediment and carbonation. Both sediment and carbonation ruin the hydrometer measurement. I have to wait for the sediment to settle and measure only the liquid part, and the liquid part needs to be still, not carbonated. But I'll do what I can!
I suppose you could use the rice and koji hold the temp at 140f for 8 hours so the starches malt, basically make amazake then test the sugar content add yeast and brew.
i was thinking the same thing.
I have read that while brewing Rice wine it can get higher than you would get with wine brewing. Something about parallel fermentations allows it to get higher. 22% could be accurate.
Thanks for your comment! Well, one way to exceed the yeast's alcohol tolerance is to breed a more alcohol tolerant yeast over time in a multiple-stage brewing process -- for example, with an oyangju recipe. But my cheongju was from a two-stage brew, and it didn't taste like 20%, which is why I doubted my measurement.
I have another great idea 💡
Buy a commercial makgeolli as a control. Use your instruments and calculation to adjust the margin of error.
If the commercial stuff is 5% and your calculation gives you 7% you know you are off by 2%....
Does this make sense 🤣 or am I going crazy 😅
@@l0tus4life I would need to test on a cheongju, not on a makgeolli (since any solids suspended in the liquid interfere with measurement). I could just test on white wine... The tolerance allowed on wine labels in the US seems to be +/- 1.5% (for wine under 14% ABV). Which might not be good enough to use as a calibration. But it still would be interesting to do.
I wonder if the kind of residual sugar and compounds matters. Beer is made from mostly maltose, wine is mostly glucose and fructose. For rice wine I think it's mostly glucose (from Amylopectin) and maltotriose and maltose (from Amylose). Makgeolli is also full of Lactic acid and acetic acid, various enzymes, and undigested starches. I'm also wonder if you should retry this again but filter the cheongju through a coffee filter first, to ensure its 100% clear.
Thanks for your ideas! I'm sure I'll try a few different things next time...
I thought any remaining sugar in the final alcohol also threw off the readings from a hydrometer. The yeast eats what it can and leaves some sugar behind, so unless you're positive there is no remaining sugar this process wouldn't work correctly. But I could be wrong, only been into this hobby for a year or so and just have my first sake fermentating. I'm planning on doing the boiling method as it seems more precise.
Which Indian rice is best for wine except glutinous one??
I’m afraid I don’t know. I haven’t had success with basmati rice. But I know there are many kinds of rice and I also know that rice wine is brewed in many parts of India. You’ll have to try a few kinds. Use a little extra nuruk than usual.
Can u give a suggestion which apparatus is suitable to measure alcohol content and sugar content in rice wine, since u say it is not so accurate in using hydrometer and brixmeter
Some of the other methods are (1) distillation, (2) infrared spectroscopy, and (3) gas chromatography. But I don’t have the equipment for those methods!
Ooooh... Thanks for yr suggestion👍
Half joking, how about using a breathalyzer? You drink a specific amount of liquor of known alcohol percentage at a specific time of day. Then test your breath 30 minutes later, as a baseline. Next day, at exactly the same time of day, you drink the same amount of your makgeolli, and again, breathalyzer 30 minutes later. A little math, and bam, you have the ABV of your makgeolli! :)
maybe the environment of makgeolli allows for a higher alcohol tolerance of the yeast than wine.
If all else fails maybe a digital alcohol reader will be able to read it.