From owner-metabolic-reg@net.bio.net Thu Jan 30 22:00:00 1997 From: "John Kirscher" Subject: Re: A-level help needed! - Chemistry & fermentation Newsgroups: bionet.metabolic-reg,sci.chem,sci.life-extension,sci.med,sci.med.pharmacy,sci.med.nutrition,rec.crafts.brewing,rec.crafts.winemaking References: <854622079.25760@dejanews.com> Message-ID: <01bc0fa8$2b6b35a0$ea10408a@jkirscher_pc.atk.com> X-Newsreader: Microsoft Internet News 4.70.1155 NNTP-Posting-Host: jkirscher_95 Date: 31 Jan 97 18:56:20 GMT Lines: 69 Path: biosci!daresbury!nntp-trd.UNINETT.no!sn.no!nntp.uio.no!news.maxwell.syr.edu!news.mathworks.com!newsfeed.internetmci.com!pull-feed.internetmci.com!newshost.ATK.COM!jkirscher_95 Xref: biosci bionet.metabolic-reg:975 sci.chem:74141 sci.life-extension:16562 sci.med:149329 sci.med.pharmacy:40559 sci.med.nutrition:58567 rec.crafts.brewing:107085 rec.crafts.winemaking:15385 parkstone@lds.co.uk wrote in article <854622079.25760@dejanews.com>... > Hi, I'm an A-level student currently studying chemistry. I am presently > involved in an extended investigation, which makes up part of my final > grade, on the comparison of the rate of fermentation with use of different > sugar substrates. Below is my outline proposal . . . . > > During alcoholic fermentation, yeast metabolises glucose to form ethanol > and carbon dioxide using a metabolic pathway consisting of a number of > enzymes. By making the assumption that the yeast cell is a single > catalytic reactant, glucose (as a control), mannose, galactose and > fructose will be added separately to yeast solution. > > Because the multi-based pathway consists of steps, the rate of reaction > will be heavily reliant on the slowest rate determining step. Comparison > of reaction rates of each sugar with yeast will give an indication as to > whether different pathways, (for example not that of glucose) were > utilised. I do not know if this is necessary to tell you but, you have a big task on your hands. I tried to do the same analysis once, many years ago when I first started making wine. I was smart enough then to realize that I had to reduce the number of variables. In my first test, I used sugar (same brand and quantities), same water source, same containers, and varied only the yeast (note no fruit). Of the five yeast, I selected two for the next set of experiments. The second test involved only variation with water sources. The water sources were Minneapolis city water and Hamms (now Stroh) brewery artesian water. Brewery water was fastest. I did not take into account the chlorinated water in my testing (big mistake- should have waited until chlorine evaporated). The 3rd test involved sugar sources (cane vs. beet). Cane was faster. I now believed I knew the best yeast, waters, and sugars so I used two different one US gallon containers as the primary fermenter. One was low and wide in diameter, the other was tall and narrow. The low, wide container fermented faster. At this point I thought I knew all about the fermentation process. Fastest yeast, fastest water, fastest sugar, fastest container. Who knows, maybe I invented something. Ha. More about this later. Well, I bought twenty pounds of peaches; fifteen pounds of sugar, got my artesian water, bought a five gallon low, wide stainless steels pot for a primary fermenter, did all the things necessary for making the best of wines and went on vacation. Two weeks later I got back home. God was I anxious to get home. I swung open the door, was greeted by a swarm of fruit flies, and the smell of fermentation. I entered the kitchen to look at my creation. There it was! Dried, sugary material on the table (this is where I placed the fermenter since I would not be using the table for two weeks), on the floor, on the chairs, down the legs of the chairs. Every seam and crevice a liquid could possibly go, it went. My wife's words to me were, "clean that %#@%$#@ up". Lessons learned: 1. Use hot water to clean things up. 2. Place primary fermenter as close to floor as possible. 3. Fruit added to must causes more violent fermentation. 4. Allow ullage to exist between top of must and top of primary fermenter 5. Use tall primary fermenter to slow down rate of fermentation Back to the more serious part. As you can detect, there are a lot of variables I did not even take into account. Acidity, types of fruits, specific gravity, energizers, etc. As stated earlier, you have one big job. Best of luck. .