cjy (03/22/83)
I haven't submitted anything for a while, but I noticed this stream of verbage about chemicals in wine, veggies, and the like. I also noticed some confusion about how sulfur dioxide is used in the food and wine industries. While not a food chemist, I have a great many friends that are and have gone through many of the Michigan wineries. I have also made lots and lots of wine, so I know of which I speak. First of all, sulfur dioxide is used primarily to kill wild airborne yeast cells. These cells adhere themselves to many things, your nose, fruit skins, your skin - anything at all! If given sufficient quantities of sugar and water these yeast and also airborne bacteria ( I forgot! ) begin to divide and produce many by-products. Yeast will produce either ethanol or acetic acid, depending upon the strain and the amount of available oxygen. Airborne bacteria will produce lots of things, most of which are undesirable from either a health, taste, or an appearance standpoint. Yeast and bacteria can be killed in two primary ways, either heat or chemicals. With some substances ( like wine ) heat is impractical. Commercial wineries will filter finished wine until there are very few yeast cells left in the wine. Sodium ( or Potassium for salt-free diets ) metabisulfite is then added to the wine to prevent the yeast culture from starting up again. The concentration of this chemical is quite low and I really doubt if you can ever taste it. If you really want to smell sulfur, and ammonia be at a winery when they are starting a batch of wine. First of all, they will kill off all wild yeast and bacteria using sulfur dioxide. After the fruit pulp bleaches a little, they dilute it and add a controlled strain of yeast that will produce ethanol. They then add ammonia to make the yeast grow like crazy. Additional ammonia may be used to cool down the vats once the fermentation is started ( They use it in cooling coils, not in the must. ) So some wineries STINK when a new batch is started. Not all wineries use the above process, but instead will kill off the wild yeast and bacteria using heat ( pasteurization (sp?)). In so doing, however, they create a wine that is hard to clear due to the excessive amount of pectin in the must. If ammonia is not used to encourage yeast growth, there is a chance of the wine spoiling and also it takes longer to ferment. Both of these factors eventually result in higher prices to the consumer. If you are outraged at the chemicals used in wine, go make some "natural stuff". Your chances of making something considered palatable by anyone but yourself will be very small without the use of chemicals. ( If you leave enough live yeast in it, you get a poor wine, but a great laxative. ) Chuck Young at ihuxi!cjy
benson (03/23/83)
If wineries use ammoia to accelerate the yeast growth, could a similar trick be applied to yeast doughs ? Peter Benson decvax!ittvax!dcdwest!benson