Issue link: http://read.dmtmag.com/i/89494
WINERY can purchase more pure fractions of proteins from commercial ven- dors. One of the most well-known but least understood fining prac- tices is the use of egg whites. Egg whites contain a mixture of poly- saccharides and proteins, and are chosen primarily because of avail- ability and ease of use. However, it is often difficult to reproduce the same results due to variations in egg volume and consistency. Puri- fied forms of egg white proteins can also be purchased (ovalbumin H2S CH3SH CH3CH2SH CH3SCH3 CH3SSCH3 Sensory Threshold 0.8 µg/L 0.7 µg/L 0.1 µg/L 5.0 µg/L 2.5 µg/L and conalbumin). Casein is probably the best protein available because its isoelectric point (pI) – the pH at which a particular molecule or sur- face carries no net electrical charge – is close to wine pH and it does not leave a residue in wine. Gelatin is a good protein for fin- ing because it is rich in proline and reacts quite readily with tannin. However, gelatin can take a long time to form insoluble complexes with tannin, and it leaves a pro- tein residue. In addition, gelatin SULFUR COMPOUNDS FOUND IN WINE Compound Sensory Descriptor Rotten Eggs Stagnant Water Onion Mushroom Quince Clean Wine 0.3 µg/L 0.3 µg/L <0.1 µg/L 1.4 µg/L <2.5 µg/L does not react with many protein dyes, making it difficult to detect residual protein in your wine. Gel- atin also must be added to wine within a specific temperature range (see manufacturer details for exact temperatures). Table 2 provides information about the amounts of pure proteins that you can add to wine. Federal guidelines limit the amount of egg whites to 2 pounds (907.2 g) in 1 gallon of brine solution containing 1 ounce (28.35 g) of potassium chlo- Stinky Wine 16.3 µg/L 5.1 µg/L 10.8 µg/L 2.0 µg/L 5.0 µg/L Remove w/Cu2+ Yes Yes Yes No No Many of The World's Finest Wines Are Made in Concrete. Let us know when you're ready. W concretewinetanks.com (888) 807-4575 A WWW.VWM-ONLINE.COM NOV - DEC 2012 VINEYARD & WINERY MANAGEMENT 83 sonoma cast stone S E A O C N N R O O E M A E C S N T E S T C O N N T I T K S