Wednesday, June 24, 2009

~Aversion of grape wine and crab meat~



What is wine and crab?

Wine has been made for centuries from just a two simple ingredients:yeast and grape juice. Actually, any fruit juice can be used but by far the majority of all wine is made from grape juice. Wine is produced by fermenting crushed grapes using various types of yeast.Yeast consumes the sugars found in the grapes and converts them into alcohol.

Crab is an exoskeleton crustaceans , which is delicious to be eaten.Crab meat is an excellent source of high quality protein, vitamins and minerals that are needed for good nutrition.It is low in calories and fat but high in cholesterol .Therefore, most major health organizations recommend a daily limit of 300mg.


Do you know that? When you eat crab with wine , it will caused aversion or toxicity!!!

Tannins (tannic acid) are water-soluble polyphenols that are found in wine.Tannins extracted from grapes are condensed tannins. Hydrolysable tannins are extracted from the oak wood where the wine is aged in.Tannins play an important role in preventing oxidation in aging wine and appear to polymerize and make up a major portion of the sediment in wine.They have been reported to be responsible for decreases in feed efficiency, net metabolizable energy and protein digestibility in experimental animals. However, recent findings indicate that the major effect of tannins was not due to their inhibition on food consumption or digestion but rather the decreased efficiency in converting the absorbed nutrients to new body substances. (Chung KT, Wong TY, Wei CI, Huang YW, Lin Y. 1998).Crab includes the abundant of protein and wine includes a lot of tannic acid.If the two eat together,tannic acid in wine will be solidified with the protein content in crab and it cannot easily be digested because it forms an insoluble and indigestible protein coagulum in intestine.You may have symptoms such as nauseous ,have a distended and painful stomach and vomiting. It is advisable that you drink wine four hours after you have eaten crab.


How does the materials formed from tannins and protein?

The capacity of tannins to bind proteins has been recognized for centuries.The tannin's phenolic group is an excellent hydrogen donor that forms strong hydrogen bonds with the protein's carboxyl group. Precipitation of proteins by tannins is maximum at pH values near the isoelectric point of the protein. In order to have high protein affinity, tannins must be small enough to penetrate interfibrillar region of protein molecules but large enough to crosslink peptide chains at more than one point. HTs and PAs form tannin-protein complexes in similar manners. Proteins thus bound are generally resistant to attack by proteases and hence make protein indigestable.When soluble tannins interact with proteins, both soluble and insoluble complexes are formed. Soluble complexes are favored when protein concentration is in excess which there are fewer tannin attachment sites per each protein molecule. Insoluble complexes are formed when tannins are present in excess and form an hydrophobic outer layer in the complex surface.Protein digestibility is greatly reduced when tanniniferous feeds are part of the diet.


~Special thank for references~

Tannin and human health:
- http://www.ncbi.nlm.nih.gov/pubmed/9759559
Blue crab nutrition facts :
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