Why pure grape juice is always pasteurized?

Of all grape juice sold in the grocery stores, every single one is pasteurized. Why?!
If it doesn't do any good for wine, I assume the same is true for grape juice. Isn't it?
Then why not simply add SO2 and sell fresh pure grape juice?
Is it only done in Israel, because all pure grape juice is produced as Tirosh and has to be mevushal (heated/pasteurized)?
Or, there are some other reasons?

Grape juice need not always be pasteurized, but then it must be sterile bottled, filtered through membranes into sterile bottles, with the entire downstream from the membrane cartridge properly steam sterilized, and properly cleaned beforehand. By pasteurizing and hot bottling, you do the line and bottle sterilizations all at one time, with the wine. Juice is an environment rich in nutrients for a fermentative organism, or with oxygen, a nonfermentative organism. SO2 can only inhibit fermentation, but it rarely will kill fermentative organisms, and it is only a temporary measure. Sorbate also, and some organisms can metabolize sorbate. There are ways to kill fermentative organisms, especially yeast,using methyl and ethyl carbonates, but the resulting carbamate is a suspected carcinogen, and the substances are controlled. there is simply no good way to chemically remove the risk of refermentation.

So why don't the grape juice makers sterile filter? Probably because it is much less expensive not to, and grape juice is a price sensitive commodity.

This kind of answers is what makes this forum invaluable. I wouldn't find an answer in my wine books for sure.
One more question on this. Does the membrane filter out with 100% success any wild yeast in the juice? And other organisms like Salmonella and E coli. Because if not, the producer wouldn't take the risk.

The answer, of course, is that a membrane filter is absolute to its particular rating. yeasts are filtered out at o.65 microns, most bacteria at 0.45 microns, and 0.2 microns will absolutely get out anything except the smallest viruses- it is used mostly for pharmaceuticals. From the standpoint of sweet wine, for instance 0.45 microns is sufficient. It will take out any wine-related bacteria, of which e. coli and salmonella are not a concern. I don't know whether they are smaller than 0.45 micron, but would doubt it. In any case, they would certainly be filtered out at 0.2 .

I see. And after bottling, would it hold a week or two as the fresh orange juice or it can be stored for several months?
I assume that the fresh juice is much better than dead pasteurized. E.g. all these organic food stores can buy such a product.

Assuming sterile bottles, a properly sanitized bottling line and an intact filter, and assuming exclusion of air and some sort of antioxidant, and assuming a good closure, there is no reason to assume it would not last for a long time, not just a week or two.

Thanks for the answers Craig. Sounds like a niche business for those who eat all organic and fresh. All vitamins preserved. Everything is great. But in life it's not that simple.

Stability of Non-Pasteurized, Refrigerated Muscadine Grape Juice
ABSTRACT

The stability of nonpasteurized muscadine grape juice processed with and without 100 mg/L potassium metabisulfite was monitored during storage at 3°C. The muscadine flavor intensity, sweetness, off-flavor levels, and color of white juices remained stable, and ethanol levels remained low for 7 wk. However, the flavor intensity and sweetness of nonsulfited white juice decreased, and off-flavor and ethanol levels increased after 7 wk. Sulfite lowered microbial levels in white juice throughout 9 wk. Red juices did not develop significant levels of off-flavors or ethanol during 9 wk, although the flavor intensity declined, especially in nonsulfited red juice. Sulfite lightened the color of red juice, but the color was stable in both sulfited and nonsulfited red juices.

http://onlinelibrary.wiley.com/doi/10.1 ... x/abstract

Is that what you want, Muscadine (Scuppernong)?

Don't know this grape, except it's table grapes. I thought of grapes used for winemaking, but found only an article about Muscadine. The point is that it doesn't hold for long, although it is unclear from the abstract if the juice was kept sealed or open.

Muscadine is an interesting grape that is an entirely different species than the European wine grape. But there are plenty of different species- Vitis Labrusca, for instance , is the species from which the Concord grape variety was developed, a native American variety. Muscadine is Vitis Rotundifolia, also a native American variety. What makes it so unique is that it has an extra chromosome, so that it cannot interbreed with other varieties, cannot hybridize. Those with the same number of chromosomes can do so, and produce hybrids of various qualities, some of which were good enough to become instrumental in cold weather viticulture, others of which were best as rootstocks, and most of which are forgettable grapes of no distinction whatsoever. But as I say, Vitis Rotundifolia can't do it. But one thing it can do that no other grape varieties can is to survive and thrive in the hot, humid weather of the American south. some are fuzzy, some are smooth, all are very aromatic, perfumed and musky fruit which is not for everybody, but those who enjoy sweet, perfumed wines might enjoy a Muscadine wine. there was actually a wine industry in the south making such wine, which was something like Concord, but sickeningly perfumed.

Muscadine is an interesting grape that is an entirely different species than the European wine grape. But there are plenty of different species- Vitis Labrusca, for instance , is the species from which the Concord grape variety was developed, a native American variety. Muscadine is Vitis Rotundifolia, also a native American variety. What makes it so unique is that it has an extra chromosome, so that it cannot interbreed with other varieties, cannot hybridize. Those with the same number of chromosomes can do so, and produce hybrids of various qualities, some of which were good enough to become instrumental in cold weather viticulture, others of which were best as rootstocks, and most of which are forgettable grapes of no distinction whatsoever. But as I say, Vitis Rotundifolia can't do it. But one thing it can do that no other grape varieties can is to survive and thrive in the hot, humid weather of the American south. some are fuzzy, some are smooth, all are very aromatic, perfumed and musky fruit which is not for everybody, but those who enjoy sweet, perfumed wines might enjoy a Muscadine wine. there was actually a wine industry in the south making such wine, which was something like Concord, but sickeningly perfumed.