This doesn't make sense. The concentrate is supposed to be denser, so a smaller volume provides the same end result. Given that the ABV is supposed to be the same, unless sugar is being added, using less juice
In the dark ages of wine kits, you got 5l of concentrate in a can, and some yeast. They made a grape-like product with some alcohol, and were not very good.
In the 1990s, WineXpert claims to have "invented the modern wine kit". They added a bunch of fresh juice to the concentrate to give them a more "varietal character". In order to make them "shelf stable", the fresh juice portion needed to be flash pasteurized so they wouldn't start fermenting (because of natural yeasts) on the shelf. In fact, Mosti Mondiale makes (or made) 23l kits that had to be shipped cold because they were in fact fresh juice. In the years that followed, manufacturers added more juice, oak additions and even grapeskin packs to further enhance our experience. Life was good!
Recently, winexpert and others are downsizing their kits, and claiming no reduction in quality. My question is... Which is harder on grape juice : flash pasteurization or vacuum concentration? The kit manufacturers seem to be leaning towards the former and if that is the case, wouldn't the logical outcome be that they would go back to pure concentrate kits? I sure hope not!
I believe it's about saving money! A smaller volume of juice costs less, fits in a smaller bag which fits into a smaller box which is lighter and costs less to ship. Combine that with some marketing gobbledygook, and the result is the kits we will be getting from now on.
I have Bottled a new stag's leap merlot and agree it tastes better out of the carboy than the old version. However, wines that mature faster also fade faster (the 2 times rule), so for me, this experiment is going to last 3 years!