Perfect timing for this question Country Vines as I have a very timely qoute that will help explainthisfrom Tim Vandergrift who is the Technical Services Manager, Winexpert Ltd.
"First, kits will always have some concentrate in them. This is because concentrate isn't just used to reduce size (and thus shipping and associated costs) it is also used as a preservative.
Compared to fresh grape juice, concentrate has a much lower, and very heavily buffered pH. Lower pH means lower growth rates of spoilage organisms. Buffered means that even when you rehydrate concentrate, the pH stays low until the yeast cracks the sugars away from acids and de-bonds come ions.
Also, concentrate has high sugar levels, which acts as a preservative. This seems counter-intuitive, but sugar in high concentrations is lethal to bacteria--ever wonder why the sugar in the sugar bowl never spoils? It's because when bacteria touch it, they die from osmotic pressure differential.
Next, there are concentrates, and there are concentrates. You can run all five of your concentrator elements and the 21 brix grape juice you pour in one end will come out 78 brix at the other (brix means 'percentage of solid material by weight, so higher brix means more solids dissolved in the liquid, mostly sugar), or you can turn off two of them and have it come out at 52 brix, with more flavour, aroma and TDS--all of which contribute to the character of the finished wine.
Now, if you are making a 7.5 litre kit, you can't use 52 brix concentrate--the kit would have to be at least 10 litres for that to work well, if you are to add enough fresh juice to make an appreciable difference. Why? Well, because it is terrifically difficult to package kits below 33 brix. In order to stay shelf-stable for more than a few months, the kits need to be high enough in sugar, and low enough in pH to prevent spoilage.
Now, as for the juice portion, why does a bottle of Stag's Leap Merlot cost $40 USD (or about $65 CAD where I live) and a bottle of Chilean or Aussie Merlot go for five bucks in Costco, and why does Two-Buck Chuck Merlot go for three bucks in Trader Joe's? Because one of those growing regions is associated with much higher quality wines, perhaps partly from prestige, but mainly due to the fact that they restrict yields and have much higher quality raw materials. This cost is passed on to the people who buy the grapes, and consequently the finished product, kit or commercial wine, is in a much higher price bracket.
Bottom line: there is a diret and linear relationship between the quality of the kit you get and the price you pay.
The good news, however, is that the difference is something like three dollars a bottle between the cheapest kit you can get, and the most expensive. Compare that between the $37 a bottle between Chuck and Stag's leap, and it looks like a bargain!"
