Every wonder how they make wine kits. Well here is an article from Winexpert that does a great job in explaining the process.
From reading the side panels on wine kit boxes, you’ll see that Winexpert kits contain concentrate, juice and other winemaking staples like acid and sulphite. However, just how these things came together to make your kit isn’t as obvious. For the most part, about 75% of the methods used to construct wine kits, in the beginning at least, are exactly the methods used in making wine.
To start, Winexpert contracts to purchase grapes from growers by specifying conditions at harvest (acid, pH, brix, and colour), as well as organoleptic qualities (flavour and aroma). These specifications are very rigid, for although the grapes may change radically from harvest to harvest, the kits must maintain very high levels of consistency, so consumers can make repeat purchasing decisions. When the grapes are ripe, they are harvested and taken to a winery, where they are sulphited and crushed. At this point, white and red grape processing diverges.
White grapes are pressed, and the juice is pumped into a settling tank. Enzymes are added to break down pectins and gums, which would otherwise make clearing difficult after fermentation. Bentonite is added to the juice and re-circulated. After several hours, the circulation is shut off, and the tank is crash-chilled below freezing. This helps precipitate grape solids out, and prevents spoilage.
Red grapes are crushed, sulphited and pumped through a chiller to a maceration tank, where special enzymes are added. These break down the cellulose membrane of the grape skins, extracting colour, aroma and flavour. The tank is chilled to near freezing to prevent the must from fermenting. After 2 to 3 days, the red must is pumped off, pressed and settled, much the same way as with the whites.
When the tank is settled and the juice almost clear, it is roughly filtered, the sulphite is adjusted, and it is either pumped into tanker trucks for shipment to the kit facility, or into a vacuum concentrator.
A vacuum concentrator works like the reverse of a pressure cooker. When pressure inside the tank is lowered, water can be made to boil at very low temperatures. So boiling the juice at a low temperature prevents browning and caramelization. The water comes off as vapor, leaving behind concentrated grape juice. Because some aromatic compounds can be carried away in this vapor, a fractional distillation apparatus on the concentrator recovers these essences, returning them to the concentrate after processing.
Any acids, sulphur dioxide, or pectic enzymes added along the way in these processes are used in accordance with federal regulations regarding wine processing. The acids are used to balance flavour and achieve pH targets. The sulphur dioxide prevents browning and spoilage.
The juices and concentrates are now shipped to Winexpert's facility where they are pumped into nitrogen purged tanks, tested for quality and stability, and held at very low temperatures. This both speeds up the formation of wine diamonds (crystals of potassium bitartrate from the tartaric acid naturally occurring in the wine), and preserves them until they are to be used.
After the Quality Control checks are passed, the juices and concentrates are blended into the formulations that make up the different kits, in giant blending tanks. When the formulation is finally adjusted and approved, the must is pumped through the pasteuriser. This is a type of heat exchanger that rapidly heats and then cools the must, killing yeast and spoilage organisms, but not burning or caramelizing the must. From there it goes into the bag filler, which purges the sterile bags with a double flush of nitrogen, and then fills each bag to a very strict tolerance.
The bags are then automatically capped and loaded into the kit boxes that come from the box former, after which the packaged additives are placed on top. The boxes are sealed, shrink-wrapped and packed on a skid for a Quality Assurance microbiological hold.
Depending on the product, this hold can be from 3 days to more than a week, while the product is examined for signs of bacterial or yeast activity. If the product passes this examination, it is then shipped to the warehouse, and from there to dealers, and finally, into the hands of the winemaking customer.