"The type of pasteurizer differs in almost every establishment. As the industry is of comparatively recent development commercially, there are few models on the market and each manufacturer has constructed the model best suited to his particular ideas or requirements. There are two general types, however, (1) open, double-bottomed kettles in which the juice is heated to the required temperature and then drawn off, and (2) continuous pasteurizers in which the juice is heated to the required temperature as it passes through the water bath.
"The presses also show great variation in different establishments, either hydraulic, screw or lever power being used, and there is a marked difference between the types of pomace containers. Sometimes the crushed grapes are heaped on burlap cloths the sides of which are folded in, and these burlaps are placed one on top of the other in the press; sometimes press baskets take the place of these burlaps.
"The manufacturers in California and those in the grape-growing regions of the Rocky Mountains seem to have adopted entirely different methods of handling the juice after it is first pasteurized and stored. Most of the eastern juices are red and are obtained from the Labrusca varieties, generally the Concord. When the juice comes from the presses, some manufacturers strain it to remove the coarse particles and then pour it directly into well-sterilized bottles; others siphon it off the sediment in the containers in which it is stored after the first pasteurization and pour it into pasteurized bottles. In either case, the bottles are securely corked and then repasteurized. The California juices, however, both red and white, are made exclusively from Vinifera varieties. They are allowed to settle in the original containers and are siphoned out of these and carefully filtered to make them clear and bright.
"The clearing of the juice is sometimes facilitated by fining or adding a small quantity of a substance which coagulates and when settling carries down with it the solid matters causing cloudiness in the liquid. Such finings may be applied at the time of the first pasteurization or just before the final filtration and bottling. In the latter case the juice is drawn off the settlings in containers, the finings are added, and the juice again pasteurized into other receptacles. When it clears, it is either bottled directly or first passed through a filter, drawn into carefully sterilized bottles, securely corked, and then repasteurized. Care must be taken that the final sterilization is not at a higher temperature than the previous one; otherwise, solid matter may be precipitated and the must clouded again.