The length of time required for dipping can only be ascertained by experience, and must differ with the strength of the lye, with the heat of the solution, and with the thickness of the skin of the grapes. Thus in different localities the strength of the lye and the length of immersion must always be different, and may even differ from year to year. When properly dipped, the skin of the grapes must show some very minute cracks, similar to cracks in glass which has been heated and suddenly immersed in or sprinkled with ice-cold water. Deep cracks are not desirable, as they will cause the juice of the pulp to leak out, after which the raisins will sugar. In Valencia the grapes used for dipping are the various varieties of Muscats, while in Smyrna both Muscats and Sultanas are used. Corinths are never dipped, as they dry readily and make superior raisins without this process.
Drying and Curing.
—After the grapes are dipped, they must be immediately dried either in the sun, or in sun and shade alternately, or entirely in the shade. According to the circumstances attending the drying of the grapes, the color of the raisins becomes more or less red or yellow, transparent or opaque. The most perfect amber color is attained in the shade, while in the sun the color rapidly changes to reddish, a less desirable color in dipped raisins. The more favorable is the weather for drying, the choicer will be the raisins, and the better their color. If the sun is very warm and the chances are otherwise favorable for drying, the trays should be exposed to the sun only long enough to have their dip thoroughly evaporated, and for this purpose one day in the sun may suffice. After this the stacking of the trays is advisable, and only occasionally may the trays be spread if the drying does not proceed rapidly enough. Such shade-dried dipped raisins will assume a beautiful amber-yellow color, and bring several cents more than those exposed to very warm sun. If, however, the weather is not very warm, the grapes must be dried in the sun, and the grower has then to be satisfied with the color that nature will give to his raisins. Dipped raisins do not necessarily require turning, as they generally dry well anyhow in from four to six days in fair weather. For this class of raisins dryers are very useful to help finish the drying. Such dryers must be almost air-tight, as sandstorms would invariably spoil the raisins, which, on account of their stickiness, are almost impossible to afterwards cleanse. Dipped raisins should always be dried on their trays, and on special drying grounds, which should be so constructed that no sand can blow on them, or at least so arranged that in case of rain the sand from the ground will not be splashed over the trays. In California we have at present no such drying-floors, but it will pay any one who intends dipping his grapes to construct them either of bricks, bituminous rock or lumber.
Stemming, Grading and Packing.
—Dipped raisins should be stemmed when well dried, and then graded in two grades. The proper receptacles for them are either sacks lined with paper, or twenty-pound boxes, in which they may be packed without fancy paper, or in the same way as prunes or other dried fruit. So far no uniform method of packing such raisins has been adopted in this State.
As to the usefulness and future of dipped raisins, not much can be said at present. Our importations of Valencia raisins, which are mostly dipped, are considerable, and as long as this class of cooking raisins is in demand, there is no good reason why we should not compete and endeavor to supply the demand. We can produce them as well as Spain can, and the only reason why we have not competed with Spain so far is that sun-dried raisins are so readily produced here, that it has not been to our advantage to produce anything else. There are, however, many places in our State which will grow Muscatel grapes of good quality, but with too thick skins to make them proper for sun-dried raisins. For all such localities the dipping process is to be recommended, as it will enable the growers to produce marketable raisins, and to profitably supply the demand for this variety of raisins now imported to this country from abroad. In localities with early and copious fall rains, the dipping process will enable the growers to finish quickly before the rains set in. California dipped second-crop Muscatels and Sultanas have brought as high as seven cents per pound wholesale.