The following account of raisin-making is given by Husmann:[20]
"In the raisin districts grapes are ripe by the middle of August, the season often lasting into November. The average time necessary for drying and curing a tray of raisins is about three weeks, depending on the weather, the earliest picked grapes drying in ten days and the later ones often taking four weeks or more.
"The method of drying is very simple. The bunches are cut from the vines and placed in shallow trays 2 feet wide, 3 feet long, and 1 inch high on which the grapes are allowed to sun-dry, being turned from time to time by simply placing an empty tray upside down on the full one and then turning both over and taking off the top tray. After the raisins are dried they are stored away until they are packed and prepared for shipment. Some of the larger growers, in order not to run so much risk in drying on account of rain, and also to enable them to handle the crop fast enough, have curing houses, where the curing is finished after having been partially done outside."
"The operation of dipping and scalding is designed to accomplish several purposes, namely, to cleanse the fruit, to hasten its drying, and to give the dried fruit a lighter color. In dipping and drying, the fruit, immediately after being cut from the vines, is either dipped in clear water to first rinse it of particles of dust and other foreign matter, or it is taken direct to the scalder and immersed in a boiling alkaline mixture called 'legia' (lye) until the grapes show an almost imperceptible cracking of the skin, the operation consuming perhaps from one-fourth to one-half of a minute. This dipping calls for skill on the part of the operator, the duration of the emersion depending on the strength and temperature of the mixture and the condition of the fruit. Desiccation follows the scalding process, which is accomplished on trays in the sun, the same as undipped raisins cured entirely by solar heat. On account of the scald they cure rapidly, and the fruit is also often of lighter color when cured.
"The following formula has been used for Sultana and Sultanina grapes at Fresno:
"Fifteen pounds of 'Greenbank's 98-per cent lye' are boiled in 100 gallons of water. This mixture is for grapes containing 25 per cent of sugar. Should their sugar content be less, enough lye is added to remove the bloom and open the pores of the skin of the grapes. After dipping, the grapes are spread on trays and sulphured for 1 to 1-1/2 hours. Observation will show whether it may be necessary to vary this formula a trifle to suit conditions of ripeness and influence of temperature. The length of time required for dipping is ascertained by experience, and differs with the strength of the lye, the heat of the solution, and the thickness of the skins of the grapes."