The Raisin Industry / A practical treatise on the raisin grapes, their history, culture and curing

by Gustavus A. Eisen

—The sweatboxes should be made of strong lumber one inch thick. The length and width should be according to the size of the tray, and always one inch larger every way than the tray, in order that the raisins may be let down readily, or that they may receive a tray. The height of a sweatbox should be from six to eight inches, no more, as a greater depth will make them too heavy to be handled with ease by two men. Six inches in depth is better than eight. In order to secure the box and prevent it from splitting, the sides should be bound with hide, iron bands or with twisted galvanized wire. The latter is the strongest and best, costs the least, and is the easiest to put on.

Trays for Drying.

—The tray consists of a wooden frame made of well-dried half-inch lumber, nailed to cleats of one inch by one and one-half inch and of desired length. The lumber most commonly used is well-seasoned spruce. Pine, if not well seasoned, is apt to give the raisins a taste of the wood or of rosin, while redwood may discolor the raisins if exposed to rain or very heavy dew. But as the lumber attains age, it also becomes less injurious to the grapes. Cottonwood or poplar-wood, which can be obtained in some places, make most useful lumber for trays, as they do not contain any taste or other substance apt to injure the raisins. The size of the tray varies according to the idea of the raisin-grower, but the size generally adopted is two by three feet. Formerly a smaller tray was used, but no smaller ones are now made. A larger size, three by three feet, is used by several growers, but, while it has the advantage of holding more grapes, it is also less readily handled than the smaller tray. In the southern part of California, a tray two and one-half by three feet is very popular. The tops of the trays are bought in the shape of shingles, which should be well dried before being nailed, as they will otherwise shrink up and cause cracks to form in the tray, greatly to the detriment of the drying of the raisins. Loss is also caused by loose raisins dropping through such cracks. The cleats should be wet or green, or they will split in nailing. If too dry, they should be soaked in water over night or for a few hours. The shingles should be planed on the side which is to be placed upwards. The cost of the lumber for the trays varies from nine to twelve and one-half cents in the shooks. For nailing the trays together, a frame is made of wood and iron. The cleats are placed on the two short, opposite sides, with a heavy bar of iron immediately underneath so as to clinch the nails. The planed shingles are then placed on top and nailed to the cleats with round-wire nails, which clinch automatically on the lower side as soon as they strike the iron bar. No cleats are required on the long side of small size trays, but if a larger tray is used a bar on each side may be required to give the tray sufficient strength. A good workman, after a few days of practice, can comfortably nail up four hundred trays a day. When the season is over, every tray should be nailed up and washed, or at least swept clean and stored dry. The age of a tray, if cared for, is about ten years.

CALIFORNIA LYE-DIPPED RAISINS.

General Notes.

—In California the dipping of raisins in solutions of lye is yet in its very infancy, and I do not think that in the whole State over ten tons of lye-dipped raisins have been placed on the market yearly. But undoubtedly this process is destined to become of considerable importance, especially in localities where the drying of the first crop is accomplished with difficulty in the open air. The first and also most important condition in producing superior dipped raisins is that the grapes should be absolutely ripe. Unripe grapes will not produce any good raisins when dipped, but will turn reddish and otherwise become inferior.

Dipping Process.

—A good location for dipping raisins is by the side of an irrigation ditch, provided the water in the latter can be depended upon to flow constantly while the operation of dipping lasts. If not, the water must be procured by pumping or by means of pipes from reservoirs or water-works. Flowing water is of great importance in producing good dipped raisins, and is required for the perfect washing of the grapes. For this purpose, if no ditch is available, a large trough may be used to advantage, and so arranged that the water in it can be kept changing through a continuous flow. The following is a cheap and efficient arrangement for dipping in actual use in one of the largest raisin vineyards, and can be recommended on account of its cheapness and easy working: On one side of the trough is a stationary iron kettle with a fireplace underneath. By the trough is also placed an upright post, about five feet high, and on this balanced a horizontal beam with a double motion. It can be raised and lowered at either end, or swung to the left or right with ease. On one end of the beam is a hook on which to hang the grape bucket. On the other side of the trough is a rough assorting table. Two or more buckets are needed. These buckets are common galvanized-iron buckets, perforated thickly with holes, the latter not large enough to let any loose grapes through. In the kettle is kept constantly boiling a solution of water and potash. Soda is not suitable. The very best potash should be used in the proportion of about one pound to twelve gallons of water. The ripe grapes are now brought to the table and emptied in the buckets. A bucket is then hung on the beam, the latter swung and the bucket for a second lowered first in the pure water and then in the boiling potash; but it is immediately withdrawn and immersed in the water-trough. When rinsed for a few seconds, the grapes are taken out and spread on common raisin trays. If the weather is warm, the trays are stacked one on top of the other, and the grapes thus prepared are dried in the shade.

The rinsing of the fruit before drying is of great importance, and by far not sufficiently understood. In Valencia the finest raisins are treated that way and thoroughly rinsed before being dipped in the lye. But nowhere in Spain are the grapes rinsed in water afterwards, and it is yet an undecided question if this rinsing improves or injures the raisins. It is certain that the washing cleanses the berries, as the water in the kettle is sometimes dark and dirty; but if it is an advantage to deprive the berries of the lye which more or less sticks to them is very doubtful. It is well known here that lye-dipped raisins are apt to mold if the rains set in while the drying lasts, while we are told that in Spain the dipped raisins do not spoil even if subjected to several showers of rain. From this it will seem as if rinsing after dipping is not necessary or perhaps even injurious, but that, on the contrary, rinsing before dipping is of the utmost importance. It may be possible that the lye which adheres to the grapes will, in a great measure, prevent them from molding.

In Spain no olive oil is used for mixing in the lye, and it is not likely that the oil process will come in vogue in California until it is fully demonstrated that it not only greatly improves the grapes, but that it also enables the grower to realize a correspondingly better price for his raisins. Those who care to experiment with it cannot do better than to follow the practice as it is used in Smyrna, for a full account of which we beg to refer to the [article] under that heading. We might here only point out that the oil-dipped raisins of Smyrna bring many times the price of the lye-dipped raisins of Valencia. The arrangement of dipping, kettles, etc., may, of course, be greatly varied. Steam may be used for heating the lye and the rinsing water, if it is desired to keep the latter hot, and regular trays might be used to hold the grapes, instead of the buckets referred to above. Every grower will no doubt vary these appliances to suit his own fancy, and improve upon the methods of others. As an example of the devices used by another grower, we here reproduce the following from an essay on bleaching raisin grapes, compiled by the chief viticultural officer, and especially referring to the system used by Mr. Byron Jackson: “Mr. Jackson places the grapes on a tray made with a frame of iron, which is covered with wire gauze with a quarter-inch mesh. The frame projects upwards on the sides to prevent the fruit floating off while in the dip, and is made to receive, as a cover, the wooden tray on which the fruit goes to the dryer. When dipped and rinsed, the wooden tray is placed over the dipping tray, and two men transfer the fruit by turning over the two.”