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The timing of commencement of harvesting is a compromise between the better yields obtained from fruit of higher sugar content and the increased later in the season. This dilemma has resulted in the practice of beginning harvest on a more or less fixed date, which for Sultanas is usually after mid August.

Maturity (sugar content) may be determined by taking a representative sample of fruit from the area in question and tested by a refractometer.

The recommended minimum harvest maturity level for sultanas is minimum 18,6 % sugar.

The grapes are hand-picked into the container (“dip tins” or “buckets like plastic baskets”). The most commonly used containers are made of sheet steel and plastic baskets have perforated bottoms and sides to allow free flow of dipping lye through the fruit during dipping.

No mechanical harvesting of fresh grape, for drying purpose is being used.

Theory of Drying:

The grape berry is naturally very resistant to water loss, as it has a heavy, hydrophobic (water-repellent) “bloom” consisting of over-lapping wax platelets. The cuticle, in particular the outer waxy layer, is the structure, which limits the drying rate of the grape berry.

During drying, water moves outward through the cells of the flesh and skin, the passes through the “bloom” and into the air surrounding the berries. This air becomes very humid and its removal is essential for rapid drying. Ideal drying conditions are provided by a light wind on a hot dry day, when heat is supplied rapidly to the berries and moist air around them is continually removed.

Drying of Sultanas:

Early in season, Sultanas may be dried by simply placing them out in the direct sun, without any pre-drying treatment. In this way “naturals” similar to American Thompson Seedless raisins are produced. They are dark reddish brown, with bluish tinge due to the bloom, and have a distinctive flavor.

However, in Turkey pre-drying treatments that hasten drying are used. Sultanas are dipped in an alkaline lye known to growers as dipping lye.

Formerly it was believed that the lye treatment removed the waxy bloom, but it has since been shown that almost no wax is removed and that the effect is reversible by washing.

Drying times are reduced from about 3-4 weeks for untreated Sultanas to 7-10 days for treated Sultanas dried on a bed under average conditions. Such fast drying leads to rapid rise in sugar concentration, which inhibits the action of the enzyme (polyphenol oxidase) responsible for darkening in untreated fruit. The enzyme is localized in the skin of the berry where drying begins. The natural golden-yellow color of fresh sultanas is thus preserved in treated grapes dried under good conditions. However, when rain or high humidity interrupts fast drying, conditions may become suitable for the darkening reaction to proceed, and darker fruit is produced.

The level of emulsion in the tank is maintained by daily additions from a smaller stock tank, which generally keeps the dip sufficiently alkaline. For a fresh made mixture the PH is about 11. If the PH falls below 9.5, the dip is likely to ferment, so potassium carbonate is added to raise the PH to 10 or more. Usually this is necessary only when treating fruit that has been heavily damaged by rain.

Drying Beds:

Growers under our program must have drying beds of cement or good clay free of cracks and loose material.

Beds are to be throughly cleaned and weeded before drying and completely covered with overlapping wowen polypropylene sheets supplied by us.

An ideally prepared drying bed is higher than surrounding ground within possibilities to help prevent the access of grit, sand or stone into drying fruit.

The grapes are briefly dipped in a lye (solution of 5% potassium carbonate and 1.5% of natural acidic olive oil in water) to accelerate drying.

The dipped grapes are laid down on the beds in such a way to leave a clear strip ideally of 20 cm. from the outer edge of the sheeting. The ground around the edge of the beds should be free loose stones.

Sultanas shall than be delivered directly to us either in bulk or in the special plastic boxes supplied by us. Clean cotton cloth bags containing 50 kgs (+10%) sultanas are also acceptable.

Sultanas delivered in bulk are put into the plastic boxes in our factory by ourselves.

Sultanas produced under our special organization can not be stored at grower’s premises and have to be delivered to us immediately upon completion of harvesting.

These sultanas will be fumigated before storage at the premises of us and kept in approved store until processing. All plastic boxes are to put on pallets and the top layers will be covered with polypropylene hoods.

All stocks are checked and rotated regularly and fumigated if any when deemed necessary. All sultanas are sieved once more in natural conditions before process.

After mechanical washing, and cleaning, the sultanas shall undergo the special cleaning process.