Dried Apricot Preparation
Fruit selection:
Ripe fruit which has a tart flavour should not be dried, as the tartness will be accentuated by drying. The fruit should have a firm sweet flesh. The trees are shaken over a large 6*6m tarpaulin, and the fruit is then graded and packed in crates for shipment to the drying area. Only 30% of the fruit of a tree will be ready at any one time. First the upper branches, then the middle branches, and finally the lower part of the tree. Over-ripe fruit, and fruit showing signs of disease are selected out at this stage.
Fruit Processing:
Once the fruit arrives at the drying site, it is washed by placing the fruit into plastic net baskets. These are placed in a bigger tank of water, and the fruit is agitated to give a washing action. As well as cleaning the fruit, this action helps the fruit absorb sulphur. Any leaf debris should be removed from the water.
The fruit can then be treated in one of two ways:
1. Whole apricots can be placed in a single layer on the tray. Fruit of the same variety and size should be placed together to ensure equal drying. During filling, a stack of trays is build up in a vertical column to ensure the fruit retains its moisture. When 26 trays have been filled, 26 trays are placed in the sulphur chamber. Once the fruit has dried to 50% of its moisture, the stone can be removed, and the de-stoned apricot is placed back on the tray to dry to 20% moisture. At this stage, the fruit can be overlapped, to make the best use of the trays. The advantage of this method is that fruit can be processed more quickly initially. However, the flavour of the kernal is altered, reducing its value.
2. Alternatively, using serated knives, the fruit is cut, the stone is removed, and the halves are layed out on the drying frames. When 26 frames are ready, these are stacked and placed in a sulphuring chamber.The advantage of this method is that the drying time is shorter, and the fruit only has to be handled once. This method is especially suitable for larger fruit. The inside of the fruit can also be checked for infestation.
Unripe fruit should be separated and allowed to ripen before processing.
Trays of sulphured apricot halves drying in the sun.
Sulphuring:
The trays are stacked two abreast, with the ends of alternate layers extending beyond the edge of the stack by about 10cm, to ensure good circulation of the smoke. A chamber of polythene over a
wooden frame is then placed over the stack of filled trays, and the sulphur tin is placed in front of
the trays. Small openings in the polythene ensure a good circulation of smoke. The sulphur is laid in a thin layer in a tray made of steel sheet of dimensions 60*15*10 cm. It is lit at one end, which ensures a slow burn over 5 hours. The fruit stays in the chamber for at least 8 hours, and is usually removed the following morning. All the sulphur must be burned up. If necessary, any unburnt sulphur can be broken up and relit.
The target sulphur dioxide level in the fruit is 1500 ppm. This is obtained by a slow burning of high quality, dry sulphur. Usually 1kg of sulphur is required for 100 kg of ripe fruit, but this may vary depending on the quality of the sulphur and the ripeness of the fruit. There is a simple test that can be done to measure the sulphur dioxide level in the fruit. It is important that the target level is reached. Over time the sulphur levels in the fruit decreases, and this can cause the fruit to lose its orange colour. Proper use of sulphur is highly beneficial in preserving colour, preserving vitamin content, and in preventing infestation. Fruit can be re-sulphured by simply moistening the dried fruit, sulphuring, and then laying the fruit out in the shade to dry. Obtaining high quality dry sulphur is always a challenge. The sulphur should burn completely. If it
does not, this is a sign that the moisture content is too high. Moist sulphur should be pulverised and
laid out in the sun to dry. Nothing should be added to the sulphur to speed the combustion.
Metabisulfite Dipping:
7% solution for 5 minutes. This means 70g per litre
Sun drying:
The drying time depends on the weather conditions and the fruit size and variety. It usually spends one day in a solar drier for the moisture content of apricot halves to be reduced to 30%. The trays can be placed in a stack to allow final drying to 25% in the shade. The sign that the fruit is ready to be picked from the trays is that it is no longer sticky to the touch. During the drying process, the trays have to be inspected regularly to make sure that the fruit is not
over dried.
Equilibration:
Once the fruit is no longer sticky to the touch, it can be picked from the trays and placed in a mound
of fruit in a cool dry place. The underneath of the trays should be wiped with a damp cloth to soften
any syrup sticking fruit to the mesh. This makes the task of removing dried fruit easier. At the picking stage, the fruit is inspected and graded. Strict quality control is needed at this stage. Workers wear aprons, have short sleeves, and covered hair. If partly dried fruit is removed at this stage before it is properly dried, it will stick to other fruit at a later stage and cause clumping. Partly dried fruit should be placed in a thin layer in the shade until it is fully dried. This is a slow drying stage when the moisture in the fruit equalises, with smaller, drier fruit absorbing moisture from larger fruit. This stage lasts 2-3 days. During equilibration, the mound of dried apricots should be stirred by hand. The test that the fruit is ready for packing, is that hands
pushed into the mound of apricots come out dry. Also, the apricots do not clump together.
Storage:
The fruit is packed into sealed polythene sacks of 25kg each, and labelled with the production date,
and sulphur content. It is important for the storage area to be kept clean, free of mice and rats, with good ventilation, with netted windows. This prevents moth entry which tend to lay eggs on fruit causing subsequent infestation.
Sun-dried tomatoes
Sulphuring: Burn 500g of sulphur for 100kg fruit.
Metabisulfite Dipping:
7% solution for 5 minutes. This means 70g per litre