Fumigating (Flowline by Courtesy Van Arsdel, Copley and Morgan -Food Dehydration 1973) (2)Product Handling This is done in two stages Stage 1 Inspection. The grapes are inspected when fed to the line, and diseased and damaged fruit removed. In some instances, large bunches are broken down to smaller ones to facilitate quicker drying Dipping The grapes are dipped for 2-3 seconds in a lye bath(94"C)in a solution of 0.25 percent sodium hydroxide, then washed in cold water Tray loading In California the fruit is loaded on to wooden trays which are racked on to trucks and transferred to the sulphuring house Sulphuring. The trucks are held in the sulphuring house for about 4 ours, exposed to the fumes of burning sulphur- 2kg of sulphur being used per tonne of grapes in the chamber Drying. The trucks are then transferred to a tunnel dryer, where they remain until dried down to about 12 percent moisture. The trays are loaded 19kg per square metre, or 3 1/2-4Ib per square foot. The inlet temperatures in the first tunnel must be kept low, otherwise SO2 losses by heat will cause discolouration. 74"C should be adequate in the first stage, with a finishing temperature of 55"C. An SO, target of 2000ppm should be aimed at to maintain the bright colour desired The dried fruit are then stored in'sweat' boxes until they are ready for secondary Processing. During this period the boxes should be fumigated at two weekly intervals to kill any infestation, and the'sweating is merely a process of conditioning the fruit at ambient temperature and allowing it to reach equilibrium by moisture diffusion through the mass of product. The effect is similar to that in conditioning vegetables in bins after primary drying except in the case of fruit there is no heated air-flow and conditioning is natural at ambient temperature Stage 2 The raisins are fed from the sweat boxes on to a rotary /aspirated screen to remove extraneous matter. Stemming. They pass into a stemming machine which mechanically removes the raisins from the panicles by a trigging action. The fruit must not be higher than 12 percent moisture, otherwise thestems will be too soggyFumigating (Flowline by Courtesy Van Arsdel, Copley and Morgan - Food Dehydration 1973) (2) Product Handling This is done in two stages Stage 1. Inspection. The grapes are inspected when fed to the line, and diseased and damaged fruit removed. In some instances, large bunches are broken down to smaller ones to facilitate quicker drying. Dipping. The grapes are dipped for 2-3 seconds in a lye bath (94°C) in a solution of 0.25 percent sodium hydroxide, then washed in cold water. Tray loading. In California the fruit is loaded on to wooden trays which are racked on to trucks and transferred to the sulphuring house. Sulphuring. The trucks are held in the sulphuring house for about 4 hours, exposed to the fumes of burning sulphur - 2kg of sulphur being used per tonne of grapes in the chamber. Drying. The trucks are then transferred to a tunnel dryer, where they remain until dried down to about 12 percent moisture. The trays are loaded 19kg per square metre, or 3 1 /2-41b per square foot. The inlet temperatures in the first tunnel must be kept low, otherwise SO, losses by heat will cause discolouration. 74°C should be adequate in the first stage, with a finishing temperature of 55°C. An SO, target of 2000ppm should be aimed at to maintain the bright colour desired. The dried fruit are then stored in ’sweat’ boxes until they are ready for secondary processing. During this period the boxes should be fumigated at two weekly intervals to kill any infestation, and the ‘sweating’ is merely a process of conditioning the fruit at ambient temperature and allowing it to reach equilibrium by moisture diffusion through the mass of product. The effect is similar to that in conditioning vegetables in bins after primary drying except in the case of fruit there is no heated air-flow and conditioning is natural at ambient temperature. Stage 2. The raisins are fed from the sweat boxes on to a rotary/aspirated screen to remove extraneous matter. Sfemming. They pass into a stemming machine which mechanically removes the raisins from the panicles by a strigging action. The fruit must notbe higher than 12 percent moisture,otherwise thestems will be too soggy I90