LABORATORY ANALYTICAL TESTS Rs aving received samples representative of a batch of finished product, or coming raw material, the staff will carry out the following tests Moisture For moisture tests, either a vacuum oven, set at 70'C, or a fan assisted air oven set at 100-103.C, is used. The former is more accurate, albeit slower, on account of the low temperature used, as this prevents the charring and burning of the sample when it is completely dried out, and allows a more exact result to be calculated Samples of raw vegetable should be grated finely before testing, and dry products should be ground in a small coffee grinder The sample material is dried down to zero moisture, and th weight expressed as a percentage of the original to the nearest 0. 1 percent. Two hours is the average time for drying down most dehydrated vegetables, from 8 percent to zero moisture; raw vegetable samples will take 16 hr. These times apply when using an air oven. A more rapid calculation of moisture in dry products can be made by using an infrared moisture tester. The sample must be finely ground so that it passes through a 10 mesh sieve; a given weight is dried out under an infra red lamp, the loss in weight being recorded by a scale on the tester. Results can be obtained in up to 7min, and in as short a period as 4min for some vegetables These moisture testers, however, are not as accurate as the oven-type, and results can vary about 0.5 percent when compared with the latter. It is nevertheless, an indispensable instrument for the shift chargehand to use for rapid tests on material in course of process, particularly for testing products drying in finishing bins, where it is important for the operator to know the drying end-point accurately, before discharging the material to the packing department Sulphur Dioxide Tests for SO2 concentration are carried out by the Monier Williams method,or what was described in the early days of dehydration as the 'Committee method. The former method is rather more accurate but the latter is more generally used with vegetables, for the sake of speed Basically, the calculation is made by boiling a 20g sample of the ground product in dilute hydrochloric acid and titrating iodine into the distillate as ws 250ml of distilled water are placed in a 500ml flask connected by a splash-head to a vertical condenser terminating in a bubbler feeding into 600ml beake 20g of the dried product for analysis are put into the distilled water inLABORATORY ANALYTICAL TESTS Having received samples representative of a batch of finished product, or incoming raw material, the staff will carry out the following tests: Moisture For moisture tests, either a vacuum oven, set at 70°C, or a fan assisted air oven, set at 10Oo-103"C, is used. The former is more accurate, albeit slower, on account of the low temperature used, as this prevents the charring and burning of the sample when it is completely dried out, and allows a more exact result to be calculated. Samples of raw vegetable should be grated finely before testing, and dry products should be ground in a small coffee grinder. The sample material is dried down to zero moisture, and the loss in weight expressed as a percentage of the original to the nearest 0.1 percent. Two hours is the average time for drying down most dehydrated vegetables, from 8 percent to zero moisture; raw vegetable samples will take 16 hr. These times apply when using an air oven. A more rapid calculation of moisture in dry products can be made by using an infrared moisture tester. The sample must be finely ground so that it passes through a 10 mesh sieve; a given weight is dried out under an infra red lamp, the loss in weight being recorded by a scale on the tester. Results can be obtained in up to 7min, and in as short a period as 4min for some vegetables. These moisture testers, however, are not as accurate as the oven-type, and results can vary about 0.5 percent when compared with the latter. It is, nevertheless, an indispensable instrument for the shift chargehand to use for rapid tests on material in course of process, particularly for testing products drying in finishing bins, where it is important for the operator to know the drying end-point accurately, before discharging the material to the packing department. Sulphur Dioxide Tests for SO, concentration are carried out by the Monier Williams method, or what was described in the early days of dehydration as the 'Committee' method. The former method is rather more accurate but the latter is more generally used with vegetables, for the sake of speed. Basically, the calculation is made by boiling a 20g sample of the ground product in dilute hydrochloric acid and titrating iodine into the distillate as follows: 250ml of distilled water are placed in a 500ml flask connected by a splash-head to a vertical condenser terminating in a bubbler feeding into a 600ml beaker. 20g of the dried product for analysis are put into the distilled water in 234