METHODS OF ANALYSIS MOISTURE IN POTATO GRANULES BY VACUUM I Apparatus Balance accurate to± 25mm Hg or less. pable of maintaining vacuum equivalent to 4. Aluminium moisture dishes, diameter 2-1/2in, height 5/8in. with slip-over cover 5. Gas drying bottle containing concentrated H2SO4 6. Desiccator containing drying agent ( Silica Gel self-indicating) II Method 1. Weigh approximately 2g of potato granules into an aluminium dish previously dried at 98-100"C to constant weight, and cooled to room temperature in a desiccator. Duplicate test 2. Place dishes with cocked lids(do not remove lids) in vacuum oven for 6hr at 70'C under vacuum equivalent to 25mm of mercury. When the correct vacuum pressure is obtained, the time interval of 6hr is then begun. At this time, air at the rate of 2 bubbles per second is allowed to enter the vacuum oven through a sulphuric acid drying bottle. 25mm of mercury means that the internal pressure in the vacuum oven will be 5mm of mercury above perfect vacuum 3. Remove the dishes after tightening their covers. Transfer to the desiccator, and allow to cool to ambient temperature Ilo 4. approximately 10-15min)before weighing Calculate the moisture Loss in weight x 100 1. Moisture le weight 2. Duplicate samples should be within+0.1% moistureMETHODS OF ANALYSIS MOISTURE IN POTATO GRANULES BY VACUUM OVEN I Apparatus 1. 2. Vacuum oven. 3. 4. 5. 6. Balance accurate to f 0.001g. Vacuum pump capable of maintaining vacuum equivalent to 25mm Hg or less. Aluminium moisture dishes, diameter 2-1 /2in., height 5/8in., with slip-over cover. Gas drying bottle containing concentrated H,SO,. Desiccator containing drying agent. (Silica Gel self-indicating). I1 Method 1. Weigh approximately 2g of potato granules into an aluminium dish previously dried at 98"-100"C to constant weight, and cooled to room temperature in a desiccator. Duplicate test. Place dishes with cocked lids (do not remove lids) in vacuum oven for 6hr at 70°C under vacuum equivalent to 25mm of mercury. When the correct vacuum pressure is obtained, the time interval of 6hr is then begun. At this time, air at the rate of 2 bubbles per second is allowed to enter the vacuum oven through a sulphuric acid drying bottle. 25mm of mercury means that the internal pressure in the vacuum oven will be 5mm of mercury above perfect vacuum. Remove the dishes after tightening their covers. Transfer to the desiccator, and allow to cool to ambient temperature (approximately 10-15min) before weighing. 2. 3. 4. Calculate the moisture. I11 Calculations Loss in weight x 100 sample weight 1. % Moisture = 2. Duplicate samples should be within 5 0.1% moisture - *^