Determination of moisture content and equilibrium relative humidity of dried fruit—Sultanas

A vacuum oven method is recommended for the determination of the moisture content of sultanas, drying to constant weight at 70°C, and at a pressure of 5 mm Hg or less, for 24 hr. It is shown that accuracy of better than 0·5 per cent cannot be guaranteed and that day to day variation, and oven position variation are encountered. A distillation method, using toluene as the entrainer, over a period of $\text{2}\text{1}\text{2}\text{hr}$, gives satisfactory estimates of moisture content when a ‘rapid’ but less accurate estimate is required. Data are presented for the moisture content/equilibrium relative humidity (e.r.h.) relationship of Turkish sultanas.