Method for the determination of water content in sultana raisins using a water activity probe

A new method for the fast (less than 5 min) and accurate (better than 0.5% error in water content) measurement of water in sultana raisins without the need for sample weighing has been developed. The method is based on a commercially available water sensor and probe. Additionally, a raisin press has been developed to prepare the sample for analysis in one step. The results obtained with the proposed method correlate well (R2=0.999) with those obtained using a high speed blending Karl Fischer auto-titrator. The method shows good analytical characteristics, the analysis time is short, and no expensive or dangerous chemical consumables are used. The method can thus be used easily by non-experienced personnel, either on site, or in the laboratory.