An evaluation of a microwave technique for moisture content determination in snap beans

A study was conducted to compare a microwave oven procedure to the convection oven method for moisture determination of snap beans. Emphasis was on correlating microwave measurements with convection oven drying results. Drying parameters considered were sample preparation, microwave drying time, and number of samples per microwave load. A dehumidifier was used to obtain a range of initial moisture values. The majority of the pods were pureed in a food processor for the microwave treatment combination procedure. The preliminary results for the convection oven revealed that whole or puree sample preparation had little effect on indicated moisture contents for the ranges tested. Whole sample preparation was selected as the reference moisture technique and was used to evaluate the microwave procedure. Microwave oven preliminary results indicated that time intervals and number of samples had a major effect upon the indicated moisture content. The time intervals (8, 10, 12, and 18 minutes) and the number of samples per load (2, 3, and 4) were evaluated for the treatment combinations to determine percent moisture. For determination of moisture in snap beans using the microwave oven at the No. 6 power setting, the indicated moisture contents given by drying three (10 gram) samples for 12 minutes were significantly different than convection dried samples at the 99% level of probability. Even though they were statistically diffeernt, the moisture contents had the best linear relationship with the convection moisture contents. A convection percent moisture prediction equation was established. Thus, the time reduction from 24 hours to 12 minutes offered by the microwave procedure has potential for moisture determination in snap beans.