The PAL-ACID Pocket Acidity Meters measure the total acidity in fruit juices. Citric acid is the predominant acid type in citrus fruits, tomatoes, and pears. Tartaric acid is the predominant acid type in grapes. Other acids, such as malic acid, are also present. The PAL-ACID measures the total acidity in sample and converts it into citric and tartaric acid concentrations. The units measure the total acidity in sample and convert it into citric or tartaric acid concentrations respectively. The PAL-ACID1 measures in the citric acid scale, and the PAL-ACID2 in the tartaric acid scale.