ARS | Publication request: Evaluation of a rapid, portable and easy-to-use device to measure acidity in citrus

Submitted to: Citrograph
Publication Type: Trade Journal
Publication Acceptance Date: June 10, 2011
Publication Date: June 15, 2011
Citation: Obenland, D.M., Sievert, J., Arpaia, M. 2011. Evaluation of a rapid, portable and easy-to-use device to measure acidity in citrus. Citrograph. 2(3):41-43.

Technical Abstract: Determination of titratable acidity in citrus is a time-consuming and sometimes tedious process, but is commonly practiced in the measurement of citrus maturity. Recently, a new acidity meter has come onto the market that measures titratable acidity using conductivity. This instrument is easy-to-use and fast, but information on the accuracy of using conductivity to determine acidity in citrus is not available. Measurements of navel orange and mandarin juice samples of a wide range of acidities were performed using both conventional titration using an automatic titration system and the new acidity meter. Acidity values for the two methods of determination were generally quite close to each other (within 0.1%), except in the case of low acid (less than 0.7%) fruit where the difference between the two methods was sometimes greater. Since fruit would generally be fairly acid during the early part of the season when the instrument would likely be most commonly used, this may not be a significant issue. This instrument could serve well as a means of initially screening for acidity in either the field or packinghouse, with conventional titration being used as the final determinant of acidity during state regulatory testing for maturity.