High precision measurement of dissolved solids (Brix) in soft drinks and juices is an important element of quality control and quality assurance. Refractometry and density-based methods are most commonly used for this purpose. Whichever method is selecte

High precision measurement of dissolved solids (Brix) in soft drinks and juices is an important element of quality control (QC) and quality assurance (QA). There are in principle many ways to measure dissolved solids, but refractometry and density-based methods are most commonly used for this purpose. Whichever method is selected, there are advantages, disadvantages and limitations. This paper addresses important differences between the methods. The basic principles are outlined and practical aspects of applying the methods are discussed with reference to modern digital instruments. Reference is made to the RFM 340 digital automatic refractometer from Bellingham & Stanley and the models DMA 48 and DMA 58 digital density meters from Paar.