Detection method of black goji berry anthocyanin content based on colorimetry

Black goji berries are rich in anthocyanin, which is a natural water-soluble pigment widely found in plants. Anthocyanin has functions such as an antioxidant and antimutagen, which are extremely beneficial for human health. Currently, analyzing black goji anthocyanin content requires professional instruments in laboratories, and the process is difficult and time-consuming. Anthocyanin appears red and is relatively stable in acidic solutions, while in basic solutions, it appears blue but is unstable. Utilizing this characteristic, we aimed to develop a method for detecting the anthocyanin content in black goji berries. We hypothesized that there is a one-to-one correspondence between the concentration of an anthocyanin solution and the RGB values of its color. We selected 60% ethanol with a pH value of 1 as the solvent to prepare a series of 30 anthocyanin solutions ranging from 50 mg/L to 1500 mg/L in 50 mg/L increments. By making and measuring color cards for these 30 solutions, we obtained a correspondence table between RGB values and anthocyanin concentrations. We designed and developed a detector composed of a color sensor and a microprocessor. We used the color sensor to measure RGB values and embedded the correspondence table into the microprocessor. The microprocessor searched for the color card with the smallest color difference to the solution being tested, read the corresponding anthocyanin concentration value, and converted it into the anthocyanin content of the sample. We further established a standard curve of RGB values versus anthocyanin concentrations according to Beer-Lambert's Law. We utilized this standard curve to improve the method for measuring anthocyanin concentration.