Accurate identification of soluble solid content in citrus by indirect laser-induced breakdown spectroscopy with its leaves

Abstract The soluble solid content (SSC) is vital to distinguish citrus quality, and non-destructive detection on site in the identification of SSC for citrus is urgently demanded. In this paper, a new approach was proposed to accurately identify citrus’s SSC using indirect laser-induced breakdown spectroscopy (LIBS) with its leaves. Forty-five Ehime Kashi No.28 citruses with surrounding leaves picked at two different times were prepared for LIBS experiment. The genetic algorithm-support vector machine model had the best identification result with cross-validation set accuracy of 91.2% and the prediction set accuracy of 92.03%. Furthermore, the influence of element in citrus leaves on SSC identification was analyzed by one-way analysis of variance, which showed that magnesium in citrus leaves was notably related to SSC due to its participation in photosynthesis and carbohydrates transportation. All in all, the results demonstrated that the indirect LIBS with citrus leaves could be a non-destructive and reliable approach for accurate identification of citrus SSC on spot.