Evaluation of the optical layout and sample size on online detection of apple watercore and SSC using Vis/NIR spectroscopy

• Published in: Journal of food composition and analysis 2023-10, Vol.123, p.105528, Article 105528
• Main Authors: Han, Chang, Jifan, Yin, Hao, Tian, Jinshan, Yan, Huirong, Xu
• Format: Article
• Language: English
• Subjects: Apple size; apples; food composition; near-infrared spectroscopy; Online detection; Optical layout; Optical simulation; prediction; sample size; Soluble solids content; statistical analysis; Vis/NIR spectroscopy; Watercore
• ISSN: 0889-1575
• DOI: 10.1016/j.jfca.2023.105528

Visible near-infrared (Vis/NIR) spectroscopy has the capability of identifying apple watercore disorder online. However, the various distributions of watercore tissues had significant effects on the prediction of soluble solids content (SSC) and watercore severity index (WSI). In this study, based on the optical simulation method, two optical configurations were evaluated and applied to two batch samples. Under the dual-light source layout, the partial least squares regression (PLSR) model demonstrated superior prediction performance for SSC of identical-sized apples (batch 1). The root mean square error of the calibration set (RMSEC) was 0.34%, the root mean square error of the prediction set (RMSEP) was 0.37%, and the residual predictive deviation (RPD) was 3.78. RMSEC, RMSEP, and RPD for the PLSR-based WSI prediction model were 2.00%, 1.82%, and 1.69. While for apples of varying sizes (batch 2), with better RMSEC, RMSEP and RPD values of 0.35%, 0.43%, and 3.58 for SSC and 5.01%, 5.00% and 1.21 for WSI than in dual-light source layout, the four-light source layout outperformed the dual-light source layout. The experimental findings demonstrated that a detection system with a four-light source layout can mitigate the effects of apple size and watercore distribution on the efficacy of SSC and WSI prediction. •Physical and chemical indicators of different size samples were compared.•Different optical layouts were simulated and applied for indicators’ prediction.•Sample size significantly affected watercore apple SSC and WSI prediction.•Four-light source layout would improve detecting accuracy of different size apples.