Non-destructive measurement of firmness and soluble solids content in bell pepper using NIR spectroscopy

• Published in: Journal of food engineering Vol. 94; no. 3; pp. 267 - 273
• Main Authors: Penchaiya, Pathompong, Bobelyn, Els, Verlinden, Bert E., Nicolaï, Bart M., Saeys, Wouter
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2009; [New York, NY]: Elsevier Science Pub. Co; Elsevier
• Subjects: accuracy; Bell pepper; Bell peppers; Biological and medical sciences; Calibration; cultivars; Derivatives; Firmness; Food engineering; Food industries; food quality; Fruit; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; General aspects; least squares; Mathematical models; Near infrared; near-infrared reflectance spectroscopy; Non-destructive method; nondestructive methods; Nondestructive testing; Preprocessing; Reflectance; soluble solids; Soluble solids content; Spectroscopy; sweet peppers; texture; total solids; Vegetable; Soluble solids content; Fruit; Non-destructive method; Bell pepper; Firmness; Near infrared; Vegetable; Reflectance; Measurement; Vegetables; Solid; Non destructive method; Near infrared spectrometry; Quality
• ISSN: 0260-8774; 1873-5770
• DOI: 10.1016/j.jfoodeng.2009.03.018

The potential of near infrared (NIR) reflectance spectroscopy over the range 780–1690 nm was investigated to measure the soluble solids content (SSC) and firmness of bell pepper fruit. Partial least squares (PLS) calibration models were constructed based on a calibration dataset which included data from two cultivars (Solution and Ferrari) and two harvest times (2005 and 2006). The effect of Savitzky–Golay second derivative preprocessing and extended multiplicative signal correction (EMSC) on the accuracy of the calibration models was investigated and the best results were obtained with the former. The SECV were equal to 5.9 N and 0.59 °Brix for firmness and SSC, respectively. When the model was applied to an external data set including data from cv. Solution and a different harvest season, the satisfactory SEP values of 4.49 N and 0.7 °Brix were obtained, but for firmness a bias of 5.6 N was observed. From these results it can be concluded that NIR spectroscopy can be used as a non-destructive technique for measuring the SSC in bell pepper, but that further research is needed to make it robust for firmness prediction.