Optical non-destructive techniques for small berry fruits: A review

Abstract Small berries including strawberry and blueberry are extensively consumed fruits with great economic values due to their characteristic flavor and appearance as well as potential health benefits. This review elaborated the optical non-destructive techniques viz. Vis-NIR spectroscopy, computer vision system, hyperspectral imaging, multispectral imaging, laser-induced method and thermal imaging, and their applications for quality and safety control of small berry fruits. The discussion regarding the photoacoustic technique, X-ray technique, Terahertz spectroscopy, odor imaging, micro-destructive testing and smart mobile terminal-based analyzer was also presented. Furthermore, we proposed our personal understanding of the technical challenges and further trends for these optical non-destructive techniques: 1) owing to the relatively low detection limit, the so-called micro-destructive techniques may be alternative to the traditional non-destructive techniques in both practical and fundamental research; 2) we suggest that the research articles like “collecting data first, and then modeling the relevant properties of agricultural products by machine learning” should be less produced in related fields. That's because such research methods are likely to be suspected of “cheating”. It is recommended that some modeling competitions can be carried out in the agricultural engineering field to avoid or reduce the “cheating” model.