Spectroscopic approaches for non-destructive shell egg quality and freshness evaluation : Opportunities and challenges

Shell egg quality and freshness are traditionally assessed by destructive laboratory-level methods, thus restricting the possibilities to be easily guaranteed in the industrial chain. Non-destructive techniques are therefore of paramount importance, giving accuracy, speed, and instantaneous results. Among these techniques, spectroscopy is promising because it would allow the development of on-line applications for shell egg grading, with clear benefits for both industries and consumers. However, there are still few works in the literature about this topic. Thus, this review presents recently published (years 2015-2020) applications of spectroscopy methods (i.e., VIS-NIR, NIR, Raman, microwaves, hyperspectral imaging, pulsed IR thermography) to the non-destructive assessment of shell egg quality and freshness, with the aim of boosting the research in this field giving some directions for the fulfilment of industrial needs. Indeed, spectroscopic techniques have been proven to be useful tools for the evaluation of shell egg quality and freshness. The advances in instrumentation and data analysis allow to predict shell egg quality by non-destructive, fast, and environmentally friendly approaches. However, the industrial implementation still requires robust calibration transfer to simplified hand-held systems for low-cost and easy use.