Two-parameter Lorentzian distribution for monitoring physical parameters of golden colored fruits during drying by application of laser light in the Vis/NIR spectrum

Inadequate drying conditions of tropical fruits can alter the cellular structure and chemistry, which can lead to undesirable characteristics of the final product. The purpose of this research is to test the feasibility of light scattering of three laser sources operating in the Vis/NIR range by calculating a two-parameter Lorentzian distribution (LD) for quality assessment of two golden-colored fruits, namely mango and litchi, during drying. Linear mixed models showed that blue light at 473 nm was the most adequate to monitor changes in browning (R-2 = 0.81) and moisture content (R-2 = 0.80) of litchi. For mango, NIR light at 785 nm was affected by the hardness (p < 0.001), whereas moisture content showed a strong influence on the calculated LD functions at both 532 (p < 0.001) and 785 (p < 0.05) nm with a good fitting of the prediction model (R-2 = 0.91). Laser light can provide an economically-effective solution to obtain information from the fruit tissue non-destructively during industrial drying processes. Industrial relevance: Convective drying is still the most common dehydration technique in industrial applications, while many agricultural products remain susceptible to thermal damage. Quality parameters of these products are not only affected by drying conditions, but are also crop-specific. Meanwhile, the use of laser light backscattering is an innovative and rapid technique to estimate a range of quality parameters during drying of agricultural products. The results of this research provide a basis for robust, in-line quality control during industrial drying processes. In this respect, the application of laser backscattering systems presents many advantages: rapid, real-time product information, eradication of laborious and costly destructive analytical methods, continuous monitoring to avoid over-drying (improved energy efficiency) and quality losses, easy integration into existing drying systems and high resistance to harsh conditions typically found in dryers such as high temperatures and dust. (C) 2016 Elsevier Ltd. All rights reserved.