## 1 Introduction  
Near-infrared (NIR) spectroscopy is considered a well-established analytical routine method to measure chemical composition in a wide range of samples. NIR spectroscopy is a fast method compared to other routine methods used in conventional and commercial analytical laboratories [1; 2; 3]. This technique has been widely used as an analytical tool due to its ability to measure different types of samples or materials including powders, liquids, solids, and slurries with little or no sample preparation [4; 5; 6; 7; 8; 9; 10]. In recent years, novel applications of NIR spectroscopy have been possible due to the availability of inexpensive and portable instrumentation [4; 5; 6; 7; 8; 9; 10]. Advantages of these instruments such as portability allow researchers and the food manufacturing industry to move away from the laboratory into the field, and to analyze samples during the processing, transport, and storage of agricultural products and foods [6; 8; 11; 12; 13; 14]. Assessing and monitoring the chemical composition and safety of food ingredients and commodities are still achieved by the application of traditional analytical methods [5; 6; 15; 16]. Most of the traditional methods and techniques used to assess the quality of foods are based on either conventional laboratory techniques (e.g., proximate analysis) or occasionally with measurements that can be implemented as at/on-line measurements [5; 6; 15; 16]. However, these approaches are no longer suitable for fulfilling the requirements of an agile and modern food or waste industry, due to the higher safety and quality standards imposed, that include the demand for high-throughput information or data systems in the production line [15; 16]. This can also be exacerbated by the increased number of samples that need to be analyzed, depending on the demands of the quality and safety systems implemented by the industry [15; 16]. Different applications and examples of NIR spectroscopy have shown that this technique can contribute as an analytical tool to monitor the composition of samples during the process of a wide range of foods and ingredients. Consequently, the use of NIR spectroscopy has become a relevant tool during the development of decision support management or quality control systems that are applied during the evaluation and processing of foods [11; 12; 13; 14; 15; 16]. In addition to process control, the traceability of ingredients, foods, or even processes have become a common practice by the modern food industry [17]. The development and implementation of traceability systems require accurate, comprehensive, and systematic knowledge about the processes [17]. The traceability of ingredients or even processes is of relevant importance to guarantee the safety of the foods' and products' manufacturer [17]. In this context, the process and production of BSFL from different waste streams do not avoid these requirements where the traceability of the production system (e.g., assuring the consistency and traceability of the organic waste utilized during the process) is considered of importance to the transparency and sustainability of the waste industry as well as its inclusion in a circular economy [1; 3]. When an NIR spectroscopic method or protocol needs to be defined, several issues need to be considered including the type of instrument, the wavelength range used or required, the signal-to-noise ratio needed for the application, etc. [18; 19; 20; 21; 22]. Sample preparation and presentation can also differ significantly between instruments (e.g., lab vs. portable), the type of sample to be analyzed (e.g., fresh vs. dry, intact vs. powder samples), or the application to be developed (e.g., quantitative or qualitative analysis) [18; 19; 20; 21; 22]. It is well known that depending on the sample presentation or preparation, the NIR spectra can differ [18; 19; 20; 21; 22].