## 1 Introduction  
With the increasing growth of the global economy and population, the associated increase in food consumption has resulted in large volumes of food waste (FW). Moreover, the amount of FW is predicted to grow by 44% from 2005 to 2025 [1]. FW is usually incinerated with municipal solid waste or dumped in landfills [2, 3]. However, incineration and landfills can have harmful effects on human health and can contribute to global warming and environmental pollution through toxic gas emission, ground water contamination, air pollution, fire hazards, and so on [2, 4, 5]. Thus, FW should be properly managed to prevent negative environmental impact. Therefore, recycling technology and related biotechnology are undergoing rapid development [2, 6, 7, 8]. As a typical recycling method, FW is often converted into organic fertilizer (OF) because the former is a valuable resource that contains plant nutrients, which can mitigate the serious organic matter deficit of agricultural soils [2, 3]. Despite the advantages of FW fertilizer, in the Republic of Korea, it is not considered a good additive for OF because of its high level of sodium chloride (NaCl). Note that soil salinity is one of the most significant abiotic constraints, as high salinity severely affects agricultural productivity and disturbs the soil nutrition balance [9]. The high NaCl concentrations in Korean food are attributed to kimchi, soy sauce, and soybean paste, which are fermented and stored in high-saline water for food preservation. Therefore, NaCl is a limiting factor for FW fertilizer production with Korean FW [10]. In addition, kimchi has high capsaicin content, and capsaicin has negative effects on plant growth; this is another major limiting factor for FW fertilizer [11]. Thus, the government of the Republic of Korea has restricted the NaCl content in OF to 2% and established the maximum permissible content of Korean FW in OF as 30% [12]. However, some entrepreneurs have recently produced OF mixed with a high percentage of Korean FW (over 30%) to reduce production costs. These illegal products have been distributed and sold nationwide. Therefore, a nondestructive evaluation technique for food-waste components (FWC) in OF has drawn considerable research attention. Hyperspectral imaging (HIS) can simultaneously acquire spatial and spectral data from a target by combining image processing and spectroscopy techniques, and is a powerful tool for agricultural analyses [13; 14; 15]. Rapid improvements in HSI technology have facilitated nondestructive evaluation of soil nutrition, fertilizer quality, plant productivity, and so on. HSI technology has also been used in fertilizer nutrient analysis, salt stress assessment, plant growth monitoring according to fertilizer type, etc. For instance, [PERSON] et al. (2016) developed a soil salinity model for satellite hyperspectral remote-sensing data and used it to evaluate salt stress on winter wheat [16]. Further, [PERSON] et al. (2018) investigated the spectral signature of a soil and fertilizer mixture and developed a quantification equation incorporating the diagnostic depth and the soil fertilizer concentration [17]. [PERSON] et al. (2018) evaluated the nitrogen fertilizer levels of a tea plant using visible and near-infrared HSI techniques with multivariate classification algorithms; hence, they discriminated tea plants subjected to three different nitrogen treatments [18]. Finally, [PERSON] et al. (2019) proposed a HSI method, including multivariate techniques, to discriminate fertilized from unfertilized grasses and showed that specific wavelengths can be effectively used to assess the influence of different fertilizers on the grasses [19]. However, to the best of the authors' knowledge, no nondestructive HIS technology for FWC evaluation in OF within the visible-near-infrared (Vis/NIR) region has been developed to date.