## 3 Applications of Infrared Spectroscopy in BSFL as Feed or Food
### Functional and Technological Properties--Protein  
BSFL have been shown to have functional and technological properties that make them ideal to include in different food systems [5; 11], including as a partial substitute for meat in a beef burger patty [53]. In fact, the use of FTIR spectroscopy was reported to reveal different structural changes between flours and protein concentrates of BSFL samples [53; 54; 55]. The study of [PERSON] and collaborators (2021) showed that BSFL flour fractions and protein concentrates have great potential as novel functional ingredients for use in food applications [54].  
Attenuated total reflectance (ATR) in combination with FTIR spectroscopy was evaluated as a tool to monitor changes in the composition of BSFL collected at two growing stages (fifth and sixth instar) and two waste stream diets (bread and vegetables, soy waste) [56]. The ratio between the absorbances corresponding to the amide groups at 1635 cm\({}^{-1}\) and lipids between 2921 and 2849 cm\({}^{-1}\) was used to analyze and classify the BSFL samples according to the type of diet (high proportion of carbohydrates (e.g., bread-vegetable mix) compared with soy waste) [56].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Technique** & **Parameter** & **Sample** & **Algorithm** & **R\({}^{2}\)** & **RMSEP (\%)** & **Ref.** \\ \hline SWIR Hyperspectral & Moisture & Data points or images & PLS & 0.93–0.97 & 1.83–2.59 & [52] \\  & CP & & & 0.6–0.93 * & 0.55–0.99 & \\  & CF & & & 0.88–0.91 * & 1.34–1.67 & \\  & Fiber & & & 0.85–0.87 * & 0.46–0.53 & \\  & Ash & & & 0.92–0.96 * & 0.25–0.32 & \\ \hline Hyperspectral Imaging & \multirow{2}{*}{CP} & 19 generations & \multirow{2}{*}{PLS} & \multirow{2}{*}{0.70–0.78} & \multirow{2}{*}{1.42–1.62} & \multirow{2}{*}{[18]} \\ (1000 to 2500 nm) & & & & & \\  & & & & & \\  & & & & & \\ \hline Portable NIR \({}^{\text{A}}\) & CP & BSFL flour & PLS and SVM & 0.74–0.86 & 1.18–1.36 & [19] \\  & Lipids & & PLS and SVM & 0.76–0.96 & 3.05–7.41 & \\ \hline \end{tabular} R\({}^{2}\): coefficient of determination in cross-validation; RMSEP: root mean square of the standard error in cross validation; CP: crude protein; CF: crude fat; PLS: partial least squares, SVM: support vector machines; * Different pre-processing methods were used by the authors. \({}^{\text{A}}\) Two instruments were compared by the authors of this study.  
\end{table}
Table 1: Calibration and cross-validation statistics reported for the measurement of proximate composition in black soldier fly larvae using different vibrational spectroscopy technologies, hyperspectral, and near infrared.  
The chemical composition and structural properties of the BSFL flows (full fat and defatted) were assessed using ATR-FTIR spectroscopy [57]. The FTIR spectra showed that the defatting of the samples caused structural modifications, and these can be observed in changes in the absorbance values around the amide I at 1650 cm\({}^{-1}\) and amide II at 1540 cm\({}^{-1}\) wave numbers [57]. The analysis of the FTIR spectra showed that defatting influences specific functional groups as well as the nutritional value of the BSFL [57].