Near‐infrared spectroscopy (NIRS) for monitoring the nutritional composition of black soldier fly larvae (BSFL) and frass

BACKGROUND The demand for protein obtained from animal sources is growing rapidly, as is the necessity for sustainable animal feeds. The use of black soldier fly larvae (BSFL) reared on organic side streams as sustainable animal feed has been receiving attention lately. This study assessed the ability of near‐infrared spectroscopy (NIRS) combined with chemometrics to evaluate the nutritional profile of BSFL instars (fifth and sixth) and frass obtained from two different diets, namely soy waste and customised bread‐vegetable diet. Partial least squares (PLS) regression with leave one out cross‐validation was used to develop models between the NIR spectral data and the reference analytical methods. RESULTS Calibration models with good [coefficient of determination in calibration (Rcal2): 0.90; ratio of performance to deviation (RPD) value: 3.6] and moderate (Rcal2: 0.76; RPD value: 2.1) prediction accuracy was observed for acid detergent fibre (ADF) and total carbon (TC), respectively. However, calibration models with moderate accuracy were observed for the prediction of crude protein (CP) (Rcal2: 0.63; RPD value: 1.4), crude fat (CF) (Rcal2: 0.70; RPD value: 1.6), neutral detergent fibre (NDF) (Rcal2: 0.60; RPD value: 1.6), starch (Rcal2: 0.52; RPD value: 1.4), and sugars (Rcal2: 0.52; RPD value: 1.4) owing to the narrow or uneven distribution of data over the range evaluated. CONCLUSION The near‐infrared (NIR) calibration models showed a good to moderate prediction accuracy for the prediction of ADF and TC content for two different BSFL instars and frass reared on two different diets. However, calibration models developed for predicting CP, CF, starch, sugars and NDF resulted in models with limited prediction accuracy. © 2023 Society of Chemical Industry.