Rapid Determination of Amino Acids in Chinese Wolfberry (Lycium bararum L.) Fruit by Using Fourier Transform Infrared Spectroscopy and Partial Least Square Regression

The content and amino acid composition of Chinese wolfberry (Lycium bararum L.) produced from various regions was analyzed. Wolfberry contains high amounts of aspartic acid (1.445 ± 0.290 g/100 g), glutamine (1.380 ± 0.252 g/100 g), and lysine (0.254 ± 0.048 g/100 g) and is ideally grown in Zhongning. This study presents a new method for predicting three amino acids (aspartic acid, glutamine, and lysine) in Chinese wolfberry. The robustness and strength of the prediction model for each parameter vary with spectral pretreatment and wavelengths. An optimal prediction model was also established. High relative percent deviation (RPD) values (4.95 for aspartic, 4.89 for glutamine, and 4.28 for lysine) for validation and high R values (0.9948 for aspartic, 0.986 for glutamine, and 0.9836 for lysine) for blind validation were obtained. The results showed that FT-IR spectroscopy can be an effective method for evaluation of amino acids in Chinese wolfberry.