2017 ASHS Annual Conference

NIRS uses near infrared light to quickly scan samples for substances and is being utilized as a nondestructive screening system for quality analysis. It is especially useful to sort large quantities of plant material for compounds where HPLC analysis is commonly used, although standard curves must be initially developed for each assay. Freeze dried strawberry samples were analyzed for detection of sucrose, glucose, and fructose (80 samples), and for pelargonidin-3-glucoside anthocyanin and total anthocyanin (TAC) content (208 samples). Values ranged from 5.5 to 11% SSC, 3.55-4.18 pH, 6.3-153.3 mg/g dwt sucrose, 127-377 mg/g dwt glucose, and 189-407 mg/g dwt for fructose. Total anthocyanin content was 4.6-33.8 mg/g dwt and pelargonidin-3-glucoside was 3.3 to 26.4 mg/g dwt. The NIR spectra of the strawberry fruit powder were collected by a Bruker FT-NIR spectrometer, Multi Purpose Analyzer (MPA). The spectra were calibrated against soluble solids content (SSC), pH, titratable acidity, individual sugars, P3G and TA by partial least squares (PLS) regression. Poor models were obtained for titratable acidity and pH (0.41 and 0.12). The best calibration models had coefficients of determination (R²) of 0.92 (SSC), 0.77 (fructose), 0.78 (glucose), 0.94 (sucrose), and 0.80 (P3G, TAC) and RPD values of 2.08 to 2.22. Our results show that NIRS provides a rapid and accurate estimation of sugars and anthocyanin in strawberry.