Development of NIRS calibration curves for sugars in baked sweetpotato

Authors: AMANKWAAH, V.A. - Csir-Crops Research Institute; WILLIAMSON, S. - North Carolina State University; REYNOLDS, RONG - Former ARS Employee; IBRAHEM, R. - North Carolina State University; PECTOA, K.V. - North Carolina State University; ZHANG, X. - International Center For Tropical Agriculture (CIAT); OLUKOLU, B.A. - University Of Tennessee; TRUONG, VAN-DEN - Retired ARS Employee; CAREY, E. - International Potato Center; ZUM FELDE, T. - International Potato Center; SSALI, R. - International Potato Center; YENCHO, G. CRAIG - North Carolina State University

Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2023
Publication Date: 6/1/2024
Citation: Amankwaah, V., Williamson, S., Reynolds, R., Ibrahem, R., Pectoa, K., Zhang, X., Olukolu, B., Truong, V.-D., Carey, E., Zum Felde, T., Ssali, R., Yencho, G. 2024. Development of NIRS calibration curves for sugars in baked sweetpotato. Journal of the Science of Food and Agriculture. 104(8):4801-4807. https://doi.org/10.1002/jsfa.12800.
DOI: https://doi.org/10.1002/jsfa.12800

Interpretive Summary: High-throughput phenotyping is required to facilitate the breeding of sweetpotato varieties to meet consumer preferences, especially on sweetness. In this study, a rapid method assessing the concentration of sugars (glucose, fructose, sucrose, maltose) in sweetpotatoes was developed using near-infrared spectroscopy (NIRS). The method will enable breeders to screen sweetpotato genotypes for sugar profiles that better meet consumer preferences without resorting to wet chemistry procedures such as high-pressure liquid chromatography which can be expensive, high maintenance, and time-consuming particularly when dealing with numerous samples from the breeding programs.

Technical Abstract: Background: Variability in sugar content between raw and cooked sweetpotato storage roots impact nutritional and dietary importance with implications for consumer preference. High-throughput phenotyping is required to breed varieties that satisfy consumer preferences. Results: Near-infrared reflectance spectroscopy (NIRS) calibration curves were developed for analysing sugars in baked storage roots using 147 genotypes from a population segregating for sugar content and other traits. The NIRS prediction curves had high coefficients of determination in calibration (R^2c) of 0.96 (glucose), 0.93 (fructose), 0.96 (sucrose), and 0.96 (maltose). The corresponding coefficients of determination for cross-validation (R^2cv) were 0.92 (glucose), 0.89 (fructose), 0.96 (sucrose) and 0.93 (maltose) and were similar to the R^2c for all sugars measured. The ratios of the standard deviation of the reference set to the standard error of cross-validation were greater than three for all sugars. These results confirm the applicability of the NIRS curves in efficiently determining sugar content in baked sweetpotato storage roots. External validation was performed on an additional 70 genotypes. Coefficients of determination (r^2) were 0.88 (glucose), 0.88 (fructose), 0.86 (sucrose) and 0.49 (maltose). The results were comparable to those found for the calibration and cross-validation in fructose, glucose, and sucrose, but were moderate for maltose due to the low variability of maltose content in the population. Conclusions: NIRS can be used for screening sugar content in baked sweetpotato storage roots in breeding programs and can be used to assist with the development of improved sweetpotato varieties that better meet consumer preferences.