Non-destructive identification of varieties of Hawaii-grown avocados using near-infrared spectroscopy: Feasibility studies using benchtop and handheld spectrometers

Authors: GODBOUT, JEMMA - University Of Hawaii; Ladizinsky, Nicolas; HARRIS, SERENITY - University Of Hawaii; Postler, Melissa; Sun, Xiuxiu; Matsumoto Brower, Tracie; Liang, Peishih

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2024
Publication Date: 6/6/2024
Citation: Godbout, J.M., Ladizinsky, N.C., Harris, S., Postler, M.L., Sun, X.N., Matsumoto Brower, T.K., Liang, P. 2024. Non-destructive identification of varieties of Hawaii-grown avocados using near-infrared spectroscopy: Feasibility studies using benchtop and handheld spectrometers. PLOS ONE. 19(6). Article e0303532. https://doi.org/10.1371/journal.pone.0303532.
DOI: https://doi.org/10.1371/journal.pone.0303532

Interpretive Summary: Avocados are an important economic crop of Hawaii, contributing to approximately 3% of all avocados grown in the United States. To export Hawaii-grown avocados, growers must follow strict United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) regulations. Currently, only the Sharwil variety can be exported without quarantine treatments, which negatively impact the quality of avocados. Hawaii avocado growers must positively identify the avocados variety as Sharwil with APHIS prior to export. Currently, variety identification relies on physical characteristics or generic markers, which can be erroneous, time consuming and costly. This study evaluated the feasibility of using near-infrared spectroscopy to non-destructively identify Sharwil from other varieties and achieved 95% total classification rates.

Technical Abstract: Avocados are an important economic crop of Hawaii, contributing to approximately 3% of all avocados grown in the United States. To export Hawaii-grown avocados, growers must follow strict United States Department of Agriculture Animal and Plant Health Inspection Service (USDA-APHIS) regulations. Currently, only the Sharwil variety can be exported relying on a systems approach, which allows fruit to be exported without quarantine treatment; treatments that can negatively impact the quality of avocados. However, for the system's approach to be applied, Hawaii avocado growers must positively identify the avocados variety as Sharwil with APHIS prior to export. Currently, variety identification relies on physical characteristics or generic markers, which can be erroneous, time consuming and costly. This study evaluated the feasibility of using near-infrared spectroscopy to non-destructively discriminate between three different Hawaii-grown avocado varieties, Sharwil, Beshore, and Yamagata, and to positively identify Sharwil from the other two varieties. The classifiers achieved 90% and 95% total classification rates for discriminating the three varieties from one another and positively identifying Sharwil, respectively. Results from chemometric methods and chemical analysis confirmed that fat content was a key contributor to the performance of classifiers. Physical characteristics of the skins and other biochemical parameters such as cellulose and starch contents could also be important but were not validated in this study. Future work should include collecting more samples of avocado spectra from more varieties (including Sharwil) as well as across different seasons to improve the performance and robustness of classifiers.