{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,21]],"date-time":"2026-04-21T22:06:04Z","timestamp":1776809164111,"version":"3.51.2"},"reference-count":23,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2024,1,5]],"date-time":"2024-01-05T00:00:00Z","timestamp":1704412800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Cooperative Research Program for Agriculture Science &amp; Technology Development","award":["RS-2022-RD010265"],"award-info":[{"award-number":["RS-2022-RD010265"]}]},{"name":"Cooperative Research Program for Agriculture Science &amp; Technology Development","award":["520210017"],"award-info":[{"award-number":["520210017"]}]},{"name":"Rural Development Administration","award":["RS-2022-RD010265"],"award-info":[{"award-number":["RS-2022-RD010265"]}]},{"name":"Rural Development Administration","award":["520210017"],"award-info":[{"award-number":["520210017"]}]},{"name":"Kangwon National University, Republic of Korea","award":["RS-2022-RD010265"],"award-info":[{"award-number":["RS-2022-RD010265"]}]},{"name":"Kangwon National University, Republic of Korea","award":["520210017"],"award-info":[{"award-number":["520210017"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Apples are widely cultivated in the Republic of Korea and are preferred by consumers for their sweetness. Soluble solid content (SSC) is measured non-destructively using near-infrared (NIR) spectroscopy; however, the SSC measurement error increases with the change in apple size since the distance between the light source and the near-infrared sensor is fixed. In this study, spectral characteristics caused by the differences in apple size were investigated. An optimal SSC prediction model applying partial least squares regression (PLSR) to three measurement conditions based on apple size was developed. The three optimal measurement conditions under which the Vis\/NIR spectrum is less affected by six apple size levels (Levels I\u2013VI) were selected. The distance from the apple center to the light source and that to the sensor were 125 and 75 mm (Distance 1), 123 and 75 mm (Distance 2), and 135 and 80 mm (Distance 3). The PLSR model applying multiplicative scatter correction pretreatment under Distance 3 measurement conditions showed the best performance for Level IV-sized apples (Rpre2 = 0.91, RMSEP = 0.508 \u00b0Brix). This study shows the possibility of improving the SSC prediction performance of apples by adjusting the distance between the light source and the NIR sensor according to fruit size.<\/jats:p>","DOI":"10.3390\/s24020316","type":"journal-article","created":{"date-parts":[[2024,1,5]],"date-time":"2024-01-05T03:43:00Z","timestamp":1704426180000},"page":"316","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":8,"title":["Performance Improvement of Partial Least Squares Regression Soluble Solid Content Prediction Model Based on Adjusting Distance between Light Source and Spectral Sensor according to Apple Size"],"prefix":"10.3390","volume":"24","author":[{"given":"Doo-Jin","family":"Song","sequence":"first","affiliation":[{"name":"Department of Interdisciplinary Program in Smart Agriculture, Kangwon National University, Chuncheon-si 24341, Republic of Korea"}]},{"given":"Seung-Woo","family":"Chun","sequence":"additional","affiliation":[{"name":"Department of Interdisciplinary Program in Smart Agriculture, Kangwon National University, Chuncheon-si 24341, Republic of Korea"}]},{"given":"Min-Jee","family":"Kim","sequence":"additional","affiliation":[{"name":"Agriculture and Life Sciences Research Institute, Kangwon National University, Chuncheon-si 24341, Republic of Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3528-6630","authenticated-orcid":false,"given":"Soo-Hwan","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Interdisciplinary Program in Smart Agriculture, Kangwon National University, Chuncheon-si 24341, Republic of Korea"}]},{"given":"Chi-Kook","family":"Ahn","sequence":"additional","affiliation":[{"name":"Korea Agriculture Technology Promotion Agency, Iksan-si 54667, Republic of Korea"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9088-5978","authenticated-orcid":false,"given":"Changyeun","family":"Mo","sequence":"additional","affiliation":[{"name":"Department of Interdisciplinary Program in Smart Agriculture, Kangwon National University, Chuncheon-si 24341, Republic of Korea"},{"name":"Department of Biosystems Engineering, Kangwon National University, Chuncheon-si 24341, Republic of Korea"}]}],"member":"1968","published-online":{"date-parts":[[2024,1,5]]},"reference":[{"key":"ref_1","unstructured":"Korea Rural Economic Institute (2023, October 20). The Consumer Behavior Survey for Food 2018. (Report No. E16-2018). KREI. Available online: https:\/\/www.krei.re.kr\/krei\/researchReportView.do?key=67&pageType=010101&biblioId=519796&pageUnit=10&searchCnd=all&searchKrwd=&pageIndex=31&engView=."},{"key":"ref_2","unstructured":"Korea Rural Economic Institute (2023, October 20). The Consumer Behavior Survey for Food 2020. (Report No. E16-2020-1). KREI. Available online: https:\/\/www.krei.re.kr\/krei\/researchReportView.do?key=67&pageType=010101&biblioId=527882&pageUnit=10&searchCnd=all&searchKrwd=&pageIndex=10&engView=."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1065","DOI":"10.11002\/kjfp.2016.23.7.1065","article-title":"Quality characteristics and sensory evaluation of Fuji apple based on commodity price","volume":"23","author":"Ku","year":"2016","journal-title":"Korean J. Food Preserv."},{"key":"ref_4","first-page":"208","article-title":"Discrimination of Internally Browned Apples Utilizing Near-Infrared Non-Destructive Fruit Sorting System","volume":"22","author":"Kim","year":"2021","journal-title":"J. Korea Acad. Ind. Coop. Soc."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"10","DOI":"10.1016\/j.biosystemseng.2017.03.015","article-title":"Spatial assessment of soluble solid contents on apple slices using hyperspectral imaging","volume":"159","author":"Mo","year":"2017","journal-title":"Biosyst. Eng."},{"key":"ref_6","unstructured":"Ma, S.D. (2010). Development of Non-Destructive Sorting System for Fruits Using Near Infrared Spectroscopic. [Ph.D. Thesis, The Chosun University]. Available online: https:\/\/oak.chosun.ac.kr\/handle\/2020.oak\/8907."},{"key":"ref_7","unstructured":"Yoon, J.M., So, M.H., Han, C.S., and Kim, H.Y. (2014, January 29\u221231). Comparison of Prediction Models of the Sugar Content for a Nondestructive Sorting System Based on Near-Infrared. Proceedings of the KIIT Conference, Cheonan, Republic of Korea."},{"key":"ref_8","first-page":"117","article-title":"Implementation of real-time SSC measurement system of fruits using the NIR","volume":"18","author":"So","year":"2020","journal-title":"J. Korean Inst. Inf. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1016\/j.rse.2007.02.005","article-title":"Quantitative analysis of salt-affected soil reflectance spectra: A comparison of two adaptive methods (PLSR and ANN)","volume":"110","author":"Farifteh","year":"2007","journal-title":"Remote Sens. Environ."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"130","DOI":"10.5307\/JBE.2011.36.2.130","article-title":"Comparison of performance of measuring method of VIS\/NIR spectroscopic spectrum to predict soluble solids content of \u2018Shingo\u2019 Pear","volume":"36","author":"Suh","year":"2011","journal-title":"J. Biosyst. Eng."},{"key":"ref_11","first-page":"457","article-title":"Nondestructive Determination of the Soluble Solid and Acid Contents of Peach Using VIS\/NIR Real-Time Transmission Spectra","volume":"5","author":"Hwang","year":"2000","journal-title":"J. KSAM"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"465","DOI":"10.2503\/jjshs.62.465","article-title":"Nondestructive determination of sugar content in satsuma mandarin using near infrared (NIR) transmittance","volume":"62","author":"Kawano","year":"1993","journal-title":"J. Jpn. Soc. Hortic. Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"104017","DOI":"10.1016\/j.chemolab.2020.104017","article-title":"Optimization and comparison of models for prediction of soluble solids content in apple by online Vis\/NIR transmission coupled with diameter correction method","volume":"201","author":"Xia","year":"2020","journal-title":"Chemom. Intell. Lab. Syst."},{"key":"ref_14","unstructured":"Shin, H.S. (2011). Development of Models to Predict Sugar Content of Melon Using Spectroscopic Analysis. [Master\u2019s Thesis, The Chonnam University]. Available online: http:\/\/www.riss.kr\/link?id=T12380671."},{"key":"ref_15","unstructured":"Luo, C., Xue, L., Liu, M., Li, J., and Wang, X. (2010). International Conference on Computer and Computing Technologies in Agriculture, Springer."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"102979","DOI":"10.1016\/j.infrared.2019.102979","article-title":"Comparison and optimization of models for SSC on-line determination of intact apple using efficient spectrum optimization and variable selection algorithm","volume":"102","author":"Tian","year":"2019","journal-title":"Infrared Phys. Technol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"110945","DOI":"10.1016\/j.jfoodeng.2022.110945","article-title":"Non-destructive prediction of soluble solid contents in Fuji apples using visible near-infrared spectroscopy and various statistical methods","volume":"321","author":"Lee","year":"2022","journal-title":"J. Food Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"109955","DOI":"10.1016\/j.jfoodeng.2020.109955","article-title":"Quantitative detection of apple watercore and soluble solids content by near infrared transmittance spectroscopy","volume":"279","author":"Guo","year":"2020","journal-title":"J. Food Eng."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"103443","DOI":"10.1016\/j.infrared.2020.103443","article-title":"Multi-factor fusion models for soluble solid content detection in pear (Pyrus bretschneideri \u2018Ya\u2019) using Vis\/NIR online half-transmittance technique","volume":"110","author":"Xia","year":"2020","journal-title":"Infrared Phys. Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"64","DOI":"10.1016\/j.biosystemseng.2020.06.010","article-title":"An optimal zone combination model for on-line nondestructive prediction of soluble solids content of apple based on full-transmittance spectroscopy","volume":"197","author":"Tian","year":"2020","journal-title":"Biosyst. Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1366\/000370203321535033","article-title":"Short-wavelength near-infrared spectra of sucrose, glucose, and fructose with respect to sugar concentration and temperature","volume":"57","author":"Golic","year":"2003","journal-title":"Appl. Spectrosc."},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Zhang, B., Zhang, M., Shen, M., Li, H., Zhang, H., and Zhao, J. (2020, January 13\u201315). Prediction of Soluble Solids Content During Storage of Apples with Different Maturity Based on VIS\/NIR Spectroscopy. Proceedings of the 2020 ASABE Annual International Virtual Meeting, Online.","DOI":"10.13031\/aim.202000943"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"3740527","DOI":"10.1155\/2022\/3740527","article-title":"Study on the effect of apple size difference on soluble solids content model based on near-infrared (NIR) spectroscopy","volume":"2022","author":"Jiang","year":"2022","journal-title":"J. Spectrosc."}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/2\/316\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T13:40:30Z","timestamp":1760103630000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/24\/2\/316"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,1,5]]},"references-count":23,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2024,1]]}},"alternative-id":["s24020316"],"URL":"https:\/\/doi.org\/10.3390\/s24020316","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,1,5]]}}}