J. Technology and Education, Vol.26, No.2, pp.31-34 (2019)



永田 天門1,後反 克典1,坂元 知里1,松野 敏英1

定政 哲雄2高山 勝己1*

1福井工業高等専門学校 物質工学科(〒916-8507 福井県鯖江市下司町)

2福井県農業試験場 園芸研究センター (919-1123 福井県三方郡美浜町久々子35-32-1)


Judging tomato maturation based on RGB values


Amon NAGATA,1 Katsunori GOTAN,1 Chisato SAKAMOTO,1

Toshihide MATSUNO,1 Tetsuo SADAMASA2 and Katsumi TAKAYAMA1*


1 Department of Chemistry & Biology Engineering, National Institute of Technology, Fukui College

(Geshi-cho, Sabae-shi, Fukui 916-8507, Japan)

2Fukui Agricultural Experiment Station Horticultural Research Center

(Mihama-cho, Mikata-gun, Fukui919-1123, Japan)


(Received August 30, 2019; Accepted October 8, 2019)



The relationship between the RGB value of tomato surface color and taste-determined components such as Brix, acidity, glutamic acid, and asparagine acid was investigated in this study. Pictures of tomato, HANAKOMACHI, fruit were taken by smartphone camera, and RGB data were acquired using free software, SUPOITOKUN. The maturation process of the tomato was classified into three stages: Green, tannish-yellow, and red. Especially, the G value decreased with the ripening of fruit. The Brix value and glutamic acid concentration were also correlated with the G value. It was revealed that farmers who are uncertain can use the G value as an effective factor for determining when to harvest tomatoes. 

Keywords: RGB value, tomato, harvest, aspartic acid, glutamic acid, Brix, acidity