Citrus Fruit Spectral Analysis Protocol

Two hundred and forty-nine fresh intact and undamaged citrus fruit (50 varieties and five of each (four of the Xuegan variety): Judaro, Miyagawa wase, Nanfengmiju, Nankou,,Kaixuangan, Red Sene, Clementine, Amakusa, Owari, Yura Wase, Taguchi wase, Cocktail grapefruit, Bendizao, Huyou, Hongyugan, Ueno Wase, Hongmeiren, Aoshima, Ougan, Green Ougan, Ponkan, Navel orange, 439, Honeybelle tangelo, Himekoharu, 60, Okitsu No.60, Lime, Sweet Spring, Gaocheng, Flame grapefruit, Valencia orange, Gonggan, Seihou, Chachigan, Huyou, Asumi, Washington Sanguine blood orange, Tarocco blood orange, Xuegan, Jincheng, Gaotaocheng, 123-1, Tsunokaori Tangor, Murcott, Manju, Moro blood orange, Haruka, Orah, Liubencheng, Sokitsu) were randomly selected after harvesting from the Citrus Breeding Base of Zhejiang Citrus Research Institute, Taizhou City, Zhejiang Province, China and immediately transported to the laboratory to be stored at cold temperature (4 ± 0.5 °C) for further spectral acquisition and vitamin C determination. Before the test, the peel surface was examined carefully again, and a simple cleaning was performed to guarantee minimal impact on further spectral collection.