Proposal of an index for the objective evaluation of the colour of red table grapes

• Published in: Food research international Vol. 28; no. 4; pp. 373 - 377
• Main Authors: Carreño, J., Martínez, A., Almela, L., Fernández-López, J.A.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 1995; Elsevier
• Subjects: Biological and medical sciences; CIELAB data; colour index; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Red grape; table grape; Vitis vinifera colour measurements; Red grape; CIELAB data; Vitis vinifera colour measurements; colour index; table grape; Measurement method; Fruit; Color index; Organoleptic properties; Grape; Color
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/0963-9969(95)00008-A

A colour index for the objective determination of the colour in red table grapes is described. This index is based on the CIELAB values. A statistical study revealed a high correlation between L ∗ and b ∗ , while a ∗ was not a representative parameter. The usefulness of this index is investigated to classify the red grapes depending on their external colour. The proposed colour index for red grapes (CIRG) is based on the parameters L ∗ (lightness), H (hue angle) and C (chroma) and its expression is “ (180-H) (L ∗ + C) ” All the colour indexes previously proposed were defined in fruits whose colour varied between yellow and red, and, therefore, were not suitable for red grapes which show a dark violet colour. This new index showed a good linearity with the visual colour of the berries and distinguished between sample groups of different external colour.