Table 1 Notation of the 8 criteria for scoring the "dye score" of the plant species from La Réunion Island biodiversity
Criterium | Description | Notation of the criterium on a scale of 1 to 10 | |||
|---|---|---|---|---|---|
1 | 3 | 7 | 10 | ||
C1—Indigenous status of species on La Réunion Island | Valued endemic plants because of their potential as a locally available resource that can lead to regional economic development in addition to the extension and conservation of biodiversity | Introduced (alien) | Native or cryptogenic | Regional endemic (Mascarenes) | Strict endemic of Reunion Island |
C2—Scientific knowledge about species | Valued the identification of species not previously described in the scientific literature, nor enhanced in the industrial field | Species perfectly described in literature and pigments identified (known structure) | Species relatively well described in the literature | Some references in literature but pigments not known | No article in the studied species |
C3—Accessibility and availability of species on La Réunion Island | Valued locally available plants that have a high economic potential for the territory. It is essential to prioritize readily accessible species that are not protected in Reunion | Protected and rare species (with difficult access) | Species accessible with permission: private land, departmental—domain, national park, but with enough plants available for collection | Abundant species in the wild with relatively easy access (no resupply problems) | Abundant species in cultivation and easy access: both in cultivation (CBNM arboretum) and in the wild (EEE), no resupply problem |
C4—Cultivability of plant species | Valued cultivability to elevate species already cultivated on the island and plants whose reproduction and cultivation methods are known | Not cultivable | Cultivable but very slow growing (e.g., 10-year-old tree) | Potentially cultivable from its reproduction mode | Cultivable and currently cultivated in La Réunion |
C5 – Plant organs used for pigment extraction | Valued sustainability by prioritizing use of the most renewable parts of the plant. Leaves can be harvested throughout the year, bark can be collected if it does not affect the future development of the plant. Flowers and fruits are seasonal but if the yield is high, these parts have potential. The collection of the woody part of a plant can kill it and are therefore not sustainable | Wood, all plant | Adventitious roots | Stems, barks, fruits, flowers | Leaves |
C6—Industrial interests and other known applications of plant species | Valued other medicinal, biogas, nutritional or other uses beyond the coloring properties of the plant—greater economic interest | No other known uses apart from traditional dyeing | 1–2 other known uses | 3–4 other known uses | Multiples known uses > 5 |
C7—Color and stability of dyes and pigments extracted from plant species | Valued rare/special colors (blue, magenta, pink, cyan, mauve, black…). Yellow, orange and red are sought in the dyeing industries to replace synthetic dyes, but only if they have an intense and stable color. Brown and beige colors are less demand | Colorless or very light-colored extract | Unattractive (beige, brown, etc.) and/or unstable color | Desired color (red, orange, yellow…) and relatively stable | Rare/special and relatively stable color (blue, magenta, pink, cyan, mauve, black…) |
C8—Yield and difficulty of color extraction | Valued plants containing water-soluble pigments and dyes that are easily extractable using water and ethanol (eco-compatible solvents) with adequate yield for industrial applications, and whose color can be realized without mordanting or fermentation | Mordanting or fermentation useful for color expression | Pigments extractable only with non-eco-compatible solvents (e.g., hexane) | Pigments extractable with EtOH aqueous in average yield | Pigments extractable with EtOH aqueous in good yield |