In 和菓子, colours are very important. Of course, you can use food colouring; but I think it's nice if you use natural colours:
| Colour | Ingredient | Taste | Potency |
|---|---|---|---|
| Red | Beetroot powder / juice | earthy, slightly sweet | strong |
| Red | Hibiscus powder | adds a tart taste | medium |
| Red | Red perilla (赤紫蘇) | herbal, slightly minty (quite traditional) | medium |
| Red | Berry powders | sweet, fruity | weak–medium |
| Red / pink | 紅麹 | mild fermented rice, slightly fruity | strong |
| Yellow | Turmeric | warm, slightly bitter | very strong |
| Yellow | Gardenia fruit (くちなし) | nearly neutral | very strong |
| Yellow | Egg yolk | rich, custardy | medium |
| Yellow | Saffron | floral, honey-like | strong |
| Green | 抹茶 | Best to avoid since we're serving sweets with the tea | strong |
| Green | よもぎ | herbal, slightly bitter | medium |
| Green | Spinach powder | mild vegetal | medium |
| Green | Barley grass powder | grassy, fresh | strong |
| Green | Pandan powder | vanilla | medium |
| Blue | Butterfly pea flower | mild, slightly earthy | strong |
| Blue | Blue spirulina | very mild algae note | very strong |
| Purple | Purple sweet potato | sweet, earthy | strong |
| Purple | Blueberry powder | fruity, sweet | weak–medium |
| Brown | Cocoa | chocolate | strong |
| Black | Black sesame | nutty, roasted | strong |
| Black | Bamboo charcoal | neutral | very strong |
| Black | Squid ink | marine umami | very strong |
She's written a whole book on traditional colours, for example:
黄土色 : A dark yellow with a slight reddish tint. Ochre (黄土) refers to the yellowish-brown soil found in northern China, Europe, and central North America. It is formed when wind carries and deposits dust from arid regions containing quartz, feldspar, mica, and other minerals. The ochre used as a pigment or paint is made by mixing clay with iron oxide obtained by refining red earth. “It nourishes Heaven and Earth.” (「天地を養」) In other words, the I Ching states that Heaven is black and Earth is yellow. Before the ground throughout Japan became covered with concrete, children would use up their ochre-colored paint or crayon much faster than any other color.