From Malay ragi (“fermenting medium, yeast”), from an Indian language such as Hindi रागी (rāgī, “finger millet”), since finger millet can be fermented. See Etymology 1.
Meanings
(uncountable) A type of yeast traditionally used in winemaking, baking, and brewing, now identified as Saccharomyces cerevisiae.
2010, M.J. Robert Nout, Kofi E. Aidoo, 2: Asian Fungal Fermented Food, Martin Hofrichter (volume editor), Karl Esser (editor), The Mycota, Volume X: Industrial Applications, page 49,
It is made from cooked gelatinised rice and red pulverised ragi (yeast cake or jui-piang) and fermented for up to 30 days at 25°C.
Finely ground and sifted round ragi yeast 3⁄4 tsp 2014, Florence Tan, Florence Tan: Best Nyonya Recipes, page 108:
Pound 5 kg of round ragi (yeast) and 5 pieces of thinly sliced ragi into powder. Mix ragi into cooled rice. 2005, Malaysia at Random, Didier Millet, page 30: