Koozh (Tamil கூழ், “porridge”) is a thin, cool, slightly sour millet porridge from Tamil Nadu in South India, made from finger millet (ragi, kezhvaragu; Eleusine coracana) or pearl millet (kambu). The millet is fermented and cooked into a thick porridge, which is then loosened with buttermilk or water and drunk, often with sliced shallots or onion and green chili on the side. It’s a summer drink, sold by street vendors as well as made at home, and a close relative of other soured grain porridges such as Nigerian ogi and Tanzanian togwa.
What Ferments It
Koozh ferments spontaneously, so its microbes vary. From six market samples of koozh, researchers isolated 69 presumptive lactic acid bacteria, grouped as Leuconostoc, Enterococcus, Streptococcus and Lactobacillus; the isolates they characterised further were mostly Enterococcus hirae, with one each of E. faecalis, Bacillus amyloliquefaciens and Lactobacillus plantarum (Ilango et al., 2016). Another study found Weissella paramesenteroides, L. plantarum and L. fermentum among isolates from koozh and other South Indian ferments (Satish Kumar et al., 2010).
Those studies tested isolates in the laboratory for acid and bile tolerance, which makes them candidates for probiotic research. It doesn’t make a bowl of koozh a probiotic: that word is for defined strains with a shown health benefit, and a spontaneous ferment contains whatever grew in it (Marco et al., 2021). Koozh does contain live bacteria when it’s eaten unheated, and the buttermilk adds its own.
Finger Millet Nutrition, and What Fermenting Changes
Finger millet has the highest calcium of the cereals and millets, about 344 mg per 100 g, and more dietary fibre and minerals than white rice. A review of the evidence also found that the health benefits often claimed for it – lower blood sugar and cholesterol, for example – come from laboratory and animal studies, and that clinical trials are lacking (Shobana et al., 2013).
Fermentation’s effect depends on how long it runs:
- In koozh made from germinated and fermented finger millet flour, the total calcium, iron, zinc and other minerals didn’t change, while free amino acids, phenolic compounds and antioxidant activity in the lab went up (Subastri et al., 2015).
- Phytic acid, which binds minerals in the gut, fell by 54% in finger millet after 72 hours of fermentation and 72% after 96 hours, and available iron and calcium rose (Makokha et al., 2002). An overnight koozh ferments for a fraction of that time, so expect a smaller effect.
- Germinating (sprouting) finger millet for 48 hours raised the share of its iron available in a simulated digestion by 20% but cut zinc by 38% (Hemalatha et al., 2007).
So koozh is a nourishing, filling, mineral-rich staple – but not because a few hours of souring transforms it.
Keeping It Safe
Koozh is a starchy, cooked food, and cooked grain left warm is how food poisoning bacteria get their chance. What protects a soured porridge is fast souring: in lactic-fermented cereal gruels, pathogens declined once the pH fell to about 4 or below, and gruels with a starter soured much faster than those without (Kingamkono et al., 1994). That’s why the method below lets the raw flour batter do its fermenting overnight, then cooks it: the porridge is cooked after souring, and drunk the same day. If you leave cooked koozh to sour, as many households do, keep it covered, make sure it’s clearly sour by morning, and refrigerate any you don’t drink; USDA advises refrigerating cooked food within 2 hours (USDA FSIS).
How It’s Served
Stir the koozh thin with buttermilk (mor) or water and a pinch of salt, and drink it cool. Sliced shallots or onion, green chili and pickles are the usual companions. For other South Indian ferments, see idli and dosa batter; for another millet drink, boza.