Origin and identity
Dahi — yogurt and the fermented heart of Indian cooking
Dahi (yogurt) is one of the oldest fermented foods in Indian culinary tradition — referenced in Sanskrit texts from 6,000 BCE, present in the Rigveda, and central to Ayurvedic nutrition as a foundational food. It is used across every Indian regional cuisine in applications ranging from marinades (tandoori chicken's yogurt-spice coating) to cooking medium (Kashmiri cooking with yogurt-braised meat) to cooling accompaniment (raita) to cooling drink (lassi and chaas). Understanding yogurt's protein behaviour — specifically why it curdles in hot curry and how to prevent it — is one of the most practically useful pieces of food science for Indian cooking.
Cooking Science
Why does yogurt curdle in hot curry and how is it prevented?
Yogurt's casein proteins are suspended in their acidic environment in a stable state. When yogurt is added to hot curry, two stresses cause curdling: thermal stress (rapid heating denatures and aggregates the casein) and mechanical stress (boiling turbulence causes aggregated proteins to merge into visible white curds). Three simultaneous techniques prevent curdling: reduce curry to a gentle simmer before adding yogurt (less thermal stress), stir continuously for 60 seconds after adding (prevents protein aggregation), and use room-temperature yogurt (less temperature shock). Each technique alone reduces curdling; all three together make it reliable.
Yogurt in Indian Cooking — Application Guide
How each use exploits different yogurt properties
- Marinade (tandoori, tikka): yogurt's lactic acid tenderises protein and helps spices adhere. The yogurt coating provides moisture during high-heat cooking, preventing the surface from charring before the interior cooks.
- Cooking medium (Kashmiri, some kormas): yogurt added to the bhunoed masala and cooked down with continuous stirring — the proteins bind the fat and spices into a creamy, stable gravy.
- Raita: raw application — yogurt's cooling, creamy character and lactic acid sourness balance hot, spiced preparations.
- Kadhi: yogurt beaten with besan (chickpea flour), then cooked for 25–30 minutes. The besan stabilises the yogurt proteins against curdling during prolonged cooking.
- Lassi and chaas: diluted with water, seasoned, churned — a cooling drink that provides probiotics and protein alongside hydration.
Related articles
Dahi (Whole Milk Yogurt) — Nutrition per 100g
Source: ICMR-NIN Nutritive Value of Indian Foods, 2017
| Nutrient | Amount | Context |
|---|---|---|
| Energy | 60 kcal | Low caloric density |
| Protein | 3.1 g | Complete protein — all essential amino acids |
| Fat | 3.7 g | Moderate for whole milk yogurt |
| Carbohydrates | 4.7 g | Primarily lactose (partially fermented) |
| Calcium | 149 mg | Excellent — high bioavailability |
| Phosphorus | 93 mg | Good |
| Vitamin B12 | 0.3 mcg | Good for vegetarians |
| Probiotics | Lactobacillus present | Live cultures in fresh yogurt — gut health |
| Lactose | ~4 g | Partially fermented — better tolerated than milk by some |
Dahi's calcium (149mg/100g) is well-absorbed — dairy calcium bioavailability (~30%) is higher than plant calcium sources. The probiotic content of fresh, home-set yogurt (Lactobacillus bulgaricus and Streptococcus thermophilus) provides gut microbiome benefits. Commercially produced yogurt that has been pasteurised after fermentation has no live cultures. For probiotic benefit, home-set or 'live culture' labelled yogurt is necessary. Yogurt's partial lactose fermentation makes it better tolerated than milk by many lactose-sensitive individuals.