Horse gram, scientifically known as Macrotyloma uniflorum, is a resilient legume cultivated across various parts of Asia and Africa. This crop has a long history of use, particularly in tropical southern Asia, where archaeological findings suggest its presence as early as 2500 BC in India. Despite its historical significance and widespread cultivation in certain regions, it often remains a lesser-known pulse compared to other more common legumes. Horse gram is recognized for its ability to thrive in challenging climatic conditions, including drought-prone areas, making it a valuable and adaptable food source.
Nutritional Composition of Horse Gram
Horse gram offers a dense nutritional profile, making it a noteworthy food source. A 100-gram serving of dry horse gram provides approximately 321 calories. It contains about 22 grams of protein, making it a substantial plant-based protein source. It also contains around 57 grams of complex carbohydrates, providing sustained energy.
The legume delivers 5 to 5.3 grams of dietary fiber, which contributes to digestive well-being. Beyond macronutrients, horse gram is a source of several micronutrients. It contains about 287 milligrams of calcium per 100 grams, which is a considerable amount for a pulse.
A 100-gram serving provides around 7 milligrams of iron, contributing to daily iron intake. Phosphorus is also present, around 311 milligrams per 100 grams. Other minerals such as potassium (around 1340 mg per 100 grams) and vitamins like thiamin, riboflavin, and niacin are also found.
Key Bioactive Compounds
Beyond its nutritional components, horse gram contains a variety of bioactive compounds. These include phytochemicals such as phenolic acids and flavonoids. Phenolic acids, like ferulic, vanillic, and p-hydroxybenzoic acids, are secondary metabolites recognized for their antioxidant properties. Flavonoids, including quercetin, kaempferol, and myricetin, offer cellular protection. These compounds help to neutralize unstable molecules in the body, thereby supporting cellular integrity.
Horse gram also contains certain anti-nutritional factors. Phytic acid is one such compound. Tannins and oxalic acid are also present. These substances can interfere with the absorption of certain minerals, such as iron and calcium, by forming insoluble complexes. However, specific preparation methods can help reduce the levels of these compounds.
Preparation Methods for Optimal Nutrition
Proper preparation of horse gram can enhance its nutritional availability and reduce anti-nutritional factors. Soaking the seeds in water for several hours is a common initial step. Soaking periods of 12 to 18 hours have been shown to reduce levels of phytic acid and other anti-nutrients by allowing them to leach into the water. This process also aids in softening the seeds, making them easier to cook.
Sprouting is another method to improve horse gram’s nutritional profile. Germination over 48 to 72 hours after soaking activates enzymes like phytase, which further breaks down phytic acid. Sprouting can lead to a significant reduction in phytic acid and tannins. This process can increase the bioavailability of minerals like iron and calcium, which might otherwise be bound by anti-nutrients.
Cooking methods also play a role in nutrient retention and anti-nutrient reduction. Boiling or pressure cooking horse gram after soaking and sprouting can further diminish anti-nutritional compounds. While some heat-labile bioactive compounds may decrease during cooking, the reduction of anti-nutrients is beneficial. Roasting is another method that can also reduce phytic acid.