The Gentle Art of the Wooden Ghani
A wooden ghani, known as 'kolhu' or 'marachekku' in different parts of India, is a traditional oil press. It operates on a simple, centuries-old principle: a large wooden pestle rotates slowly inside a wooden mortar, crushing oilseeds like sesame through
pressure and friction. Historically powered by bullocks and now often by a slow-speed motor, the key to the ghani is its gentle pace. Unlike modern steel expellers that spin at high speeds, a wooden ghani turns slowly. This deliberate slowness is the entire point. The wood itself acts as a natural insulator, and the low-speed rotation ensures that minimal heat is generated during extraction, keeping the oil from getting hot. This process, a form of cold-pressing, is purely mechanical, using no chemical solvents or external heat.
What Are Phenolic Compounds?
To understand the ghani's benefits, we first need to talk about what's inside the sesame seed. Sesame oil is rich in bioactive compounds, including a special class of antioxidants called phenols. In sesame, the most important of these are lignans, with names like sesamin, sesamolin, and sesamol. These phenolic compounds are powerful antioxidants, which means they help protect the body's cells from damage caused by unstable molecules called free radicals. This protective action is linked to a wide range of health benefits, including supporting cardiovascular health and reducing inflammation. Think of them as the seed's delicate, health-preserving treasures.
Heat: The Enemy of Nutrients
The main difference between traditional and modern oil extraction is heat. Modern industrial methods often use high-speed expellers and solvent extraction with chemicals like hexane, followed by refining, bleaching, and deodorising at temperatures that can exceed 200°C. While this process is efficient, yielding more oil per batch and creating a product with a long shelf life, it comes at a nutritional cost. Sensitive compounds like phenols are fragile and begin to degrade when exposed to high temperatures. Studies on olive oil, another phenol-rich oil, show that heating can reduce polyphenol concentration by 40% at 120°C and up to 75% at 170°C. This heat exposure during refining strips the oil of its vitamins, beneficial phenols, and natural flavour, fundamentally altering it from its original state.
How Ghanis Preserve Sesame's Goodness
The wooden ghani method masterfully avoids the problem of heat. By slowly crushing the seeds, the temperature of the oil rarely rises above 40-45°C. This low-temperature environment is crucial for preventing the thermal degradation of the oil's most valuable components. The sensitive phenolic compounds, like sesamin and sesamolin, remain intact, along with other nutrients like Vitamin E and essential fatty acids. The result is an unrefined oil that retains the full nutritional profile of the original sesame seed. Research has confirmed that cold-pressed oils contain significantly higher levels of these beneficial bioactive compounds compared to their refined counterparts. The process doesn't just prevent loss; it actively preserves the oil's natural antioxidant capacity, colour, and authentic nutty flavour.
Making an Informed Choice
When you choose an oil, you're choosing a processing method. While refined oils offer a higher smoke point and a neutral taste, they are nutritionally compromised. Wood-pressed sesame oil, on the other hand, delivers the full spectrum of the seed's health benefits. Look for labels that say 'wood-pressed', 'cold-pressed', 'ghani', or 'chekku' to ensure you're getting a minimally processed product. The richer colour, more robust aroma, and slightly shorter shelf life are not flaws; they are signs of an authentic, nutrient-dense oil. For daily cooking like tempering and sautéing, wood-pressed sesame oil is an excellent choice, adding both flavour and functional health benefits to your meals.
