The Ancient Wisdom of the Ghani
For centuries, the 'ghani'—also known as 'chekku' or 'kolhu'—has been the heart of traditional oil extraction in India. This simple but effective machine is essentially a large mortar and pestle. Traditionally, a heavy wooden pestle rotates slowly inside
a wooden vessel, crushing seeds like sesame through sheer pressure. In villages, this pestle was turned by a bullock walking in a circle; today, most ghanis use a slow-moving motor. The key to this method is its gentle nature. The slow, continuous crushing releases oil without generating destructive levels of heat, a stark contrast to modern industrial techniques.
What 'Cold-Pressed' Truly Means
The term 'cold-pressed' refers to oil extracted mechanically without external heat or chemical solvents. A wooden ghani is a perfect example of a true cold-press method. As the wooden pestle turns, it generates some friction, but the wood itself helps absorb this heat, keeping the oil's temperature low—typically below 40-50°C. This low-temperature environment is critical. It ensures that the delicate nutrients, enzymes, and antioxidants naturally present in the sesame seeds are preserved in the final oil. The result is an unrefined, pure oil that retains the authentic flavour, aroma, and nutritional integrity of the original seeds.
The Industrial Method: Speed, Heat, and Chemicals
Industrial oil extraction prioritises one thing above all: maximum yield. To achieve this, manufacturers use high-speed machines, high temperatures, and often, chemical solvents. The process typically starts with roasting the seeds at temperatures anywhere from 120°C to over 200°C. While this helps break down the seed structure to release more oil, it's the first step in degrading its quality. After pressing in large metal expellers, the remaining oil cake is often washed with a solvent like hexane to extract every last drop. The resulting crude oil then undergoes refining, which involves further heating, bleaching, and deodorising to create a uniform, shelf-stable product with a neutral taste.
Nutrient Destruction Under High Heat
The high temperatures used in industrial processing are destructive to the sensitive nutrients in sesame seeds. Heat-sensitive vitamins, especially Vitamin E, and vital antioxidants like sesamin and sesamolin are significantly degraded. These compounds are what give sesame oil many of its celebrated health benefits, including fighting oxidative stress. Furthermore, high heat can alter the very structure of the oil's fatty acids, potentially leading to the formation of trans fats and other harmful compounds. In contrast, the low-temperature ghani method preserves these beneficial components, delivering an oil that is richer in antioxidants, vitamins, and healthy unsaturated fats.
Flavour and Aroma: The Ultimate Test
Perhaps the most immediate difference between the two methods is in the taste and smell. Wooden-ghani cold-pressed sesame oil boasts a robust, nutty, and earthy flavour that is true to the seed itself. This makes it a flavourful addition to dressings, drizzles, and low-heat cooking. Industrially extracted refined sesame oil, having been heated, bleached, and deodorised, is often much milder and more neutral. While it has a higher smoke point suitable for high-heat frying, this comes at the cost of the oil's natural character and complexity. The rich aroma and taste of ghani-pressed oil are direct indicators of its minimal processing and high nutrient retention.
