This blog post explores the principles behind how supercritical fluid technology extracts sesame oil more cleanly and safely, along with its diverse industrial applications.
Have you heard of supercritical sesame oil? It’s a name you can easily find in supermarkets these days. Of course, for a poor college student like me, buying supercritical sesame oil, which is even more expensive than regular sesame oil, is out of the question. Nevertheless, supercritical sesame oil is steadily selling, and its market is also steadily expanding. Why is supercritical sesame oil selling steadily despite its high price? Let’s find out.
Before learning about supercritical sesame oil, let’s first understand what a supercritical fluid is. A supercritical fluid literally refers to a state beyond the critical point. Simply put, it describes another phase of existence beyond solid, liquid, and gas. The critical point signifies the threshold where a substance no longer remains in its specific state and acquires new physical properties. The reason this supercritical phase is unfamiliar to most people is that maintaining it requires immense heat and pressure. Water becomes supercritical at 374 degrees Celsius and 220 atmospheres of pressure, while carbon dioxide reaches this state at 31 degrees Celsius and 74 atmospheres. Simply sustaining this phase is no easy feat. So, what exactly is this supercritical phase that makes such effort worthwhile?
Supercritical fluids diffuse as rapidly and permeate as well as gases, while also acting as excellent solvents that dissolve other substances as effectively as liquids. Their applications are vast: they extract sesame oil, remove caffeine from coffee, and even restore damaged historical documents. Research into supercritical fluids began in the 1960s, initially finding primary use in industrial fields like petroleum refining. However, over time, its potential for use in various industries like food, pharmaceuticals, and environmental restoration has gained increasing attention. Among these, supercritical carbon dioxide is particularly favored as a safe material for extracting foods like sesame oil, owing to its minimal toxicity and chemical reactivity. Let’s explore how supercritical fluids are used in the extraction of sesame oil, one of the most widely known applications.
As mentioned earlier, supercritical fluids possess the permeability of a gas while also exhibiting excellent solvent capabilities. Traditionally, sesame oil was produced by roasting sesame seeds at high temperatures and then pressing them to ‘squeeze’ the oil out. This method has two major drawbacks. First, the residue left after squeezing the oil cannot be recycled. Second, sesame seeds burn during the roasting process. The dark color and bitter taste of conventional sesame oil result directly from this burning.
However, the sesame oil extraction process using supercritical fluid resolves both these issues. Since the supercritical fluid removes the oil from inside the sesame seeds while preserving their shape, the seeds retain their original form after extraction and can be reused elsewhere. Furthermore, since roasting is unnecessary, the sesame oil is extracted cleanly without burning, and nutrient damage is minimal. This is why sesame oil made using supercritical fluid is popular among consumers—it offers a purer, deeper flavor and aroma compared to regular sesame oil, along with higher nutritional value.
A major advantage of supercritical sesame oil is the near-zero risk of producing benzo[a]pyrene, a carcinogen. While conventional sesame oil may generate benzo[a]pyrene during the high-temperature roasting of sesame seeds, the supercritical method avoids this step, making it safer. While conventional methods are considered safe if temperatures remain below a certain threshold, ensuring benzopyrene levels do not exceed the standards set by the Ministry of Food and Drug Safety, some commercially available sesame oils have occasionally been reported to exceed these limits. This is precisely why supercritical sesame oil is preferred by health-conscious modern consumers—it enables the extraction of sesame oil in a safe and clean manner.
Supercritical fluid technology extends far beyond sesame oil extraction. It is also used in the process of removing caffeine from coffee and plays a crucial role in specialized fields like the restoration of ancient documents. When removing wax from old documents or paintings, supercritical fluids are gaining attention as a technology that can delicately remove only the necessary parts without damaging the document. As such, supercritical fluids are being actively researched across various industries and will likely demonstrate even more application possibilities in the future.
However, technologies utilizing supercritical fluids are still in their early stages and face some limitations due to the high cost and equipment required to maintain the necessary high temperatures and pressures. Nevertheless, as the technology advances, supercritical fluids are expected to find use in more fields. In modern society, where demands for environmental protection and sustainable production are increasing, supercritical fluid technology is gaining attention as an eco-friendly alternative to chemical solvents. It is clear that this technology holds immense potential for future development.
