We all enjoy a healthy, tasty and refreshing glass of pomegranate juice. Some of us prefer the juice over eating the arils as we may not like biting into the tasteless seeds. But do you know that the seeds are a source of a very healthy oil? In a study, Prof. Amit Arora and his team from the Indian Institute of Technology Bombay have proposed a new cost-effective, zero-waste method of extracting oil from pomegranate seeds, which also yields high-quality protein and dietary fibres.
India is the world’s largest producer of pomegranates, with a yield of 2.3 million tons in 2016 alone. With the increasing consumption of pomegranate juice, there has been an explosive increase in its waste products—the seeds—constituting about 10% of the total weight. While the oil extracted from the seeds has high medicinal value due to its anti-cancer, anti-oxidant and anti-diabetic properties, the byproducts obtained during extraction are are also rich in protein and dietary fibres.
“Considering the quality of oil and protein in pomegranate seeds, it can very well replace flax seeds. It is very similar to chia seeds in properties. It can be considered as a replacement in gaining many functional properties”, says Prof. Arora, talking about how pomegranate seeds fare against the well-known chia seeds and flax seeds.
While there have been earlier attempts to extract oil from pomegranate seeds, they could extract oil only partially, and the rest of the produce had to be discarded. The commonly-used cold-press technique, where a hydraulic press is used to squeeze out the oil, can only extract 40-50% of the oil, and is energy consuming. A popular extraction process uses organic chemicals like hexane which could lead to environmental contamination and health hazards and hence, requires a lot of care in handling and disposing of the chemicals. This increases the costs for construction and operation. A few other methods that involve high temperature and mechanical pressure not only decrease the quality of oil but also degrade the proteins, thus reducing the nutritional and economic value of the oil. Other methods of extraction, including some that use ultrasound and microwave, are sophisticated and expensive, even though they yield 95-99% of the oil.
In this study, Prof. Amit Arora and his team have tried to address these shortcomings with a new approach. They have proposed a one-pot oil-extraction method that is not only environment-friendly but can also extract a highly nutritious oil. The method is fairly simple and can also be used for small quantities of seeds, say the researchers.
In the proposed method, pomegranate seeds are dried, powdered and added to sodium phosphate and incubated for 10 minutes at 45oC. This is then mixed with an enzyme called protease that breaks down the outer covering of the seeds, releasing the oil. The seed-enzyme mixture is shaken continuously for 4 to 16 hours and then centrifuged for 20 minutes. After this, clear layers of pure oil, proteins and fibres are formed, which can then be extracted.
The researchers, after several trials of extraction with different concentrations of protease, found an optimum quantity to mix with the seeds, which could completely extract all the oil, proteins and fibres in 14 hours. They obtained a maximum yield of 98% for the oil and 93% for the proteins. The resulting products were of a higher quality than those obtained from other methods.
The researchers believe this study could help bring out some interesting uses and applications of pomegranate oil, including those in medical and cosmetics industry. Since the research was conducted on a small-scale, the feasibility of industrial-sized extraction units is yet to be studied. “So far, no adverse effects of the pomegranate seed oil have been reported. The oil tends to become rancid if kept for a long time. Studies on its shelf life and stability in food formulation need to be explored”, says Prof. Arora on the prospects of the research.