Nanoparticle lengthens food shelf-life, sustains health benefits

Purdue University assistant professor Yuan Yao has adapted the phytoglycogen nanoparticle allowing it to attach to oils and emulsify them while also acting as a barrier to oxidation.

The process of oxidation causes food to become rancid. It destabilises oil droplets in emulsified food, degrading and changing the chemical structure of the oil, causing it to go bad. This process happens in a wide range of products, shortening their shelf lives, said the study.

The findings on the nanoparticle - a starch-like substance that makes up almost a third of the dry mass of sweet corn - have been published in an early on-line version of the Journal of Agricultural and Food Chemistry.​

Yao said the breakthrough could be applied across a range of sectors where the degradation of lipids is a problem.

"This can be widely used in the food industry, cosmetics and nutritional supplements, any system in which the oxidation of lipids is a concern," ​he said. "The shelf life of a product can be low and the quality of the food can become bad because of the oxidation of the lipids."​

Citing fish oils as an example, he explained that lipid oxidation degrades Omega-3 fatty acids. These are essential for infant development and are also believed to help with chronic inflammatory and heart diseases in adults.

Emulsifier​

Yao has been able to make the nanoparticle behave like an emulsifier by modifying its surface and changing it into a phytoglycogen octenyl succinate, or PG-OS. This is thicker and denser than commonly used emulsifiers, which creates a stronger defence against oxygen, free radical and metal ions, which cause lipid oxidation.

His results also showed that ε-polylysine, a food-grade polypeptide, can be added to the oil droplets to boost protection from oxidation. Polylysine is much smaller than the PG-OS nanoparticles, allowing it to fill in the gaps between PG-OS nanoparticles.

According to Yao's study, PG-OS nanoparticles with ε-polylysine significantly increased the amount of time it took for oxidation to ruin the oil droplets, in some cases doubling the shelf life of the product. Shelf life was tested by warming the emulsifiers and checking for chemical reactions that signal oxidation has occurred.

Yao has filed a provisional patent application for the technology.