Starch-like nanoparticles help protect lipids from spoiling, study

By Katie Bird

- Last updated on GMT

A starch-like nanoparticle can help stop lipids from oxidising and therefore improve the stability of oil-in-water emulsions, according to a recent study.

Applicable in personal care products, food and dietary supplements, the modified phytoglycogen nanoparticle can help extend shelf life and stop the product from spoiling.

The team working at Purdue University, Indiana, modified the phytoglycogen, which is similar to starch but has a highly branched structure and a high molecular density in dispersion, to create phytoglycogen octenyl succinate (PG-OS).

This new molecule has emulsifying characteristics, explained the researchers.

The POS nanoparticles were then mixed with epsilon-polylysine (EPL), a polyamide which is used, among other applications, as a food preservative and emulsifying agent.

Fish oil was then used by the researchers in order to test the ability of PG-OS, EPL, and a mix of the two, to protect against the oxidation of the lipid.

The oil was stored at 55 degrees centigrade for up to 6 days and levels of hydroperoxide were measured, which reflects the formation of the intermediate compounds of lipid oxidation, the scientists explained.

In addition, the researchers measured the TBARS value, which reflects the formation of the final products of lipid oxidation.

Substantial reductions in oxidation

All measurements were compared with waxy corn starch octenyl succinate as a control, and in general the combination of EPL and PG-OS led to substantial reductions of both hydroperoxide and TBARS for all emulsions.

According to the scientists, the PG-OS/EPL complex has two basic features that make it successful at protecting against lipid oxidation.

Firstly, the mixture is thick and dense so can form a strong physical barrier around the lipid molecules to help protect against pro-oxidative compounds such as oxygen and metal ions.

Secondly, the complex is positively charged at the surface of the oil phase due to the EPL molecules. This repels metal ions, explained the scientists.

“Therefore, a combined use of PG-OS and EPL effectively blocked the permeation of pro-oxidative compounds and resulted in high lipid oxidative stability of emulsions,”​ the researchers concluded.

Source: Journal of Agriculture and Food Chemistry
​DOI:10.1021/jf903170b
Phytoglycogen octenyl succinate, an amphilic carbohydrate nanoaparticle, and epsilon-polylysine to improve lipid oxidative stability of emulsions
​Siqi L Scheffler, Xue Wang, Lei Huang, Fernanda San-Martin Gonzales, Yuan Yao

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