Effect of alkaline and high-pressure homogenization on the extraction of phenolic acids from potato peels

Phenolic acids were extracted from potato peels with NaOH treatment and a high-pressure homogenization (HPH) process. Total phenolic content, total flavonoid content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity and extraction yield were determined with different treatment conditions. Significant improvement was observed after the alkaline and HPH treatments. HPLC analysis shows that the phenolic compounds contained gallic acid, sinapic acid, vanillic acid, syringic acid, protocatechuic acid, p-coumaric acid, chlorogenic acid, caffeic acid and ferulic acid. The yields of these specific phenolic acids varied with different treatments. Scanning electron microscope, nuclear magnetic resonance and particle size measurements suggest that changes in cellular structure may be the mechanisms for the improvement in extraction rendered by the HPH and NaOH treatments. In conclusion, the combined treatment of NaOH and HPH increased the extraction yield and functionality of the phenolic acids from the potato peel residues. Industry relevance High-pressure homogenization as a process method has been applied widely in food industry. It can help with emulsification and sterilization significantly. But the potential of High-pressure homogenization as an assist method to improve the yield of extraction from food and food waste has not been developed. The positive effect of phenolic and flavonoids has been proved and found in potato peels. However, the release of these bioactive components is a difficulty with traditional method. The High-pressure homogenization can reduce the particle size apparently and release the bioactive compound. For potato peels, the production can be added into bread, meat, beverage, etc. to increase the fiber and nutrition. For other sorts of similar material, the high-pressure homogenization can be a novel to improve the extraction process of bioactive component bound in cell wall instead of inside the cell. In this article, we developed a new method with high-pressure homogenization and alkaline treatment to improve the extraction process dramatically. Meanwhile, the process can be scale up to industry with minor modification and adjustment.