The enhanced Huyou (Citrus changshanensis) segment peeling of ultrasound combined with pectinase and cellulase is reflected on the sonicated segment rather than enzymes

Abstract

The combinations of enzymatic and ultrasound treatment in different manners were conducted on Huyou segment, to improve the membrane peeling. The results indicated that ultrasound-assisted enzymatic hydrolysis was the optimal treatment method for peeling the Huyou segment membrane. This approach led to higher total segment membrane peeling rates and lower peeling loss throughout the peeling process. Additionally, compared to the control (enzymatic treatment alone), the samples peeled with the US-assisted enzymatic hydrolysis process (UEH) retained more than 91 % of total soluble solids and 86 % of titratable acids. Compared with native enzyme treatments, the catalytic activity of pectinase and cellulase increased by 30.84 % and 10.84 % after ultrasonication, respectively, with the conformational variation of enzymes observed from the fluorescence spectroscopy and circular dichroism. Despite the enhanced activity of ultrasonicated enzymes, the pre-sonicated treatment followed native enzyme hydrolysis showed a significantly higher peelability (81.33 ± 4.78 %), as well as greater release of D-galacturonic acid (168.92 ± 3.685 mmol/L) and glucose (35.995 ± 1.686 mmol/L) than ultrasonicated enzymes. The microstructure of the peeled segments revealed that the segment after sonication showed more folds and holes in the membrane, accelerating the enzyme diffusion within the membrane and hydrolysis. The mild segments surface rupture is a crucial factor to display the promoted hydrolysis effect of ultrasonicated enzymes on Huyou segments. Ultrasound-assisted enzymatic hydrolysis potentially provides an effective strategy to improve the peelability without compromising the comprehensive quality of Huyou segments.