Comparison of Effect of Gear Juicer and Colloid Mill on Microstructure, Polyphenols Profile, and Bioactivities of Mulberry (Morus indica L.)

Mulberry (Morus indica L.) fruits are rich sources of polyphenols with multiple health benefits. The gear juicer and colloid mill were compared in mulberry juice production and further marc water extraction based on polyphenol yield, phytochemical profiles, bioactivities, as well as microstructure of residues. Higher content of phenolic compounds, stronger antioxidative, and alpha-Glucosidase inhibition activities were obtained in colloid mill-processed juice. The extraction kinetics of marc was investigated under three conditions (stirring, ultrasound, and combined stirring and ultrasound) at 25 A degrees C for 2.5 h. Based on total polyphenol and monomeric anthocyanin yield, the optimum extraction condition for gear juicer marc was combination of ultrasound with stirring for half an hour. While ultrasound for 1 h was optimized for water extraction of colloid mill marc. Using the optimized extraction condition, total polyphenols and monomeric anthocyanin obtained from colloid mill-processed samples, including juice and marc extract, were approximately 46 and 68 % higher than those in gear juicer-processed samples. Compared to gear juicer, colloid mill processing generated smaller particle size and more disrupted microstructure, which contributed to higher content of phenolic compounds in colloid mill juice. Moreover, changes in the microstructure of mulberry marc were intensified by extraction conditions, which improved polyphenol extraction efficiency, especially for colloid mill marc. These results provided valuable information for comparing gear juicer and colloid mill in mulberry as well as other berries for juice production and marc water extraction, and emphasized the great potential of colloid mill in berry processing.