Improving apple juice expression and quality by pulsed electric field on an industrial scale

Abstract

This study investigated the Pulsed Electric field (PEF) effect on apple mash, regarding quantitative, qualitative and sensory attributes, on an industrial scale. PEF treatment (E = 650 V/cm, tPEF = 23.2 ms, q = 32 kJ/kg) was applied to apple mash at the flow rate of 4400 kg/h in a module of colinear design made of four treatment chambers. Juice yield significantly increased from 71.1% to 76.3% due to PEF treatment. A significant increase of 8.8% was also observed for the native polyphenols concentration when an inhibitor of the enzymatic oxidation was added. Juice colour was significantly altered by the PEF treatment. The saturation in the yellow rose significantly from 17.9 to 26.8.The juice from treated mash was less turbid and was described by odour intensity and typical odour of apple significantly higher than the untreated sample. Similarly, the overall and typical taste of apple juice were significantly more intense. The chemical composition (Fructose, Glucose and Malic acid) of juice did not vary despite a significant increase of the dry matter for treated samples. On the contrary, a significant depletion of fructose and glucose was noted for the pomace from treated mash as compared to the control.