An Assessment of Oat Hulls as a Press Aid for the Apple Juice Processing Industry

Abstract

Oat hulls were assessed in laboratory and pilot plant tests as a potential pressing aid for the fruit juice industry. Laboratory tests, using 0.5–3.0% w/w press aids showed average weight yields of apple juice of 78.0, 77.5, 76.6, and 74.5% for Silvacel 116, Silvacel 133, rice hulls and whole oat hulls, respectively. A control (no press aid) gave an average juice yield of 73.0%.When oat hulls were processed into a slivered form, the average juice yield increased from 74.5% to 76.5% and compared favora bly with the yield from rice hulls. Pilot plant tests, using slivered oat hulls at the 2.0% w/w level with late season Ida Red apples, gave 77.9% juice yield compared to 71.7% for the control where the apple pulps were treated with pectinase before pressing. No quality defects were detected in the finished juice product. These results suggest an opportunity for improved oat hull utilization and a value-added contribution by oat hulls, as a replacement for more expensive press aid imports in the Canadian fruit juice processing industry.