Valorisation of waste olive pomace: Laboratory and pilot scale processing to extract dietary fibre

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The olive oil industry generates large quantities of waste pomace which has the potential to be used as a source of functional dietary fibre in the food ingredients sector. It was determined that hexane extracted olive pomace still retained 10.6% soluble dietary fibre (SDF) although the total sugar content of 27% was low. The lower and upper yields from single trials on freeze dried olive pomace (10 g) for hexane extracted IDF and SDF were 41-53% and 0.5-2.5%, respectively. These results tentatively indicated that pH and homogenization (high shear mixing) were important factors in affecting IDF and SDF yields. The increase in quantity to pilot scale with 36 kg (wet weight) frozen olive pomace, equivalent to 5.65 kg (dry weight) focused on recovery yield of SDF using an alkaline treatment approach combined with wet milling for 2 h. There was no increase in microbial contamination during the trial. While a relatively high yield of SDF at 5.6% was obtained, the monosaccharide content was low, and this fraction did not exhibit gelation properties. A lower-than-expected IDF yield (13.6%) was obtained during the pilot trial compared with initial laboratory results (41.3-53.0%). However, this process enriched the fibre content from 40% to more than 70% in the majority of the IDFs collected during the pilot trial. The highest water and oil holding capacities were indicated to be 6.9 and 4.1, respectively, which were associated with IDF extracted at pH 4.5. This study revealed that SDF could be recovered from olive pomace and the recovery of IDF could be scaled up where physical disruption and pH conditions caused apparent changes in the yields, and water and oil holding capacities of dietary fibre fractions.
Original languageEnglish
Article number100045
JournalCleaner and Circular Bioeconomy
Early online date3 May 2023
DOIs
Publication statusE-pub ahead of print - 3 May 2023

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