Microbial Application to Improve Olive Mill Wastewater Phenolic Extracts

Abstract

Olive mill wastewater (OMW) contains valuable and interesting bioactive compounds, among which is hydroxytyrosol, which is characterized by a remarkable antioxidant activity. Due to the health claims related to olive polyphenols, the aim of this study was to obtain an extract from OMW with an increased level of hydroxytyrosol by means of microbial enzymatic activity. For this purpose, four commercial adsorbent resins were selected and tested. The beta-glucosidase and esterase activity of strains of Wickerhamomyces anomalus, Lactiplantibacillus plantarum, and Saccharomyces cerevisiae were also investigated and compared to those of a commercial enzyme and an Aspergillus niger strain. The W. anomalus strain showed the best enzymatic performances. The SP207 resin showed the best efficiency in selective recovery of hydroxytyrosol, tyrosol, oleuropein, and total phenols. The bioconversion test of the OMW extract was assessed by using both culture broths and pellets of the tested strains. The results demonstrated that the pellets of W. anomalus and L. plantarum were the most effective in hydroxytyrosol increasing in phenolic extract. The interesting results suggest the possibility to study new formulations of OMW phenolic extracts with multifunctional microorganisms.

An Enzyme Cascade Reaction for the Recovery of Hydroxytyrosol Dervatives from Olive Mill Wastewater

“…However, the proof of concept of a flow system for the valorization of OMWW using b-glucosidase and both catalytic activities of promiscuous hydrolase/acyltransferase PestE_I208A_L209F_N288A was already successful as confirmed by our results. To further reduce the cost of the process, purified b-glucosidase could be co-immobilized [19] or, even cheaper, microbial pretreatment of OMWW could be applied to release HT from oleuropein [20].…”

Olive Pomace and Pâté Olive Cake as Suitable Ingredients for Food and Feed

“…This process involves the stabilization of wastes and by-products, and the extraction of addedvalue compounds that could be entirely treated or directly added as functional ingredients for designing new foods or valuable ingredients with medium-and high-added value [2]. Since the highest content (in the order of 70%) of phenolic compounds is found in the unwrapped part and in the outer parts of the olive fruit [3], several studies have focused on the detection of phenolic content in olive oil by-products [4,5].…”

Microbiological and Enzymatic Activity Modulates the Bitter Taste Reduction in Decanted Coratina Olive Oil

“…Esterase activity was evaluated using a spectrophotometric method based on the initial rate of increase in the absorbance at 410 nm. The esterase activity was assayed using p -nitrophenyl-acetate ( p -NPA, Sigma-Aldrich, Milan, Italy) according to the method described by Romeo et al [ 20 ], with some modifications. At the time of the assay, 200 µL of crude extract was transferred into a spectrophotometer cuvette containing 2.9 mL of Tris-HCl buffer 0.1 M pH 7.5 and 200 µL of 0.15 M p -NPA in ethanol.…”