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This work assesses the in vitro antimicrobial activity of an aqueous olive mill waste extract (AE-2) on the growth of diverse cocktails of foodborne pathogens species (Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella Enterica). The effects were evaluated by Response Surface Methodology, using a two-block (D optimal and full factorial) sequential design, with two independent variables (hydroxytyrosol concentration 0-3000 ppm and pH 3.5-6.5) and the percentage of inhibition (%I) as the dependent variable. S. Enterica and E. coli behaviours were similar but different from L. monocytogenes and S. aureus. The models predicted the complete inhibition of the four foodborne pathogen cocktails in the region defined by 3.80-3.87 pH and 1200-1314 ppm hydroxytyrosol. Within the experimental region, the model showed the best predictions for L. monocytogenes and the worst for S. Enterica, but the errors never exceeded 46%. This study could promote the use of olive by-products as natural preservatives in the food industry, especially in acidic matrices., LWT - Food Science and Technology, 164, ISSN:0460-1173, ISSN:0023-6438, ISSN:1096-1127

10 Páginas.-- 3 Tablas.-- 2 Figuras, The olive oil production is an important industrial sector in many Mediterranean areas, but it is currently struggled by the necessity of a proper valorisation of the olive mill solid waste or alperujo. The alperujo is the main by-product generated during the two-phase olive oil extraction, accounting for up to 80% of the initial olive mass. The alperujo is a source of valuable compounds, such as the pomace olive oil or highly interesting phenolic compounds. In the present research, a novel biorefinery approach has been used for phenolic compounds recovery. However, the extraction of these valuables compounds generates different exhausted phases with high organic matter content that are required to be managed. This study consists of the evaluation of the anaerobic biodegradability of the different fractions obtained in a novel biorefinery approach for the integral valorisation of alperujo. The results show that the different phases obtained during the biorefinery of the alperujo can be effectively subjected to anaerobic digestion and no inhibition processes were detected. The highest methane yield coefficients were obtained for the phases obtained after a two-months storages, i.e., suspended solids and liquid phase free of suspended solids, which generated 366 ± 7 mL CH4/g VS and 358 ± 6 mL CH4/g VS, respectively. The phenol extraction process reduced the methane yield coefficient around 25% due to the retention of biodegradable compounds during the extraction process. Regardless of this drop, the anaerobic digestion is a suitable technology for the stabilization of the different generated residual phases, whereas the high market price of the extracted phenols can largely compensate the slight decrease in the methane generation., This research has received funding from EIT Food, the innovation community on Food of the European Institute of Innovation and Technology (EIT), a body of the EU, under the Horizon 2020, the EU Framework Programme for Research and Innovation. EIT Food is Europe’s leading agri-food innovation initiative, with the aim to create a sustainable and future-proof food sector. The initiative is made up of a consortium of key industry players, start-ups, research centres and universities from across Europe. EIT Food aims to collaborate closely with consumers to develop new knowledge and technology-based products and services that will ultimately deliver a healthier and more sustainable lifestyle for all European citizens.

Both autohydrolysis and acidic pretreatments have already been commercialised to allow for the bioconversion of lignocellulosic biomass to valuable products. Recent fundamental research has shown that the pretreatment of lignocellulosic biomass can be enhanced by the suppression of lignin repolymerisation. This work evaluates the application potential of a carbocation scavenger additive that prevents lignin repolymerisation for the autohydrolysis and acidic pretreatment of woody biomass. The results show that the enhancing effect of the scavenger is strongly dependent on the type of biomass. While it proved hardly beneficial in the pretreatment of hardwoods, the pretreatment of recalcitrant softwoods could be greatly enhanced. Softwood has an exceptionally high recalcitrance to biochemical conversion compared to other biomass types, though the reasons for this behaviour have hardly been understood so far. Our study revealed that lignin repolymerisation is a major factor accounting for the exceptional softwood recalcitrance. A sensitivity analysis of pretreatment temperature and time showed that the scavenger can enhance the enzymatic digestibility of softwood cellulose by up to 113% in autohydrolysis and up to 142% in dilute acid pretreatments. The scavenger proved effective for both softwood sawdust and wood chips. Its mode of action in pretreatment was shown to be particularly suitable for the implementation in two-stage pretreatments, which are of high commercial relevance.