Hazelnut skin is a rich source of polyphenols but is generally discarded during the roasting process of hazelnuts. Previous studies reported the extraction and identification of these compounds using different solvents and procedures; however, there are few reports on their enrichment and purification. In this study, three types of Amber-lite macroporous resins (XAD 16, XAD 4, and XAD 7) were compared to evaluate the enrichment of polyphenols via adsorption and desorption mechanisms. The operating condition parameters for polyphenol adsorption/desorption of each resin were determined, the kinetics of adsorption were examined, and a method for polyphenol recovery was developed using static and dynamic adsorption/desorption. Antioxidant activity and high-performance liquid chromatography-diode array detection were used to confirm the increase in polyphenol obtained using the adsorption/desorption technique. XAD16 showed the highest adsorption capacity, with a recovery of 87.7%, and the adsorption kinetics fit well with a pseudo-second-order model. The highest poly-phenol desorption ratio was observed using an ethanol/water solution (70% v/v) at a flow rate of 1.5 bed volume/h.

Recent advancements in the genomic characterization of A. butzleri revealed putative virulence genes and highlighted the possible pathogenic mechanisms used by this foodborne pathogen. It is therefore possible to study the transcriptomes of these bacteria to explore possible virulence mechanisms under conditions that mimic the infection process.

Six food-grade tannins obtained from different woods were used as a source of polyphenolic compounds at two concentrations (0.5% and 1% w/w) in yogurt formulations and monitored during 3 weeks of storage. Yogurt containing tannins showed significantly higher total phenolic content (+200%), antioxidant activity (+400%), and syneresis (+100%) than control. These changes were higher with fortification at 1%. Tannin origin also significantly influenced the yogurt composition and yogurt obtained from a Turkish gall showed higher values of total phenolic content (4 mg GAE/g) and antioxidant activity (17 μM Trolox/g). Yogurt color was evaluated by CIELab parameters, and their values were influenced by tannin origin and concentration. The addition of tannins did not significantly affect the number of lactic acid bacteria. Yogurt with a lower amount of tannins (0.5% w/w) received higher consumer acceptability but significant differences in preferences were due to tannin origin. In particular, yogurt added with tannin obtained from Quebracho wood at 1% w/w showed higher consumer preference. The obtained results would provide an opportunity for dairy producers to develop a novel dairy food with high nutritional quality.