The increase in diet-related chronic diseases has prompted the search for health-promoting compounds and methods to ensure their quality. Blueberry pomace is a rich yet underutilized source of bioactive polyphenols. For these high-value bioactive molecules, ultrasound-assisted extraction (USAE) is an attractive and green alternative to conventional extraction techniques for improving purity and yields. This study aimed to assess the impact of USAE parameters (sonication time, solvent composition, solid/liquid ratio, pH and temperature) on the recovery of phenolic compounds from blueberry pomace and antioxidant activity of the extracts. Total phenolic, flavonoid and anthocyanin contents (TPC, TFC and TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity were analysed. USAE in 50% ethanol/water was the most efficient, yielding the highest TPC (22.33 mg/g dry matter (DM)), TFC (19.41 mg/g DM), TAC (31.32 mg/g DM) and DPPH radical scavenging activity (41.79 mg Trolox/g DM). USAE in water showed the lowest values even at low (1/40) solid/liquid ratio (7.85 mg/g DM, 3.49 mg/g DM, and 18.96 mg/g DM for TPC, TFC and TAC, respectively). Decreasing the solid/liquid ratio in water or 50% ethanol significantly increased TPC, TFC, TAC and DPPH radical scavenging. With ethanol, increasing the temperature in the range 20–40 °C decreased TPC but increased TFC and DPPH radical scavenging activity. Anthocyanin profiles of water and ethanolic extracts were qualitatively similar, consisting of malvidin, delphinidin, petunidin and cyanidin. These findings indicate that USAE is a method of choice for extracting high-value bioactive phenolics from blueberry pomace. Selective enrichment of different phenolic fractions is possible under select extraction conditions.

This study of selected plants of the Rutaceae family was carried out to investigate their phenolic content, antioxidant activity, and the in vitro inhibitory potential of extracted phenolics towards enzymes relevant for hyperglycemia and hypertension. The phenolic content, antioxidant activity and phenolic extract-mediated inhibitory activities for α-glucosidase and α-amylase were evaluated by spectrophotometry. The content of individual phenolics and the angiotensin I-converting enzyme (ACE) inhibitory activity of the phenolic extracts were evaluated by LC/MS-MS and RP-HPLC methods, respectively. A higher percentage of free phenolic content was seen for all the selected plants of the Rutaceae family (85.43–92.82% of the total phenolic content) than of the bound form (7.18–14.57% of total phenolic content). The major predominant bound phenolic in lemon and red blood orange was hesperidin. The major predominant bound phenolic in pummelo, shamouti and clementine was ferulic acid. The highest ACE and α-glucosidase inhibitory activity of the extracted phenolics from lemon was associated with free phenolic extracts obtained at 30 °C with values of 100% inhibition. Red blood orange free phenolic extract (30 °C) elicited the highest α-amylase inhibition activity (32.3%). In contrast, extracted bound phenolics after acid and base hydrolysis from all selected plants from the Citrus species were shown to induce activation of the ACE and α-amylase enzymes.

Ellagic acid (EA) is one of the plant phenolics associated with human health benefits. It derives from ellagitannins found in some nuts, seeds, and fruits, especially berries. Strawberries are considered a functional food and nutraceutical source, mainly because of their high concentration of EA and its precursors. This review presents the current state of knowledge regarding EA, focusing on its content in strawberry plants, stability during processing and storage of strawberry-based foods, production methods, and relevance to human health. As alternatives to acid-solvent extraction, fermentation-enzymatic bioprocesses hold great promises for more eco-efficient production of EA from plant materials. Strawberry fruits are generally rich in EA, with large variations depending on cultivar, growth conditions and maturity at harvest. High EA contents are also reported in strawberry achenes and leaves, and in wild strawberries. Strawberry postharvest storage, processing and subsequent storage can influence EA content. EA low concentration in strawberry juice and wine can be increased by incorporating pre-treated achenes. Widespread recognition of strawberries as functional foods is substantiated by evidence of EA biological effects, including antioxidant, antiinflammatory, antidiabetic, cardioprotective, neuroprotective, and prebiotic effects. The health benefits attributed to EA-rich foods are thought to involve various protective mechanisms at the cellular level. Dietary EA is converted by the intestinal microbiota to urolithins, which are better absorbed than EA and may contribute significantly to the health effects attributed to EA-rich foods. Based on the evidence available, strawberry EA shows strong promises for functional, nutraceutical, and pharmaceutical applications. Future research should be directed at quantifying EA in different parts of the strawberry plant and in their byproducts; optimizing EA production from byproducts; understanding the biological actions of EA-derived metabolites in vivo, including the interactions between EA metabolites, other substances and food/biological matrices; characterizing the conditions and microorganisms involved in urolithin production; and developing delivery systems that enhance EA functionality and bioactivity.

Blueberry pomace is a rich source of high-value bioactive polyphenols with presumed health benefits. Their incorporation into functional foods and health-related products benefits from coencapsulation and protection of polyphenol-rich extracts in suitable carriers. This study aimed to create a water-in-oil-in-water (W₁/O/W₂) double emulsion system suitable for the coencapsulation of total phenolics (TP) and anthocyanins (TA) from a polyphenol-rich extract of blueberry pomace (W₁). The effect of critical physical parameters for preparing stable double emulsions, namely homogenization pressure, stirring speed and time, was investigated by measuring the hydrodynamic diameter, size dispersity and zeta potential of the oil droplets, and the encapsulation efficiency of TP and TA. The oil droplets were negatively charged (negative zeta potential values), which was related to the pH and composition of W₂ (whey protein isolate solution) and suggests stabilization by the charged whey proteins. Increasing W₁/O/W₂ microfluidization pressure from 50 to 200 MPa or homogenization speed from 6000 to 12,000 rpm significantly increased droplet diameter and zeta potential and decreased TA and TP encapsulation efficiency. Increasing W₁/O/W₂ homogenization time from 15 to 20 min also increased droplet diameter and zeta potential and lowered TA encapsulation efficiency, while TP encapsulation did not vary significantly. In contrast, increasing W₁/O homogenization time from 5 to 10 min at 10,000 rpm markedly increased TA encapsulation efficiency and reduced droplet diameter and zeta potential. High coencapsulation rates of blueberry polyphenols and anthocyanins around 80% or greater were achieved when the oil droplets were relatively small (mean diameter < 400 nm), with low dispersity (<0.25) and a high negative surface charge (−40 mV or less). These characteristics were obtained by homogenizing for 10 min at 10,000 rpm (W₁/O), then 6000 rpm for 15 min, followed by microfluidization at 50 MPa.