Optimization of Extraction Conditions for Gracilaria gracilis Extracts and Their Antioxidative Stability as Part of Microfiber Food Coating Additives.

Incorporation of antioxidant agents in edible films and packages often relies in the usage of essential oils and other concentrated hydrophobic liquids, with reliable increases in antimicrobial and antioxidant activities of the overall composite, but with less desirable synthetic sources and extraction methods. Hydroethanolic extracts of commercially-available red macroalgae Gracilaria gracilis were evaluated for their antioxidant potential and phenolic content, as part of the selection of algal biomass for the enrichment of thermoplastic film coatings. The extracts were obtained through use of solid-liquid extractions, over which yield, DPPH radical reduction capacity, total phenolic content, and FRAP activity assays were measured. Solid-to-liquid ratio, extraction time, and ethanol percentages were selected as independent variables, and response surface methodology (RSM) was then used to estimate the effect of each extraction condition on the tested bioactivities. These extracts were electrospun into polypropylene films and the antioxidant activity of these coatings was measured. Similar bioactivities were measured for both 100% ethanolic and aqueous extracts, revealing high viability in the application of both for antioxidant coating purposes, though activity losses as a result of the electrospinning process were above 60% in all cases.

Characterization of Nutritional, Physicochemical, and Phytochemical Composition and Antioxidant Capacity of Three Strawberry "Fragaria × ananassa Duch." Cultivars ("Primoris", "Endurance", and "Portola") from Western Region of Portugal.

In this study, nutritional composition (protein, lipids, carbohydrates, ash, and moisture), physicochemical properties (soluble solid content, titratable acidity, texture and instrumental colour on surface, and internal section), phytochemicals (total phenolic content and anthocyanin content), and antioxidant capacity (DPPH-2,2'-diphenyl-1-picrylhydrazyl radical scavenging capacity and ferric-reducing antioxidant power) of three strawberry (Fragaria × ananassa Duch.) cultivars (cv. "Primoris", cv. "Endurance", and cv. "Portola") produced in the western region of Portugal (Caldas da Rainha) were evaluated. From the obtained, results no significant differences (P > 0.05) in nutritional composition were detected in all of the cultivars; with the exception of lower protein content observed in cv. "Portola" (0.57 g/100 g ± 0.04; P < 0.05). Regarding the a* value of whole strawberry fruits, no significant differences (P > 0.05) were found in any of the cultivars, which revealed a similar redness. The cv. "Endurance" revealed the highest bioactivity content compared to the other cultivars. Overall, these results provide important information about the high quality of strawberry produced in the western region of Portugal and may be used as a tool for adding value to a functional food in the Mediterranean diet due to the phytochemical composition and nutritional value of strawberry fruits.

Tryptophan depletion and formation of alpha-aminoadipic and gamma-glutamic semialdehydes in porcine burger patties with added phenolic-rich fruit extracts.

The effect of added fruit extracts on the oxidation of muscle proteins in porcine burger patties subjected to cooking and chill storage was studied. Extracts from arbutus berries (Arbutus unedo L., AU), common hawthorns (Crataegus monogyna L., CM), dog roses (Rosa canina L., RC), and elm-leaf blackberries (Rubus ulmifolius Schott, RU) were prepared, characterized, added to burger patties (3% of total weight), and evaluated as inhibitors of protein oxidation. Negative (no added extract, C) and positive control (added quercetin, 230 mg/kg, Q) groups were also included in the design. Protein oxidation was assessed by means of tryptophan loss using fluorescence spectroscopy (FS) and formation of the specific protein carbonyls alpha-aminoadipic (AAS) and gamma-glutamic semialdehyde (GGS) using liquid chromatography and mass spectroscopy (LC-MS). Both advanced methodologies (FS and LC-MS) were found to be reliable and specific protein oxidation measurements that allow us to gain chemical insight into protein oxidation. The mechanisms likely involved in the oxidative reactions affecting proteins during cooking and storage of burger patties are profusely discussed. Phenolic-rich fruit extracts protected tryptophan residues against oxidation and inhibited the formation of both semialdehydes in burger patties during cooking and subsequent chill storage. In general, RC, RU, and AU were the most effective inhibitors of protein oxidation, with this effect being more intense than that of pure polyphenols like quercetin. These fruit extracts could be considered functional ingredients as their antioxidant actions contribute to the enhancement of the nutritional value of the meat products.