In Vitro Antioxidant Activity, Bioaccessibility, and Thermal Stability of Encapsulated Strawberry Fruit (Fragaria × ananassa) Polyphenols

Development of antioxidant films based on anthocyanin microcapsules extracted from purple corn cob and incorporated into a chitosan matrix

Biodegradable food packaging films were prepared from chitosan incorporated with microencapsulated anthocyanins powder (MAP) that was extracted from purple corn cob using the casting method. Anthocyanins extracts were microencapsulated with maltodextrin, gum arabic, and soy protein using a spray-drying method. The film based on chitosan and MAP (CHt@MAP) was prepared through citric acid cross-linking and plasticization with glycerol. The structural analysis of the CHt@MAP film revealed a semicrystalline structure by X-ray diffraction. The interactions were mainly via electrostatic and hydrogen bonding, as confirmed by Fourier-transform infrared. Based on scanning electron microscopy, the morphology of the films revealed evidence of the presence of MAP on the surface and cross-section. The microcapsules inside the films produced an increase in thickness (0.18-0.21 mm), lower water vapor permeability (12.4-8.5 × 10-10 g m-1s-1Pa-1), and reduced elongation at break (217 % to 165 %), as well as tensile strength (1.3 to 0.45 MPa) compared to the chitosan film. Furthermore, the antioxidant activity of CHt@MAP film was high, with a radical scavenging activity of 56 %. It also exhibited a strong barrier to UV and visible light. The results indicate that the CHt@MAP film preserves the shelf life of blueberries at room temperature and could be used as an active packaging film for foods.

Anti-Inflammatory Effect of Extract from Fragaria ananassa Duch. Calyx via MAPK and NF-κB Signaling Pathway

Currently, Fragaria ananassa Duch. are discarded as by-products except for the fruit part, so we developed a natural material using the top (= calyx), one of the by-products, and prepared an extract using 70% ethanol to investigate its effects on anti-inflammatory mechanisms. The polyphenol content of 70% ethanol extracts from Fragaria ananassa Duch. calyx was measured to be 265.86 ± 0.85 mg TAE/100 g, respectively. The antioxidant activity was confirmed through the electron donating ability and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging ability measurements. When extracts from Fragaria ananassa Duch. calyx was treated to LPS-induced RAW 264.7 cells, it was confirmed that the production of inflammation-related factors, NO, PGE2, iNOS, COX-2, TNF-a, and IL-6, was inhibited. In addition, it was confirmed that extracts from Fragaria ananassa Duch. calyx affected the MAPK signaling pathway by reducing the protein expression of p-ERK, p-JNK, and p-p38, which are the upper signaling pathways. In addition, it was confirmed to reduce the protein expression of p-p65 and p-IκB, which are NF-κB signaling pathways. Therefore, this study suggests that extracts from Fragaria ananassa Duch. calyx affect the regulation of the production of major inflammation-related factors by inhibiting the MAPK and NF-κB signaling pathway. These results confirmed that extracts from Fragaria ananassa Duch. calyx have the potential to be developed as a new natural material with anti-inflammatory activity.

Microencapsulation of Extracts of Strawberry (Fragaria vesca) By-Products by Spray-Drying Using Individual and Binary/Ternary Blends of Biopolymers

Valorization of agricultural and food by-products (agri-food waste) and maximum utilization of this raw material constitute a highly relevant topic worldwide. Agri-food waste contains different types of phytochemical compounds such as polyphenols, that display a set of biological properties, including anti-inflammatory, chemo-preventive, and immune-stimulating effects. In this work, the microencapsulation of strawberry (Fragaria vesca) plant extract was made by spray-drying using individual biopolymers, as well as binary and ternary blends of pectin, alginate, and carrageenan. The microparticle morphologies depended on the formulation used, and they had an average size between 0.01 μm and 16.3 μm considering a volume size distribution. The encapsulation efficiency ranged between 81 and 100%. The kinetic models of Korsmeyer-Peppas (R2: 0.35-0.94) and Baker-Lonsdale (R2: 0.73-1.0) were fitted to the experimental release profiles. In general, the releases followed a "Fickian Diffusion" mechanism, with total release times varying between 100 and 350 (ternary blends) seconds. The microparticles containing only quercetin (one of the main polyphenols in the plant) showed higher antioxidant power compared to the extract and empty particles. Finally, the addition of the different types of microparticles to the gelatine (2.7 mPa.s) and to the aloe vera gel (640 mPa.s) provoked small changes in the viscosity of the final gelatine (2.3 and 3.3 mPa.s) and of the aloe vera gel (621-653 mPa.s). At a visual level, it is possible to conclude that in the gelatine matrix, there was a slight variation in color, while in the aloe vera gel, no changes were registered. In conclusion, these microparticles present promising characteristics for food, nutraceutical, and cosmetic applications.

Chemical and Thermal Characteristics of PEF-Pretreated Strawberries Dried by Various Methods

By increasing the permeability of the cell membrane of the treated material, pulsed electric fields (PEF) enhance the internal transport of various chemical substances. Changing the distribution of these components can modify the chemical and thermal properties of the given material. This study aimed to analyze the impact of PEF (1 kV/cm; 1 and 4 kJ/kg) applied to strawberries prior to drying by various methods (convective, infrared-convective, microwave-convective, and vacuum) on the chemical and thermal properties of the obtained dried materials (sugars content, total phenolic content, and antioxidant capacity (ABTS and DPPH assays); thermal properties (TGA and DSC); and molecular composition (FTIR)). PEF could have induced and/or enhanced sucrose inversion because, compared to untreated samples, PEF-pretreated samples were characterized by a lower share of sucrose in the total sugar content but a higher share of glucose and fructose. Reduced exposure to oxygen and decreased drying temperature during vacuum drying led to obtaining dried strawberries with the highest content of antioxidant compounds, which are sensitive to these factors. All PEF-pretreated dried strawberries exhibited a lower glass transition temperature (Tg) than the untreated samples, which confirms the increased mobility of the system after the application of an electric field.

Valorization of Agricultural By-Products (Fragaria vesca) through the Production of Value-Added Micro/Nanostructures Using Electrohydrodynamic Techniques

An innovative approach for the production of bio-micro/nanostructures with high-value compounds from agricultural by-products was studied. This research aimed to valorize bioactive compounds existing in the by-products of the plants of Fragaria vesca (wild strawberry). The particle characteristics, morphology, size, release properties, and antioxidant activity of micro/nanostructures containing the extract of by-products of the plants of Fragaria vesca or quercetin (one of the main polyphenols in the plant) were analyzed. The electrohydrodynamic (EHD) technique was utilized for encapsulation. The results showed that the morphology and size of the structures were influenced by the concentration of zein, with 10% w/v zein concentration leading to irregular and non-uniform nanostructures, while 20% w/v zein concentration resulted in a mixture of microparticles and thin fibers with an irregular surface. The type and concentration of the core material did not significantly affect the morphology of the micro/nanostructures. In vitro release studies demonstrated the controlled release of the core materials from the zein micro/nanostructures. The release profiles were analyzed using the Korsmeyer-Peppas and Weibull models, which provided insights into the release mechanisms and kinetics. The most relevant release mechanism is associated with "Fickian Diffusion". The antioxidant activity of the structures was evaluated using an ABTS radical-scavenging assay, indicating their potential as antioxidants. In conclusion, the EHD technique enabled the successful encapsulation of Fragaria vesca by-product extract and quercetin with zein, resulting in micro/nanostructures with different morphologies.

Preparation and Physicochemical Analysis of Camellia sinensis cv. 'Ziyan' Anthocyanin Microcapsules

The new tea cultivar Ziyan has a high content of anthocyanin and ester catechins in the raw material, but the conventional processing and application methods are limited. To explore its application potential, the freeze-drying method was used to prepare microcapsules with an embedding time of 30 min, solid content of 30%, and core to wall ratio of 1:10 (g/g). The anthocyanin recovery was 95.94 ± 0.50%, and the encapsulation efficiency was 96.15 ± 0.11%. The stability of microcapsules and composite wall materials was evaluated in the simulation system. Results showed that microcapsules employing a maltodextrin-gum arabic ratio of 2:8 (w/w) as the wall material significantly reduced degradation rates, extending anthocyanin half-life under various storage conditions. Characterization indicated improved physical properties of Ziyan anthocyanin powder post-microencapsulation. FT-IR and DSC- revealed the formation of a new phase between anthocyanins and wall materials, leading to increased enthalpy and enhanced thermal stability. The microencapsulation results of this experiment proved that the storage stability of anthocyanin was effectively enhanced.