Screening of antioxidant potential of dichloromethane and methanolic extracts of twenty-seven seaweeds from the Peniche coast was performed by: total phenolic contents (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and oxygen radical absorbance capacity (ORAC). Seaweeds revealing the highest antioxidant activity were screened for cytoprotective potential in MCF-7 cells, including the mitochondrial membrane potential analysis and the caspase-9 activity. High correlation was found between TPC of seaweed extracts and their scavenging capacity on DPPH and peroxyl radicals. The highest antioxidant activity was displayed by the methanolic fraction of brown seaweeds belonging to Fucales, however Ulva compressa presented the highest cytoprotective effect by blunting the apoptosis process. These results suggest that high antioxidant activity may not be directly related with high cytoprotective potential. Thus, seaweeds reveal to be a promising source of compounds with potential against oxidative stress.

Aurantiochytrium sp. is a heterotrophic microalgae that, in certain growth conditions, besides producing significant amounts of squalene, may potentially produce other bioactive compounds with high value and commercial interest such as docosahexaenoic acid (DHA), carotenoids, among others. Antioxidant compounds, naturally occurring in microalgae sources, have been identified as free radical or active oxygen scavengers, with beneficial effects on oxidation and oxidative damage inhibition in human body and foods. Several in vitro methodologies have been proposed to evaluate the antioxidant capacity, such as free radicals: 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2 -azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+), and reactive species including hydrogen peroxide (H2O2), singlet oxygen (O2), and superoxide anion (O2-) (Balboa et al., 2013). The main objective of the present study was to evaluate the antioxidant activity of aqueous and ethanolic extracts of Aurantiochytrium sp., by means of different methodologies: reducing and scavenging activity by total phenolics content (TPC, Singleton & Rossi, 1965), DPPH (Custódio et al., 2012), and oxygen radical absorbance capacity (ORAC, Dávalos et al., 2004). The obtained results indicated that the microalgae Aurantiochytrium sp. is rich in antioxidant compounds, by reducing activity through total phenolics and DPPH, as well as scavenging activity by ORAC. Moreover, it is evident the higher selectivity of ethanol as solvent for the extraction of antioxidants compounds. The potential of this microalgae biomass as a good, natural and sustainable source for use as a functional food ingredient is evident, representing an opportunity with additional benefits due to the antioxidant role in diseases prevention and treatment.

Smoothies are a popular and convenient way for to consume bioactive compounds from fruits and vegetables such as total phenolics, carotenoids and flavonoids, with the preservation treatment being an important action to guarantee the safety and extension of shelf-life. The main goal of this study was to evaluate the impact of heat treatment (HT) on smoothie prepared with “Fuji “apple (41%), pineapple (31%), cabbage (8%), pumpkin (10%) and banana (10%), by response surface methodology (RSM), where the temperature (70–100 °C) and treatment time (0.5–10.5 min), were the dependent variables. After optimization of HT conditions, a validation assay was performed to guarantee the minimal changes on color and reduction of 90% of polyphenoloxidase enzyme (PPO). Antioxidant activity (Ferric reducing antioxidant power assay (FRAP), DPPH, ABTS), total phenolics content (TPC), pH and solids soluble content were also analyzed. Predicted models of color parameters (L*, a*, ºh) and PPO enzymatic activity were found to be significant (p < 0.05) with regression coefficients (R2) of 0.84, 0.86, 0.92 and 0.97, respectively. From the RSM-generated model, the HT conditions that ensure a minimal green loss of smoothie and inactivation of PPO enzyme was at 85 °C over 7 min. In the validation study, these conditions were tested and proved to be sufficient to achieve the main goals. In the heat-treated smoothie, increases in TPC (10%) and antioxidant capacity (ABTS: 50%, DPPH: 17%, FRAP: 13%) were attained. This study demonstrated that RSM was efficient to select the optimal conditions of HT and improve the important quality properties that influence the product quality and the potential consumer’s health (TPC and antioxidant capacity).

Throughout the ages, macroalgae have provided humankind with elements beneficial to human health, and often with bioactive abilities. Yet, while today we fully acknowledge such potential, especially that of the most widely known species, an even greater number of species remain unaknowledged. This holds particularly true for the highly diverse phylum Rhodophyta (red seaweeds) and, therefore, the present study aims to unveil the antioxidant and the antimicrobial potential of twelve red seaweed species collected in central Portugal. Results obtained from the antioxidant assays ABTS and TPC highlighted the high scavenging capacity of the coralline algae Corallina officinalis, Ellisolandia elongata and Amphiroa rigida, and the high phenolic content of Porphyra umbilicalis, whereas the antimicrobial analyses through MIC determination emphasized the activities of Sphaerococcus coronopifolius and Mesophyllum lichenoides against, respectively, Bacillus subtilis and Saccharomyces cerevisiae. This study raised awareness of the bioactive potential waiting to be discovered regarding less known Rhodophyta species, such as Amphiroa rigida and Mesophyllum lichenoides. Therefore, we believe this study provides extra steps in pinpointing Rhodophyta species with bioactive potential, encouraging further studies tailored toward a biotechnological perspective, and, ultimately, influencing current perspectives regarding the exploration of seaweeds.

The present study investigated the effect of malaxation times (Mt) (0, 15, 30, 45 and 60 min), during the industrial extraction of cv. Arbequina oils at 25 °C on total phenolic content of olive pastes. Additionally, the possibility of applying a lab-made potentiometric electronic tongue (E-tongue), comprising 40 lipid/polymer sensor membranes with cross sensitivity, to discriminate the olive pastes according to the Mt, was evaluated. The results pointed out that the olive pastes’ total phenolic contents significantly decreased (p-value < 0.001, one-way ANOVA) with the increase of the Mt (from 2.21 ± 0.02 to 1.99 ± 0.03 g gallic acid equivalents/kg olive paste), there being observed a linear decreasing trend (R-Pearson = −0.910). These findings may be tentatively attributed to the migration of the phenolic compounds from the olive pastes to the extracted oil and water phases, during the malaxation process. Finally, the E-tongue signals, acquired during the analysis of the olive pastes’ methanolic extracts (methanol:water, 80:20 v/v), together with a linear discriminant analysis (LDA), coupled with a simulated annealing (SA) algorithm, allowed us to establish a successful classification model. The E-tongue-LDA-SA model, based on 11 selected non-redundant sensors, allowed us to correctly discriminate all the studied olive pastes according to the Mt (sensitivities of 100% for training and leave-one-out cross-validation). The satisfactory performance of the E-tongue could be tentatively explained by the known capability of lipid/polymeric sensor membranes to interact with phenolic compounds, through electrostatic interactions and/or hydrogen bonds, which total content depended on the Mt.

The objective of this work was to evaluate the antioxidant properties of Lavandula latifolia waste obtained after essential oil distillation. Samples of 12 wild populations of the Lavandula genus collected between 2009 and 2010 were hydrodistilled and their by-products were analyzed using the FolineCiocalteu, free radical scavenging activity (2,2-diphenyl-1- picrylhydrazyl), and the ferric reducing antioxidant power (FRAP) methods. Rosmarinic acid, apigenin, and luteolin contents were analyzed by high-performance liquid chromatographyediode array detection. The mean of total phenolic content ranged from 1.89 ± 0.09 mg gallic acid equivalents/g dry weight to 3.54 ± 0.22 mg gallic acid equivalents/ g dry weight. The average value of the half maximal effective concentration (EC50) for scavenging activity ranged from 5.09 ± 0.17 mg/mL to 14.30 ± 1.90 mg/mL and the variability of the EC50 in FRAP ranged from 3.72 ± 0.12 mg/mL to 18.55 ± 0.77 mg/mL. Annual variation was found among this samples and the environmental conditions of 2009 were found to be more favorable. The plants collected from Sedano showed the highest antioxidant power. Our results show that rosmarinic acid and apigenin in L. latifolia contributed to the antioxidant properties of the waste. In conclusion, the by-product of the distillation industry could be valorizing as a source of natural antioxidants.

This work presents a methodology for simultaneously measuring the total content of three classes of phenolic compounds (hydroxybenzoic acids, hydroxycinamic acids and flavonoids), as well the total phenolic content using a single UVvis spectrum. To test the methodology, samples of propolis were used. Firstly, an experimental design based in the Response Surface Methodology established that the best hydroethanolic solution for propolis phenolic compounds extraction had 80% of ethanol. Secondly, calibration models were developed with multiple linear regression, coupled with the leaps algorithm for variable selection, using UV-vis spectra of mixed standard solutions (gallic acid, ferulic acid and quercetin mixtures), all with orthogonal concentrations established by a multilevel fractional factorial design. The model’s estimation and prediction performance had linearity between predicted and expected concentration values, with slope ranging from 0.996–1.04 and determination coefficients higher than 0.995. A quality control solution presented acceptable repeatability and accuracy (relative standard deviation percentage and percentage relative error were lower than 4.8%). Analysis of propolis phenolic compounds extracts showed acceptable precision (relative standard deviation percentages lower than 1.6%) and acceptable accuracy (recoveries assays ranged between 98 and 112%). Overall, the present multi-parametric analytical technique can be a first approach for chemical characterization of phenolic compounds extracts, such as that obtained from the propolis samples, considering its advantages of simplicity, rapidity, precision and accuracy. Moreover, this methodology can be adapted to other sample matrices, provided that the typical UV-vis absorption spectra of their classes of phenolic compounds shows partial overlapping, allowing multivariate calibration.

The valorization of agro-industrial by-products has aroused great interest nowadays, due to their richness in phenolic compounds, including polyphenols, and their biological activities of high value for various areas. In this work, the recovery and concentration of these compounds, from hydroalcoholic extracts from hull and also blanching water, were studied, being two residues of large volume in the almond industry. The enrichment is given by sorption/desorption processes in columns packed with Molecularly Imprinted Polymers (MIPs), having used the polymers MIP-OA-3, MIPQUER-2 and MIP-QUER-3, and evaluating the enrichment efficiency against a gradient of several solvents in the elution steps. The hull extracts were obtained essentially by ultrasound, having worked with a hydroethanolic fraction 50/50 (v/v), due to their yield and equivalent favoring in the extraction of different polyphenolic families, being subsequently submitted to the sorption process. The characterization of the elutions of both by-products was mainly done by determining the total phenolic content (TPC) and the antioxidant activity by the DPPH method (EC50), and the best results were reinforced with chromatographic analyses by HPLC-DAD at 280 and 360 nm. The results show that the process allowed the selective fractionation and enrichment of phenolic compounds, observing fractions with a high degree of enrichment when compared to the initial extract, both at the TPC and EC50 levels. The intermediate hydroethanolic fractions, as well as the methanolic fractions, present the best results in terms of enrichment, as evidenced by the inverse relationship between TPC and EC50. It was also possible to verify differences in the enrichment trend between the OA3 column and the Q2 Q3 columns, revealing different affinities provided by the polymers. Chromatograms reveal significant changes in the chemical profile, both between fractions, extract and columns, suggesting and proving the enrichment of certain phenolic compounds, particularly flavonoids. In general, the results obtained indicate that the MIPs used have a high potential for phenolic enrichment from complex extracts, being able to fractionate and enrich, contributing to strategies for sustainable recovery of waste and development of processes aligned with the principles of green chemistry. Among these results, maximum TPC values of 615.66 ± 28.23 mg GAE/g Extract (hull) and 918.32 ± 34.54 mg GAE/g Extract (blanching water) were observed, together with EC50 values of 0.025 ± 0.000 and 0.028 ± 0.002 mg/mL, respectively. A value of 1135.64 ± 11.55 mg GAE/g Extract and 0.017 ± 0.000 mg/mL was also observed, indicating a high phenolic recovery.

Carob (Ceratonia siliqua L.) fruit is obtained from the evergreen carob tree, native to the Mediterranean region 1,2 and produced mainly in Portugal, Italy, Morocco and Turkey 3– 5. Portugal has a high-cultivated extent with relevant carob fruit production at low prices. Carob products containing phenolic substances exhibit antioxidant capacity and can promote human health, and aid in preventing chronic diseases 6,7. Currently, carob powder (CP) production is mainly achieved after the pulp separation despite having been demonstrated that seeds improve the extraction efficiency of bioactive compounds like polyphenols 4. This study aimed to produce an integral CP through an innovative process and assess its physicochemical and bioactive properties in different particle sizes throughout a simulated gastrointestinal tract (GIT) digestion. The sugar content profile obtained throughout GIT digestion indicates that the highest present sugar in undigested carob powders is digested and broken into simple sugars like glucose and fructose, potentiating CPs as a functional and within healthy food intake recommendations ingredient to use. The total phenolic content and antioxidant activity obtained for the ≤100 μm fraction are correlated and gastric digestion promotes the increase in TPC value compared to chemically extracted samples (undigested). The >100 μm fractions display a distinct profile from ≤100 μm, possibly due to higher content in insoluble fibers, which hinders the release of these bioactive compounds from the carob matrix. This study showed that the particle-size affects the sugar, antioxidant and total phenol content under gastrointestinal tract digestion. The ≤100 μm fraction obtained the best suitable profile as a functional food ingredient.

This study aimed to investigate the effects of combined ultrasound and osmotic pretreatment conditions on the drying kinetics and antioxidant properties, such as total phenolic content (TPC), total flavonoid content (TFC), vitamin C content, and DPPH radical scavenging activity, of dried Citrus macroptera (Satkara) fruits. The fruit slices were immersed in 10% aqueous solutions of sucrose (S), glucose (G), and fructose (F) followed by an ultrasound treatment (40 kHz) for 10, 20, or 30 min. The samples were then dried in a convective oven at 50, 60, or 70 ◦C and 30% relative humidity with a constant air velocity of 3 m s−1 . Four thin-layer kinetic models, namely Page, Newton, Henderson and Pabis, and Logarithmic, were evaluated. Among these, Page was found to be the most suitable model for predicting the drying kinetics. The pretreatment process accelerated the drying process significantly, reducing the drying time up to 6 h. Additionally, the pretreated samples exhibited improved retention of quality attributes, with vitamin C being best preserved in S solutions, TPC in both S and F solutions, TFC in F solutions, and DPPH in all three sugar solutions (S, F, and G). The application of ultrasound during osmotic treatment also had a positive impact on TPC and TFC retention, whereas it presented a negative effect on vitamin C when used for a prolonged duration and a negligible one on the antioxidant capacity. Overall, this study provides a new perspective on the drying kinetics of Satkara fruits, and their respective properties after drying, and being subjected to combined ultrasound and osmotic pretreatment. These findings will contribute to the development of effective and efficient drying methods suitable for industrial applications to produce dried Satkara products with a minimum quality degradation.