Collagen isolated from byproducts of common carp was hydrolyzed with alcalase enzyme to obtain peptide fractions. The resulting >30 kDa (PF1), 10–30 kDa (PF2), 3–10 kDa (PF3) and <1 kDa (PF4) fractions were studied for their antioxidant and functional properties. All peptide fractions illustrated antioxidant activity at different concentrations (1, 5, and 10 mg/mL). Although PF4 indicated the highest DPPH radical-scavenging activity (87%) at a concentration of 1 mg/mL, the highest reducing power (0.34) and hydroxyl radical scavenging activity (95.4%) were also observed in PF4 at a concentration of 10 mg/mL. The solubility of the peptide fractions was influenced by pH. The lowest solubility of the peptide fractions was observed at pH 4. The highest emulsifying activity index (EAI) was observed for PF4 (121.1 m²/g), followed by PF3 (99.6 m²/g), PF2 (89.5 m²/g) and PF1 (78.2 m²/g). In contrast to what has been found in the case of EAI, the emulsion stability of the peptide fractions decreased at lower molecular weight, which ranged from 24.4 to 31.6 min. Furthermore, it was revealed that PF1 had the highest foam capacity (87.4%) and foam stability (28.4 min), followed by PF2 and PF3. Overall, the findings suggest that peptide fractions isolated from byproducts of common carp are a promising source of natural antioxidants for application in functional food and pharmaceutical products.

An ultrasound-assisted method was used for the extraction of phenolics from defatted black cumin seeds (Nigella sativa L.), and the effects of several extraction factors on the total phenolic content and DPPH radical scavenging activity were investigated. To improve the extraction efficiency of phenolics from black cumin seed by ultrasonic-assisted extraction, the optimal extraction conditions were determined as follows: ethanol concentration of 59.1%, extraction temperature of 44.6 °C and extraction time of 32.5 min. Under these conditions, the total phenolic content and DPPH radical scavenging activity increased by about 70% and 38%, respectively, compared with conventional extraction. Furthermore, a complementary quantitative analysis of individual phenolic compounds was carried out using the HPLC-UV technique. The phenolic composition revealed high amounts of epicatechin (1.88–2.37 mg/g) and rutin (0.96–1.21 mg/g) in the black cumin seed extracts. Ultrasonic-assisted extraction can be a useful extraction method for the recovery of polyphenols from defatted black cumin seeds.

Plant-based proteins are gaining in attraction compared with animal-based proteins due to their superior ethical profiles, growing concerns on the part of various organizations about animal health and welfare, and increased global greenhouse-gas emissions in meat production. In this study, the response surface methodology (RSM) using a Box–Behnken design (BBD) was applied to optimize the ultrasound-assisted alkaline extraction of cherimoya-seed proteins as valuable by-products. The effects of three pH, temperature, and time factors on the protein-extraction yield and protein content were investigated. The pH at 10.5 and temperature of 41.8 °C for 26.1 min were considered the optimal ultrasound-assisted alkaline-extraction conditions since they provided the maximum extraction yield (17.3%) and protein content (65.6%). An established extraction technique was employed to enhance the cherimoya-seed protein yield, purity, and functional properties. A thermogravimetric analysis (TGA) of the samples showed that the ultrasound-assisted alkaline extraction improved the thermal stability of the protein concentrate.

Microwave-assisted hydrothermal extraction (MAHE) was optimized using a Box-Behnken design (BBD) of the response surface methodology (RSM) for optimal recovery of pectin from tangerine peel (TPP). The effects of three factors (pH, irradiation time and temperature) on extraction yield (EY), galacturonic acid content (GAC) and degree of esterification (DE) of pectin were investigated. The optimal extraction conditions were as follows: pH 1.7, irradiation time 12 min and temperature 109 °C. Under these conditions, the EY, GAC and DE were 30.4, 72.3 and 45.2%, respectively. The low methoxyl content of MHAE (45.2%) compared to CE is confirmed by the ¹H NMR and FTIR spectra, and the emulsifying activity is 57.65% and 50.56% for CE and MHAE, respectively. The total phenolic content (TPC) of pectin produced using MAHE is 41.2 mg GAE/g, thus indicating higher antioxidant properties compared to pectin produced with CE, which had a TPC of 38.4 mg GAE/g. In addition, the X-ray diffraction (XRD) and surface morphological analysis (SEM) results showed that TPP had a rough surface and crystalline structure. Overall, our findings show that TTP from MAHE can be used as a natural antioxidant ingredient in the functional food and pharmaceutical industries.

The table olive industry generates high amounts of wastewater annually during the alkaline treatment, fermentation, and washing steps of olives. High conductivity and salt content, as well as the high organic and biophenol contents of these waters, is a worldwide problem, especially in the Mediterranean region, which is the major table olive producing area. There is a wide variety of bioactives found in wastewater derived from table olive processing. The main compounds of table olive wastewater, such as those derived from phenolic, hydrocarbon, and sugar fractions, can be recovered and reused. In this review, the table olive manufacturing processes and the volumes and composition of wastewater generated from the different methods of table olive processing are discussed. In addition, biophenols of table olive water and their biological activities are also introduced. The high concentrations of valuable biophenols, such as tyrosol and hydroxytyrosol, show promising potential for valorizing table olive wastewater; however, more research is needed in this area.