Recovery of Bioactive Compounds from Industrial Exhausted Olive Pomace through Ultrasound-Assisted Extraction

The use of by-products as a source of bioactive compounds with economic added value is one of the objectives of a circular economy. The olive oil industry is a source of olive pomace as a by-product. The olive pomace used in the present study was the exhausted olive pomace, which is the by-product generated from the air drying and subsequent hexane extraction of residual oil from the olive pomace. The objective was to extract bioactive compounds remaining in this by-product. Various types of green extraction were used in the present study: solvent extraction (water and hydroalcoholic); ultrasound-assisted extraction; Ultra-Turrax-assisted extraction; and enzyme-assisted extraction (cellulase; viscoenzyme). The phenolic profile of each extract was determined using HPLC-DAD and the total phenolic content (TPC) and antioxidant activity (ABTS, DPPH, and ORAC) were determined as well. The results showed significant differences in the yield of extraction among the different methods used, with the enzyme-assisted, with or without ultrasound, extraction presenting the highest values. The ultrasound-assisted hydroethanolic extraction (USAHE) was the method that resulted in the highest content of the identified phenolic compounds: 2.021 ± 0.29 mg hydroxytyrosol/100 mg extract, 0.987 ± 0.09 mg tyrosol/100 mg extract, and 0.121 ± 0.005 mg catechol/100 mg extract. The conventional extraction with water at 50 °C produced the best results for TPC and antioxidant activity of the extracts. The extracts from the USAHE were able to inhibit Gram-positive bacteria, especially Bacillus cereus, showing 67.2% inhibition at 3% extract concentration.

Goji berry is a rich source of carotenoids, particularly zeaxanthin dipalmitate (ZDP), a bioactive compound linked to antioxidant and eye-health benefits. This study presents a green ultrasound-assisted extraction (UAE) approach for the efficient extraction and optimization of ZDP, total carotenoids, phenolics, and antioxidant compounds from goji berry. A Box-Behnken design within the response surface methodology (RSM) was employed to optimize three key variables-ultrasound amplitude, extraction time, and solvent-to-solid ratio-under mild conditions (40% ethanol, room temperature). Quadratic models best described the responses for total carotenoids, ZDP, and total phenolic content (TPC), whereas a two-factor interaction (2FI) model provided the best fit for total antioxidant compounds. The optimal UAE conditions (25% amplitude, 2 min, and 3.27:1 g/g ratio) significantly enhanced the extraction efficiency of carotenoids and phenolics, while also improving mineral content (phosphorus, copper, selenium) and color quality, indicating improved nutritional and sensory properties of the extract. These findings highlight the potential of UAE as a sustainable technique for producing carotenoid- and phenolic-rich goji berry extracts that can serve as natural colorants and antioxidant ingredients in functional foods and nutraceutical formulations. PRACTICAL APPLICATIONS: This study demonstrates that UAE can efficiently recover ZDP and phenolic compounds from goji berry within a short time, enhancing both nutritional and color properties. The resulting extracts can be applied in foods, beverages, and nutraceuticals as natural colorants and antioxidant-rich ingredients, offering a sustainable alternative to synthetic additives and supporting the development of functional products with added health benefits.

The rising amount of food industry waste has sparked interest in its valorization as a source of bioactive compounds. This study combines bibliometric analysis and a systematic review to map the scientific literature on the recovery of bioactive compounds from food byproducts, focusing on green extraction strategies and their alignment with the principles of the circular economy. A total of 176 documents, published between 2015 and 2025, were analyzed. The analysis shows significant growth after 2020 and highlights bioactive compounds, extraction, and the circular economy as the primary research themes. Italy, Spain, and Brazil emerged as the leading countries in scientific production. The systematic review covers green extraction techniques, including ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE), enzyme-assisted extraction (EAE), and natural deep eutectic solvent extraction (NADES). UAE- and NADES-based processes were the most frequently applied extraction techniques, mainly targeting phenolic compounds and flavonoids. Significant progress has been observed, particularly in the advancement of extraction technologies, in the recovery of key bioactive compounds, and in their industrial applications. These methods recover phenolics, flavonoids, anthocyanins, and other compounds with antioxidant, antimicrobial, and cardioprotective properties, which have potential applications in functional foods, nutraceuticals, pharmaceuticals, cosmetics, and biodegradable packaging. Nutraceuticals and functional foods represent the main application areas, followed by cosmetics and pharmaceuticals. Despite progress, challenges remain, including scalability, equipment costs, solvent recovery, and process standardization. The green extraction of bioactive compounds from food byproducts shows promise and can support the goals of the 2030 Agenda.

Phenolic compounds and contaminants in olive oil and pomace – A narrative review of their biological and toxic effects

Optimization of the conditions for ultrasound-assisted extraction of phenolic compounds from Opuntia ficus-indica [L.] Mill. flowers and comparison with conventional procedures

In this study, solid olive mill waste (SOMW) was used to obtain antioxidant compounds using solid–liquid extraction. The effect of different extraction methods, namely microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), Soxhlet, and conventional solvent extraction, on the yield, total phenolics, and total antioxidant activity of SOMW extracts was investigated. Untreated and dried SOMW were subjected to extraction with water and methanol. The antioxidant activity of the extracts was evaluated using the DPPH assay, while their total phenolic content was measured using the Folin–Ciocalteu method. For the characterisation of the extracts, HPLC-DAD analysis was performed. The results showed that the extraction yield was significantly influenced (p < 0.05) by the solvent used, the material treatment prior to extraction, the moisture content of SOMW samples, and the extraction time. The optimised parameters were water, as the extraction solvent, and MAE as the extraction technique (extraction temperature of 50 °C and time of 1 h). The evaluation of the antioxidant activity of the extracts indicated that phenolics were the dominant bioactive compounds. The extracts were found to be rich in several hydroxytyrosol derivatives. Therefore, SOMW can be a valuable resource for bioactive compounds using conventional and innovative extraction techniques.

Artichoke leaves, an important waste product of the food industry, have an important antioxidant and antimicrobial capacity. Although there are several studies in the literature to determine their antioxidant and antimicrobial activity, a comparison of green extraction technologies including microwave, ultrasound probe and ultrasound bath methods in relation to the maceration technique has not been performed. Also, several parameters such as the extraction temperature, power, extraction mode and extraction time are important parameters for obtaining targeted compounds in the highest amount. For this reason, we aimed to compare various extraction methods including microwave-assisted extraction, ultrasound-assisted extraction with probe, ultrasound-assisted extraction in a water bath and maceration in terms of extraction parameters for obtaining bioactive compounds from artichoke leaves. Microwave-assisted extraction at two different power values, ultrasound-assisted extraction with probe in continuous or pulsed mode with two different extraction times each, ultrasound-assisted extraction in a water bath at two different power values with two different extraction times each and maceration with two different times were used for the extraction. The extraction temperature is an important parameter affecting the thermal degradation of bioactive compounds. We used a constant extraction temperature of 50 °C. Total phenolic and total flavonoid content, antioxidant capacity, phenolic compound profile analysis by LC-QTOF-MS and antimicrobial activity by agar diffusion and broth microdilution methods were determined. The bioactive compounds were found to be significantly affected by the parameters used in each extraction method. The microwave-assisted extraction method was more efficient than the other extraction methods at both power values. This method also required the shortest extraction time. The ultrasound-assisted probe extraction method was the second most efficient method. The type of process, continuous or pulsed, did not affect the results, but shortening the extraction time led to lower results. A longer extraction time of the ultrasound-assisted extraction in a water bath method led to better results, similar to the ultrasound-assisted probe extraction, regardless of the used power. The extracts were highly effective against many opportunistic and pathogenic microorganisms. This study provides valuable insights into the extraction parameters of different extraction methods to obtain bioactive compounds from artichoke leaves, which could have potential applications in the food and pharmaceutical industries.

The present study aimed to extract phenolic compounds from Ferulago angulata (Chavir) through maceration and ultrasound-assisted extractions (UAE). Both extraction processes were conducted at varying ethanol (Et): water (Wt) ratios of 20:80, 80:20, 50:50, 0:100, and 100:0, with agitation rates of 100 and 250 rpm, 80 and 140 rpm, extraction time of 2 and 4 hr, 5 and 15 min, respectively, for maceration and UAE. The extracts were evaluated for total phenol content (TPC) and DPPH radical scavenging activity. The highest TPC of maceration extracts was in 747.25 mg/100 g obtained for Et 100% (2 hr and 100 rpm) while for UAE was in the range 788.43 mg/100 g for Et 100% (5 min and 80 rpm). The highest antioxidant scavenging activity was 76.57% for maceration extract while it was 86.06% for UAE extract. Extraction method and conditions had significant effect on the amount of effective compounds extracted. Practical applications Extraction method and conditions have a significant effect on the extraction of bioactive compounds from the plants. Ferulago angulata (Chavir) has high levels of phenolic and antioxidant compounds. The amount of phenolic and antioxidant compounds in Chavir extract which was extracted by ultrasound was higher than maceration method. Ethanol was recognized as the best solvent for the extraction of phenolic and antioxidant compounds from Chavir.

Ultrasound increases the aqueous extraction of phenolic compounds with high antioxidant activity from olive pomace

The objective of this work was to gain insight into the operating conditions that affect the efficiency of ultrasound-assisted extraction (UAE) parameters to achieve the best recovery of bioactive compounds from broccoli leaf and floret byproducts. Therefore, total phenolic content (TPC) and the main sulfur bioactive compounds (sulforaphane (SFN) and glucosinolates (GLSs)) were assayed. Distilled water was used as solvent. For each byproduct type, solid/liquid ratio (1:25 and 2:25 g/mL), temperature (25, 40, and 55 °C), and extraction time (2.5, 5, 7.5, 10, 15, and 20 min) were the studied variables to optimize the UAE process by using a kinetic and a cubic regression model. TPC was 12.5-fold higher in broccoli leaves than in florets, while SFN was from 2.5- to 4.5-fold higher in florets regarding the leaf's extracts obtained from the same plants, their precursors (GLS) being in similar amounts for both plant tissues. The most efficient extraction conditions were at 25 °C, ratio 2:25, and during 15 or 20 min according to the target phytochemical to extract. In conclusion, the type of plant tissue and used ratio significantly influenced the extraction of bioactive compounds, the most efficient UAE parameters being those with lower energy consumption.

Currently, interest in finding new feedstock as sources of natural food antioxidants is growing. The extracted olive pomace (EOP), which is an agro-industrial residue from the olive pomace extracting industries, is generated yearly in big amounts, mainly in the Mediterranean countries. EOP was subjected to an ultrasound assisted extraction with ethanol-water mixtures. The effect of main parameters, such as ethanol concentration (30–70% v/v), ultrasound amplitude (20–80%), and extraction time (5–15 min), on the extraction of antioxidant compounds was evaluated according to a Box–Behnken experimental design. The antioxidant capacity of the resulting extracts was determined by measuring their content in total phenolic compounds (TPC) and flavonoids (TFC), as well as their antioxidant activity by DPPH, ferric reducing antioxidant power (FRAP), and ABTS assays. Considering the simultaneous maximization of these five responses, the optimal conditions were found to be 43.2% ethanol concentration, 70% amplitude, and 15 min. The ultrasound assisted extraction of EOP under these optimized conditions yielded an extract with a phenolic and flavonoid content (per gram of EOP) of 57.5 mg gallic acid equivalent (GAE) and 126.9 mg rutin equivalent (RE), respectively. Likewise, the values for DPPH, ABTS, and FRAP assay (per gram of EOP) of 56.7, 139.1, and 64.9 mg Trolox equivalent, respectively were determined in the optimized extract.

Background: In this research, guava leaves are utilised as a potential source of natural antioxidants. Various extraction techniques have been applied for the extraction of phenolic compounds from plants. However, the high temperature and long extraction time used in these methods can cause degradation of the bioactive compounds. In order to overcome this limitation, ultrasound assisted extraction is one of the techniques that can be applied. The advantages of this method include increased extraction yield, less solvent amount required, lower temperature and shorter extraction time. Objective: The main objective of this work is to apply ultrasound assisted method in the extraction of antioxidant from guava leaves. The effect of extraction time, temperature and the solid-to-liquid ratio on the extraction performance are investigated. Method: The extraction was conducted by following the standard method described in the literature. Total phenolic content and antioxidant activity were analysed according to Folin-Ciocalteu and 1,1- Diphenyl-2-picryl-hydrazyl (DPPH) method, respectively. Results: The results show that both total phenolic content and antioxidant activity increase with an increase in extraction time. The most appropriate temperature was found to be 55 °C, while increasing the solid-to-liquid ratio led to a drastic drop in the phenolic content and the antioxidant activity of the guava leaves. Conclusion: The ultrasound assisted extraction method was successfully applied in the extraction of antioxidant compounds from guava leaves. The utilisation of guava leaves in this manner is expected to reduce the amount of waste disposal from food industries.

Producción Científica

Optimization of ultrasound-assisted extraction of bioactive compounds from coffee pulp using propylene glycol as a solvent and their antioxidant activities

Butterfly pea flower, also known as Asian pigeon wings, has been widely used as an ingredient in food and medicine due to the high content of various types of antioxidants that are beneficial to health. One of the technologies used to extract the bioactive compound from the plant is the ultrasound-assisted extraction (UAE) method. This study aimed to investigate the effect of different extraction times from 10 min to 30 min and types of solvent: water, aqueous methanol and aqueous ethanol on the phenolic compound and antioxidant activity present in the butterfly pea flower. The total phenolic content (TPC) was determined using Folin-Ciocalteu assay while the antioxidant was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay. Based on this study, the optimal condition to increase the extract yield from butterfly pea flower was found to be at a 20-min sonication, while the highest TPC and antioxidant activity were achieved at a 30-min sonication using aqueous methanol. Compared with maceration, UAE demonstrated better results in percentage yield, TPC and antioxidant activity when using aqueous methanol. This approach indicated that UAE is an efficient technique for obtaining bioactive compounds from butterfly pea flowers.