Flavonoids are a group of plant constituents called phenolic compounds and correspond to the nonenergy part of the human diet. Flavonoids are found in vegetables, seeds, fruits, and beverages such as wine and beer. Over 7000 flavonoids have been identified and they have been considered substances with a beneficial action on human health, particularly of multiple positive effects because of their antioxidant and free radical scavenging action. Although several studies indicate that some flavonoids have provident actions, they occur only at high doses, confirming in most investigations the existence of anti-inflammatory effects, antiviral or anti-allergic, and their protective role against cardiovascular disease, cancer, and various pathologies. Flavonoids are generally removed by chemical methods using solvents and traditional processes, which besides being expensive, involve long periods of time and affect the bioactivity of such compounds. Recently, efforts to develop biotechnological strategies to reduce or eliminate the use of toxic solvents have been reported, reducing processing time and maintaining the bioactivity of the compounds. In this paper, we review, analyze, and discuss methodologies for biotechnological recovery/extraction of flavonoids from agro-industrial residues, describing the advances and challenges in the topic.

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Lippia graveolens is a traditional crop and a rich source of bioactive compounds with various properties (e.g., antioxidant, anti-inflammatory, antifungal, UV defense, anti-glycemic, and cytotoxicity) that is primarily cultivated for essential oil recovery. The isolated bioactive compounds could be useful as additives in the functional food, nutraceuticals, cosmetics, and pharmaceutical industries. Carvacrol, thymol, β-caryophyllene, and p-cymene are terpene compounds contained in oregano essential oil (OEO); flavonoids such as quercetin O-hexoside, pinocembrin, and galangin are flavonoids found in oregano extracts. Furthermore, thermoresistant compounds that remain in the plant matrix following a thermal process can be priced in terms of the circular economy. By using better and more selective extraction conditions, the bioactive compounds present in Mexican oregano can be studied as potential inhibitors of COVID-19. Also, research on extraction technologies should continue to ensure a higher quality of bioactive compounds while preventing an undesired chemical shift (e.g., hydrolysis). The oregano fractions can be used in the food, health, and agricultural industries.

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La digestibilidad es la facilidad con la que los alimentos se convierten en el sistema digestivo en sustancias útiles para la nutrición; ésta comprende la hidrólisis de moléculas complejas y la absorción de moléculas pequeñas en el intestino. La microbiota es fundamental en estos procesos y el mal funcionamiento de estos microorganismos está asociado con enfermedades metabólicas. El objetivo de este estudio fue caracterizar y evaluar la digestibilidad y el efecto prebiótico del extracto de fruto de Stenocereus queretaroensis, ya que se desconocen su valor nutricional y funcionalidad. El extracto se obtuvo del fruto a 4 °C usando un extractor de jugo; posteriormente, se filtró y liofilizó; además, se determinó su valor y calidad nutricional parcial mediante análisis fisicoquímicos y proximales. Asimismo, se establecieron técnicas para evaluar la digestibilidad oral, gástrica e intestinal y para evaluar el efecto prebiótico. El extracto mostró un color rojo (L* = 17.21 ± 0.1, a* = 38.61 ± 0.1, b* = 10.60 ± 0.2), con un pH de 3.78 ± 0.1, sin grasa cruda y 0.77 ± 0.0 % (p/p) de fibra cruda, 1.36 ± 0.0 % de proteína, 88.82 ± 0.8 % de extracto libre de nitrógeno y efecto prebiótico para Bacillus coagulans, Lactobacillus sporogenes y L. delbrueckii.

BACKGROUND About 75% of the total grape production worldwide is destined for wine production. Many agro‐industrial wastes are derived from the various stages of wine production that are not usually used. The present study explores grape pomace from the winemaking industry as a fermentation substrate for the extraction of phenolic compounds through two fermentation systems, submerged and solid‐state fermentation, using Aspergillus niger GH1 as a biological model. RESULTS Both fermentation systems showed polyphenolic compounds release. The highest values for polyphenol content extraction were through solid‐state fermentation without supplementation with 2.262 g L−1 of hydrolysable tannins (HT) and 3.684 g L−1 of condensates tannins (CT). For submerged fermentation, however, the best results were obtained in the non‐supplemented medium obtaining 0.182 g L−1 of HT and 0.198 g L−1 of CT. A kinetic fermentation under the best fermentation conditions was carried out. The enzymatic activities associated with the extractive process were demonstrated (tannase, ellagitannase, β‐glucosidase, xylanase, and α‐L‐arabinofuranosidase). Among the main compounds identified were hydroxycinnamic acids, anthocyanins, proanthocyanidins, catechins, hydroxybenzoic acids, and flavonols. CONCLUSION Grape pomace constitutes a nutrient‐rich material that can be used as a fermentation substrate to extract bioactive compounds. A. niger GH1 was shown to be able to synthesize hydrolytic enzymes capable of degrading grape pomace to release polyphenolic compounds. This study reveals the effectiveness of both types of fermentation and the influence of fermentation parameters on the recovery of polyphenols and on the mechanisms involved in these bioprocesses, which stand out for being eco‐friendly alternatives for the recovery of compounds of industrial interest. © 2021 Society of Chemical Industry (SCI).

Aguamiel is a natural sap produced by some species of agave plants, such as Agave salmiana, A. atrovirens , or A. angustifolia . It is a product with a high concentration of fructose, glucose or sucrose, although its composition may vary depending on the season in which it is produced, and may also contain agave fructans (or agavins) or fructooligosaccharides (FOS). It has been reported that FOS can be produced by enzymes that act on sucrose or inulin, transfructosylating or hydrolyzing these materials, respectively. Due to the sugar content in aguamiel, the application of an enzymatic complex produced by Aspergillus oryzae DIA MF was carried out. This complex was characterized by 1-D electrophoresis SDS-PAGE, and its transfructosylation and hydrolysis activities were determined by HPLC. In order to determine the conditions at which the concentration of FOS in this beverage increased, kinetics were carried out at different temperatures (30, 50, and 70°C) and times (0, 1, 2, 3, 4, 5, 10, and 15 h). Finally, the antioxidant and prebiotic activities were evaluated. FOS concentration in aguamiel was increased from 1.61 ± 0.08 to 31.01 ± 3.42 g/ L after 10 h reaction at 30°C applying 10% enzymatic fraction-substrate (v/v). Antioxidant activity was highly increased (34.81–116.46 mg/eq Trolox in DPPH assay and 42.65 to 298.86 mg/eq Trolox in FRAP assay) and growth of probiotic bacteria was higher in aguamiel after the enzymatic treatment. In conclusion, after the application of the enzymatic treatment, aguamiel was enriched with FOS which improved antioxidant and prebiotic properties, so it can be used as a functional food.

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