Bioprocessing of Brewers’ Spent Grain Enhances Its Antioxidant Activity: Characterization of Phenolic Compounds and Bioactive Peptides

This research was developed under the project "FUNBREW Biotransformation of brewers' spent grain: increased functionality for novel food applications" funded by the European Union's Horizon 2020 Research and Innovation Program under grant agreement No. 727473 (ERANet SUSFOOD2).Brewers’ spent grain (BSG) is the major by-product of the brewing industry which remain largely unutilized despite its nutritional quality. In this study, the effects of fermentation on BSG antioxidant potential were analyzed. A biotechnological protocol including the use of xylanase followed by fermentation with Lactiplantibacillus plantarum (Lactobacillus plantarum) PU1, PRO17, and H46 was used. Bioprocessed BSG exhibited enhanced antioxidant potential, characterized by high radical scavenging activity, long-term inhibition of linoleic acid oxidation and protective effect toward oxidative stress on human keratinocytes NCTC 2544. Immunolabelling and confocal laser microscopy showed that xylanase caused an extensive cell wall arabinoxylan disruption, contributing to the release of bound phenols molecules, thus available to further conversion through lactic acid bacteria metabolism. To clarify the role of fermentation on the antioxidant BSG potential, phenols were selectively extracted and characterized through HPLC-MS techniques. Novel antioxidant peptides were purified and identified in the most active bioprocessed BSG.European Union (EU) 72747

Determination of Polar Compounds in Guava Leaves Infusions and Ultrasound Aqueous Extract by HPLC-ESI-MS

Literature lacks publications about polar compounds content in infusion or guava leaves tea. Because of that, a comparison between different times of infusion and a conventional ultrasound aqueous extract was carried out. Several polar compounds have been identified by HPLC-ESI-MS and their antioxidant activity was evaluated by FRAP and ABTS assays. Four different classes of phenolic compounds (gallic and ellagic acid derivatives, flavonols, flavanones, and flavan-3-ols) and some benzophenones were determined. The quantification results reported that the order, in terms of concentration of the classes of polar compounds in all samples, was flavonols > flavan-3-ols > gallic and ellagic acid derivatives > benzophenones > flavanones. As expected, the aqueous extract obtained by sonication showed the highest content in the compounds studied. Significative differences were noticed about the different times of infusion and five minutes was the optimal time to obtain the highest content in polar compounds using this culinary method. All the identified compounds, except HHDP isomers and naringenin, were positively correlated with antioxidant activity.This work was funded by the Project cofinanced by FEDER-Andalucía 2007–2013 (Cod. 461100) and Andalusian Regional Government Council of Innovation and Science (P11-CTS-7625). The author Elixabet Díaz-de-Cerio also would like to thank the CEIBiotic for the “Ayudas a la Enseñanza Práctica” Grant (CADP2-71). Ana María Gómez-Caravaca and Vito Verardo thank the Spanish Ministry of Economy and Competitiveness (MINECO) for “Juan de la Cierva” postdoctoral contract

Semi-continuous hydrolysis of onion skin wastes with subcritical water: pectin recovery and oligomers identification

The semi-continuous hydrolysis of onion skin wastes (OSW) using subcritical water (SubW; working conditions: 105-180 ºC; 5 MPa; 2.5 mL/min) has been studied in this work. Liquids after hydrolysis showed a sharp increase in total organic carbon (>30 mg/g OSW) at temperatures above 145 ºC, when SubW began to promote the partial hydrolysis of the structural components of OSW. Among them, pectin was one of main components recovered (extraction yield up to 9% at 145 ºC), whereas cellulose was barely hydrolyzed in the range of temperatures studied. The composition of pectin demonstrated that SubW promoted the recovery of the valuable RG-I (21.1±1.1 mol %) regions compared to acid water extraction processes (10.8±0.9 mol %). The control of the hydrolysis conditions was found to be critical, since high temperatures and long hydrolysis times led to the formation of organic acids (acetic, formic and levulinic) and degradation products such as furfural (up to 0.8 mg/g OSW) from the C5 sugars. Finally, the High Heating Value (HHV) calculated for the solid residue obtained at 180 ºC (16.4±0.2 MJ/kg) indicated the potential use of this residue as a fuel, once the valuable compounds (phenolics and pectins) have been recovered.Agencia Estatal de Investigación (AEI) though projects PID2020-116716RJ-I00/ AEI / 10.13039/501100011033 and PID2019-104950RB-I00 / AEI / 10.13039/501100011033 and by the Junta de Castilla y León (JCyL) and the European Regional Development Fund (ERDF) through projects BU301P18 and BU050P20. Benito-Román post-doctoral contract was funded by JCyL and EDRF through project BU050P20 and by AEI through project PID2020-116716RJ-I00. E. Díaz de Cerio post-doctoral contract was funded by JCyL through project BU050P20. P. Alonso-Riaño predoctoral contract was funded by JCyL through ORDEN EDU/556/2019, de 5 de junio

Optimization of Sonotrode Ultrasonic-Assisted Extraction of Proanthocyanidins from Brewers’ Spent Grains

Brewing spent grains (BSGs) are the main by-product from breweries and they are rich of proanthocyanidins, among other phenolic compounds. However, literature on these compounds in BSGs is scarce. Thus, this research focuses on the establishment of ultrasound-assisted extraction of proanthocyanidin compounds in brewing spent grains using a sonotrode. To set the sonotrode extraction up, response surface methodology (RSM) was used to study the effects of three factors, namely, solvent composition, time of extraction, and ultrasound power. Qualitative and quantitative analyses of proanthocyanidin compounds were performed using HPLC coupled to fluorometric and mass spectrometer detectors. The highest content of proanthocyanidins was obtained using 80/20 acetone/water (v/v), 55 min, and 400W. The established method allows the extraction of 1.01 mg/g dry weight (d.w.) of pronthocyanidins from BSGs; this value is more than two times higher than conventional extraction.This project was supported by the University of Granada (project PPJI2017.16)

Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production

Production of small peptides and low molecular weight amino acids by subcritical water from fish meal: Effect of pressurization agent

The hydrolysis of the water-soluble protein (WSP) fraction from tuna fish meal was evaluated by subcritical water (subW) by using N2 and CO2 as different pressurization agents in the temperature range from 140 to 180 °C. For both gases, the amino group release increased by increasing working temperature while the Lowry response decreased due to production of smaller-size peptides and free amino acids. The free amino acid content was higher with CO2 than with N2. At 180 °C, 344 ± 5 and 275 ± 3 mg of free amino acids per g of WSP were released, respectively; although, in both systems the smallest molecular weight amino acids, glycine and alanine, were preferentially released. The free amino acids content obtained by enzymatic hydrolysis with commercial proteases Alcalase and Novozym was much lower with the highest hydrolysis yield determined for histidine. These results have been supported by size exclusion chromatography analysis.This work was supported by the Agencia Estatal de Investigación (AEI) and Ministerio de Ciencia e Innovación (MICINN) [grant numbers PID2019-104950RB-I00 / AEI / https://doi.org/10.13039/501100011033, PID2020-116716RJ-I00/ AEI /https://doi.org/10.13039/501100011033] by the AEI, MICINN, UE Next GenerationEU (Plan de Recuperación, Transformación y Resiliencia) [grant numbers TED2021-129311B-I00, PDC2022-133443-I00] and the Junta de Castilla y León (JCyL) and the European Regional Development Fund (ERDF) [grant number BU050P20]. Benito Román post-doctoral contract was funded by AEI through project PID2020–116716RJ-I00. P. Alonso-Riaño and P. Barea predoctoral contracts were funded by JCyL and the European Social Fund (ESF) by ORDEN EDU/556/2019, de 5 de junio and by ORDEN EDU/1868/2022, de 19 de diciembre. E Díaz de Cerio and A.E. Illera post-doctoral contracts were funded by JCyL and ERDF through project BU050P20. R. Melgosa contract was funded by a Beatriz Galindo Research Fellowship [BG20/00182]

Health Effects of Psidium guajava L. Leaves: An Overview of the Last Decade

Today, there is increasing interest in discovering new bioactive compounds derived from ethnomedicine. Preparations of guava (Psidium guajava L.) leaves have traditionally been used to manage several diseases. The pharmacological research in vitro as well as in vivo has been widely used to demonstrate the potential of the extracts from the leaves for the co-treatment of different ailments with high prevalence worldwide, upholding the traditional medicine in cases such as diabetes mellitus, cardiovascular diseases, cancer, and parasitic infections. Moreover, the biological activity has been attributed to the bioactive composition of the leaves, to some specific phytochemical subclasses, or even to individual compounds. Phenolic compounds in guava leaves have been credited with regulating blood-glucose levels. Thus, the aim of the present review was to compile results from in vitro and in vivo studies carried out with guava leaves over the last decade, relating the effects to their clinical applications in order to focus further research for finding individual bioactive compounds. Some food applications (guava tea and supplementary feed for aquaculture) and some clinical, in vitro, and in vivo outcomes are also included.The author Vito Verardo thanks the Spanish Ministry of Economy and Competitiveness (MINECO) for “Ramón y Cajal” post-doctoral contract

Exploratory Characterization of Phenolic Compounds with Demonstrated Anti-Diabetic Activity in Guava Leaves at Different Oxidation States

Psidium guajava L. is widely used like food and in folk medicine all around the world. Many studies have demonstrated that guava leaves have anti-hyperglycemic and anti-hyperlipidemic activities, among others, and that these activities belong mainly to phenolic compounds, although it is known that phenolic composition in guava tree varies throughout seasonal changes. Andalusia is one of the regions in Europe where guava is grown, thus, the aim of this work was to study the phenolic compounds present in Andalusian guava leaves at different oxidation states (low, medium, and high). The phenolic compounds in guava leaves were determined by HPLC-DAD-ESI-QTOF-MS. The results obtained by chromatographic analysis reported that guava leaves with low degree of oxidation had a higher content of flavonols, gallic, and ellagic derivatives compared to the other two guava leaf samples. Contrary, high oxidation state guava leaves reported the highest content of cyanidin-glucoside that was 2.6 and 15 times higher than guava leaves with medium and low oxidation state, respectively. The QTOF platform permitted the determination of several phenolic compounds with anti-diabetic properties and provided new information about guava leaf phenolic composition that could be useful for nutraceutical production

New analytical approaches to asses the phenolic composition os Guava (Psidium Guavaja L.) leaves with antidiabetic related factors bioactivity

Non-communicable diseases are one of the most concerning health problems worldwide, due to the mortality and morbidity rates, and the high cost for the public health system. In the last years, diabetes mellitus (DM) and its risk factors, which include cardiovascular complications, have become one of the illnesses under study. Prior to drug treatment, a change in lifestyle is recommended, physical activity and a plant-based diet, due to the beneficial effects beyond its nutritional composition. Psidium guajava L., popularly known as guava, is a small tree belonging to the myrtle family (Myrtaceae). It is native from America, although its ability to adapt itself to several edapho-climatic conditions, allows its cultivation in areas such as Andalusia region. In particular, preparations of the leaves have traditionally been used in folk medicine for managing several diseases. Currently, there is clear evidence that these beneficial effects are promoted by secondary metabolites present in guava leaves. In this regard, there is increasing interest in studying their bioactive composition, mainly of phenolic compounds, and their effect on DM and some of its risk factors. Consequently, the overall aims of this dissertation are: To assess different advanced analytical tools in phenolic-enriched extracts of Psidium guajava L. leaves and to study their in vivo bioactivity to consider the possibility for further nutraceutical and/or functional food development.Tesis Univ. Granada. Programa Oficial de Doctorado en: QuímicaFinanciación con cargo a fondos del Centro Tecnológico de Investigación y Desarrollo del Alimento Funcional (CIDAF) procendentes de diferentes proyectos, contratos y subvenciones de las Administraciones Central y Autonómica; a la Agencia IDEA, la Diputación de Granada, así como al plan propio de la Universidad de Granada