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Current extraction techniques towards bioactive compounds from brewer’s spent grain - a review

Publication . Bonifácio-Lopes, T.; Teixeira, José A.; Pintado, Manuela

Background: Brewer’s spent grain is one of the most abundant by-products of the brewing industry and is rich in various bioactive compounds (phenolic acids, insoluble dietary fiber and proteins). While at the present brewer’s spent grain is mainly used as animal feed its rich nutritional content makes it an interesting alternative for food applications. Scope and approach: As the range of applications of the bioactive compounds extracted from by-products has been growing in recent years, there is the need to obtain and characterize these bioactive compounds. Extraction methods (supercritical carbon dioxide, autohydrolysis, alkaline hydrolysis, solvent extraction, ultrasound assisted extraction, dilute acid hydrolysis, enzymatic hydrolysis, microwave assisted extraction) have been developed and are always being subjected to new approaches to allow better extraction yields of the bioactive compounds. Key findings and conclusions: This review aims to provide a better understanding of the current advantages and limitations of brewer’s spent grain extraction processes and to provide a background of brewer’s spent grain composition and applications.

2019Journal article

Open access

Physicochemical characterisation and release behaviour of curcumin-loaded lactoferrin nanohydrogels into food simulants

Publication . Araújo, João F.; Bourbon, Ana I.; Simões, Livia S.; Vicente, António A.; Coutinho, Paulo J. G.; Ramos, Oscar. L.

Whey protein nanostructures can be used as vehicles for the incorporation of nutraceuticals (e.g., antioxidants or vitamins) aimed at the development of functional foods, because nanostructures provide greater protection, stability and controlled release to such nutraceuticals. Fundamental knowledge is required regarding the behaviour of nanostructures when associated with nutraceuticals and their interactions with real food matrices. In this study, a lactoferrin (LF) nanohydrogel was developed to encapsulate curcumin (nutraceutical model) and its behaviour was evaluated in terms of the LF structure and the interaction with curcumin. The release kinetics of curcumin from LF nanohydrogels was also assessed using food simulants with a hydrophilic nature (10% ethanol) and lipophilic nature (50% ethanol). This system was able to encapsulate curcumin at 80 μg mL−1 with an efficiency of ca. 90% and loading capacity of ca. 3%. Through spectroscopic characterisation, it is suggested that LF and curcumin bind via hydrophobic interactions and the average binding distance between LF and curcumin was found to be 1.91 nm. Under refrigerated conditions (4 °C), this system showed stability for up to 35 days, while at room temperature (25 °C) it was shown to be stable for up to 14 days of storage. The LF nanohydrogel presented higher release rates of curcumin in a lipophilic food simulant (stable after ca. 7 h) as compared to a hydrophilic simulant (stable after ca. 4 h). LF nanohydrogels were successfully incorporated into a gelatine matrix and showed no degradation in this process. The behaviour of this system and the curcumin release kinetics in food stimulants make the LF nanohydrogel an interesting system to associate with lipophilic nutraceuticals and to incorporate in refrigerated food products of a hydrophilic nature.

2020Journal article

Restricted access

Simultaneous partial nitrification and 2-fluorophenol biodegradation with aerobic granular biomass: reactor performance and microbial communities

Publication . Ramos, Carlos; Amorim, Catarina L.; Mesquita, Daniela P.; Ferreira, Eugénio C.; Carrera, Julián; Castro, Paula M. L.

An aerobic granular bioreactor was operated for over 4months, treating a synthetic wastewater with a high ammonium content (100mgNL-1). The inoculum was collected from a bioreactor performing simultaneous partial nitrification and aromatic compounds biodegradation. From day-56 onwards, 2-fluorophenol (2-FP) (12.4mgL-1) was added to the feeding wastewater and the system was bioaugmented with a 2-FP degrading bacteria (Rhodococcus sp. FP1). By the end of operation, complete 2-FP biodegradation and partial nitrification were simultaneously achieved. Aerobic granules remained stable over time. During the 2-FP loading, a shift in the community structure occurred, coinciding with the improvement of 2-FP degradation. DGGE analysis did not allow to infer on the bioaugmented strain presence but pyrosequencing analysis detected Rhodococcus genus by the end of operation. Together with other potential phenolic-degraders within granules, these microorganisms were probably responsible for 2-FP degradation.

2017Journal article

Restricted access

Design of β-lactoglobulin micro- and nanostructures by controlling gelation through physical variables

Publication . Simões, Lívia S.; Araújo, João F.; Vicente, António A.; Ramos, Oscar L.

β-lactoglobulin (β-Lg) is the major protein fraction of bovine whey serum and its principal gelling agent. Its gelation capacity enables conformational changes associated with protein-protein interactions that allow the design of structures with different properties and morphologies. Thus, the aim of this work was to successfully use β-Lg, purified from a commercial whey protein isolate, to develop food-grade micro- (with diameters between 200 and 300 nm) and nano- (with diameters ≤ 100 nm) structures. For this purpose, the phenomena involved in β-Lg gelation were studied under combined effects of concentrations (from 5 to 15 mg mL−1), heating temperature (from 60 to 80 °C) and heating time (from 5 to 25 min) for pH values of 3, 4, 6 and 7. The effects of such conditions on β-Lg structures were evaluated and the protein was fully characterized in terms of size, polydispersity index (PDI) and surface charge (by dynamic light scattering – DLS), morphology (by transmission electron microscopy - TEM) and conformational structure (circular dichroism, intrinsic and extrinsic fluorescence). Results have shown that β-Lg nanostructures were formed at pH 3 (with diameters between 12.1 and 22.3 nm) and at 7 (with diameters between 8.9 and 35.3 nm). At pH 4 structures were obtained at macroscale (i.e., ≥ 6 μm) for all β-Lg concentrations when heated at 70 and 80 °C, independent of the time of heating. For pH 6, it was possible to obtain β-Lg structures either at micro- (245.0 – 266.4 nm) or nanoscale (≤ 100 nm) with the lowest polydispersity (PDI) values (≤ 0.25), in accordance with TEM analyses, for heating at 80 °C for 15 min. Intrinsic and extrinsic fluorescence data and far-UV circular dichroism spectra measurements revealed conformational changes on β-Lg structure that support these evidences. A strict control of the physical and environmental conditions is crucial for developing β-Lg structures with the desired characteristics, thus calling for the understanding of the mechanisms of protein aggregation and intermolecular interaction when designing β-Lg structures with novel functionalities.

2020Journal article

Open access

β-lactoglobulin micro- and nanostructures as bioactive compounds vehicle: In vitro studies

Publication . Simões, Lívia S.; Martins, Joana T.; Pinheiro, Ana C.; Vicente, António A.; Ramos, Oscar. L.

β-Lactoglobulin (β-Lg) is known to be capable to bind hydrophilic and hydrophobic bioactive compounds. This research aimed to assess the in vitro performance of β-Lg micro- (diameter ranging from 200 to 300 nm) and nano (diameter < 100 nm) structures associated to hydrophilic and hydrophobic model compounds on Caco-2 cells and under simulated gastrointestinal (GI) conditions. Riboflavin and quercetin were studied as hydrophilic and hydrophobic model compounds, respectively. Cytotoxicity experiment was conducted using in vitro cellular model based on human colon carcinoma Caco-2 cells. Moreover, the digestion process was simulated using the harmonized INFOGEST in vitro digestion model, where samples were taken at each phase of digestion process - oral, gastric and intestinal - and characterized in terms of particle size, polydispersity index (PDI), surface charge by dynamic light scattering (DLS); protein hydrolysis degree by 2,4,6-trinitrobenzene sulfonic acid (TNBSA) assay and native polyacrylamide gel electrophoresis; and bioactive compound concentration. Caco-2 cell viability was not affected up to 21 × 10−3 mg mL−1 of riboflavin and 16 × 10−3 mg mL−1 quercetin on β-Lg micro- and nanostructures. In the oral phase, β-Lg structures’ particle size, PDI and surface charge values were not changed comparing to the initial β-Lg structures (i.e., before being subjected to in vitro GI digestion). During gastric digestion, β-Lg structures were resistant to proteolytic enzymes and to acid environment of the stomach – confirmed by TNBSA and native gel electrophoresis. In vitro digestion results indicated that β-Lg micro- and nanostructures protected both hydrophilic and hydrophobic compounds from gastric conditions and deliver them to target site (i.e., intestinal phase). In addition, β-Lg structures were capable to enhance riboflavin and quercetin bioaccessibility and bioavailability potential compared to bioactive compounds in their free form. This study indicated that β-Lg micro- and nanostructures were capable to enhance hydrophilic and hydrophobic compounds bioavailability potential and they can be used as oral delivery systems.

2020Journal article

Open access