Addition of Spirulina to Craft Beer: Evaluation of the Effects on Volatile Flavor Profile and Cytoprotective Properties

Abstract

SPME-GC-MS and PTR-ToF-MS techniques were applied to describe the content of volatile flavor compounds in a craft beer before and after adding spirulina. The obtained results showed that the volatile profile of the two beer samples differed. Furthermore, to chemically characterize biomass spirulina, a derivatization reaction followed by GC-MS analysis was performed, highlighting a high content of molecules belonging to different chemical classes, such as sugars, fatty acids and carboxylic acids. A spectrophotometric analysis of total polyphenols and tannins, investigation into the scavenging activity towards DPPH and ABTS radicals and confocal microscopy of brewer’s yeast cells were carried out. Moreover, the cytoprotective and antioxidant properties towards the oxidative damage induced by tert-butyl hydroperoxide (tBOOH) in human H69 cholangiocytes were investigated. Finally, the modulation of Nrf2 signaling under oxidative stress conditions was also evaluated. Both samples of beer were shown to contain similar levels of total polyphenols and tannins, with slightly increased levels in that containing spirulina 0.25% w/v. Moreover, the beers were found to be endowed with radical scavenging properties towards both DPPH and ABTS radicals, albeit with a weak contribution of spirulina; however, a higher riboflavin content was detected in spirulina-treated yeast cells. Conversely, the addition of spirulina (0.25% w/v) appeared to improve the cytoprotective properties of beer towards tBOOH-induced oxidative damage in H69 cells and reduce intracellular oxidative stress. Accordingly, the cytosolic Nrf2 expression was found to be increased.

Identification of Volatile Molecules and Bioactivity of Gruyt Craft Beer Enriched with Citrus aurantium var. dulcis L. Essential Oil

“…Confocal microscopy of yeast cells enabled the examination of riboflavin autofluorescence, which in turn elucidated essential information regarding the cofactor riboflavin [ 22 , 23 ]. Several factors, such as pH and the presence of other molecules, can affect riboflavin fluorescence.…”

“…A SPME device from Supelco (Bellefonte, PA, USA) with 1 cm fiber coated with 50/30 μm DVB/CAR/PDMS (divinylbenzene/carboxen/polydimethylsiloxane) was chosen to extract the components. The operative conditions followed Taiti et al [ 23 ]. Component desorption was ensured by inserting the fiber directly into the GC injector maintained at 250 °C in splitless mode.…”

“…For each treatment, the cell viability was expressed as percentage of viable cells with respect to the vehicle control (treated with 0.05% (v/v) EtOH). A higher than 30% reduction in cell viability with respect to the control was considered as a biologically significant cytotoxic effect of the treatments [45] The cytoprotective abilities of the tested samples were assessed against the oxidative damage induced by tBOOH (500 µM) [23]. To this end, a subtoxic concentration, which induced about a 40% inhibition of the cell viability in previous experiments, was used.…”

Detection of Secondary Metabolites, Proximate Composition and Bioactivity of Organic Dried Spirulina (Arthrospira platensis)

“…In our previous work, the effects of adding spirulina to craft beer were evaluated. The results demonstrated that spirulina, in addition to modifying the content of compound esters, improved the cytoprotective properties of beer towards tBOOH-induced oxidative damage in H69 cells and reduced intracellular oxidative stress [11].…”

“…To describe the chemical composition of spirulina, a derivatization reaction was performed according to Taiti et al [11]. The analysis was performed using the same apparatus GC-FID/GC-MS and the same capillary column (Varian Factor Four VF-Agilent, Santa Clara, CA, USA).…”