Interactions between polyphenols and volatile compounds in wine: A literature review on physicochemical and sensory insights

Wine polyphenols (PPhs) and volatile organic compounds (VOCs) are responsible for two of the main sensory characteristics in defining the complexity and quality of red wines: astringency and aroma. Wine VOCs’ volatility and solubility are strongly influenced by the matrix composition, including the interactions with PPhs. To date, these interactions have not been deeply studied, although the topic is of great interest in oenology. This article reviews the available knowledge on the main physicochemical and sensory effects of polyphenols on the release and perception of wine aromas in orthonasal and retronasal conditions. It describes the molecular insights and the phenomena that can modify VOCs behavior, according to the different chemical classes. It in-troduces the possible impact of saliva on aroma release and perception through the modulation of polyphenols–aroma compounds interactions. Limitations and possible gaps to overcome are presented together with updated approaches used to investigate those interactions and their effects, as well as future perspectives on the subject

Ian Devereux MSc, PhD, FNZIC, AMAusIMM (1940-2020) - geoscientist and founder of Rocklabs

Obituar

The contribution of varietal thiols in the diverse aroma of Italian monovarietal white wines

Thanks to their low odor detection thresholds, free varietal thiols (VTs) play a key role in the primary aroma of wines, to which they confer an intense scent reminiscent of box tree, grapefruit, citrus fruits, passionfruit and cat urine odor. Excluding wines from a few VT-rich grapevine cultivars, VTs appear to be present in most cultivars at trace levels, although a comprehensive dataset is still missing. The low concentration of VTs combined with their high reactivity and matrix complexity make their determination in wines a challenging task. In this research an optimized liquid chromatography - tandem mass spectrometry (LC-MS/MS) method was validated and used for the quantification of 4-methyl-4-sulfanylpentan-2-one (4-MSP), 3-sulfanylhexan-1-ol (3-SH), 3-sulfanylhexyl acetate (3-SHA) and ethyl 3-sulfanylpropionate (E3SP) in 246 samples (vintage 2019) representative of 18 monovarietal Italian white wines. VTs were detected in all cultivars even though higher values of 3-SH were found in Lugana, Müller-Thurgau and Verdicchio cultivars. Müller-Thurgau wines showed the highest level of 4-MSP, that was mainly correlated to the odor descriptors of passionfruit and box tree/cat urine. The VTs composition of Müller-Thurgau was confirmed on a second set of 50 wines from different vintages. From a sensory perspective, the samples of Müller-Thurgau showed the best positive correlations between chemical variables and the odor descriptors thiol note, passion fruit and box tree/cat urine. These notes are significantly related to 4-MSP, suggesting that it could play a relevant olfactory role for the aroma of Müller-Thurgau wines. Sorting analysis allowed to group these wines according to their thiolic characteristics. The chemical variables and the odor descriptors attributable to the thiol notes are important for Müller-Thurgau and Lugana wines, while the contribution of thiol notes was sensorially negligible for the other wines.18openNoMinistry of Education, University and Research (MIUR) under the PRIN 2017 grant (Prot. 2017RXFFRR, CUP code B38D19000120006)Carlin, Silvia; Piergiovanni, Maurizio; Pittari, Elisabetta; Tiziana Lisanti, Maria; Moio, Luigi; Piombino, Paola; Marangon, Matteo; Curioni, Andrea; Rolle, Luca; Rìo Segade, Susana; Versari, Andrea; Ricci, Arianna; Parpinello, Giuseppina Paola; Luzzini, Giovanni; Ugliano, Maurizio; Perenzoni, Daniele; Vrhovsek, Urska; Mattivi, FulvioCarlin, S.; Piergiovanni, M.; Pittari, E.; Tiziana Lisanti, M.; Moio, L.; Piombino, P.; Marangon, M.; Curioni, A.; Rolle, L.; Rìo Segade, S.; Versari, A.; Ricci, A.; Parpinello, G.P.; Luzzini, G.; Ugliano, M.; Perenzoni, D.; Vrhovsek, U.; Mattivi, F

Experimental study of dense pyroclastic density currents using sustained, gas-fluidized granular flows

© 2014, Springer-Verlag Berlin Heidelberg. We present the results of laboratory experiments on the behaviour of sustained, dense granular flows in a horizontal flume, in which high-gas pore pressure was maintained throughout the flow duration by continuous injection of gas through the flume base. The flows were fed by a sustained (0.5–30 s) supply of fine (75 ± 15 μm) particles from a hopper; the falling particles impacted an impingement surface at concentrations of ~3 to 45 %, where they densified rapidly to generate horizontally moving, dense granular flows. When the gas supplied through the flume base was below the minimum fluidization velocity of the particles (i.e. aerated flow conditions), three flow phases were identified: (i) an initial dilute spray of particles travelling at 1–2 m s−1, followed by (ii) a dense granular flow travelling at 0.5–1 m s−1, then by (iii) sustained aggradation of the deposit by a prolonged succession of thin flow pulses. The maximum runout of the phase 2 flow was linearly dependent on the initial mass flux, and the frontal velocity had a square-root dependence on mass flux. The frontal propagation speed during phase 3 had a linear relationship with mass flux. The total mass of particles released had no significant control on either flow velocity or runout in any of the phases. High-frequency flow unsteadiness during phase 3 generated deposit architectures with progradational and retrogradational packages and multiple internal erosive contacts. When the gas supplied through the flume base was equal to the minimum fluidization velocity of the particles (i.e. fluidized flow conditions), the flows remained within phase 2 for their entire runout, no deposit formed and the particles ran off the end of the flume. Sustained granular flows differ significantly from instantaneous flows generated by lock-exchange mechanisms, in that the sustained flows generate (by prolonged progressive aggradation) deposits that are much thicker than the flowing layer of particles at any given moment. The experiments offer a first attempt to investigate the physics of the sustained pyroclastic flows that generate thick, voluminous ignimbrites

Membrane-Bound IL-21 Promotes Sustained Ex Vivo Proliferation of Human Natural Killer Cells

NK cells have therapeutic potential for a wide variety of human malignancies. However, because NK cells expand poorly in vitro, have limited life spans in vivo, and represent a small fraction of peripheral white blood cells, obtaining sufficient cell numbers is the major obstacle for NK-cell immunotherapy. Genetically-engineered artificial antigen-presenting cells (aAPCs) expressing membrane-bound IL-15 (mbIL15) have been used to propagate clinical-grade NK cells for human trials of adoptive immunotherapy, but ex vivo proliferation has been limited by telomere shortening. We developed K562-based aAPCs with membrane-bound IL-21 (mbIL21) and assessed their ability to support human NK-cell proliferation. In contrast to mbIL15, mbIL21-expressing aAPCs promoted log-phase NK cell expansion without evidence of senescence for up to 6 weeks of culture. By day 21, parallel expansion of NK cells from 22 donors demonstrated a mean 47,967-fold expansion (median 31,747) when co-cultured with aAPCs expressing mbIL21 compared to 825-fold expansion (median 325) with mbIL15. Despite the significant increase in proliferation, mbIL21-expanded NK cells also showed a significant increase in telomere length compared to freshly obtained NK cells, suggesting a possible mechanism for their sustained proliferation. NK cells expanded with mbIL21 were similar in phenotype and cytotoxicity to those expanded with mbIL15, with retained donor KIR repertoires and high expression of NCRs, CD16, and NKG2D, but had superior cytokine secretion. The mbIL21-expanded NK cells showed increased transcription of the activating receptor CD160, but otherwise had remarkably similar mRNA expression profiles of the 96 genes assessed. mbIL21-expanded NK cells had significant cytotoxicity against all tumor cell lines tested, retained responsiveness to inhibitory KIR ligands, and demonstrated enhanced killing via antibody-dependent cell cytotoxicity. Thus, aAPCs expressing mbIL21 promote improved proliferation of human NK cells with longer telomeres and less senescence, supporting their clinical use in propagating NK cells for adoptive immunotherapy