Alternative Mechanisms of Astringency – What is the Role of Saliva?

Abstract

Astringency is described as a "dry puckering-like sensation" in the mouth following consumption of tannins including tea polyphenols. The current model describing astringency is based on precipitation of salivary proline-rich proteins by polyphenols and/or altered salivary lubrication. Because dryness from astringency is detected by oral tissues this suggests other interactions, possibly through direct alteration of the lubricating mucosal pellicle, which may also expose the oral mucosa below. A loss of mucosal lubrication is likely to be fundamental in astringency development and it seems likely that astringent stimuli alter the salivary bulk, saliva rheology and the saliva pellicle leading to an increase of friction in the oral cavity. PRACTICAL APPLICATIONSFor the consumer, high levels of astringency in foods may lead to them becoming unpalatable. However, as the health benefits of many plant-based astringent molecules, such as polyphenols, have become more apparent there is a desire to increase their levels in the diet. Currently, because of the complexity of astringency and the likelihood of multiple mechanisms occurring simultaneously, there is still a gap in knowledge regarding how these mechanisms affect each other and how these lead to altered mouthfeel after consumption of astringent stimuli. A good understanding of astringency development in the oral cavity may lead to an advancement of mechanisms that may prevent the astringency without reducing levels of the astringent molecules in food.

Crosstalk between purinergic receptors and canonical signaling pathways in the mouse salivary gland

“…Saliva production is regulated by autonomic neural inputs that generate the intracellular second messengers inositol 1,4,5 trisphosphate (InsP 3 ) and cyclic adenosine monophosphate (cAMP) to promote fluid secretion and protein exocytosis [22, 23]. Although muscarinic receptor activation results in Ca 2+ -evoked fluid and protein secretion, the majority of sustained protein secretion is induced by adrenergic receptor activation.…”

Charge related astringency of chitosans

“…A recent debate has focused on the involvement of chemoreceptors relative to mechanoreceptors (Carpenter, 2013;Sch€ obel et al, 2014). Gibbins and Carpenter (2013) provided a comprehensive analysis of plausible mechanisms based on polyphenols interacting with proteins in the saliva, in the mobile salivary film, and in the mucin rich mucosal pellicle covering the oral mucosal epithelium. Since chitosan interacts with a range of salivary proteins, including mucins, it too can be involved at all three locations; supporting the possibility of several astringency mechanisms (Lee et al, 2012).…”

Characterization of Vernaccia Nera (Vitis vinifera L.) Grape and Wine

“…This leads to minor astringency, largely due to the low pH, high acidity and the presence of carbon dioxide, which are peculiar characteristics of sparkling wine. Also, the content of the flavan-3-ols esterified with gallic acid in the proanthocyanidins should be low due to their astringent behaviour (Gibbins & Carpenter, 2013). The flavonoid content in the grapes showed minor changes during ripening, and it was highest at harvest (about 5.6 g/kg), but less than 52% of the amount was extractable, corresponding to 2.95 g/kg (Fig.…”

“…The high amount of anthocyanins and their cumarate form can make the anthocyanins of VN quite stable to oxidation during the winemaking, leading to high colour intensity in the wine. The sensorial properties of proanthocyanidins are mainly due to both their number of units and their flavan-3-ol structures (Gibbins & Carpenter, 2013). Therefore, the proanthocyanidins of the skin and seeds were characterised by phloroglucinolysis.…”