The Molecular Mechanism Of Oral Astringency Induced By Span Series Of Emulsifiers

Mucin is a type of highly hydrated glycoprotein that is the main component of mucus.Mucin plays a crucial role in the sensory experience of foods and in the health of human body.Many ingredients in foods,such as tannins(polyphenols)and whey proteins,can cause astringency.Given the importance of astringency on people’s preference for food and human health,it is necessary to explore the possibility of interactions between emulsifiers(Span-20,Span-40,Span-60 and Span-80)which are mostly used in beverages and mucin,and to further explore their influences on oral sensation.This study has important value and significance to the development of a new type of good-taste and healthly drink for the food industry.Firstly,artificial saliva was used to simulate human oral saliva,studying the interaction between mucin and four emulsifiers Span-20,Span-40,Span-60 and Span-80 with decreasing hydrophilic-lipophilic balance(HLB)values in the digestion(Shaking in a shaker for 25 min at 37 °C,150 r/min in the oral cavity.The results showed that the interaction between the emulsifiers and mucin is non-covalent force,which is mainly relying on hydrophobic interactions and hydrogen bonds.And the interaction between Span-20、Span-40 and Span-60 were inversely correlated with the HLB value;The strong hydrophobicity of Span-80 makes the structure of mucin more overlapping,and the addition of Span-80 has little effect on the particle size of mucin and tends to make it smaller,resulting in a more compact and irregular particles.It was further found that mucin could induce irreversible flocculation of Span-60 emulsion,and the addition of oil phase promoted the interaction between Span-60 and mucin.Secondly,through the study ofthe effects of oil fraction(?)and particle size on the interaction of Span-60 stabilized emulsion with mucin.The result showed that the degree of irreversible flocculation of mucin-induced Span-60 emulsions with different oil fractions or particle sizes gradually increased with the increase of oil phase ratio(0.01,0.05,0.1)and the decrease of particle size(from homogenization,ultrasound to microfluidization),which leads to a gradual increase in the particle size of the complex.Finally,through the research on the effect of intake Span-60 solution and its stabilized emulsion on whole human unstimulated saliva in oral cavity.The results showed that the binding of Span-60 to salivary proteins resulted in the aggregation of salivary proteins,disrupting the network structure of the mucins,resulting in loss of saliva lubrication.With the increase of oil phase ratio(0.01,0.05,0.1)and the decrease of particle size(from homogenization to ultrasound),the degree of irreversible flocculation of mucin-induced Span-60 emulsions with different oil fractions or particle sizes gradually increased,which leads to a gradual increase in the particle size of the complex.That is,ingestion of Span-60 in the oral cavity causes instability of the salivary protein and may cause astringency.The results of this study are of certain guiding significance to the development of a new type of good-taste and healthly drink in the food industry.