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[Display omitted] • Retention in the mouth following brushing determines the efficiency of toothpastes. • New in vitro methodologies developed to evaluate toothpaste retention in the oral cavity. • Retention in the oral cavity depends on the type of polymer used in the formulation. • The use of polymers with strong mucoadhesive properties can improve retention in the mouth. Retention of active ingredients of toothpastes in the mouth following brushing determines the efficiency of these oral care formulations. In this study, new in vitro methodologies for the observation and measurement of toothpaste retention in the oral cavity were developed and used to evaluate the efficiency of formulations containing different mucoadhesive hydrophilic polymers. The findings suggest that using Carbopol ETD 2020 and Carbopol Ultrez 10 as binders in toothpaste prolongs the retention time of these formulations in the oral cavity. The in vitro methodologies tested, coupled with texture analysis, were able to accurately characterise the behaviour of the toothpaste and produce detailed images showing how it is retained in the oral cavity. This study has not only produced a new method for studying the behaviour of toothpaste and other formulations in the oral cavity but is also the first to investigate how different types of mucoadhesive binders can be used to improve toothpaste retention. [ABSTRACT FROM AUTHOR]

[Display omitted] • The oral cavity has a very diverse bacterial flora that inhabits it. • Modern oral care products are complex formulations containing many ingredients. • Advanced formulations provide extended release of ingredients vital for dental health. • Further research on new ways of increasing the retention time of formulations in the mouth is needed. This review explores the physical, chemical and structural properties of key components of oral care products, whilst looking at the challenges which need to be overcome to continue to improve the efficacy of oral care, and improve dental health. Oral care has been an essential part of all populations and cultures around the world for thousands of years. To maintain good oral health, dental plaque causing bacteria and malodour must be controlled whilst also strengthening and protecting the teeth to prevent dental caries. Advanced modern formulations need to provide controlled and extended release of ingredients vital for dental health. With modern day products such as toothpastes and mouthwashes, it has never been easier to maintain good oral hygiene and health, yet the incidence of dental caries is still on the rise. The complex formulations of modern toothpastes and mouthwashes makes them one of the most sophisticated pharmaceutical products on the market today. The demands of the consumer coupled with the complexity of the oral cavity make it one of the most challenging development processes. [ABSTRACT FROM AUTHOR]

Polysaccharides have many roles across both the food and pharmaceutics industries. They are commonly used to enhance viscosity, stabilise emulsions and to add bulk to food products. In the pharmaceutics industry, they are also utilised for their mucoadhesive nature. Mucoadhesive polysaccharides can facilitate retention of active ingredients at mucosal sites for a prolonged time and formulations can be designed to control their release and bioavailability. This study investigates how polysaccharides, with differing physicochemical properties (e.g. functional groups and molecular weight), affect the release and perception of flavour compounds from films. Polysaccharide films were prepared using either high or low viscosity carboxymethyl cellulose, pullulan or hydroxypropyl methylcellulose. Glucose, vanillin or a combination of both was also added to the films to assess the effect of flavour release and perception over time. The films were assessed for glucose release in vitro , swelling and disintegration times, and mucoadhesive ability. Results show that flavour release and perception depend on the polysaccharide matrix properties; this includes how quickly the films dissolve, the rate of release of tastant compounds, and the mucoadhesive strength of the polysaccharide. A higher viscosity and slower disintegration time resulted in slower release of glucose in vitro and flavour perception in vivo . [ABSTRACT FROM AUTHOR]

• Heating time increases oral retention of whey protein up to 1 min post-consumption. • Heating whey protein concentrate increases free thiol concentration. • Heating changes secondary and tertiary structures of whey protein concentrate. • Circular dichroism found protein unfolding and changes to β-barrel with heating. • Nuclear magnetic resonance found heating leads to hydrophobic group exposure. This study investigated structural changes and the in vivo retention in the oral cavity of heated whey protein concentrate (WPC). Heated WPC was shown to have both a higher retention time in the oral cavity compared to unheated whey protein up to 1 min post swallow, and a concomitant increase in free thiol concentration. Nuclear magnetic resonance and circular dichroism demonstrated structural changes in the secondary and tertiary structures of the WPC upon heating. Structural loss of the β-barrel was shown to increase during heating, leading to the exposure of hydrophobic regions. The increase in free thiols and hydrophobic regions are two factors which are known to increase mucoadhesive strength and hence increase oral retention of heated whey protein which may subsequently increase the perception of mouthdrying. [ABSTRACT FROM AUTHOR]

The mucoadhesion between polymeric substances and mucosal membranes, widely exploited in the pharmaceutics industry to prolong drug residence, has been investigated as a means of retaining taste or aroma molecules in the oral cavity. This study shows that the mucoadhesive properties of carboxymethyl cellulose, a commonly used polysaccharide in the food and pharmaceutics industry, can modify retention, release and perception of sodium over time. A three-part study was designed coupling in vitro retention using ex vivo porcine tongue, sensory perception with a trained panel and in vivo retention of sodium ions in human volunteers. The findings suggest that although salt perception is stunted in samples containing a random coil, ionic, mucoadhesive thickener, the retention of sodium ions in the mouth is prolonged due to the mucoadhesive nature of the polysaccharide. Not only has this study-investigated mucoadhesion of liquid formulations in the oral cavity but it is also the first to link the mucoadhesive nature of a commonly used polysaccharide to the organoleptic properties of a food. [ABSTRACT FROM AUTHOR]

Whey proteins are becoming an increasingly popular functional food ingredient. There are, however, sensory properties associated with whey protein beverages that may hinder the consumption of quantities sufficient to gain the desired nutritional benefits. One such property is mouth drying. The influence of protein structure on the mouthfeel properties of milk proteins has been previously reported. This paper investigates the effect of thermal denaturation of whey proteins on physicochemical properties (viscosity, particle size, zeta-potential, pH), and relates this to the observed sensory properties measured by qualitative descriptive analysis and sequential profiling. Mouthcoating, drying and chalky attributes built up over repeated consumption, with higher intensities for samples subjected to longer heating times ( p < 0.05). Viscosity, pH, and zeta-potential were found to be similar for all samples, however particle size increased with longer heating times. As the pH of all samples was close to neutral, this implies that neither the precipitation of whey proteins at low pH, nor their acidity, as reported in previous literature, can be the drying mechanisms in this case. The increase in mouth drying with increased heating time suggests that protein denaturation is a contributing factor and a possible mucoadhesive mechanism is discussed. [ABSTRACT FROM AUTHOR]