Dynamic modelling of whey protein–saliva interactions in the mouth and relation to astringency in acidic beverages (original) (raw)
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The astringency of whey protein beverages is caused by their acidity
International Dairy Journal, 2008
Our objective was to determine if the acidity of whey protein solutions was responsible for their astringency. Panelists rated acidic whey protein and acid-only solutions for astringency and sourness. Acidic whey protein solutions contained 6% or 1% whey protein isolate and phosphoric acid at a pH of 3.4. Acid-only solutions were formulated to match the whey protein solutions for either total acidity or for pH. The acid-only solutions matched for total acidity were more astringent than the whey-containing solutions, while those matched for pH were significantly less astringent. Sourness was reduced by the whey proteins, most likely because of the decreased concentration of free hydrogen ions. The astringency of acidic whey protein solutions appears to be caused by their high acidity and not directly by the whey proteins.
2014
Oral nutritional supplement drinks (ONS) are beverages high in dairy proteins that are prescribed to individuals at risk of malnutrition. Consumption of ONS is poor in elderly care facilities, with patients commenting that the sensory attributes of these drinks reduce their enjoyment and willingness to consume. Mouth drying is an attribute of ONS found to build with repeated consumption, which may further limit liking of these products. This study investigated the sources of drying sensations by sequential profiling, with a trained sensory panel rating a range of model milk systems and ONS over repeated sips and during after-effects. Sequential profiling found that fortification of milk with both caseinate and whey protein concentrate significantly increased the perception of mouth drying over repeated consumption, increasing by between 35 and 85% over consumption of 40 mL. Enrichment of ONS with either whey protein concentrate or milk protein concentrate to a total protein content of 8.7% (wt/wt) resulted in whey and casein levels of 4.3:4.4% and 1.7:7.0% respectively. The product higher in whey protein was substantially more mouth drying, implying that whey proteins may be the most important contributor to mouth drying in ONS. However, efforts to mask mouth drying of protein-fortified milk by increasing sweetness or fat level were unsuccessful at the levels tested. Increasing the viscosity of protein-fortified milk led to a small but significant reduction in mouth drying. However, this approach was not successful when tested within complete ONS. Further analysis is required into the mechanism of protein-derived mouth drying to mask negative sensations and improve the enjoyment and consumption of protein-rich ONS.
Whey protein mouth drying influenced by thermal denaturation
Food Quality and Preference, 2017
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.
Sensory quality evaluation of whey-based beverages
2010
Whey is a by-product of the cheese industry which was often disposed as waste in the past, causing high environmental contamination. Considerable efforts have been made over the past years to find new outlets for whey utilization and to reduce environmental pollution (González-Martínez et al., 2002; Douaud, 2007; Jeličić et al., 2008). Whey and its protein concentrates are used as ingredients in the food industry mainly due to their foaming and emulsifying properties (Hall and Iglesias, 1997; Ji and Hauque, 2003; Jovanović et al., 2005) and nutritional and biological attributes (Mistry et al., 1996; Smithers et al., 1996; Kenny et al., 2001; Carunchia Whetstine et al., 2005; Herceg et al., 2008; Akpinar-Bayizit et al., 2009). The main Veronika Legarová and Lenka Kouřimská
Physico-Chemical Properties of Milk Whey Protein Agglomerates for Use in Oral Nutritional Therapy
Food and Nutrition Sciences, 2013
Agglomerates based on milk whey proteins and modified starch (MS) were developed for patients with dysphagia. Calcium caseinate (CaCas), whey protein isolate (WPI), concentrate (WPC) and hydrolysate (WPH) were used. The sources were agglomerated with the MS and an increase in the porosity and viscosity of the agglomerates were observed. In all the systems evaluated, the WPI agglomerate at a concentration of 112 g/L showed a viscosity between 2122 and 5110 cP, and the agglomerates of WPC and WPH between 1115 -2880 cP and 2600 -6651 cP, respectively. CaCas exhibited high values in water and milk of 3200 cP and 6651 cP, respectively, and low values of 640 cP in juice. In sensory tests, the 70% WPI: 30% MS juice obtained a score 6.97, an improvement in relation to the other agglomerates, but not differing (p = 0.681) from the commercial thickener, 6.91 (p = 0.380). Based on these results, the 70% WPI: 30% MS was suggested for use in the nutritional therapy of patients with dysphagia.
Food Hydrocolloids, 2008
Human whole saliva (HWS) is a complex physiological secretion that performs a number of essential functions such as protection of oral health, lubrication of mouth tissues, as well as predigestion of food. In addition, saliva forms the perireceptor environment of the oral cavity and, by its interactions with food and beverages, influences the transduction of aroma, taste and tactile (mouthfeel) perceptions. We investigate and report the impact of addition of compounds commonly found in oral health and beverage products (sodium dodecyl sulphate (SDS), citric acid and tea polyphenols: epigallocatechin gallate (EGCG), epicatechin (EC), rutin) on the interfacial shear elasticity of HWS obtained from a single subject. The aim of this work is to probe the relationship between surface shear elasticity of saliva and the astringent (puckering-like) mouthfeel arising from the consumption of products containing the investigated ingredients. Saliva proteins are extremely surface active and adsorb to the air-liquid interface to form a high-elastic ''solid-like'' surface film. Our findings show that the interfacial shear elasticity G 0 of saliva is significantly reduced when mixed with citric acid, SDS or a tea polyphenol containing a galloyl ring in the molecule (EGCG). These results support the hypothesis that astringency arises from aggregation of salivary proteins, thereby reducing lubrication of oral tissues. Minor or no effect is observed from the interaction of saliva with EC or rutin. Furthermore, we investigate the possibility of using mucins as a simple model for saliva. Two selected mucins, tested at different concentrations and ionic strength, failed to mimic the elastic interfacial behaviour shown by saliva.
Relationships between saliva and food bolus properties from model dairy products
Food Hydrocolloids, 2011
During food consumption, complex oral processing occurs to transform the food into a bolus, ready to be swallowed. The objective of this study was to relate food, saliva and bolus properties, by using model dairy products, to better understand the role of saliva in bolus formation. Un-stimulated and stimulated saliva was collected from 5 subjects and biochemical and enzymatic properties were measured. Food bolus was then obtained from 8 different dairy products, varying in composition and ranging from liquid to gelled samples. The rate of saliva incorporation, pH, spreading ability and bolus rheological properties were determined. Some correlations seemed to exist between lysozyme activity and bolus properties. Subject and food product had a significant effect on almost all bolus properties. The rheology of bolus was highly correlated with food product texture. Even though preliminary, this approach could be used to better understand stimulus release and perception during food consumption.
Correlations between saliva protein composition and some T–I parameters of astringency
2001
Saliva samples were collected from 12 panellists immediately before and after the sensory assessment of two red wine samples and the salivary proteins in all samples were analysed by high performance liquid chromatography (HPLC). Three peaks appeared in the majority of the chromatograms and the areas of these peaks were individually correlated for each assessor against four astringency time±intensity (T±I) parameters (time to maximum intensity, total duration, maximum intensity and area under the T±I curve). Astringency was not correlated with the total area in the saliva chromatograms. However, statistically signi®cant correlations were obtained between the area of particular proteins and the sensory data indicating that the concentration of individual proteins in saliva might be more important for astringency than the total protein content. Signi®cant correlations were also obtained between the relative concentration of individual proteins and the T±I data.
Investigation of milk proteins binding to the oral mucosa
Food & Function, 2013
High protein dairy beverages are considered to be mouth drying. The drying sensation may be due to the product protein content; however the mechanism of this mouth drying is uncertain. This study investigated the potential adhesion of milk proteins to porcine oral mucosa in vitro. Purified casein and b-lactoglobulin were fluorescently labelled, placed on porcine oral mucosal tissues and their resistance to wash out with simulated saliva was monitored using fluorescence microscopy. Casein was found to be more adhesive to porcine mucosa than b-lactoglobulin. Some investigation into the reason for this difference in mucoadhesion was conducted by thiol-content analysis, rheology and zeta-potential measurements. The higher viscosity of casein solution and smaller zeta-potential is believed to be responsible for its better retention on mucosal surfaces. These findings suggest that casein and whey protein are both capable of binding and eliciting mouth drying in high protein dairy beverages. d Royal Berkshire NHS Trust, RG1 5AN Reading, UK † Electronic supplementary information (ESI) available: Scheme of the regions of porcine tongue dissected for tissue specimens, TLC of labelled proteins and DLS of casein solutions. See
Food Hydrocolloids, 2021
In recent years, the dynamic aspects of the oral perception of food have increasingly been taken into account in food texture characterization. At the same time, the experimental settings of instrumental measurements have also been emulating "oral contexts" more closely. The aspects related to in-mouth handling that have been incorporated into food studies include using saliva as a key material. Semisolid (or liquid) food does not usually need mastication but undergoes more subtle processes involving the tongue and palate, among other buccal structures, in which saliva is omnipresent. Creaminess, mouthfeel and astringency are central sensory sensations for which oral handling and consequently, saliva is pivotal. The present review examines the experimental considerations involved in using saliva in the rheology and tribology of liquid and semisolid foods. It also analyses some instrumental parameters that have been related to sensory attributes of liquid and semisolid foods.