Tribology and rheology of potato protein and pectin mixtures and Maillard conjugates

This study aimed to compare the tribological and rheological properties of plant proteins versus their mixtures or conjugates with polysaccharides. We hypothesize that combining potato proteins (Po) with pectin (Pe) at various concentrations (0.5–5.0 wt%, ratios 1:1 and 1:2 w/w) will improve the lubrication performance of plant proteins by virtue of viscosity modification and boundary lubrication. Po showed shear thinning behavior with limited concentration-dependence in boundary and mixed lubricity. Pe on the other hand showed pronounced concentration-dependent flow and lubrication behavior delivering favorable boundary and viscous lubricity. Pe dominated the lubrication and high shear rate flow behavior in Po + Pe mixtures, governed mainly by the concentration of Pe and the hydrodynamic volume rather than the total concentration of the biopolymers. Maillard reaction (≤33% degree of conjugation) led to more negatively-charged protein-polysaccharide conjugates versus the sole biopolymers (p < 0.05). The conjugation decreased the second plateau shear viscosity of the Po + Pe mixtures and led to improvement in boundary and mixed lubricity when a reduced entrainment speed parameter was used. Findings from this study may inspire future studies combining plant proteins with polysaccharides to enhance their lubrication behavior and eventually improve the textural properties of plant-based foods

Viscosity of food influences perceived satiety: A video based online survey

Food texture seems to offer a promising strategy for the control of expected satiety, satiety, satiation and daily caloric intake. The aim of this study was to examine the effect of food texture, more specifically the effect of different levels of viscosity, on perceived satiety through an online survey where the viscosity levels of protein-based beverages were visually perceived using a newly developed video-based demonstration. Whey protein beverages were prepared with viscosities being manipulated using xanthan gum and their viscosity and tribological properties were measured instrumentally. Subjects (n=211) watched beverages being poured in videos streamed online and were instructed to imagine drinking them. The results showed that instrumentally measured HV (high viscous) and MV (medium viscous) beverages were visually perceived by the participants as being more satiating immediately and 2 h later after the imagined drinking event as compared to LV (low viscous) beverages (p<0.05). Also, sensory attributes such as visually perceived smoothness, thickness, creaminess and watery were shown to be important factors in the perception of satiety (the creamier or thicker the beverage the higher the perceived satiety scores). Therefore, a video-based online demonstration is a highly feasible and convenient tool to measure the effect of food texture on perceived/expected satiety that can be useful in Covid-19 pandemic situation, latter necessitates online participation in many situations. More importantly, key role of food/beverage texture expressed through visual cues alone, may open new avenues of informing consumers about the degree of the perceived satiety/fullness even before the product is consumed

Effects of oral lubrication on satiety, satiation and salivary biomarkers in model foods: A pilot study

With a dramatic increase in overweight and population with obesity over the last decades, there is an imminent need to tackle this issue using novel strategies. Addressing obesity issues by generating satiety in food to reduce energy intake has been one of those prominent strategies and often textural interventions have been used to generate satiety, specifically in short-term trials. This study aimed to investigate the role of preloads varying in their oral lubrication properties on appetite sensations, food intake, salivary friction and concentration of salivary biomarkers (proteins, α-amylase and mucins) in collected human saliva (n = 17 healthy participants). The preloads were model foods (flavoured hydrogels) either high or low in their lubricating properties, assessed both by instrumental and sensorial measurements. The results showed that hunger and desire to eat decreased immediately after preload and remained decreased for 10 and 20 min, respectively, after preload in the high lubricating condition compared to control (all p < 0.05). Fullness increased immediately after preload and remained increased for 10 and 20 min, respectively, after preload in high lubricating condition compared to control (p < 0.05). However, after controlling the values for baseline, such significant effect of the intervention did not exist anymore. Only the effect of time is observed. Consuming high lubricating hydrogels showed no effect on food intake and salivary biomarkers in this pilot study. Salivary lubrication correlated with feeling of fullness. Considering the issue of large time-interval (30 min) between preload and next meal in this study, it is worthwhile investigating the immediate effects of oral lubrication on appetite control, food intake and salivary biomarkers