The influence of flavour enhancement and protein fortification of pureed meals on perceived palatability, appetite and food intake in older people

Flavour enhancement has been identified as a potential strategy to counteract the loss of taste in pureed foods (1,2) , making them more palatable and recognisable for older people (3) . However, it is unclear whether flavour enhancement with protein fortification of pureed diets can influence appetite and dietary intake. Thus, the aim of this study was to explore the influence of flavour-enhanced and protein-enriched pureed meals on perceived appetite, palatability, and intake in older people. Forty-one healthy older people were recruited in Reading, UK to partake in a randomised, crossover study involving three study days. Participants consumed a standard breakfast, followed by one of three ad-libitum pureed lunches (high protein (HP), high-protein-with-aroma (HP-Aro) or low-protein (LP)) and three hours later an ad-libitum pureed buffet-style meal. Intake of the ad-libitum meals were measured by weighing food leftovers, perceived appetite and palatability were rated using a visual analogue scale and remaining intakes for the day assessed using food diaries. SPSS was used to carry out all statistical analysis. Differences in energy and macronutrient intake between the three ad-libitum pureed lunch meals were examined using repeated measures analysis of variances (RM-ANOVA) with pair-wise comparisons (Bonferroni corrected). This test was also applied to assess the effects of these meals on subsequent intake at the ad-libitum buffet meal and total day intake. Post-lunch appetite sensations were analysed using Friedman’s test with Wilcoxon signed-rank test. Changes in self-reported palatability ratings between the three pureed lunch meals were evaluated using RM-ANOVA with pair-wise comparisons (Bonferroni corrected). Statistical significance was accepted at p<0.05 in all analysis. Participants’ intake of ad-libitum pureed lunch was significantly higher when they consumed the HP+Aro pureed meal compared to the HP and LP pureed meals (p<0.001). Protein fortification with or without flavour enhancement significantly reduced energy intake (EI) and macronutrient intake at subsequent ad-libitum meal (p<0.001). Even though protein fortification did not affect EI for the rest of the day, it led to greater total protein intake (p<0.001). However, participants had higher total EI, carbohydrate and fat intake across the study day when they had LP pureed lunch compared to when they had HP pureed lunch (p<0.001) but no difference occurred between the LP and HP + Aro conditions (p=0.72). Protein fortification led to significantly greater satiety (p<0.001) and fullness (p=0.04) post lunch. Palatability ratings were significantly improved with flavour enhancement (p<0.05). The study suggested that intakes and liking of pureed meals are greater through the combination of flavour enhancement and protein fortification among older people. Also, although protein fortification could suppress appetite which might lead to reduced EI across the whole day, this may be mitigated by the combined addition of the flavour enhancer.