Texture measurements of protein enriched foods for elderly.

Abstract

Elderly people require nutritious food with a high protein content in their diet, and at the same time the food should be attractive and easy to swallow. A good diet not only helps in protecting the health but it also speeds up recovery during illness. There were two main aims of this thesis. The first was to examine how protein enrichment of a barley porridge influenced sensory and texture properties of the porridge. In the second part, commercial dairy products were classified based on sensory, viscosity and texture analysis. In both the experiments correlations between sensory and instrumental texture methods was examined. The barley porridge was enriched with two protein sources, Skim Milk Powder (SMP) and Whey Protein Concentrate 80 (WPC80). The design factors in porridge development, in addition to protein sources, were protein concentrations (4%, 7% and 10%) and protein addition time (before and after cooking). In the SMP porridge samples, sensory scores for the attributes increased with the increase in protein concentration. The protein addition time (before and after cooking) had a greater influence on WPC80 porridge samples compared to protein concentration. The instrument texture results of firmness, consistency, cohesiveness and index of viscosity were correlated with sensory attributes . Colour analyses showed that the yellow tone was significantly different (p<0.05) for the factor protein concentration. The increase in protein concentration shifts colour saturation towards yellow. Based on sensory analysis and texture and viscosity measurements of 14 commercial products it was possible to characterise the products into International Dysphagia Diet Standardisation Initiative (IDDSI) classification system for people with chewing and swallowing problems. The sensory attributes thickness with spoon, thickness in mouth and swallow had a high correlation (R2= 0.90, 0.89 and 0.89) with instrumental measured texture properties. The main conclusions were that the protein concentration affected SMP protein enriched porridge samples significantly, whereas protein addition time significantly affected WPC80 porridge samples. Additionally, the denaturation of proteins in the WPC80 porridge affected the appearance, texture and sensory properties of the porridge. Test of commercial dairy products showed that the international classification system, IDDSI provided a simple classification system for products aimed for elderly people with swallowing problems.