Development of a low cost protein rich yoghurt for use in nutritional support

Abstract

This study was conducted at Egerton University with the aim of developing protein rich yoghurt for use in nutritional support. Yoghurt was made by blending milk and either egg white or whole egg at 30%(w/v). Skim milk powder was added at l2%(w/v). The mixture was pasteurized at 74°C for 4 seconds, then cooled to 45°C and inoculated with 3%(w/v) Direct Vat Set (DVS) yoghurt starter culture containing Streptococcus salivaris species thermophilus and Lactobacillus delbrfikii species bulgaricus. Fermentation was done at 45°C for 3 hours in a water bath maintained at 45 1: 1 "C. Consequently, the product was placed under cold storage at 6°C to cool and stop further acid development. Analysis was carried out for product physico-chemical and sensory properties. The control, (0% treatment) had all the ingredients contained in the enriched yoghurt except eggs. Preliminary sensory evaluation results showed that enrichment with whole egg gave a product significantly different fiom control on difierence testing. Whole egg enrichment was therefore eliminated. Other treatments involved enrichment with albumin at levels of 0%, 15%, 30%, and 45%. Chemical analysis results showed increase in protein content to 8.50%, ash to 0.96% and total solids to 24.68% at 45% enrichment. Moisture decreased to 75.32%. Starter culture activity significantly decreased with increase in added albumin. There was no significant effect of treatment on level of lactic acid produced on diiferent days for the first five days of cold storage. Enrichment significantly reduced susceptibility of the product to Wheying off. There was no significant difference between the enriched products and the control as evaluated both by a panel of trained panelists and consumers. The acceptable organoleptic properties with increased nutrient density made the developed product suitable for use among people with special nutritional requirements. Organoleptiwlly acceptable yoghurt of up to 8.5% protein has been developed by adding egg white to milk for use in nutritional support.