The influence of ultrasound on fermentation of goat milk supplemented with whey protein concentrates

Abstract

Due to specific chemical composition of goat milk one of the main problems in production of goat milk yogurt is weakness and lack of consistency, as well as prolonged fermentation time. To obtain a satisfactory consistency of set-style yogurt made of goat milk, an increase in the content of non-fat solids is required. For this purpose supplementation of milk with whey protein concentrates can be used. Possibility of application of ultrasound treatment of goat milk supplemented with 1% WPC was used in order to shorten fermentation time. Three series of samples were produced from goat milk supplemented with 1% WPC: A - standard treatment, B - ultrasound treatment 200W/10 min and C - ultrasound treatment 400W/10 min. Physicochemical properties of raw milk, milk supplemented with 1% WPC, heat treated milk and milk after ultrasound treatment were investigated. Furthermore, during fermentation change of viscosity and pH were investigated. Based on data analysis it was concluded that the samples C had the shortest time of fermentation. At the end of fermentation highest viscosity values also had samples.

Specifičan proteinski sastav i puferni kapacitet kozijeg mleka utiču na produženo vreme fermentacije i lošiju strukturu čvrstog jogurta. Kako bi se dobio čvrsti jogurt od kozijeg mleka zadovoljavajućih reoloških karakteristika, neophodno je povećati sadržaj suve materije bez masti što se može postići dodatkom koncentrata proteina surutke. U cilju skraćenja trajanja fermentacije, u radu je ispitivana mogućnost primene ultrazvučnog tretmana kozijeg mleka sa dodatkom KPS u proizvodnji čvrstog jogurta. Za proizvodnju čvrstog jogurta korišćene su tri serije uzoraka kozijeg mleka sa dodatkom 1% KPS podvrgnute različitim tretmanima: A - standardni tretman; B - ultrazvuk 200W/10 min i C - 400W/10 min. Vršeno je ispitivanje fizičko-hemijskih karakteristika sirovog mleka, mleka nakon dodatka 1% KPS, termički tretiranih mleka, i mleka nakon ultrazvučnih tretmana. Takođe, u toku fermentacije praćena je promena viskoziteta i pH vrednosti. Na osnovu dobijenih rezultata utvrđeno je da je fermentacija najkraće trajala kod uzoraka C, koji su ujedno imali najviše vrednosti viskoziteta na kraju fermentacije.