Coagulation of uf concentrated milk 1. influence of protein concentration, milk heat treatment

Abstract

Rheology of UF concentrated milk coagulation, in relation to milk heat treatment, was researched by the dynamic measurements with the low amplitude oscillation method. Milk was heat treated using four different treatments: A – 72°C, 15 s; B – 77°C, 120 s; C – 85°C, 120 s; D – 100°C, 120 s. Using ultrafiltration, heat treated milk was concentrated to CF 1; CF 2; CF 5 and CF 6. High heat milk treatment completely inhibits coagulation process of samples with standard protein level. By the increase of protein concentration the negative effect of milk heat treatment is reduced and partly, compensated yielding in moderate increase of storage modulus. In the case of extreme heat treatment, casein concentration has light effect on coagulation process resulting in significant reduction of storage modules of samples with highest protein concentration.

U radu je, pomoću dinamičkih merenja, metodom kontinuelnih oscilacija proučavan tok koagulacije mleka koncentrovanog ultrafiltracijom, u zavisnosti od stepena koncentrovanja mleka i režima njegove termičke obrade. Uticaj termičke obrade mleka obuhvatio je praćenje četiri režima termičke obrade mleka (A – 72°C, 15 s; B – 77°C, 120 s; C – 85°C, 120 s; i D – 100°C 120 s). Termički obrađeno mleko je koncentrovano ultrafiltracijom do CF 1 CF 2, CF 5 i CF 6. Praćenjem toka koagulacije pojedinih uzoraka ustanovljeno je da se povećanjem koncentracije kazeina može donekle kompenzovati delovanje umereno visokih temperatura, ali da se pri korišćenju ekstremno visokih temperatura termičke obrade ne mogu porastom koncentracije kazeina značajnije kompenzovati nepovoljni efekti delovanja visokih temperatura.