Effect of calcium, citrate and urea on the stability of ultra-high temperature treated milk: A full factorial designed study

Abstract

The composition of raw milk is important for the stability of dairy products with a long shelf-life. Based on known historical changes in raw milk composition, the aim of this study was to get a better understanding of how possible future variations in milk composition may affect the stability of dairy products. The effects of elevated calcium, citrate, and urea levels on the stability of ultra-high temperature (UHT) treated milk stored for 52 weeks at 4, 20, 30, and 37 • C were investigated by a two-level full factorial designed study with fat separation, fat adhesion, sedimentation, color, pH, ethanol stability, and heat coagulation time as response variables. The results showed that elevated level of calcium lowered the pH, resulting in sedimentation and significantly decreased stability. Elevated level of citrate was associated with color, but the stability was not improved compared to the reference UHT milk. Elevated levels of urea or interaction terms had little effect on the stability of UHT milk. Storage conditions significantly affected the stability. In conclusion, to continue produce dairy products with high stability, the dairy industry should make sure the calcium content of raw milk is not too high and that storage of the final product is appropriate.

Raw Cow Milk Protein Stability under Natural and Technological Conditions of Environment by Analysis of Variance

“…In many papers [ 18 , 22 , 65 , 66 , 67 , 68 , 69 , 70 ], HS was monitored in relation to technological modifications of milk, such as pH adjustment or other artificial additives, e.g., Ca (CaCl 2 ), citrate, phosphates (different forms) with a targeted shift of milk buffering capacity (MBC) or whey protein and casein additions (technological improvement of raw material). The effects of elevated calcium, citrate, and urea levels on the stability of UHT milk stored for 52 weeks at 4, 20, 30, and 37 °C were investigated by Karlsson et al [ 4 ]. An elevated level of calcium lowered the pH, resulting in sedimentation and significantly decreased stability.…”

“…The values of mentioned indicators are then decisive for the processing of raw milk into dairy products. Dairy products with a long shelf-life must show good stability, mainly influenced by raw milk composition [ 4 ]. Thus milk quality is also important regarding the possibility of applying the added value in the dairying.…”

“…As an indicator of protein stability, this heat stability (HS; also milk thermostability) is also an important technological property of raw milk as its evaluation can contribute to higher added value in dairy [ 7 , 8 , 9 , 10 ]. The composition of raw milk is essential for the stability of dairy products with a long shelf-life [ 4 ]. A sample of milk with short HS is generally considered to be unstable in terms of processability.…”

“…Several HS studies have been performed during technological modifications of milk. While the change in calcium (CaCl 2 ) level showed a high effect on the raw cow milk HS [ 4 , 34 , 35 , 36 , 37 ], the modifications of the citrate and urea concentration did not affect this HS value [ 4 ]. The HS of calcium citrate fortified milk was higher than the control milk and other calcium (different salts) fortified milk [ 38 ].…”

Improving ultra high temperature processability of high protein beverages

“…This leads to higher levels of free ionic calcium in 7.5-RMPC. High ionic calcium in milk products is often considered detrimental to their stability during thermal processing (Karlsson et al, 2019;Lewis, Grandison, Lin, & Tsioulpas, 2011;Singh, 2004). However, 7.5-RMPC showed significantly higher heat stability than 7.5-RSMP (HCT values of 6.80 and 1.80 min, respectively) (Fig 4.2).…”