Magnesium in milk

This review draws attention to the significance of magnesium in milk, both the technical and human health aspects. Magnesium has been subject to less research than calcium in both aspects. Magnesium is present in cows' milk in ∼10% of the concentration of calcium. About two-thirds of the magnesium is soluble, whereas about one third of calcium is soluble. Although magnesium is less significant than calcium in dairy systems, it warrants more investigation. Magnesium plays numerous physiological roles in the human body and is implicated in many critical health issues such as metabolic syndrome and skeletal muscle loss. Despite its well-established significance in health, magnesium is often reported as an under-consumed nutrient. Milk and dairy products are already one of the main sources of dietary magnesium. There is an opportunity to develop milk and dairy products as efficient vehicles for supplementary dietary magnesium delivery with more research into fortification options

Altering the casein to whey protein ratio to enhance structural characteristics and release of major yoghurt volatile aroma compounds of non-fat stirred yoghurts

Altering the casein:whey protein ratio (CN:WP) is an important determinant of the quality of yoghurt. In this study, the textural, rheological, microstructural and volatile aroma compound release properties of non-fat stirred yoghurts with varying CN:WP were compared. Yoghurts were manufactured using different fortifiers (whey protein isolate, sodium caseinate, low-heat skim milk powder) to achieve varying CN:WP at total protein levels of 4, 4.5 and 5%. At all protein levels, yoghurts with lower CN:WP were firmer and stiffer than those with higher CN:WP. Yield stress of gels increased when the CN:WP deviated from the unfortified CN:WP, 3.2:1. Samples with low CN:WP also had a more elastic gel at 4.5 and 5% total protein. Alteration of CN:WP did not significantly alter volatile aroma compound release from yoghurts. The results demonstrate that CN:WP, and not only total protein or total solids, is an essential consideration when formulating non-fat stirred yoghurts with acceptable qualities

The rheological properties of calcium-induced milk gels

The study investigated the calcium-induced gelation of milk during heat treatment. Rheological measurements showed that the addition of 10-20 mM calcium chloride caused thickening or gelation of milk on heating at 70 C. Thickening was observed with 10 mM addition, while gelation was evident with ≥12.5 mM additions, as indicated by an increase in the storage modulus (G′) of the calcium-added milk. The final G′ and breaking stress of milk gels made from ≥12.5 mM added calcium increased with calcium addition. Pre-heat treatment significantly affected the strength of calcium-induced milk gels. Strong milk gels were obtained by the addition of 20 mM calcium chloride to pre-heated milk and holding at 70 C for 60 min followed by cooling to 20 C. The technology of making calcium-induced milk gels can be exploited commercially to make non-fermented dairy gels