Partition of Main and Trace Minerals in Milk:  Effect of Ultracentrifugation, Rennet Coagulation, and Dialysis on Soluble Phase Separation

Abstract

A study was carried out on the effect of soluble-phase separation on mineral distribution in milk. Fractioning was carried out by rennet coagulation (RC), ultracentrifugation (UC), and dialysis (D) against a large volume of water (1:10). Reconstituted skim milk powder was used and calcium, magnesium, sodium, potassium, phosphorus, manganese, zinc, citrate, lactose, and nitrogen were determined in the soluble fraction. The results of the first two procedures were comparable, except for Zn, which was lower in RC; greater precision was achieved with UC, especially for manganese. On fractioning by dialysis, Ca and Zn levels in the diffusate were higher than in the soluble fractions obtained by UC and RC as a result of long dialysis times (24 h) and low operating temperature (5 °C). With dialysis, Na and K levels in the diffusate were lower than with the other procedures. Of the three procedures assayed, UC appeared to be the best suited for work in series. Keywords: Dialysis; rennet coagulation; ultracentrifugation; mineral balance; milk salts

Distribution of calcium, magnesium, phosphorus, zinc, manganese, copper and iron between the soluble and colloïdal phases of ewe's and goat 's milk

“…The soluble phase was separated by high-speed centrifugation as described by De la Fuente et al (1996) in a Sorvall Combi Plus ultracentrifuge (Wilmington, USA): 30 mL of milk was centrifuged (100 000 g) at 20°C for 1 h using a 5D-RT-1250 rotor. The supematant was carefully removed and vacuum-filtered through Whatman 40 paper.…”

“…Calcium and magnesium were measured by flame atomic absorption spectrometry and phosphorus was estimated colorimetrically by a molybdenum blue method after sample digestion in a microwave oyen according to De la Fuente et al (1996). Mn, Zn, Fe and Cu were measured by graphite furnace atomic absorption spectrometry using the procedures proposed by De la Fuente et al (l995a,b).…”

“…Methods which include isolation by acidic precipitation are unsuitable, as alteration of the pH causes redistribution of the elements that are to be analyzed, so that the original distribution is lost (Frans son and Lônnerdal, 1983). And again, it seems c1ear (Singh et al, 1989;De la Fuente et al, 1996) that separation by dialysis favors the passage of mineraIs, particularly calcium and zinc, from the micellar complex to the soluble phase.…”

Copper, zinc, calcium and magnesium content of alcoholic beverages and by-products from Spain: Nutritional supply

“…The digest was then cooled and the resulting solution diluted with ultra-pure water depending on the expected Zn, Ca and Mg concentrations. The adding of 0.2 ml of LaCl 3 solution as a matrix modifier in order to avoid the phosphate interferences (De la Fuente et al 1996;Moreno-Torres et al 2000) was done for the Ca and Mg measurements ( Jodral-Segado et al 2003). Zn, Ca and Mg determinations were carried out by direct aspiration into the flame atomic absorption spectrophotometer.…”

Calcium and Magnesium Levels in Agricultural Soil and Sewage Sludge in an Industrial Area from Southeastern Spain: Relationship with Plant (Saccharum officinarum) Disposition

“…A second dilution was prepared by taking different aliquots of the previous dissolution and diluting them with ultra pure water. In order to avoid the phosphate interference, 0.2 ml of LaCl 3 solution was added as matrix modifier (De la Fuente et al, 1996;Moreno-Torres et al, 2000). Calcium and magnesium determination were carried out by direct aspiration into the flame atomic absorption spectrophotometer (Perkin-Elmer 1100B double beam atomic absorption spectrophotometer, Perkin-Elmer Corp., CT).…”