Characterization of caseinomacropeptides released from renneted raw and UHT treated milks

Abstract

Summary -The kinetics of release of the glycosylated and carbohydrate-free forms of caseinomacropeptide (CMP) was studied in renneted rawand UHT (140 oC for 10 s) milks. The new chromatographic method utilized allowed quantitative determinations of both molecular torrns. UHT treatment leads to a 40% decrease of the final content in glycosylated forms compared to the value determined in raw milk. The results obtained show that carbohydrate-free ic-casein constitutes 52% of whole x-cassin. When milk is UHT treated,~-Iactoglobulin only seems to influence the release of the glycosylated form. Nevertheless, no conclusion can be drawn concerning the localization in the micellar structure of both molecular forms of x-caseln.

Quantitative determination of bovine κ-casein macropeptide in dairy products by Liquid chromatography/Electrospray coupled to mass spectrometry (LC-ESI/MS) and Liquid chromatography/Electrospray coupled to tamdem mass spectrometry (LC-ESI/MS/MS)

“…For total CMP AB standard (row 2), A and B forms of aglyco-CMP represented 31% and 16% of the total CMP AB confirming the predominance of the aglyco-CMP A compared with aglyco-CMP B . These values fitted well within the range of values reported in the literature (Walstra & Jenness, 1984, Chapter 6;Vreeman et al, 1986; Ferron-Baumy, Molle´, Garric, & Maubois, 1992). Commercial total CMP AB gave approximately the same results (row 3).…”

Quantity and carbohydrate content of glycomacropeptide fractions isolated from raw and heat-treated milk

“…However, only 33% of the GMP was released and isolated from milk that had undergone VHTLT treatment. As reported by Ferron-Baumy et al (1992), there was a decrease in the amount of GMP released and isolated from milk as the severity of heat treatment increased. The reduced release of GMP from-heat-treated samples was most likely due to the denatured whey proteins in the milk interacting with k-casein, reducing the accessibility of chymosin to the cleavage site of k-casein (Hindle & Wheelock, 1970;Van Hooydonk et al, 1987;Veith & Reynolds, 2004).…”

“…It is well known that, during heating of milk, b-lactoglobulin can form a complex with k-casein at the micelle surface, which limits rennet hydrolysis of k-casein and release of GMP (Calvo, Law, & Leaver, 1995;Van Hooydonk, DeKoster, & Boerrigter, 1987). As it is not only the peptide but also the carbohydrate moieties (especially NeuNAc content) that are thought to be responsible for the various reported biological activities of GMP (Li & Mine, 2004b;Manso & Lopez-Fandino, 2004;Yvon, Beucher, Builloteau, Huerou-Luron, & Corring, 1994), and as processing conditions are likely to influence glycosylation (Ferron-Baumy, Molle, Garric, & Maubois, 1992), it is necessary to understand how milk heat treatments influence the carbohydrates bound to GMP. In this paper, the effect of milk heat treatment on the quantity of GMP recovered and the carbohydrates associated with this GMP after hydrolysis by rennet are reported.…”

Article

“…The concentration of CMP measured in whey at the cutting (0.91 g·L -1 ) was in agreement with those obtained from renneted raw milk by FerronBaumy et al [7]. The concentration of CMP in whey decreased thereafter, showing that the CMP was degraded from the drawing step.…”