Zur Lipolyse der Milch durch technologische Beeinflussungen 1. Mitt. Stand der Kenntnisse und Untersuchungen zur Beeinflussung von Milch und Rahm durch Pumpen

Abstract

Durch die zunehmende Mechanisierung und Automatisierung der Milcherzeugung und ‐Verarbeitung kann es zu einer stärkeren mechanischen und thermischen Beeinflussung der Milch kommen. Es wird ein kurzer Überblick über die am Milchfett auftretenden Veränderungen gegeben. Zur Ermittlung des Grades der Veränderungen kann u. a. die Bestimmung des freien Fettes, der freien Fettsäuren, von Enzymaktivitäten und physikalischen Eigenschaften herangezogen werden. Dazu wird über die gebräuchlichsten Untersuchungsmethoden berichtet. Weiterhin werden Ergebnisse der Prüfung der Beeinflussung der Milch durch Pumpen dargestellt.

The milkfat globule membrane—methodologies for measuring milkfat globule (membrane) damage

“…Finally, differences in the susceptibility of individual milks, which depend on the vulnerability of the MFGM and the balance of activating factors and inhibiting factors, have been observed (Deeth & FitzGerald, 1995;Evers, 2003). The above reasons would explain why, in some studies, differences between repeated measurements of the same treatment were larger than those between different treatments (Kirst, 1980a).…”

“…For example, the desorption of XO also depends on factors other than mechanical activation (e.g. trace element content and temperature) and, therefore, this enzyme has been considered to be of only limited use for the determination of the degree of mechanically induced changes in the MFGM (Kirst, 1980a). Wiking et al (2003) found that their assay for measuring the XO activity in milk plasma was not sensitive enough to detect the effect of mechanical stress inflicted on fat globules by pumping.…”

“…Consequently, in various studies, the FFA concentration has been measured to determine the degree of MFG(M) damage (Te Whaiti & Fryer, 1976b;de Boer & Nooy, 1980;Fl . uckiger & H. anni, 1980;Kirst, 1980aKirst, -c, 1981Kirst, , 1996Fl . uckiger, H. anni, Jegerlehner, & Graber, 1981;Herbst et al, 1984;Rudzik, 1987;Evers et al, 2001b;Wiking, Bj .…”

“…The MFGM markers selected include xanthine oxidase (XO) (Reuter, Kurzhals, Back, & Biewendt, 1975;Stannard, 1975;Wiking et al, 2003), alkaline phosphatase (Stannard, 1975;Deeth & Fitz-Gerald, 1978;Salvatierra, Stannard, & Parkinson, 1978), 5 0 -nucleotidase (Baumrucker & Keenan, 1973;Keenan et al, 1983), adenosine triphosphatase (Baumrucker & Keenan, 1973), phosphodiesterase I (Keenan et al, 1983) and acid phosphatase (Keenan et al, 1983). XO activity has been determined using polarographic, radioenzymic or colorimetric methods (Kirst, 1980a). Deeth and Fitz-Gerald (1978) found that the release of alkaline phosphatase into the milk plasma increased with increasing time of agitation.…”

“…As in the case of the free fat centrifugation method, various versions of the method have been reported. Lagoni and Peters (1959) and Kirst (1980a) extracted the sample three times with a mixture of diethyl ether and petroleum ether, and thus essentially used the R . ose Gottlieb principle (Gottlieb, 1892) except for the digestion step, whereas Aule and Worstorff (1975), Deeth and Fitz-Gerald (1978) and Lehman (1988b) used either hexane or petroleum ether as the solvent.…”