TAG composition of ewe's milk fat. Detection of foreign fats

Abstract

The TAG composition of 45 samples of ewe's milk, collected throughout the year from five Spanish breeds, was analyzed according to their carbon number by using short capillary column GC. The TAG content had a bimodal distribution with maxima at C 38 (12.8%) and C 52 (8.4%). The TAG composition did not vary significantly with respect to the time of year of sampling but was affected by the breed. Multiple regression equations based on TAG content are proposed to detect foreign fats in ewe's milk fat. Analysis of known mixtures of lard, palm oil, and cow's milk fat with ewe's milk fat have experimentally confirmed the accuracy of the equations.Paper no. J10404 in JAOCS 80, 219-222 (March 2003). KEY WORDS:Ewe's milk fat, foreign fat, short capillary column GC, triacylglycerols.The lipid fraction of milk and the products of its degradation, mainly volatile FFA, play an important role in the flavor of cheeses. Different studies have indicated that lipolysis depends on the composition of the TAG of ewe's milk fat, i.e., chain length and degree of unsaturation (1,2). Thus, Batelli and Peregrino (3) observed that lipolysis had a pronounced effect on TAG composition within a low M.W. range during prolonged ripening. The determination of TAG classes according to their carbon number (CN) has been reported as an effective criterion for assessing milk origin (4-6). TAG determination also has been proposed as a means to detect mixtures of foreign fats in milk fat and by the European Community (EC) as an official method for assessing cow milk fat purity (7). TAG composition has been studied in cow's and goat's milk but less so in ewe's milk, where most of the published data refer to a limited number of samples (2,(8)(9)(10)(11). The exception is a study carried out by Muir et al. (12) where samples were taken from ewes, mainly of the Frisone breed, for the duration of 1 yr.FA composition of milk fats varies considerably in response to factors such as feed. It has also been reported that the composition of TAG changes with lactation period (13) or season (12).The objective of this work was, first, to study the range of variation in the composition of TAG, using GC, in ewe's milk fat from five breeds located in different regions and collected throughout the year and, second, to propose multiple regression equations based on the TAG content to detect foreign fat in ewe's milk fat. MATERIAL AND METHODSSamples. Forty-five milk samples were collected at monthly intervals during the milking period from five ovine herds. They were taken from the storage tanks containing milk from the whole herd. Each herd consisted of a different breed: CH (Churra breed with 130 head), W (Awassi breed with 2,500 head), M (Manchega breed with 2200 head), A (Assaf breed with 480 head), A × C (cross between Assaf and Castellana breeds with 170 head). The herds were located in different parts of Spain. For statistical analysis, the samples were distributed in four groups or seasons.Samples from the herds M and W were taken through the year between January ...

Application of Chromatographic and Infra-Red Spectroscopic Techniques for Detection of Adulteration in Food Lipids: A Review

“…The improved system was successful in detecting non-milk fat component in goat milk fat [41] as well as lard in ewe's milk fat [42]. Fontecha and co-workers [41] employed a fairly high number of goat milk samples from five different herds of goats to develop a formula to define pure goat milk fat in terms of TAG composition.…”

“…The formula was found to be useful to indicate deviations of goat milk due to 3 to 5% adulterations either by palm oil or tallow. According to Goudjil and coworkers [42], use of capillary column GC system would be able to detect lard adulterations exceeding 5% in ewe's milk fat based on the multiple linear regression equations obtained using the TAG composition of pure ewe's milk fat and its adulterated blends [ Table 1] [42]. In another study, Simoneau and co-workers [43] employed capillary GC column to detect plant based cocoa butter equivalents (CBE) in CB.…”

“…Minimum detection 10% (w/w) [22] Milk fat of cow and ewe Lard and palm oil in milk fats of cow and ewe GC fitted with high-temperature capillary column to determine The deviation in M value of the model ∑ ai Ci = M + e using values of C42, C44, C48, C50, and C52 indicated adulteration. Minimum detection was 5% (w/w) [42] Milk fat of goat Palm oil and tallow mixed in goat milk fat GC fitted with short capillary column The deviation in M value of the model ∑ ai Ci = M + e using values of C42, C44, C48, C50, and C52 indicated adulteration. Minimum detection was 5% (w/w) [41] Cocoa butter Plant fats in cocoa butter High resolution GC fitted with high-temperature capillary column…”

Adulteration of Argentinean milk fats with animal fats: Detection by fatty acids analysis and multivariate regression techniques

“…Analytical techniques that have been proposed for this fact include the determination of physicochemical properties, constituents of unsaponificable matter and water-soluble and insoluble volatile fatty acids (Van Ruth, Bremer & Frankhuizen, 2010b;Ulberth, 2000). Moreover, the gas chromatography (GC) analysis of TAG or FA profiles of MF in combination with multivariate statistical data processing have been used to detect adulterations in milk and dairy products with foreign fats (Van Ruth et al (2010a); Fontecha, Mayo, Toledano & Juárez, 2006;Goudjil, Fontecha, Fraga, & Juarez, 2003;Povolo, Bonfitto, Contarini & Toppino, 1999;Fontecha, Díaz, Fraga & Juárez, 1998;Ulberth, 1995 andPrecht 1992).…”

Use of changes in triacylglycerols during ripening of cheeses with high lipolysis levels for detection of milk fat authenticity

“…GC determination of the TAGs employing packed or capillary columns followed by multiple regression analysis of the GC results has been proposed by the European Union (EU) as an official method for verifying milk fat purity by detecting levels of 2-5% foreign fat, depending on the source of the added fat (Banfi & Bergna, 1999;EU, 2001;Molkentin & Precht, 2000;Naviglio & Raia, 2003). Moreover, previous studies using short capillary column GC carried out at our laboratory to determine the authenticity of goats' and ewes' milk fat had yielded equations specific for estimating the purity of each of these two types of milk fats (Fontecha, Dı´az, Fraga, & Jua´rez, 1998;Goudjil, Fontecha, Fraga, & Jua´rez, 2003).…”