Distribution of Conjugates of Alkylphenols in Milk from Different Ruminant Species

Abstract

Conjugated alkyphenols in milk constitute a reservoir for species-related alkylphenols in dairy products. The distributions of conjugated alkylphenols between different conjugation pathways (sulfation, phosphorylation, and glucuronidation) were determined in cows', sheep's, and goats' milk. Species-related p- and m-cresols and 3- and 4-ethylphenols were found to be mostly conjugated with sulfate with minor amounts associated with phosphate and glucuronide conjugates in all milks. Similar distributions were observed for alkylphenols in the urine and milk from the same ewe. Phenol was present in minor amounts distributed sporadically between different conjugates in the milks. Sulfate-conjugated phenol was not detected in the ewe's urine, which included equal amounts of glucuronide and phosphate conjugates. The amounts of alkylphenols were different in sheep's milk from different sources suggesting that there were effects of feed, breed, and individual animal variation on the metabolism of alkylphenols.

Terpenoids and benzenoids in La Serena cheese made at different seasons of the year with a Cynara cardunculus extract as coagulant

“…It has already been mentioned that benzaldehyde, 2-phenylethanal, benzoic acid methyl ester and benzyl alcohol are common components of flowers (Buchbauer et al, 1996;Knudsen et al, 1993), but their presence in cheeses, as well as that of alkylphenols, is probably more related to the microbial metabolism of aromatic amino acids (Christensen et al, 1999;Yvon et al, 1998). Kilic and Lindsay (2005) found higher amounts of alkylphenol conjugates in milk and urine of ewes grazing on pasture than for ewes held in pens.…”

“…Ethyl benzene, propyl benzene and all of the xylene isomers decreased significantly with cheese age (Po0.001), while, benzyl alcohol, 2-phenylethanol, benzoic acid ethyl ester as well as the phenolic compounds increased significantly (Po0.01) during cheese ripening. The para isomer of cresol possibly originates from tyrosine catabolism during cheese ripening (Christensen et al, 1999), although it could be also released from the alkylphenol conjugates present in ewes' milk, which is particularly rich in these compounds (Kilic & Lindsay, 2005). In cheese 2-phenylethanol could originate from phenylalanine catabolism (Christensen et al, 1999).…”

“…The isomers of dimethyl benzene (xylene), trimethyl benzene and tetramethyl benzene have been tentatively identified on the basis of the general rule of order of elution by increasing boiling point. Two isomers of methyl-phenol (cresol) have been detected in milk and cheese samples, and these are probably 4-methyl-phenol (p-cresol) and 3-methyl-phenol (m-cresol), the major isomers found in ruminant milk (Kilic & Lindsay, 2005). Previously published studies using X -cyclodextrin columns made it possible to compare the order of elution of isomers in this study with previously published data (Kellerhals, online Varian-Chrompack Application Note; Sidisky, 1994).…”

Arylsulphatase activity in milk and rennet from different sources

“…Recent studies in this laboratory indicated that species-related alkylphenols, including p-and m-cresols and 3-and 4-ethylphenols in ruminant milks, were present predominantly as sulphate esters (Lopez & Lindsay, 1993;Kilic & Lindsay, 2005). Species-related free alkylphenols have been found to contribute to the flavour of specialty cheeses (Ha & Lindsay, 1991).…”

Protective Role of Selenium Against Over-Expression of Cancer-Related Apoptotic Genes Induced By O-Cresol in Rats

“…They have been found in food and drink (3,4), air, sediment, soil, and water (5)(6)(7)(8)(9). According to the US EPA, air cresol levels are about 32 ng m -3 , rising to 1.5 μg m -3 for o-cresol in the vicinity of intense traffi c and gas stations.…”