Control of the Maillard reaction by ferulic acid.

This study investigated how ferulic acid (FA) affects the formation of certain Maillard reaction products (MRPs), i.e., early MRPs, fluorescent and non-fluorescent advanced glycation end products (AGEs), and melanoidins in model systems. Glycation mixtures were prepared containing soy glycinin or bovine serum albumin (final concentration 10mg/ml) and fructose (222mM) in 0.2% KOH in the presence or absence of FA (12.95mM) and incubated at 60°C for 60min. The extent of the MR was estimated by analysis of free amino groups, the incorporation of sugar into the protein backbone as well as the formation of N(ϵ)-(carboxymethyl)lysine (CML), fluorescent AGEs (λexc=337nm, λem=350-550nm) and melanoidins (absorbance at 420nm). Formation of CML and fluorescent AGEs was reduced by nearly 90% by the addition of FA while early MRPs and melanoidins were inhibited to a lesser extent (∼10% and 28%, respectively) compared to AGE formation. A controlled formation of early MRPs was achieved by use of FA, and it is a new finding. To the best of our knowledge, for the first time the use of FA as a reliable means of obtaining novel glycoprotein preparations containing low amounts of AGEs, with the potential to be used as functional food ingredients, is proposed.

Formation of N(epsilon)-(carboxymethyl)lysine and loss of lysine in casein glucose-fatty acid model systems.

Advanced glycation end-products (AGEs) and advanced lipoxidation end-products (ALEs) form when proteins are heated with reducing sugar or lipid. N(epsilon)-(Carboxymethyl)lysine (CML) is the most commonly studied AGE/ALE in foods, but the relative importance of dietary sugar and lipid as its precursors is uncertain. The aim of this study was to determine the relative amounts of CML formed from fatty acid and glucose in a model food system. Model systems were prepared by heating casein (3.2%) with glucose or fatty acid (oleic, linoleic, linolenic, or arachidonic acid) (200 mM) or a mixture of glucose and linolenic acid (200 mM of each precursor) at 95 degrees C for up to 8 h. CML was determined by ultrapressure liquid chromatography-tandem mass spectrometry. The amount of CML formed from casein and glucose incubated at 95 degrees C for 8 h was 15-fold higher than that obtained when casein was heated with arachidonic acid under the same conditions. However, the loss of lysine in the casein-arachidonic acid incubations was 83% compared to 54% loss in the casein-glucose incubations. The loss of lysine in casein-fatty acid model systems increased with degree of unsaturation of the fatty acid. The formation of lipid peroxidation products during oxidation of fatty acids might be a potent factor for loss of lysine in the casein-fatty acid systems.

Determination of Nepsilon-(carboxymethyl)lysine in food systems by ultra performance liquid chromatography-mass spectrometry.

We report the use of ultra pressure liquid chromatography (UPLC), coupled to a tandem mass spectrometer operated in multiple reaction monitoring mode to determine the advanced glycation endproduct, Nepsilon-(carboxymethyl)lysine (CML). The procedure was applied to acid hydrolyzates of protein isolated from a range of foods (milks processed at different temperatures, butter, cheese, infant formulae, bread, raw and cooked minced beef and olive oil). Highest levels of CML were determined in white bread crust (15.2 +/- 0.63 mmol/mol Lys), wholemeal bread crust (13.1 +/- 0.61 mmol/mol Lys) and evaporated full-fat milk (4.86 +/- 0.77 mmol/mol Lys). Lowest levels of CML were measured in raw minced beef beef (0.03 +/- 002 mmol/mol Lys), raw full-fat cow's milk (0.08 +/- 0.03 mmol/mol Lys) and pasteurized skimmed cow's milk (0.09 +/- 0.002 mmol/mol Lys). CML could not be detected in olive oil.