ascorbic-acid and hexanoic-acid

Physical properties of whey protein isolate (WPI) coating solution incorporating ascorbic palmitate (AP) and alpha-tocopherol (tocopherol) were characterized, and the antioxidant activity of dried WPI coatings against lipid oxidation in roasted peanuts were investigated. The AP and tocopherol were mixed into a 10% (w/w) WPI solution containing 6.7% glycerol. Process 1 (P1) blended an AP and tocopherol mixture directly into the WPI solution using a high-speed homogenizer. Process 2 (P2) used ethanol as a solvent for dissolving AP and tocopherol into the WPI solution. The viscosity and turbidity of the WPI coating solution showed the Newtonian fluid behavior, and 0.25% of critical concentration of AP in WPI solution rheology. After peanuts were coated with WPI solutions, color changes of peanuts were measured during 16 wk of storage at 25 degrees C, and the oxidation of peanuts was determined by hexanal analysis using solid-phase micro-extraction samplers and GC-MS. Regardless of the presence of antioxidants in the coating layer, the formation of hexanal from the oxidation of peanut lipids was reduced by WPI coatings, which indicates WPI coatings protected the peanuts from oxygen permeation and oxidation. However, the incorporation of antioxidants in the WPI coating layer did not show a significant difference in hexanal production from that of WPI coating treatment without incorporation of antioxidants.

Topics: Aldehydes; alpha-Tocopherol; Antioxidants; Arachis; Ascorbic Acid; Caproates; Food Handling; Gas Chromatography-Mass Spectrometry; Lipid Peroxidation; Milk Proteins; Oxidation-Reduction; Peanut Oil; Plant Oils; Solutions; Viscosity; Whey Proteins

Post-translational modifications of proteins take place during the aging of human lens. The present study describes a newly isolated glycation product of lysine, which was found in the human lens. Cataractous and aged human lenses were hydrolyzed and fractionated using reverse-phase and ion-exchange high performance liquid chromatography (HPLC). One of the nonproteinogenic amino acid components of the hydrolysates was identified as a 3-hydroxypyridinium derivative of lysine, 2-ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine). The compound was synthesized independently from 3-hydroxypyridine and methyl 2-[(tert-butoxycarbonyl)amino]-6-iodohexanoate. The spectral and chromatographic properties of the synthetic OP-lysine and the substance isolated from hydrolyzed lenses were identical. HPLC analysis showed that the amounts of OP-lysine were higher in water-insoluble compared with water-soluble proteins and was higher in a pool of cataractous lenses compared with normal aged lenses, reaching 500 pmol/mg protein. The model incubations showed that an anaerobic reaction mixture of Nalpha-tert-butoxycarbonyllysine, glycolaldehyde, and glyceraldehyde could produce the Nalpha-t-butoxycarbonyl derivative of OP-lysine. The irradiation of OP-lysine with UVA under anaerobic conditions in the presence of ascorbate led to a photochemical bleaching of this compound. Our results argue that OP-lysine is a newly identified glycation product of lysine in the lens. It is a marker of aging and pathology of the lens, and its formation could be considered as a potential cataract risk-factor based on its concentration and its photochemical properties.

Topics: Aged; Aging; Ascorbic Acid; Caproates; Cataract; Chromatography, High Pressure Liquid; Chromatography, Ion Exchange; Glycation End Products, Advanced; Humans; Hydrolysis; Lens, Crystalline; Light; Lysine; Magnetic Resonance Spectroscopy; Middle Aged; Models, Chemical; Pyridinium Compounds; Time Factors; Ultraviolet Rays; Water