Reinhard Marcuse

Bio: Reinhard Marcuse is an academic researcher. The author has contributed to research in topics: Lipid oxidation & Linolenic acid. The author has an hindex of 4, co-authored 5 publications receiving 363 citations.

The effect of some amino acids on the oxidation of linoleic acid and its methyl ester

Abstract: Manometric studies of the effect of certain amino acids on oxidation (measured as oxygen consumption) of linoleic acid, as well as the methyl esters of linoleic acid and linolenic acid dispersed in water or phosphate buffers at pH 7 to pH 5 have shown that 1. The amino acids tested (except cysteine) have a potential antioxidative effect. 2. The antioxidative capacity of different amino acids may be rather different (it is especially pronounced in the case of histidine and tryptophane). 3. Under suitable conditions extremely low amino acid concentrations may have rather strong effect. 4. The antioxidative efficiency is less pronounced than in earlier experiments with linoleate at pH>7, and decreases with decreasing pH. 5. There may be a tendency towards a prooxidative inversion with relatively high amino acid concentrations, or at low pH. 6. The antioxidative effect is enhanced and a prooxidative effect may be lowered or inverted into an antioxidative one by an addition of phosphate, or an emulsifier like Tween. 7. A strong inhibitory effect is obtained by combined addition of phosphate and emulsifier like Tween, together with the amino acid. 8. The antioxidative tendency was stronger in the case of methyl linoleate than with linoleic acid, and was also stronger with methyl linoleate than with methyl linolenate.

Studies on the TBA test for rancidity grading: II. TBA reactivity of different aldehyde classes

Abstract: The TBA reactivities of several aldehydes, most of them known as ordinary products of lipid autoxidation, have been investigated systematically. Gas liquid chromatography-purified alkanals, 2-alkenals and 2,4-alkadienals were reacted with TBA in water solution. The formation of pigments with maximum absorbance at 450 and 530 nm was measured at optimum time-temperature conditions-different for readings at 450 and 530 nm- and values for absorbance per mole aldehyde were calculated. These values show that on reaction with TBA all studied aldehydes build a yellow 450 nm pigment, while only 2,4-alkadienals and, to a lesser extent, 2-alkenals produce the red 530 nm pigment. Consequently both pigments are measures of aldehydic products of lipid autoxidation: In the case of predominant unsaturated aldehyde formation, determination of the pigment with maximum absorbance at 530 nm is preferable. However, if alkanals are predominant, the determination of the yellow pigment at 450 nm is more apporpriate, as it grants higher sensitivity.

Fat oxidation at low oxygen pressure. i. kinetic studies on the rate of fat oxidation in emulsions

Abstract: Oxidation was measured by oxygen consump-tion in a Warburg apparatus, modified to main-tain constant partial oxygen pressure by auto-matic electrolytic generation of oxygen with automatic recording of the oxygen consumed.

Fat oxidation at lwo oxygen pressure: II. Kinetic studies on linoleic acid oxidation in emulsions in the presence of antioxidants

Abstract: Earlier reported kinetic studies on the dependence of lipid oxidation on oxygen pressure in emulsions were continued by studying this relationship in the presence of antioxidants. The substances tested represented two types of antioxidants, phenolic inhibitors (α-tocopherol, BHA, PG) and amino acid-retarders (glycine, alanine, histidine, tryptophane). The inhibiting effect of the first mentioned group, i.e., the formation of an induction period was, in general, not dependent on oxygen pressure, while the retardation caused by amino acids was stronger at low oxygen pressure than in air. The effect of lowering oxygen pressure was practically the same, when phenolic inhibitors were added as without such addition. It was, however, enhanced by the addition of amino acid-retarders. When representatives of these two types of antioxidants were added in combination, their synergistic effect was considerably enhanced at low oxygen pressure.

Determination of aldehydic lipid peroxidation products: malonaldehyde and 4-hydroxynonenal

Abstract: Publisher Summary This chapter discusses the methods used for the qualitative and quantitative determination of aldehydes in biological systems. It focuses on 4-hydroxynonenal (HNE) and malondialdehyde (MDA). 4-Hydroxynonenal is produced as a major product of the peroxidative decomposition of polyunsaturated fatty acids (PUFA) and possesses cytotoxic, hepatotoxic, mutagenic, and genoroxic properties. Increased levels of HNE are found in plasma and various organs under conditions of oxidative stress. In addition to HNE, lipid peroxidation generates many other aldehydes that may also be of toxicological significance. Malondialdehyde is in many instances the most abundant individual aldehyde resulting from lipid peroxidation, and its determination by thiobarbituric acid (TBA) is one of the most common assays in lipid peroxidation studies. In vitro MDA can alter proteins, DNA, RNA, and many other biomolecules. Recently, it has been demonstrated with monoclonal antibodies that malonaldehyde-altered protein occurs in atheroma of hyperlipidemic rabbits.

Lipid Oxidation in Oil-in-Water Emulsions: Impact of Molecular Environment on Chemical Reactions in Heterogeneous Food Systems

Abstract: The susceptibility of lipids to oxidation is a major cause of quality deterioration in food emulsions. The reaction mechanism and factors that influence oxidation are appreciably different for emulsified lipids than for bulk lipids. This article reviews the current understanding of the lipid oxidation mechanism in oil-in-water emulsions. It also discusses the major factors that influence the rate of lipid oxidation in emulsions, such as antioxidants, chelating agents, ingredient purity, ingredient partitioning, interfacial characteristics, droplet characteristics, and ingredient interactions. This knowledge is then used to define effective strategies for controlling lipid oxidation in food emulsions.