Bertram J. F. Hudson

Natural Antioxidants Not Exploited Commercially

Reports in recent years both in the popular and scientific press have stressed the value and advantages of natural ingredients as food preservatives. There is an implied assumption of safety for compounds that occur naturally in foods and that have been consumed for many centuries. It is not the intent of the authors to debate the issue of superiority of either natural or synthetic food components as to the safety or functional properties. It is preferable, however, to use substances that do not pose problems of proof of safety. Caution should be employed in the use of natural compounds: except for the major commercial synthetic versions (tocopherols, ascorbic acid) they have not usually been subjected to scrutiny and scientific evaluation as have the artificial synthetic compounds (BHA, BHT). Their potential as mutagens, carcinogens, teratogens, or as other pathogens must be investigated.

Polyhydroxy flavonoid antioxidants for edible oils. structural criteria for activity

Abstract The antioxidant properties of a series of polyhydroxy flavonoids and related compounds have been evaluated. The results have been correlated with the structures of the compounds concerned, which hale been shown to Junction mainly as primary antioxidants. The ability of some such compounds to form complexes with copper has been demonstrated from a study of UV spectra and is probably a contributing factor to the stabilising effects of such compounds. Antioxidant activity is favoured by a multiplicity of phenolic hydroxyl groups and depends critically on the co-operation of the 4-carbonyl with either the 3- or the 5-hydroxyl groups. Dihydro-flavones are slightly more active than the corresponding flavones.

Phenolic acids and related compounds as antioxidants for edible oils

Abstract A series of hydroxy aromatic acids, esters and lactones have been evaluated as antioxidants for lard at 120°C at 0·025%, 0·05% and 0·1% concentrations. Most of the compounds studied are direct biochemical precursors of chalcones and these, in turn, of various flavonoids commonly occurring in plant material. Antioxidant efficiency has been shown to be very dependent on the number of phenolic hydroxyl groups in the molecule and also to be promoted by steric hindrance. Cinnamic acids are more effective than corresponding benzoic acids, and phenylacetic and phenylpropionic acids are even more effective. 3,4-Dihydroxy chalcone is more effective than the analogous caffeic acid. In general, the presence of a carbonyl group in the molecule appears to be necessary in this series for a high level of antioxidant activity.

Polyhydroxy chalcones and flavanones as antioxidants for edible oils

Abstract A series of 11 polyhydroxy chalcones, and in 4 cases, flavanones derived from them by isomerisation, some of which occur naturally in plant tissues, have been shown to be potent antioxidants for lard. Most of these compounds, not being commercially available, were prepared synthetically. Two of them, 3′,3,4-trihydroxy- and 2′4′,2,3-tetrahydroxy chalcone, are described for the first time. 3,4-Dihydroxy chalcones, such as butein and okanin, are particularly effective antioxidants in the range of concentrations 0·025–0·1%, as judged by induction period measurements. Chalcones are more effective than the corresponding flavanones. The hypothesis is put forward that the effectiveness of 3,4-dihydroxy chalcones is dependent on the formation of extended forms of resonance-stabilised free radicals.

Polyhydroxy flavonoid antioxidants for edible oils. Phospholipids as synergists

Abstract The synergistic effects of phosphatidyl ethanolamine and phosphatidyl choline in enhancing the antioxidant properties of some polyhydroxy flavonoids in lard at 100–140°C have been investigated. Phosphatidyl ethanolamine is very effective in all cases, especially when used at concentrations upwards of 0·1%, with flavonoids at levels of 0·007% to 0·07%. Phosphatidyl choline has little synergistic activity. Possible causes of the synergism are discussed. It is concluded that the presence in the synergist molecule of a strongly acid, proton generating function is of importance.

The nutritional quality of Lupinseed

Mature seeds of four Lupinus species,L. albus, L. angustifolius, L. luteus andL. mutabilis, have been analysed comprehensively to evaluate their potential for nutrition. Particular interest attaches to the comparison betweenlupinus species and soyabeans.

Favism-inducing toxins in broad beans (Vicia faba): Estimation of the vicine contents of broad bean and other legume samples

A method for the estimation of vicine in leguminous seeds and related material has been developed. It involves the extraction and isolation of mixed pyrimidine bases, thin layer chromatography and spectrophotometry. Results obtained withVicia faba (broad bean) samples from various sources are recorded and reference made to data obtained from some other leguminous crops.

Favism-inducing toxins in broad beans (Vicia faba) examination of bean extracts for pyrimidine glucosides

Methods for the isolation and identification of the pyrimidine glucoside, vicine, in extracts of broad beans, are described, By thin-layer chromatography, five fluorescing or fluorescencequenching components of the extracts are identifiable. One of them, which has been isolated from the mixture, is identified as vicine, 2:4-diamino-5:6-dihydroxypyrimidine-5-(β-D-glucopyranoside).

Inhibition of the pro-oxidant activity of copper by primary antioxidants in lard

Abstract The pro-oxidant effect of copper in lard, as judged by the development of peroxide values and the shortening of induction periods, can be counteracted by quercetin but not by BHT. On a molar basis, between 100 and 1000 times as much quercetin as copper is required for complete inhibition of the copper. This is evidence that a weak chelate is formed between quercetin and cupric ions in the oil medium.

Favism-inducing toxins in broad beans (Vicia faba) biological activities of broad beans extracts in favism — Sensitive subjects

Ingestion of broad bean seeds will precipitate an acute haemolytic anaemia (favism) in certain sensitive subjects.