Dan E. Pratt

Chia seeds as a source of natural lipid antioxidants

Chia (Salvia sp) seeds were investigated as a source of natural lipid antioxidants. Methanolic and aqueous extracts of defatted chia seeds possessed potent antioxidant activity. Analysis of 2 batches of chia-seed oils demonstrated marked difference in the fatty acid composition of the oils. In both batches, the oils had high concentrations of polyunsaturated fatty acids. The major antioxidant activity in the nonhydrolyzed extract was caused by flavonol glycosides, chlorogenic acid (7.1 × 10−4 mol/kg of seed) and caffeic acid (6.6 × 10−3 m/kg). Major antioxidants of the hydrolyzed extracts were flavonol aglycones/kaempferol (1.1 × 10−3 m/kg), quercetin (2.0 × 10−4 m/kg) and myricetin (3.1 × 10−3 m/kg); and caffeic acid (1.35 × 10−2 m/kg). Two methods were used to measure antioxidant activities. Both were based on measuring bleaching ofβ-carotene in the coupled oxidation ofβ-carotene and linoleic acid in the presence of added antioxidants.

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.

A flavonoid antioxidant in Spanish peanuts(Arachia hypogoea)

Hot methanol extracts of Spanish peanuts were found to possess antioxidant activity. Thin layer (TLC) and paper chromatography of the methanolic peanut extracts yielded 6 fluorescent bands of which one exhibited potent antioxidant activity. Further separation by TLC showed this band to be a complex mixture of 3 components that were tested for antioxidant activity. One component demonstrated all of the antioxidant activity associated with the parent band. Analysis of this antioxidant by paper chromatography and TLC, chromatographic spray reagents and spectral analysis demonstrated that the compound was dihydroquercetin.

Cottonseed flavonoids as lipid antioxidants

Methanolic extracts of cottonseeds were found to possess antioxidant activity. Separation of antioxidant components was achieved by paper, thin layer (TLC) and gas liquid chromatography (GLC) and spectral analysis. Chromatographic technique indicated that the flavonoids quercetin and rutin were the major flavonoids present. GLC analysis of the cottonseed extract eluted from TLC plates, developed in n-butanol/acetic acid/water (4:1:5, v/v/v) and ethyl acetate/methyl ethyl ketone/formic acid/water (5:3:1:1, v/v/v) solvents, corresponded in retention times to the rutin standard (10−4 M). TMS derivatives of the aglycone fraction, prepared by acid hydrolysis, correlated to the retention time of quercetin. Spectral analysis of the aglycone fraction also indicated quercetin derivatives to be present in cottonseed. The glycosyl substitution of the flavonoids were identified by the 3 chromatographic procedures to be glucose and rhamnose. Chromogenic spray reagents were used to further characterize the cottonseed flavonoids and flavonoid components on TLC and paper chromatography. The investigation, therefore, demonstrated that quercetin derivatives appear to be the main flavonoid species in cottonseed. Rutin was found to be one of the major quercetin glycosides. Quercetin and rutin are shown to possess potent antioxidant activity.

Natural Antioxidants of Soybeans and Other Oil-Seeds

Most food grade proteins derived from animal sources do not lend themselves to incorporation into certain formulated and synthesized food products without major preparative procedures. Animal proteins are, also, steadily increasing in cost and are becoming less available. In many cases oil-seed products extend, supplement, or replace more costly ingredients without detracting from the quality of the finished food. Oil-seed proteins may also be used to supplement or replace foods from other plant sources in order to enhance their nutritional value or alter their sensory characteristics.

The Role of Phloroglucinol in Browning of Chlorogenic Acid Catalyzed by Apple Polyphenoloxidase

Abstract Phloroglucinol was found by means of spectrophotometric, paper chromatographic, and quantitative chemical methods, to play a role in the PPO-catalyzed oxidation of chlorogenic acid. Phloroglucinol decreased the browning rate of chlorogenic acid in the presence of PPO, but produced a pigment of higher final absorbance and also caused browning to be reinitiated when added to a chlorogenic acid-PPO solution which had essentially stopped browning. However, no difference in the browning rates occurred when chlorogenic acid and phloroglucinol were allowed to stand together in the absence of PPO. The UV spectra of pigments resulting from mixtures of chlorogenic acid and PPO, and of chlorogenic acid, phloroglucinol, and PPO showed only minor differences. The first of these spectra was similar to that of pure chlorogenic acid and the second similar to that of a mixture of chlorogenic acid and phloroglucinol.