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Erophaca baetica is a legume endemic to the Mediterranean region. Although the fruits and seeds are large, the presence of the “locoism” which produces the alkaloid, swainsonine has prevented its use as animal feed or for human nutrition. Their protein content and chromatographic profile, amino acid composition, fatty acid composition, and polyphenol contents have been determined in order to explore the potential of the E. baetica seeds as a source of dietary protein with functional components. The protein content was found to be 36% (w/w), and an amino acid analysis revealed a deficiency in sulphur amino acids, tryptophane, and lysine. The low lysine content is probably due to the abundance of alkaloids metabolically derived from this amino acid. Oleic and linoleic acids are the major fatty acids in the seeds. The antioxidant activity of polyphenol extracts was higher than the activity of the polyphenols extracted from most edible legume seeds. Hence, E. baetica seeds represent a promising source of functional and nutritional components on the condition that the anti-nutritional alkaloids are previously removed.

The protein profile and the amino acid composition of eleven amaranth species have been studied. The following species were taken into account: A. viridis, A. powellii, A.muricatus, A. deflexus, A. graecizans, A. blitoides, A. retroflexus, A. blitum, A. albus, A. cruentus and A. hypochondriacus. Seed samples were obtained from wild populations located in the southwest of Spain. The protein profile was studied by gel filtration chromatography and denaturing electrophoresis. Profiles were similar in all taxa, with small variations in the molecular weights and amounts of the main seed proteins. Thus, after gel filtration chromatography six main fractions of around 300 kDa, 180 kDa, 120 kDa, between 40 and 50 kDa, 20 and 30 kDa and below 10 kDa were observed. On the other hand, the electrophoretic analysis showed peptides grouped into three main fractions, between 50 and 64 kDa, 33 and 37 kDa and 18 and 25 kda. The most balanced amino acid compositions were observed in the wild taxa A. muricatus, A. blitum and A. powellii showed the most equilibrated amino acid composition. A. hypochondriacus and A. graecizans showed the most deficient amino acid composition with limitations in five essential amino acids. These results show the potential of wild amaranthus taxa for their introduction as crops or their use in the improvement by hybridization mechanisms of other crops such as A. hypochondriacus.

Extraction of proteins from defatted sunflower meal has been improved by addition of the protease alcalase during alkaline extraction. This method offers several additional advantages as compared to the traditional alkaline extraction without alcalase, which is usually carried out after a sedimentation/flotation step to remove the lignocellulosic fraction. As compared to extraction without alcalase, addition of 0.1% (v/v) alcalase improved the yield of protein extraction from 57.5% to 87.4%, providing an extract that is 22% hydrolyzed. In addition, an increment of up to 4.5 times in protein solubility at low pH values is achieved, which correlates with the degree of hydrolysis. The extracts that were obtained in the presence of alcalase had a higher proline and glycine content, suggesting that the protease improves extraction of proline-rich and glycine-rich cell wall proteins that are part of the lignocellulosic fraction. These protein extracts can be directly dried without generation of wastewater, and the resulting fiber-rich material could be used for animal feeding.

This part reviews the mechanisms of oxidizing lipid-protein interactions. Hydrophobic interactions, radical reactions and formation of covalent compounds with secondary products of lipid oxidation are described.

Radical chemistry of polyunsaturated fatty acids. This part summarizes the mechanisms of lipid oxidation. The compounds that react with proteins are specially discussed.

The enzymes of the lipoxygenase pathway in plant foods are reviewed. This part analyzes the enzymes related to the descomposition or transformation of the lipidic hydroperoxides. Lipoxygenase, hydroperoxide lyase, enal isomerase, alcohol dehydrogenase, aldehyde dehydrogenase, hydroperoxide dehydrase, alene oxide ciclase and 12-Oxo-phytodienoic acid reductase in plants are described. Posible control mechanisms of the lipoxygenase pathway are also considered.

The enzymes of the lipoxygenase pathway in plant foods are reviewed. This part analyzes the enzymes related to the formation of the lipidic hydroperoxides. Lipases and lipoxygenases in plant foods are described.