Some observations on the oxidative deterioration of the lipids of crude leaf protein

Abstract

Measurements of oxygen absorption have been carried out on a sample of crude leaf protein, containing about 20% lipid, at temperatures between 37' and -1 2 ' and pH 26-6.0.An enzyme system was active in the moist but not in the freeze-dried product. Attempts to protect the lipid of the freeze-dried protein by the addition of antioxidants were unsuccessful.

The Presentation of Leaf Protein on the Table – II

“…of lipids and the fatty acids in them are highly unsaturated (Lima et al. 1965) and readily undergo oxidation (Lea and Parr 1961); this increases the ''leafy'' flavour. The lipids, including chlorophyll and its breakdown products can easily be extracted with solvents.…”

Determination of Trimethylamine in Spinach, Cabbage, and Lettuce at Alkaline pH by Headspace Solid‐Phase Microextraction

“…The fishy off‐flavor is probably associated with TMA. It has been reported that fishy odor was detected in leaf protein containing a high amount of galactolipids or phospholipids (Lea and Parr 1961). Fishy off‐flavor has been detected in dry spinach stored in nitrogen at low temperatures (Masanetz and others 1998).…”

Changes in the Relative Concentration of Fatty Acids in Stored Soybean Leaf Protein Concentrate

“…Although LPC has been shown to have a favorable balance of essential amino acids (Betschart and Kinsella, 1974a;Byers, 1971;Gerloff et al, 1965) and has been effectively used as a suppplement for human and animal diets (Doraiswamy et al, 1969;Waterlow, 1962;Woodham, 1971), there are problems associated with this potentially valuable source of protein. The presence of "grassy, hay-like" odors and flavors in stored LPC is one such problem (Protein Advisory Group, 1970;Lea and Parr, 1961;Shah, 1968). These undesirable organoleptic qualities have been associated with the oxidation of the lipid fraction of LPC (Buchanan, 1969a;Kohler and Bickoff, 1970;Lea and Parr, 1961).…”

“…The presence of "grassy, hay-like" odors and flavors in stored LPC is one such problem (Protein Advisory Group, 1970;Lea and Parr, 1961;Shah, 1968). These undesirable organoleptic qualities have been associated with the oxidation of the lipid fraction of LPC (Buchanan, 1969a;Kohler and Bickoff, 1970;Lea and Parr, 1961).…”

“…LPC is essentially a protein-lipid concentrate containing from 8 to > 20% lipid depending on the method used to prepare LPC and the solvents used to extract the lipids (Betschart and Kinsella, 1974a;Buchanan, 1969b;Hudson and Karis, 1973;Lea and Parr, 1961;Spencer et al, 1971). Factors such as crop species, maturity and cellular origin of the LPC have been reported to influence the lipid content, lipid classes, and fatty acid composition (Hudson and Karis, 1973).…”