Walnut (Juglans regia L.): Genetic resources, chemistry, by-products

MARCELA MARTÍNEZ; DIANA LABUCKAS; ALICIA LAMARQUE; DAMIÁN MAESTRI

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE

JOHN WILEY & SONS LTD

Año: 2010 vol. 90 p. 1959 - 1967

0022-5142

Walnut (Juglans regia L) is the most widespread tree nut on a worldwide basis. There is a great diversity of genotypes differing in forestry, productivity, physical and chemical nut traits. Some of them were evaluated as promising and may serve as germplasm sources for breeding. The nutritional importance of the nut is related to the seed (kernel). It is a nutrient-dense food derived mainly from its oil content (up to 740 g kg-1 in some commercial varieties), which can be extracted easily by screw-pressing, and consumed without refining. Walnut oil (WO) composition is dominated largely by unsaturated fatty acids (mainly linoleic and lesser amounts of oleic and linolenic acids). Minor components of WO include tocopherols, phospholipids, sphingolipids, sterols, hydrocarbons and volatile compounds. Phenolic compounds, present at high amounts in the seed coat but poorly extracted with the oil, have been extensively characterized and found to possess strong antioxidant properties. The oil-extraction residue is rich in proteins (unusually high in arginine, glutamic and aspartic acids) and it has been employed for formulation of various functional food products. This review describes scientific knowledge published during the last years, concerning walnut genetic resources, their composition as well as by-product obtainment and characteristics.