Phytochemical and nutritional composition of Walnut.
- Basic Botanical Data of Walnut:Juglans nigra.
- Countries of origin:Walnut.
- Naming the Walnut.
- Walnuts Ancient Uses.
- Habitat of the Walnut,Juglans nigra.
- Parts and Uses of Black Walnut:Juglans nigra.
- Walnut,Juglans nigra:Parts Used Medicinally.
- Characteristics of Walnut.
- Phytochemical and nutritional composition of Walnut.
- Qualities of Walnut,Juglans nigra.
- Common Health Benefits of Walnut,Juglans nigra.
- Medicinal Benefits,Action and Uses of Walnut Part.
- Benefit of Walnut Oil.
- Nutritional Benefits of Walnut:Brain Nourishing Effect and Pharmacological Mechanism.
- Walnuts and your health:Nutritional Profile of Walnut.
- Walnut Varieties and Grading.
- Some of the Common Walnut Species.
- Walnut Applications,Combinations,Contradications,and Safety.
- Walnut and Human Civilization:History and Archeology,World Cuisines,Folklore.
- Walnut In Pandit Heritage:Rituals and Recipes.
- Research Update:Walnut.
Phytochemical and nutritional composition of Walnut.
Constituents of Walnut:
Walnut contains quinones, oils, tannins; nuts contain essential fatty acids, including cis-linoleic and alfa-linolenic.The active principle of the whole Walnut tree, as well as of the nuts, is Nucin or Juglon. The kernels contain oil, mucilage, albumin, mineral matter, cellulose and water.
Properties of the oil:
Walnut oil is produced from the inedible nuts rejected during shelling.The oils from the different species of walnut bear a close resemblance to each other in terms of both physical and chemical characteristics.They are light yellow in colour with a greenish tinge and have a delicate nutty odour.
The walnut kernels generally contain about 60% oil, but vary from 52% to 70% depending on the variety.The major constituents of the oil are triglycerides.Free fatty acids, diglycerides, monoglycerides, sterols, sterol esters, phosphatides and vitamins are present in minor quantities.The triglyceride moiety of the oil is a mixture of triunsaturated and nonsymmetrical diunsaturated glycerides that form up to 83-95% of the total fraction.The number 2 position of the triglyceride contains primarily linoleic acid.The fatty acids of the walnut oil are predominantly (> 93%) unsaturated and consist mainly of linoleic and oleic acids (Table 1).The linoleic acid content in English walnut is higher than that in black walnut.Walnut oil has also been found to contain at least 29 volatile components, such as terpenes, alcohols and carbonyls, and the characteristic odour of the oil is attributable to the collective effect of a number of constituents.
Table 1.Fatty acid composition of walnut oil:
Palmitic 16:0 2.37
Palmitoleic 16:1 0.05
Margaric 17:0 0.04
Stearic 18:0 2.0
Oleic 18:1 19.9
Linoleic 18:2 28.3
Linolenic 18:3 1.9
Arachidic 20:4 0.04
Eicosenoic 22:6 1.0
Walnuts are also an excellent source of omega-3 fatty acids, and have been shown as helpful in lowering cholesterol.
Mounting scientific evidence suggests that omega-3s lower cholesterol, protect the heart, protect against some cancers and help ease symptoms of inflammatory diseases like arthritis. Getting more omega-3s into the diet of Canadians has become a priority of top nutritionists. Although it may sound contrary to popular perceptions, the fact is everyone needs to intake fat. It gives us energy. Polyunsaturated fats, like you find in walnuts, are high in essential fatty acids. These are called essential because you must get them from your diet. As an added bonus, fat makes food taste good. Omega-3 fatty acids are found in cold water fish, such as salmon, as well as in plant foods including walnuts, leafy greens, soybeans and flaxseed.
Energy Content: Walnut kernels are a good source of energy.Black walnut kernels provide more energy (3318 kJ/100 g) than English walnuts (2730 kJ/100 g).
Walnut kernels contain about 14.5-24% of protein, and this rises to 61-66% in dry, defatted cake. Walnut cake contains more arginine and less lysine than does casein and soya bean meal.The walnut kernel protein contains all the common amino acids, and glutamic acid (1.28 g/100 g of kernel) is the main amino acid, followed by arginine (0.85-1.19 g/100 g of kernel).The essential amino acid composition is given in Table 2.In addition to the common amino acids, walnut kernels also contain a sulphur amino acid, taurine (2-aminoethanesulphonic acid) in concentrations of about 15-46 nmol/g, depending on the variety.In humans, taurine deficiency may lead to a decreased electroretinogram and to pigmentary degeneration of the retina.Walnut kernels have the potential to replace meat as a source of dietary taurine.
Table 2.Essential amino acid content of walnut kernels(g/100g):
Arginine: 2.3 Histidine: 0.4 Isoleucine: 0.73 Leucine: 1.3 Lysine: 0.3
Methionine: 0.25 Phenylanine: 0.8 Threonine: 0.5 Tryptophan: 0.18 Valine: 0.9
The total carbohydrate content in English and black walnut kernels varies from 15.6-19.9 and 13-16 g/100g, respectively.The fibre content in both the varieties is about 2 g/100 g of kernel.Some varieties of walnut kernels contain large amounts of sugar(s).
Walnut kernels are a good source of vitamins.English walnuts contain more vitamin A (380 iu/100 g) than black walnut (30-140 iu/100 g), while the latter is a richer source (0.48~0.93 mg/100 g) of thiamin than English walnuts (0.28 mg).The contents of riboflavin (0.11-0.14 mg/100 g) and nicotinic acid (0.6-1.2 mg/100g) are almost same for all the varieties of walnut.The richest sources of vitamin C are the immature fruits or their green hulls.Unripened or green walnuts are reported to have a very high vitamin C content (1300?3000 mg/100 g), (40~50 times as high as oranges or lemons!) but these reports have yet to be verified.Dry walnut kernels are reported to contain only 2?3 mg/100 g after ripening.Walnuts contain about 200 mg /g-tocopherol and 15mg a-tocopherol/ g of nut; the d isomer is present in very minute quantities.Walnut kernels also contain vitamin K1 (0.9-1.1 mg/100 g).
In foods phenolic acids has been associated with astringency, discoloration, inhibition of enzyme activity, and antioxidant properties.Defatted kernels are found to contain some phenolic acids, namely phenylacetic, protocatechuic, syringic, vanillic, gallic, caffeic and ferulic acids, in very small quantities ranging from 0.02-0.20 g/g of kernels.
While walnuts' ability to reduce cholesterol seems to be at the heart of their health benefits, walnuts contain a host of other important vitamins, minerals, protein and antioxidants. Walnuts are cited as the largest single source of antioxidants, next to rose hips, according to a study from the University of Minnesota and University of Oslo.Walnut contain ellagic acid, an antioxidant compound that helps supports the immune system and contain several anticancer properties.
Walnuts contain about 2% on the dry matter basis pectic substances.These make up a component of dietary fibre and have a positive nutritional value such as hypocholesterolaemic effects (lowering blood cholesterol), increased excretion of faecal sterols and the capacity to bind bile salts.Pectic substances may also slow down the absorption of soluble carbohydrates, causing a smaller increase in the postprandial level of blood sugar; hence walnut kernels could play a role in the design of pectic-rich diets designed to lower blood cholesterol levels and lower the possibility of heart disease.
Walnuts are considered to be a good source of dietary minerals. The English and black walnuts contain almost similar quantities of minerals, except calcium, which is present only in moderate amounts in black walnuts.Potassium, phosphorus, magnesium and iron are found in significant quantities in these nuts.Black Walnut (Juglans nigra) is a rich source of the trace mineral chromium and is also high in iodine.The mineral composition of walnuts is given in Table 4.
Table4.Mineral content of walnut kernels(mg/100g):
Calcium Trace-108 mg.
Chloride 14-30 mg.
Copper 0.9-3.2 mg.
Iron 2.1-7.6 mg.
Magnesium 132-137 mg.
Manganese 2.4-2.7 mg.
Phosphorus 309-380 mg.
Potassium 225-328-606 mg.
Sodium 2-17 mg.
Sulphur 120-140 mg.
Zinc 2.3-3.6 mg.
Vitamin A : 30 I.U. Vitamin B : Thiamine .48 mg. Niacin : 1.2 mg. Vitamin C : 3 mg.
Calcium : 83 mg.Iron : 2.1 mg.
Fat : 64.4 gm.
Carbohydrates : 15.6 gm.
Protein : 15.0 gm.
Calories : 654
Note On Walnut Phytochemicals:
Omega-3: has many potential health benefits ranging from cardiovascular protection, to the promotion of better cognitive function, to anti-inflammatory benefits helpful in asthma, rheumatoid arthritis, and inflammatory skin diseases such as eczema and psoriasis.
Ellagic and gallic acid supports the immune system and appears to have several anti-cancer properties.
Monounsaturated fats has favorable effects on high cholesterol levels and other cardiovascular risk factors.
Polyphenols Walnuts have about 16 polyphenols, with antioxidant activity so protective that it is described as "remarkable".
Alpha-linoleic acid (ALA) lowers levels of C-reactive protein, increases levels of protective omega-3s.
Manganese and Copper are two minerals that are essential cofactors in a number of enzymes important in antioxidant defenses.
- 1.Black Walnut:Juglans nigra and Walnut Extracts Benefits.
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