Shahidi, F., C. Alasalvar, C.M. Liyana-Pathirana, 2007. Antioxidant phytochemicals in hazelnut kernel (Corylus Avellana l.) and hazelnut byproducts. J. Agric. Food Chem. 55(4):1212–1220.
Antioxidant efficacies of ethanol extracts of defatted raw hazelnut kernel and hazelnut byproducts (skin, hard shell, green leafy cover, and tree leaf) were evaluated by monitoring total antioxidant activity (TAA) and free-radical scavenging activity tests [hydrogen peroxide, superoxide radical, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical], together with antioxidant activity in a β-carotene−linoleate model system, inhibition of oxidation of human low-density lipoprotein (LDL) cholesterol, and inhibition of strand breaking of supercoiled deoxyribonucleic acid (DNA). In addition, yield, content of phenolics, and phenolic acid profiles (free and esterified fractions) were also examined. Generally, extracts of hazelnut byproducts (skin, hard shell, green leafy cover, and tree leaf) exhibited stronger activities than hazelnut kernel at all concentrations tested. Hazelnut extracts examined showed different antioxidative efficacies, expected to be related to the presence of phenolic compounds. Among samples, extracts of hazelnut skin, in general, showed superior antioxidative efficacy and higher phenolic content as compared to other extracts. Five phenolic acids (gallic acid, caffeic acid,p-coumaric acid, ferulic acid, and sinapic acid) were tentatively identified and quantified (both free and esterified forms). Extracts contained different levels of phenolic acids. These results suggest that hazelnut byproducts could potentially be considered as an excellent and readily available source of natural antioxidants.
Harrison, K., L.M. Were, 2007. Effect of gamma irradiation on total phenolic content yield and antioxidant capacity of almond skin extracts. Food Chem. 102:932-937.
Almond (Prunus amygdalus) skins are agricultural by-products that are a source of phenolic compounds. Phenolic compounds from gamma-irradiated almond skins were extracted with 40% ethanol. Total phenolic content was determined using the Folin–Ciocalteu (F–C) method. Almond skin extracts (ASE): soybean oil (1:4 v/v) mixtures containing 0.08% FeCl3 were prepared. Antioxidant activity was determined by conjugated dienes and trienes (CD and CT, respectively) measurements, peroxide value (PV), Trolox© equivalent antioxidant capacity (TEAC) and Photochemiluminescence (PCL). Phenolic content yield (p < 0.05) was higher in ASE irradiated at doses greater than 4 kGy (trial I) or 12.7 kGy (trial II) compared to the control. Increased antioxidant activity was observed in TEAC assay and PCL with lipid-soluble antioxidant capacity reagents in ASE irradiated above 4 kGy (trial I) and 12.7 kGy (trial II) compared to 0 kGy. Gamma irradiation of almond skins thus increased the yield of total phenolics content as well as enhanced antioxidant activity of extracts.
Chen, C.-Y, P.E. Milbury, S.-K. Chung, J. Blumberg, 2007. Effect of almond skin polyphenols and quercetin on human LDL and apolipoprotein B-100 oxidation and conformation. J. Nutr. Biochem. 18 (12):785-794.
Almond skin polyphenolics (ASP) and vitamin C (VC) or E (VE) inhibit the Cu2+-induced generation of conjugated dienes in human lowdensity lipoprotein (LDL) in a synergistic manner. However, the mechanism(s) by which this synergy occurs is unknown. As modification of apolipoprotein (apo) B-100 is an early, critical step in LDL oxidation, we examined the effects of combining ASP or quercetin and antioxidant vitamins on the oxidation of this moiety as well as on the alteration of LDL conformation and electronegativity (LDL-). In a dose-dependent manner, ASP (0.12-2.0 Amol/L gallic acid equivalents) decreased tryptophan (Trp) oxidation by 6.7-75.7%, increased the generalized polarity (Gp) of LDL by 21.0-81.5% at 90 min and reduced the ratio of LDL- to total LDL (tLDL) by 38.2-83.8% at 5 h. The actions of ASP on these parameters were generally additive to those of VC and VE. However, a 10-25% synergy of ASP plus VC in protecting apo B-100 Trp against oxidation may result from their synergistic interaction in prolonging the lag time to oxidation. ASP and VE acted in synergy to reduce LDL-/tLDL by 24-43%. Quercetin’s actions were similar to ASP, though more effective at inhibiting Trp oxidation. Thus, ASP and quercetin reduce the oxidative modification of apo B-100 and stabilize LDL conformation in a dose-dependent manner, acting in an additive or synergistic fashion with VC and VE.
Ritter, M.M.C., G.P. Savage, 2007. Soluble and insoluble oxalate content of nuts. Journal of Food Composition and Analysis. 20:169-174.
This study was conducted to determine the oxalate contents in common nuts either locally grown or imported into New Zealand. Samples of imported nuts were purchased from supermarkets in Christchurch while locally grown nuts were obtained directly from the growers. In this experiment gastric soluble and intestinal soluble oxalates were extracted from the nuts using an in vitro assay, which involved incubations of the food samples for 2 h at 37 1C in gastric and intestinal juice. The extracted oxalates were then determined by HPLC chromatography. Roasted pistachio nuts and chestnuts contained very low levels (<85 mg/100 g fresh weight (FW)) of gastric soluble oxalate. Peanuts, Spanish peanuts, peanut butter, ginkgo, cashew nuts and pecan nuts all contained relatively low levels of gastric soluble oxalate (147–250 mg gastric soluble oxalate/100 g FW). Almonds, Brazil, pine and candle nuts contained high levels of gastric soluble oxalate (492.0–556.8 mg/100 g FW). The intestinal soluble oxalate is the fraction that will be absorbed in the small intestine. Peanuts, Spanish peanuts, peanut butter, ginkgo and pecan nuts all contained relatively low levels of intestinal soluble oxalate (129–173 mg intestinal soluble oxalate/100 g FW). Almonds, Brazil, cashew and candle nuts contained higher levels of intestinal soluble oxalate (216–305 mg/100 g FW). Pine nuts contained the highest levels of intestinal soluble oxalate (581 mg/100 g FW), while chestnuts and roasted pistachio nuts were low (72 and 77 mg /100 g FW). Overall the mean soluble oxalate content of nuts was 78% of the gastric soluble oxalate content (41–100%). The results obtained in this study confirm that the intestinal soluble oxalate contents of nuts range widely and people who have a tendency to form kidney stones would be wise to moderate their consumption of certain nuts.
Lunn, J., J.L. Buttriss, 2007. Carbohydrates and dietary fiber. Nutrition Bulletin. 32: 21-64
The health benefits of including sufficient dietary fiber in the diet have been well described and have formed the basis of dietary recommendations around the world. However, dietary fiber is a complex dietary entity, consisting of many non-digestible components of food. Debate surrounding the definition and measurement of dietary fiber has resulted in inconsistencies in labeling, description and recommendations set across the world. In the UK, dietary recommendations are made using the fraction of non-digestible material described as non-starch polysaccharide that is measured by the Englyst method. However, the Association of Official Analytical Chemists (AOAC) methods, used widely by the food industry, capture a much greater range of non-digestible material, that some suggest should be included in any definition of dietary fiber. An attempt to resolve such discrepancies, possibly by taking an approach that considers the health effects of fractions not captured in the Englyst method, is probably overdue. Additionally, it is clear that the effects of these various non-digestible components of dietary fiber are not interchangeable, and it is important that fiber comes from a range of sources to ensure maximum health benefits from the fiber in the diet. Traditional ‘insoluble’ fibers are required to add bulk as well as rapidly fermentable, viscous fibers to bring about cholesterol lowering. There is also a convincing argument for including slowly fermented components, such as resistant starches, that are well tolerated in the digestive system and can bring about improvements in gut function. Currently there is insufficient data from well designed human intervention trials to make specific recommendations on the amounts of these fiber components in the diet, but it may be useful for health professionals to talk in terms of the different food sources of these types of fiber, as well as total fiber amounts.
Monagas, M., I. Garrido, R. Lebron-Aguilar, B. Bartolome, C. Gomez-Cordoves, 2007. Almond (Prunus dulcis (Mill.) D.A. Webb) skins as a potential source of bioactive polyphenols. J. Agric. Food Chem. 55:8498-8507.
An exhaustive study of the phenolic composition of almond (Prunus dulcis (Mill.) D.A. Webb) skins was carried out in order to evaluate their potential application as a functional food ingredient. Using the HPLC-DAD/ESI-MS technique, a total of 33 compounds corresponding to flavanols, flavonols, dihydroflavonols and flavanones, and other nonflavonoid compounds were identified. Peaks corresponding to another 23 structure-related compounds were also detected. MALDI-TOF MS was applied to characterize almond skin proanthocyanidins, revealing the existence of a series of A- and B-type procyanidins and propelargonidins up to heptamers, and A- and B-type prodelphinidins up to hexamers. Flavanols and flavonol glycosides were the most abundant phenolic compounds in almond skins, representing up to 38-57% and 14-35% of the total quantified phenolics, respectively. Due to their antioxidant properties, measured as oxygen-radical absorbance capacity (ORAC) at 0.398-0.500 mmol Trolox/g, almond skins can be considered as a value-added byproduct for elaborating dietary antioxidant ingredients.
Li, N., X. Jia, C.-Y.O. Chen, J.B. Blumberg, Y. Song, W. Zhang, X. Zhang, G. Ma, J. Chen, 2007. Almond consumption reduces oxidative DNA damage and lipid peroxidation in male smokers. J. Nutr. 137:2717 -2722.
Smoking increases the risk of several chronic diseases associated with elevated oxidative stress status. Almonds are a good source of antioxidant nutrients and may diminish smoking-related biomarkers of oxidative stress. This study investigated whether almond consumption decreases biomarkers of oxidative stress in young male Chinese smokers. The Chinese CDC researchers conducted a randomized, crossover clinical trial with 60 healthy male soldiers (18-25 y) who were habitual smokers (5-20 cigarettes/d) and supplemented their diet with 84 g almonds or 120 g pork (to control for calories) daily for 4 wk with a 4-wk washout period between treatment periods. In addition, 30 healthy nonsmoking men were provided the same daily serving of pork as reference comparison. Blood and urine were collected and assessed for biomarkers of oxidative stress. Baseline values of urinary 8-hydroxy-deoxyguanosine (8-OHdG) and malondialdehyde (MDA) and peripheral lymphocyte DNA strand breaks were significantly higher by 185, 64, and 97% in smokers than nonsmokers, whereas activities of plasma superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase were significantly lower by 15, 10, and 9%, respectively. After the almond intervention, serum a-tocopherol, SOD, and GPX increased significantly in smokers by 10, 35, and 16%, respectively and 8-OHdG, MDA, and DNA strand breaks decreased significantly by 28, 34, and 23%. No significant changes were found in smokers or nonsmokers after pork treatment. In smokers, after almond supplementation, the concentration of 8-OHdG remained significantly greater than in nonsmokers by 98%. These results suggest almond intake can enhance antioxidant defenses and diminish biomarkers of oxidative stress in smokers.
Ryan, E., K. Galvin, T.P. O’Connor, A.R. Maguire, N.M. O’Brien, 2006. Fatty acid profile, tocopherol, squalene and phytosterol content of brazil, pecan, pine, pistachio and cashew nuts. International Journal of Food Sciences and Nutrition. 57(3/4):219-228.
Nuts contain bioactive constituents that elicit cardio-protective effects including phytosterols, tocopherols and squalene. The objective of the present study was to determine the total oil content, peroxide value, fatty acid composition and levels of tocopherols, squalene and phytosterols in oil extracted from freshly ground brazil, pecan, pine, pistachio and cashew nuts. The total oil content of the nuts ranged from 40.4 to 60.8% (w/w) while the peroxide values ranged from 0.14 to 0.22 mEq O2/kg oil. The most abundant monounsaturated fatty acid was oleic acid (C18:1), while linoleic acid (C18:2) was the most prevalent polyunsaturated fatty acid. The levels of total tocopherols ranged from 60.8 to 291.0 mg/g. Squalene ranged from 39.5 mg/g oil in the pine nut to 1377.8 mg/g oil in the brazil nut. β-Sitosterol was the most prevalent phytosterol, ranging in concentration from 1325.4 to 4685.9 mg/g oil. In conclusion, the present data indicate that nuts are a good dietary source of unsaturated fatty acids, tocopherols, squalene and phytosterols.
Seeram, N.P., Y. Zhang, S.M. Henning, R. Lee, Y. Niu, G. Lin, D. Heber, 2006. Pistachio skin phenolics are destroyed by bleaching resulting in reduced antioxidative capacities. J. Agric. Food Chem. 54:7036-7040.
Pistachio shells split naturally prior to maturity leading to their unique crack-shell form. Within 24 h of harvest, hull-trapped moisture may cause shell staining. The illegal process of bleaching has been used to restore a desirable white color to pistachio shells. It is not known whether bleaching adversely affects phytochemical levels in pistachios. Therefore, we identified for the first time multiple pistachio skin phenolics as quercetin (14.9 µg/g), luteolin (10.0 µg/g), eriodictyol (10.2 µg/g), rutin (1.6 µg/g), naringenin (1.2 µg/g), apigenin (0.2 µg/g), and the anthocyanins, cyanidin-3-galactoside (696 µg/g) and cyanidin-3-glucoside (209 µg/g). We investigated the effects of bleaching (0.1-50% hydrogen peroxide) on phenolic levels and antioxidative capacities in raw and roasted nuts. Because of their flavylium cation structures, anthocyanins were the most sensitive to bleaching. Bleaching decreased total anthocyanin levels [íg/g of skins (% hydrogen peroxide)]: 905 and 549 (0%); 653 and 145 (0.1%); 111 and 18.4 (5%); 6.1 and 3.2 (25%); 0 and 0 (50%) for raw and roasted nuts, respectively. Bleaching also reduced antioxidative capacity [µM/g of Trolox (% hydrogen peroxide)]: 945 and 725 (0%); 940 and 472 (0.1%); 930 and 455 (5%); 433 and 370 (25%); 189 and 173 (50%), for raw and roasted nuts, respectively. Raw nuts preserved phenolic levels and antioxidant capacity better than roasted nuts, suggesting contributing effects of other substances and/or matrix effects that are destroyed by the roasting process. The destruction of bioactive phenolics in pistachio skins may negatively impact the potential health benefits arising from pistachio consumption.
Casal, J.S., M. Rui Alves, R.M. Seabra, B.P.P. Oliveira, 2006. Tocopherol and tocotrienol content of hazelnut cultivars grown in Portugal. J. Agric. Food Chem. 54(4):1329–1336.
Hazelnuts from 19 cultivars collected during 3 consecutive-year crops, in 2 different geographical localities, for a total of 79 samples, were evaluated for their contents in tocopherols and tocotrienols by normal-phase high-performance liquid chromatography coupled to a series arrangement of a diode array and a fluorescence detector. Seven compounds were identified and quantified. All samples presented α-, β-, γ-, and δ- tocopherols and β-tocotrienol; α- and γ-tocotrienols were detected in some of the studied samples. α-Tocopherol was the major compound in all samples, ranging from 105.9 to 226.8 mg/kg of hazelnut. Considering the generality of the obtained results, an identical qualitative and quantitative pattern was found, which can define a chemical fingerprint that may be helpful in the assessment of identity and quality of hazelnut oils. Statistical analyses were carried out in order to check for differences among cultivars, year crops, and geographical localities. Although some differences were observed when different-year crops and geographical localities were considered, neither of these factors seemed to produce considerable differences in terms of tocopherol and tocotrienol contents. Some minor differences were observed among cultivars.
