Archive

Research Area: Nutrient and Bioactive Composition

Antioxidant activity of almond seed extract and its fractions

Amarowicz, R., T. Agnieszka, A. Troszynska, F. Shahidi. 2005. Antioxidant activity of almond seed extract and its fractions. J. Food Lipids. 12:344-358.

In this study, phenolic compounds were extracted from defatted almond seeds. Phenolic compounds present in the crude extract and its fractions showed antioxidant and antiradical properties as revealed following studies using a β-­carotene-linoleate model system, total antioxidant activity (TAA) method, 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging activity and reducing power evaluation. Results of these assays showed highest values when tannins (fraction II) were tested. The content of total phenolics in fraction II was the highest (80.4 mg/g). The content of tannins in this fraction determined using the vanillin method and expressed as absorbance units at 500 nm per 1 g was 2436. The high-performance liquid chromatography (HPLC) analysis of almond seed crude extract showed the presence of phenolic compounds, namely vanillic, caffeic, p-coumaric, ferulic acids (after basic hydrolysis), quercetin, kaempferol and isorhamnetin (after acidic hydrolysis), delphinidin and cyanidin (after n-butanol-HCl hydrolysis) and procyanidin B2 and B3.

Almond (Prunus dulcis L.) protein quality

Ahrens, S., M. Venkatachalam, A.M. Mistry, K. Lapsley, S.K. Sathe, 2005. Almond (Prunus dulcis L.) protein quality. Plant Foods for Human Nutrition. 60: 123-128.

Three marketing varieties of almonds; Carmel, Mission, and Nonpareil; were analyzed for proximate composition and protein nutritive quality. Moisture, lipids, protein, ash, sugars, and tannins ranges were 3.05-4.33%, 43.37 -47.50%, 20.68-23.30%, 3.74-4.56%, 5.35-7.45%, and 0.12-0.18%, respectively. No detectable hemagglutinating and trypsin inhibitory activities were present in Carmel, Mission, and Nonpareil almonds. Amino acid analyses indicated the sulfur amino acids (methionine + cysteine), lysine, and threonine to be the first, second, and third limiting amino acids in almonds when compared to the recommended amino acid pattern for children 2-5-year old. However, compared to the recommended amino acid pattern for adults, sulfur amino acids were the only limiting amino acids in almonds tested. True Protein Digestibility (% TPD) values for Carmel, Mission, and Nonpareil were 88.55 ± 1.26, 92.25 ± 1.05, and 82.62 ± 1.47, respectively. Protein Digestibility Corrected Amino Acid Scoring (PDCAAS) values suggested almond proteins to be of poor nutritional quality.

Identification and characterization of anthocyanins by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry in common foods in the United States: vegetables, nuts, and grain

Wu, X., R.L. Prior, 2005. Identification and characterization of anthocyanins by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry in common foods in the United States: vegetables, nuts, and grains. J. Agric. Food Chem. 53, 3101-3113

Anthocyanins in common foods in the United States, other than fruits and berries, were identified and characterized by high-performance liquid chromatography (HPLC)-electrospray ionization tandem mass spectrometry coupled with diode array detection. Of all of the 40+ vegetables, nuts, and grains screened, seven vegetables, one nut, and one grain were found to contain anthocyanins; the number of anthocyanins detected varied from two in pistachio nuts to 34 in red radishes. The individual anthocyanins were identified by comparing their mass spectrometric data and retention times with those of standards, published data, and reference food samples. In all of the samples analyzed, except for sorghum, only six common anthocyanidins (delphinidin, cyanidin, pelargonidin, petunidin, peonidin, and malvidin) were found as their glycosides. Anthocyanins in certain vegetables such as red cabbage and red radish were highly conjugated with sugars and acylated groups, and thus, their structures were very complicated. Eight different either aliphatic or aromatic acylated groups (acetoyl, coumaroyl, malonoyl, p-hydroxybenzoyl, feruoyl, caffeoyl, sinapoyl, and oxaloyl) were identified in the anthocyanins. In addition to glucose, six other sugar moieties (galactose, xylose, rhamnose, rutinose, sambubiose, and laminaribiose) were observed. Three varieties of sorghum were found to contain 3-deoxyanthocyanidins and their derivatives as major anthocyanins. A number of new anthocyanins were identified in the foods studied. This paper presents complete HPLC profiles and MS spectrometric data, obtained under the same experimental conditions, for common vegetables, pistachio nuts, and sorghum that contain anthocyanins.

Phytosterol composition of nuts and seeds commonly consumed in the United States

Phillips, K.M., D.M. Ruggio, M. Ashraf-Khorassani, 2005. Phytosterol composition of nuts and seeds commonly consumed in the United States. J. Agric. Food Chem. 53, 9436-9445.

Phytosterols were quantified in nuts and seeds commonly consumed in the United States. Total lipid extracts were subjected to acid hydrolysis and then alkaline saponfication, and free sterols were analyzed as trimethylsilyl derivatives by capillary GC-FID and GC-MS. Δ5-Avenasterol was quantified after alkaline saponification plus direct analysis of the glucoside. Sesame seed and wheat germ had the highest total phytosterol content (400-413 mg/100 g) and Brazil nuts the lowest (95 mg/100 g). Of the products typically consumed as snack foods, pistachio and sunflower kernels were richest in phytosterols (270-289 mg/100 g). β-Sitosterol, Δ5-avenasterol, and campesterol were predominant. Campestanol ranged from 1.0 to 12.7 mg/100 g. Only 13 mg/100 g β-sitosterol was found in pumpkin seed kernel, although total sterol content was high (265 mg/100 g). Phytosterol concentrations were greater than reported in existing food composition databases, probably due to the inclusion of steryl glycosides, which represent a significant portion of total sterols in nuts and seeds.

Concept of a nutritious food: toward a nutrient density score

Drewnowski, A., 2005.  Concept of a nutritious food: toward a nutrient density score. Am J Clin Nutr.82:721-32.

The American diet is said to be increasingly energy-rich but nutrient poor. To help improve the nutrient-to-energy ratio, the 2005 Dietary Guidelines for Americans recommend that consumers replace some foods in their diets with more nutrient-dense options. Such dietary guidance presupposes the existence of a nutrient density standard. However, a review of the literature shows that the concept of a nutritious food is not based on any consistent standards or criteria. In many cases, healthful foods are defined by the absence of problematic ingredients—fat, sugar, and sodium—rather than by the presence of any beneficial nutrients they might contain. Past attempts to quantify the nutrient density of foods have been based on a variety of calories-to-nutrient scores, nutrients-per-calorie indexes, and nutrient-to-nutrient ratios. The naturally nutrient rich (NNR) score, which is based on mean percentage daily values (DVs) for 14 nutrients in 2000 kcal food, can be used to assign nutrient density values to foods within and across food groups. Use of the NNR score allows consumers to identify and select nutrient-dense foods while permitting some flexibility where the discretionary calories are concerned. This approach has implications for food labeling, nutritional policy making, and consumer education. The Food and Drug Administration has considered approving nutrient claims based on the ratio of a beneficial nutrient to the food’s energy content, as opposed to a specified minimum amount of a nutrient per serving size. Given the current dietary trends, the nutrient density approach can be a valuable tool for nutrition education and dietary guidance.

Oxalate content of legumes, nuts and grain-based flours

Chai, W., M. Liebman, 2005. Oxalate content of legumes, nuts and grain-based flours. Journal of Food Composition and Analysis. 18:723-29.

About 75% of all kidney stones are composed primarily of calcium oxalate and hyperoxaluria is a primary risk factor for this disorder. Since absorbed dietary oxalate can make a significant contribution to urinary oxalate levels, oxalate from legumes, nuts, and different types of grain-based flours was analyzed using both enzymatic and capillary electrophoresis (CE) methods. Total oxalate varied greatly among the legumes tested, ranging from 4 to 80 mg/100 g of cooked weight. The range of total oxalate of the nuts tested was 42-469 mg/100 g. Total oxalate of analyzed flours ranged from 37 to 269 mg/100 g. The overall data suggested that most legumes, nuts, and flours are rich sources of oxalate.

Melatonin in walnuts: influence on levels of melatonin and total antioxidant capacity of blood

Reiter, R.J., L.C. Manchester, D. Tan, 2005.  Melatonin in walnuts: influence on levels of melatonin and total antioxidant capacity of blood. Nutrition. 21:920-24.

Objective: We investigated whether melatonin is present in walnuts (Juglans regia L.) and, if so, tested whether eating walnuts influences melatonin levels and the total antioxidant status of the blood. Methods: Melatonin was extracted from walnuts and quantified by high-performance liquid chromatography. After feeding walnuts to rats, serum melatonin concentrations were measured using a radioimmunoassay and the “total antioxidant power” of the serum was estimated by using the trolox equivalent antioxidant capacity and ferric-reducing ability of serum methods. Results: Mean ± standard error melatonin concentrations were 3.5 ± 1.0 ng/g of walnut. After food restriction of rats and then feeding them regular chow or walnuts, blood melatonin concentrations in the animals that ate walnuts were increased over those in the rats fed the control diet. Increases in blood melatonin were also accompanied by increases in trolox equivalent antioxidant capacity and ferric-reducing ability of serum values. Conclusions: Melatonin is present in walnuts and, when eaten, increase blood melatonin concentrations. The increase in blood melatonin levels correlates with an increased antioxidative capacity of this fluid as reflected by augmentation of trolox equivalent antioxidant capacity and ferric reducing ability of serum values.

Hazelnut oil administration reduces aortic cholesterol accumulation and lipid peroxides in the plasma, liver, and aorta of rabbits fed a high-cholesterol diet.

Hatipoglu, A., Ö. Kanbagli, J. Balkan, M. Küçük, U. Çevikbas, G. Aykaç-toker, H. Berkkan, M. Uysal, 2004. Hazelnut oil administration reduces aortic cholesterol accumulation and lipid peroxides in the plasma, liver, and aorta of rabbits fed a high-cholesterol diet. Biosci. Biotechnol. Biochem. 68(10): 2050-2057.

Hazelnut oil (HO) is rich in monounsaturated fatty acids and antioxidants. We wanted to investigate the effect of HO on lipid levels and prooxidant–antioxidant status in rabbits fed a high-cholesterol (HC) diet. An HC diet caused significant increases in lipids and lipid peroxide levels in the plasma, liver, and aorta together with histopathological atherosclerotic changes in the aorta. Glutathione levels, glutathione peroxidase, and glutathione transferase activities decreased significantly, but superoxide dismutase activity and vitamin E and C levels remained unchanged in the livers of rabbits following HC diet. HO supplementation reduced plasma, liver, and aorta lipid peroxide levels and aorta cholesterol levels together with amelioration in atherosclerotic lesions in the aortas of rabbits fed an HC diet, without any decreasing effect on cholesterol levels in the plasma or liver. HO did not alter the antioxidant system in the liver in the HC group. Our findings indicate that HO reduced oxidative stress and cholesterol accumulation in the aortas of rabbits fed an HC diet.

Fatty acid profile, tocopherol, squalene and phytosterol content of walnuts, almonds, peanuts, hazelnuts and the macadamia nut.

Maguire, L.S., S.M. O’Sullivan, K. Galvin, T.P. O’Connor, N.M. O’Brien, 2004. Fatty acid profile, tocopherol, squalene and phytosterol content of walnuts, almonds, peanuts, hazelnuts and the macadamia nut.  Int J Food Sci Nutr. 55(3):171-178.

Nuts are high in fat but have a fatty acid profile that may be beneficial in relation to risk of coronary heart disease. Nuts also contain other potentially cardioprotective constituents including phytosterols, tocopherols and squalene. In the present study, the total oil content, peroxide value, composition of fatty acids, tocopherols, phytosterols and squalene content were determined in the oil extracted from freshly ground walnuts, almonds, peanuts, hazelnuts and the macadamia nut. The total oil content of the nuts ranged from 37.9 to 59.2%, while the peroxide values ranged from 0.19 to 0.43 meq O2/kg oil. The main monounsaturated fatty acid was oleic acid (C18:1) with substantial levels of palmitoleic acid (C16:1) present in the macadamia nut. The main polyunsaturated fatty acids present were linoleic acid (C18:2) and linolenic acid (C18:3). alpha-Tocopherol was the most prevalent tocopherol except in walnuts. The levels of squalene detected ranged from 9.4 to 186.4 microg/g. beta-Sitosterol was the most abundant sterol, ranging in concentration from 991.2 to 2071.7 microg/g oil. Campesterol and stigmasterol were also present in significant concentrations. Our data indicate that all five nuts are a good source of monounsaturated fatty acid, tocopherols, squalene and phytosterols.

Anatomy and cell wall poly-saccharides of almond (Prunus dulcis D.A. Webb) seeds

Dourado, F., A. Barros, M. Mota, M.A. Coimbra, F.M. Gama, 2004. Anatomy and cell wall poly-saccharides of almond (Prunus dulcis D.A. Webb) seeds. J Agric Food Chem.52:1364-1370.

Portuguese almond seed anatomy was analyzed by various staining techniques and light microscopy. The almonds seed coat is thin and structurally complex, with lignified celluosic tissue. The almond kernel cell walls are rich in arabinose (45%) glucose (23%) uronic acids (12%) and xylose (12%).