Monagas, M., I. Garrido, R. Lebron-Aguilar, M.C. Gomez-Cordoves, A. Rybarczyk, R. Amarowicz, B.A. Bartolome, 2009. Comparative flavan-3-ol profile and antioxidant capacity of roasted peanut, hazelnut, and almond skins. J. Agric. Food Chem., 57(22):10590-10599.
In the present study, the flavan-3-ol composition and antioxidant capacity of roasted skins obtained from the industrial processing of three commonly consumed tree nuts (i.e., peanuts, hazelnuts, and almonds), as well as fractions containing low and high molecular weight (LMW and HMW) flavan-3-ols, were studied with the aim of assessing their potential as a source of flavonoids. Roasted peanut and hazelnut skins presented similar total phenolic contents, much higher than that of almond skins, but their flavan-3-ol profiles, as determined by LC-ESI-MS and MALDI-TOF MS, differed considerably. Peanut skins were low in monomeric flavan-3-ols (19%) in comparison to hazelnut (90%) and almond (89%) skins. On the other hand, polymeric flavan-3-ols in peanut and almond skins occurred as both A- and B-type proanthocyanidins, but in peanuts the A forms (up to DP12) were predominant, whereas in almonds the B forms (up to DP8) were more abundant. In contrast, hazelnuts were mainly constituted by B-type proanthocyanidins (up to DP9). The antioxidant capacity as determined by various methods (i.e., total antioxidant capacity, ORAC, DPPH test, and reducing power) was higher for whole extracts from roasted hazelnut and peanut skins than for almond skins; however, the antioxidant capacities of the HMW fraction of the three types of nut skins were equivalent despite their different compositions and DPs. Nevertheless, the large variation in flavan-3-ol concentration, structural composition, type of interflavan linkage, and DP found among the three types of nut skins suggests large difference in their expected in vivo biological activities.
Alasalvar, C., F. Shahidi, 2009. Natural antioxidants in tree nuts. Eur. J. Lipid Sci. Technol. 111:1056-1062
The levels of natural antioxidants and phytochemicals present in tree nuts are reported. Where possible, the health claims by Food and Drug Administration and European Food Safety Authority and health effects of tree nuts are provided. The content and recommended dietary allowances of nutrient antioxidants (such as vitamins A, C, E, and the mineral selenium) present in various tree nuts are compared. Antioxidant activity and phytochemicals present among tree nuts have been thoroughly reviewed. Research findings from over 65 references, many of which have been published within the last 10 years, have been compiled and reported.
Urpi-Sarda, M., I. Garrido, M. Monagas, C. Gomez-Cordoves, A. Medina-Remon, C. Andres-Lacueva, B. Bartolomei, 2009. Profile of plasma and urine metabolites after the intake of almond [prunus dulcis (mill.) D.A. Webb] polyphenols in humans. J. Agric. Food Chem. 57:10134-10142.
Nut skins are considered to be a rich source of polyphenols and may be partially responsible for the numerous health effects associated with nut consumption. However, more bioavailability studies of nut skin polyphenols are needed to understand the health effects derived from nut consumption. The aim of the present study was to determine the profiles of both phase II and microbial-derived phenolic metabolites in plasma and urine samples before and after the intake of almond skin polyphenols by healthy human subjects (n = 2). Glucuronide, O-methyl glucuronide, sulfate, and O-methyl sulfate derivatives of (epi) catechin, as well as the glucuronide conjugates of naringenin and glucuronide and sulfate conjugates of isorhamnetin, were detected in plasma and urine samples after consumption of almond skin polyphenols. The main microbial-derived metabolites of flavanols, such as 5-(dihydroxyphenyl)-γ-valerolactone and 5-(hydroxymethoxyphenyl)-γ-valerolaclone, were also detected in their glucuronide and sulfate forms. In addition, numerous metabolites derived from further microbial degradation of hydroxyphenylvalerolactones, including hydroxyphenylpropionic, hydroxyphenylacetic, hydroxycinnamic, hydroxybenzoic, and hydroxy hippuric acids, registered major changes in urine after the consumption of almond skin polyphenols. The urinary excretion of these microbial metabolites was estimated to account for a larger proportion of the total polyphenol ingested than phase II metabolites of (epi) catechin, indicating the important role of intestinal bacteria in the metabolism of highly polymerized almond skin polyphenols. To the authors’ knowledge this study constitutes the most complete report of the absorption of almond skin polyphenols in humans.
Mandalari, G., G.T. Rich, R.M. Faulks, C. Bisignano, A. Narbad, M.S.J. Wickham, 2009. Almonds demonstrate prebiotic potential effects of almond lipid on colonic microbiota. Supplement to AgroFood Industry Hi-Tech. May/June 20(3):47-49.
Although the evaluation of almond nutrients bioaccessibility is incomplete, it may have important implications for the prevention and management of obesity and cardiovascular disease. We have shown that almond cell walls remain largely intact during simulated gastric and duodenal digestion, thus reducing lipid bioaccessibility. A large proportion of almond nutrients survived upper gastrointestinal digestion, therefore reaching the large bowel. Finely ground almonds, FG, altered the composition of human colonic microbiota during fermentation in an in vitro human colonic model by stimulating the growth of bifidobacteria and Eubacterium rectale. No significant differences in the proportions of gut bacteria groups were detected in response to defatted finely ground almonds, DG.
Thomson, C.D., A. Chisholm, S.K. McLachlan, J.M. Campbell, 2008. Brazil nuts: an effective way to improve selenium status. Am J Clin Nutr. 87:379 –384.
Background: Brazil nuts provide a rich natural source of selenium, yet no studies have investigated the bioavailability of selenium in humans. Objective: We investigated the efficacy of Brazil nuts in increasing selenium status in comparison with selenomethionine. Design: A randomized controlled trial was conducted with 59 New Zealand adults. Participants consumed 2 Brazil nuts thought to provide ≈100µg Se, 100µg Se as selenomethionine, or placebo daily for 12 wk. Actual intake from nuts averaged 53µg Se/d (possible range: 20 – 84µg Se). Plasma selenium and plasma and whole blood glutathione peroxidase (GPx) activities were measured at baseline and at 2, 4, 8, and 12 wk, and effects of treatments were compared. Results: Plasma selenium increased by 64.2%, 61.0%, and 7.6%; plasma GPx by 8.3%, 3.4%, and -1.2%; and whole blood GPx by 13.2%, 5.3%, and 1.9% in the Brazil nut, selenomethionine, and placebo groups, respectively. Change over time at 12 wk in plasma selenium (P < 0.0001 for both groups) and plasma GPx activity in the Brazil nut (P < 0.001) and selenomethionine (P = 0.014) groups differed significantly from the placebo group but not from each other. The change in whole blood GPx activity was greater in the Brazil nut group than in the placebo (P = 0.002) and selenomethionine (P = 0.032) groups. Conclusion: Consumption of 2 Brazil nuts daily is as effective for increasing selenium status and enhancing GPx activity as 100µg Se as selenomethionine. Inclusion of this high-selenium food in the diet could avoid the need for fortification or supplements to improve the selenium status of New Zealanders.
Hughey, C.A., B. Wilcox, C.S. Mindardi, C.W. Takehara, M. Sundararaman, L.M. Were. 2008. Capillary liquid chromatography-mass spectrometry for the rapid identification and quantification of almond flavonoids. J.Chromatogr. A. 1192(2):259.
A rapid negative ion ESI high-performance capillary liquid chromatography–mass spectrometry method was developed to identify and quantify flavonoids (e.g., flavanols, flavonols, flavanones and glycosides). Fifteen standards and two varieties of almond skin extract powder (Carmel and Nonpareil) were used to demonstrate the chromatographic separation, reproducibility and accuracy of the method that employed a 150mm×0.3mm ChromXP 3C18-EP-120 column. All standards eluted in less than 10 min, providing a 9–12× reduction in analysis time compared to existing methods (90–120 min). However, isomers (e.g., catechin/epicatechin and galactosides/glucosides) were not resolved and, therefore, identified and quantified collectively. RSDs for retention time and peak area reproducibility (mass spectrometry data) were <0.5% and <5.0%, respectively. Peak area reproducibility was greatly improved (from a RSD > 10%) after the implementation of a low-flow metal needle in the ESI source. Quantitation by mass spectrometry also afforded a % error less than 5% for most compounds.
Chen, C.-Y.O., J.B. Blumberg, 2008. In vitro activity of almond skin polyphenols for scavenging free radicals and inducing quinone reductase. J. Agr. Food Chem. 56:4427-4434.
Almond skins are rich in polyphenols (ASP) that may contribute to these almond oxidant defense benefits. The in vitro effect of ASP extracted with methanol (M) or a gastrointestinal juice mimic (GI) alone or in combination with vitamins C (VC) or E (VE) (1-10 µmol/L) on scavenging free radicals and inducing quinone reductase (QR) were tested to assess their potential mechanisms of action. Flavonoid profiles from ASP-M and -GI extracts were different from one another. ASP-GI was more potent in scavenging HOCl and ONOO- radicals than ASP-M. In contrast, ASP-M increased and ASP-GI decreased QR activity in Hepa1c1c7 cells. Adding VC or VE to ASP produced a combination-and dose-dependent action on radical scavenging and QR induction. In comparison to their independent actions, ASPM plus VC were less potent in scavenging DPPH, HOCl, ONOO-, and O2 – •. However, the interaction between ASPGI plus VC promoted their radical scavenging activity. Combining ASP-M plus VC resulted in a synergistic interaction, inducing QR activity, but ASP-GI plus VC had an antagonistic effect. On the basis of their total phenolic content, the measures of total antioxidant activity of ASP-M and -GI were comparable. Thus, in vitro, ASP act as antioxidants and induce QR activity, but these actions are dependent upon their dose, method of extraction, and interaction with antioxidant vitamins.
Berry, S.E.E., E.A. Tydeman, H.B. Lewis, R. Phalora, J. Rosborough, D.R. Picout, P.R. Ellis, 2008. Manipulation of lipid bioaccessibility of almond seeds influences postprandial lipemia in healthy human subjects. Am J Clin Nutr. 88:922-9.
Background: Plant cell walls are known to influence the rate and extent of lipid release from plant food tissues during digestion; however, the effect of cell wall structure on postprandial lipemia is unknown. Objective: The objective was to investigate the effects of lipid release (bioaccessibility) on postprandial lipemia by comparing lipid encapsulated by cell walls with lipid present as free oil. Design: A randomized crossover trial (n = 20 men) compared the effects of 3 meals containing 54 g fat provided as whole almond seed macroparticles (WA), almond oil and defatted almond flour (AO), or a sunflower oil blend as control (CO) on postprandial changes in oxidative stress (8-isoprostane F2α concentrations), vascular tone (peripheral augmentation index), and plasma triacylglycerol, glucose, and insulin concentrations. Results: The postprandial increase in plasma triacylglycerol was lower [74% and 58% lower incremental area under curve (iAUC)] after the WA meal than after the AO and CO meals (P <0.001). Increases in plasma glucose concentrations (0–180 min) were significantly higher after the WA meal (iAUC: 114; 95% CI: 76, 153) than after the AO meal (iAUC: 74; 95% CI: 48, 99) (P < 0.05), but no significant differences from the CO meal were observed (iAUC:88; 95% CI: 66, 109). The peak reductions in peripheral augmentation index after the WA, AO, and CO meals (-9.5%, -10.1%, and -12.6%, respectively, at 2 h) were not significantly different between meals. Plasma 8-isoprostane F2α and insulin concentrations did not differ significantly between meals. Conclusions: The bioaccessibility of lipid in almond seeds, which is regulated by the structure and properties of cell walls, plays a primary role in determining postprandial lipemia.
Sathe, S.K., N.P. Seeram, H.H. Kshirsagar, D. Heber, K.A. Lapsley. 2008. Fatty acid composition of California grown almonds. J. Food Sci. 73(9):C607-C614.
Eight almond (Prunus dulcis L.) cultivars from 12 different California counties, collected during crop years 2004 to 2005 and 2005 to 2006, were extracted with petroleum ether. The extracts were subjected to GC-MS analyses to determine fatty acid composition of soluble lipids. Results indicated palmitic (C16:0), oleic (C18:1), linoleic (C18:2), and α-linolenic (C18:3) acid, respectively, accounted for 5.07% to 6.78%, 57.54% to 73.94%, 19.32% to 35.18%, and 0.04% to 0.10%; of the total lipids. Oleic and linoleic acid were inversely correlated (r = -0.99, P = 0.05) and together accounted for 91.16% to 94.29% of the total soluble lipids. Statistically, fatty acid composition was significantly affected by cultivar and county.
Mandalari, G., R.M. Faulks, G.T. Rich, V.L. Turcos, D.R. Picout, R.B.L. Curto, G. Bisignano, G. Dugo, K. W. Waldron, P.R. Ellis, M.S.J. Wickham, 2008. Release of protein, lipid, and vitamin E from almond seeds during digestion. J. Agric. Food Chem. 56:3409-3416.
The evaluation of the bioaccessibility of almond nutrients is incomplete. However, it may have implications for the prevention and management of obesity and cardiovascular disease. This study quantified the release of lipid, protein, and vitamin E from almonds during digestion and determined the role played by cell walls in the bioaccessibility of intracellular nutrients. Natural almonds (NA), blanched almonds (BA), finely ground almonds (FG), and defatted finely ground almonds (DG) were digested in vitro under simulated gastric and gastric followed by duodenal conditions. FG were the most digestible with 39, 45, and 44% of lipid, vitamin E, and protein released after duodenal digestion, respectively. Consistent with longer residence time in the gut, preliminary in vivo studies showed higher percentages of nutrient release, and microscopic examination of digested almond tissue demonstrated cell wall swelling. Bioaccessibility is improved by increased residence time in the gut and is regulated by almond cell walls.
