Antioxidant properties of kilned and roasted malts

Compounds possessing antioxidant activity play a crucial role in delaying or preventing lipid oxidation in foods and beverages during processing and storage. Such reactions lead to loss of product quality, especially as a consequence of off-flavor formation. The aim of this study was to determine the antioxidant activity of kilned (standard) and roasted (speciality) malts in relation to phenolic compounds, sugars, amino acids, and color [assessed as European Brewing Convention units (degrees EBC) and absorbance at 420 nm]. The concentrations of sugars and amino acids decreased with the intensity of the applied heat treatment, and this was attributed to the extent of the Maillard reaction, as well as sugar caramelization, in the highly roasted malts. Proline, followed by glutamine, was the most abundant free amino/imino acid in the malt samples, except those that were highly roasted, and maltose was the most abundant sugar in all malts. Levels of total phenolic compounds decreased with heat treatment. Catechin and ferulic acid were the most abundant phenolic compounds in the majority of the malts, and amounts were highest in the kilned samples. In highly roasted malts, degradation products of ferulic acid were identified. Antioxidant activity increased with the intensity of heating, in parallel with color formation, and was significantly higher for roasted malts compared to kilned malts. In kilned malts, phenolic compounds were the main identified contributors to antioxidant activity, with Maillard reaction products also playing a role. In roasted malts, Maillard reaction products were responsible for the majority of the antioxidant activity.

Activity and location of olive oil phenolic antioxidants in liposomes

The antioxidant activity of hydroxytyrosol, hydroxytyrosol acetate, oleuropein, 3,4-dihydroxyphenylelenolic acid (3,4-DHPEA-EA) and 3,4-dihydroxyphenyielenolic acid dialdehyde (3,4-DHPEA-EDA) towards oxidation initiated by 2,2'-azobis (2-amidinopropane) hydrochloride in a soybean phospholipid liposome system was studied. The antioxidant activity of these olive oil phenols was similar and the duration of the lag phase was almost twice that of alpha-tocopherol. Trolox(R), a water-soluble analogue of alpha-tocopherol, showed the worst antioxidant activity. However, oxidation before the end of the lag phase was inhibited less effectively by the olive oil phenols than by alpha-tocopherol and Trolox(R). Synergistic effects (11-20% increase in lag phase) were observed in the antioxidant activity of combinations of alpha-tocopherol with olive oil phenols both with and without ascorbic acid. Fluorescence anisotropy of probes and fluorescence quenching studies showed that the olive oil phenols did not penetrate into the membrane, but their effectiveness as antioxidants showed they were associated with the surface of the phospholipid bilayer. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.

Interactions of ferric ions with olive oil phenolic compounds

The ferric complexing capacity of four phenolic compounds, occurring in olives and virgin olive oil, namely, oleuropein, hydroxytyrosol, 3,4-dihydroxyphenylethanol-elenolic acid (3,4-DHPEA-EA), and 3,4-dihydroxyphenylethanol-elenolic acid dialdehyde (3,4-DHPEA-EDA), and their stability in the presence of ferric ions were studied. At pH 3.5, all compounds formed a reversible 1:1 complex with ferric ions, but hydroxytyrosol could also form complexes containing > 1 ferric ion per phenol molecule. At pH 5.5, the complexes between ferric ions and 3,4-DHPEA-EA or 3,4-DHPEA-EDA were relatively stable, indicating that the antioxidant activity of 3,4-DHPEA-EA or 3,4-DHPEA-EDA at pH 5.5 is partly due to their metal-chelating activity. At pH 7.4, a complex containing > 1 ferric ion per phenol molecule was formed with hydroxytyrosol. Oleuropein, 3,4-DHPEA-EA, and 3,4-DHPEA-EDA also formed insoluble complexes at this pH. There was no evidence for chelation of Fe(II) by hydroxytyrosol or its derivatives. At all pH values tested, hydroxytyrosol was the most stable compound in the absence of Fe(III) but the most sensitive to the presence of Fe(III).

Effects of enrichment of refined olive oil with phenolic compounds from olive leaves

The possibility of preparing olive oil, with the same nutritional value and stability characteristics found in virgin olive oil, by the enrichment of refined olive oil with olive leaf polyphenols was studied. To obtain antioxidant phenols similar to those found in virgin olive oil, these components were extracted from the leaves of several olive cultivars from the Northern region of Portugal, namely, Carrasca, Ripa, Negruche, Cordovil, Verdeal, Madural, and Bical cultivars, under several conditions. The concentration of a leaf extract required for addition to refined olive oil to obtain the same stability as virgin olive oil was determined. The extract from 1 kg of leaves was sufficient to fortify 50-320 L of refined olive oil to a similar stability as a virgin olive oil sample depending on the metal concentration of the oil, cultivar, and time of the year when the leaves were picked.

Influence of sulfur amino acids on the volatile and nonvolatile components of cooked salmon (Salmo salar)

Volatile and nonvolatile compounds, which could contribute to flavor, were analyzed in salmon. One hundred twenty-three volatile compounds were identified in the headspace of two different samples of cooked salmon, including lipid-derived volatiles, Maillard-derived volatiles, sulfur volatiles, Strecker aldehydes, nitrogen heterocyclic compounds, terpenes, and trimethylamine. Significant differences between samples were found for 104 of the volatiles. Although the levels of free cysteine and methionine were low in the salmon, sulfur volatiles were formed in the cooked fish, demonstrating that there were sufficient sulfur amino acids present for their formation. Notable differences in sulfur compounds between the samples suggested that small changes in sulfur amino acids could be responsible. When this hypothesis was tested, salmon heated with cysteine had increased levels of many thiophenes, thiazoles, alicyclic sulfides, and nitrogen heterocycles. With the addition of methionine, levels of dimethyl sulfides, two alicyclic sulfides, pyrazines, some unsaturated aldehydes, and alcohols and 2-furanmethanethiol increased. The largest difference found among the nonvolatile (low molecular weight water-soluble) compounds was in inosine monophosphate.

Effects of oils rich in eicosapentaenoic and docosahexaenoic acids on the oxidizability and thrombogenicity of low-density lipoprotein

Consumption of oily fish and fish oils is associated with protection against cardiovascular disease. Paradoxically, long-chain polyunsaturated fatty acids present in low-density lipoprotein (LDL) are suggested to be susceptible to oxidation. It is not clear whether eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have similar effects on the susceptibility of LDL to oxidation or whether they affect the thrombogenicity of oxidized LDL. This study examined the influence of highly purified preparations of EPA and DHA on LDL oxidizability and LDL-supported thrombin generation in healthy human volunteers. Forty-two healthy volunteers were randomly assigned to receive olive oil (placebo), an EPA-rich oil or a DHA-rich oil for 4 weeks at a dose of 9 g oil/day. EPA and DHA were incorporated into LDL phospholipids and cholesteryl esters during the supplementation period, but were progressively lost during ex vivo copper-mediated oxidation. Following supplementation, the EPA treatment significantly increased the formation of conjugated dienes during LDL oxidation compared with baseline, whereas the DHA treatment had no effect. Neither treatment significantly affected the lag time for oxidation, oxidation rate during the propagation phase or maximum diene production. Neither EPA nor DHA significantly affected the thrombotic tendency of oxidized LDL compared with the placebo, although DHA tended to decrease it. In conclusion, there are subtle differences in the effects of EPA and DHA on the oxidizability and thrombogenicity of LDL. DHA does not appear to increase the susceptibility of LDL to oxidation to the same degree as EPA and has a tendency to decrease LDL-supported thrombin generation. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Evaluation of the inclusion of a mixture of organic acids or lactulose into the feed of pigs experimentally challenged with Salmonella Typhimurium

A mixture of organic acids and lactulose for preventing or reducing colonization of the gut by Salmonella Typhimurium was evaluated in pigs. A total of 63 4-week-old commercial piglets were randomly distributed into three different experimental dietary groups: a plain diet without additives (PD) and the same diet supplemented with either 0.4% (w/v) formic acid and 0.4% lactic acid (w/v) (AC) or 1% (w/v) lactulose (LC). After 7 days of adaptation, two-thirds of the pigs (14 from each diet) were challenged with a 2-mL oral dose of 10(8) CFU/mL of Salmonella Typhimurium, leaving the remaining animals unchallenged (UC). After 4 and 10 days post-challenge, pigs were euthanized and the ileum and caecum content were aseptically sampled to (a) quantify lactic, formic, and short-chain fatty acids (SCFA), (b) quantify bacterial populations and Salmonella by fluorescence in situ hybridization and (c) qualitatively analyse bacterial populations through denaturing gradient gel electrophoresis (DGGE). Modification of fermentation products and counts of some of the bacterial groups analysed in the challenged pigs receiving the treatments AC and LC were minimal. Treatments only influenced the bacterial diversity after 10 days post-challenge, with AC generating a lower number of DGGE bands than UC(P < 0.05). Neither the inclusion of a mixture of 0.4% (w/v) formic and 0.4% (w/v) lactic acids nor of 1% (w/v) lactulose in the feed influenced numbers of Salmonella in the ileum and caecum of experimentally challenged pigs. (C) 2009 Elsevier B.V. All rights reserved.

Effects of resistant starch type III polymorphs on human colon microbiota and short chain fatty acids in human gut models

This study probed the possible effects of type III resistant starch (RS) crystalline polymorphism on RS fermentability by human gut microbiota and the short chain fatty acids production in vitro. Human fecal pH-controlled batch cultures showed RS induces an ecological shift in the colonic microbiota with polymorph B inducing Bifidobacterium spp. and polymorph A inducing Atopobium spp. Interestingly, polymorph B also induced higher butyrate production to levels of 0.79 mM. In addition, human gut simulation demonstrated that polymorph B promotes the growth of bifidobacteria in the proximal part of the colon and double their relative proportion in the microbiota in the distal colon. These findings suggest that RS polymorph B may promote large bowel health. While the findings are limited by study constraints, they do raise the possibility of using different thermal processing to delineate differences in the prebiotic capabilities of RS, especially its butryrogenicity in the human colon.

Investigations on the effect of amino acids on acrylamide, pyrazines, and Michael addition products in model systems

Acrylamide and pyrazine formation, as influenced by the incorporation of different amino acids, was investigated in sealed low-moisture asparagine-glucose model systems. Added amino acids, with the exception of glycine and cysteine and at an equimolar concentration to asparagine, increased the rate of acrylamide formation. The strong correlation between the unsubstituted pyrazine and acrylamide suggests the promotion of the formation of Maillard reaction intermediates, and in particular glyoxal, as the determining mode of-action. At increased amino acid concentrations, diverse effects were observed. The initial rates of acrylamide formation remained high for valine, alanine, phenylalanine, tryptophan, glutamine, and Ieucine, while a significant mitigating effect, as evident from the acrylamide yields after 60 min of heating at 160 degrees C, was observed for proline, tryptophan, glycine, and cysteine. The secondary amine containing amino acids, proline and tryptophan, had the most profound mitigating effect on acrylamide after 60 min of heating. The relative importance of the competing effect of added amino acids for alpha-dicarbonyls and acrylamide-amino, acid alkylation reactions is discussed and accompanied by data on the relative formation rates of selected amino acid-AA adducts.

Effects of oils rich in eicosapentaenoic and docosahexaenoic acids on immune cell composition and function in healthy humans

Background: Supplementation of the diet with fish oil, which is rich in the long-chain n-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), is reported to decrease several markers of immune function. However, whether EPA, DHA, or a combination of the 2 exerts these immunomodulatory effects is unclear. Objective: The objective of the study was to determine the effects of supplementation with an EPA-rich or DHA-rich oil on a range of immune outcomes representing key functions of human neutrophils, monocytes, and lymphocytes in healthy humans. Design: In a placebo-controlled, double-blind, parallel study, 42 healthy subjects were randomly allocated to receive supplementation with either placebo (olive oil), EPA (4.7 g/d), or DHA (4.9 g/d) for 4 wk. Blood samples were taken before and after supplementation. Results: The fatty acid composition of plasma phospholipids and neutrophils was dramatically altered by supplementation with EPA or DHA, and the effects of EPA differed notably from those of DHA. DHA supplementation decreased T lymphocyte activation, as assessed by expression of CD69, whereas EPA supplementation had no significant effect. Neither the EPA-rich oil nor the DHA-rich oil had any significant effect on monocyte or neutrophil phagocytosis or on cytokine production or adhesion molecule expression by peripheral blood mononuclear cells. Conclusions: Supplementation with DHA, but not with EPA, suppresses T lymphocyte activation, as assessed by expression of CD69. EPA alone does not, therefore, influence CD69 expression. No other marker of immune function assessed in this study was significantly affected by either EPA or - DHA.

Lack of effect of foods enriched with plant- or marine-derived n-3 fatty acids on human immune function

Background: Greatly increasing dietary flaxseed oil [rich in the n-3 polyunsaturated fatty acid (PUFA) alpha-linolenic acid (ALA)] or fish oil [rich in the long-chain n-3 PUFAs eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids] can reduce markers of immune cell function. The effects of more modest doses are unclear, and it is not known whether ALA has the same effects as its long-chain derivatives. Objective: The objective was to determine the effects of enriching the diet with ALA or EPA+DHA on immune outcomes representing key functions of human neutrophils, monocytes, and lymphocytes. Design: In a placebo-controlled, double-blind, parallel study, 150 healthy men and women aged 25-72 y were randomly assigned to I of 5 interventions: placebo (no additional n-3 PUFAs), 4.5 or 9.5 g ALA/d, and 0.77 or 1.7 g EPA+DHA/d for 6 mo. The n-3 PUFAs were provided in 25 g fat spread plus 3 oil capsules. Blood samples were taken at 0, 3, and 6 mo. Results: The fatty acid composition of peripheral blood mononuclear cell phospholipids was significantly different in the groups with higher intakes of ALA or EPA+DHA. The interventions did not alter the percentages of neutrophils or monocytes engaged in phagocytosis of Escherichia coli or in phagocytic activity, the percentages of neutrophils or monocytes undergoing oxidative burst in response to E. coli or phorbol ester, the proliferation of lymphocytes in response to a T cell mitogen, the production of numerous cytokines by monocytes and lymphocytes, or the in vivo delayed-type hypersensitivity response. Conclusion: An intake of f less than or equal to9.5 g ALA/d or less than or equal to1.7 g EPA+DHA/d does not alter the functional activity of neutrophils, monocytes, or lymphocytes, but it changes the fatty acid composition of mononuclear cells.

Olive oil and haemostasis

Olive oil is a key component of the traditional Mediterranean diet; a diet that may explain the low rate of cardiovascular disease (CVD) in Southern European. (Extra virgin) Olive oil is a good source of monounsaturated fatty acids (MUFA) and phenolic compounds, both of which have been investigated for their effects on plasma lipids and lipoproteins, measures of oxidation and factors related to thrombosis. This issue aims to summarise the current understanding of the effects of such dietary components on the haemostatic system and subsequent risk of CVD. To date, evidence suggests that diets rich in MUFA and thus in olive oil attenuate the thrombotic response via a reduction in platelet aggregation and in postprandial FVII levels. Thrombosis is a key event in causing heart attacks and strokes, which if modulated by diet could pose a cost-effective way of reducing CVD incidence in populations that adhere to MUFA/olive oil-rich diets long-term.

Apolipoprotein E enrichment of immuno-separated chylomicron and chylomicron remnants following saturated fatty acids

Aim: We examined the effect of meat fatty acids on lipid and apolipoprotein concentrations of very low density lipoprotein (VLDL) and chylomicron/chylomicron remnants in lipid fractions with a Svedberg flotation rate (S-f) 60-400 and S-f 20-60. Methods and results: Six healthy middle-aged men received in random order mixed meals enriched with saturated (SFA), polyunsaturated (PUFA) or monounsaturated (MUFA) fatty acids on 3 occasions. VLDL and chylomicron/chylomicron remnants in the lipid fractions were separated by immunoaffinity chromatography against apo B-100. In the S-f 60-400 chylomicron/chylomicron remnants, triacylglycerol and cholesterol concentrations were significantly tower following PUFA compared with SFA and MUFA (P <= 0.05). Apolipoprotein (apo) E responses were significantly higher after SFA in chylomicron/chylomicron remnants and VLDL compared with PUFA and MUFA (P < 0.007). However, apo B responses (particle number) were higher following MUFA than SFA (P = 0.039 for chylomicron/chylomicron remnants). Composition of the chylomicron/chylomicron remnants (expressed per particle) revealed differences in their triacylglycerol and apo E contents; in the Sf 60-400 fraction, SFA-rich chylomicron/chylomicron remnants contained significantly more triacylglycerol than MUFA (P = 0.028), more apo E than PUFA- and MUFA-rich particles (P < 0.05) and in the S-f 20-60 fraction, more apo E than MUFA (P = 0.009). Conclusion: There are specific differences in the composition of chylomicron/ chylomicron remnants formed after saturated compared with unsaturated fatty acid-rich meals which could determine their metabolic fate in the circulation and subsequent atherogenicity. (C) 2005 Elsevier B.V. All rights reserved.

Acute effects of meal fatty acids on postprandial NEFA, glucose and apo E response: implications for insulin sensitivity and lipoprotein regulation?

Our aim was to determine whether meal fatty acids influence insulin and glucose responses to mixed meals and whether these effects can be explained by variations in postprandial NEFA and Apo, which regulate the metabolism of triacylglycerol-rich lipoproteins (Apo C and E). A single-blind crossover study examined the effects of single meals enriched in saturated fatty acids SFA), n-6 PUFA and MUFA on plasma metabolite and insulin responses. The triacylglycerol response following the PUFA meal showed a lower net incremental area under the curve than following the SFA and MUFA meals (P < 0.007). Compared with the SFA meal, the PUFA meal showed a lower net incremental area under the curve for the NEFA response from initial suppression to the end of the postprandial period (180-480 min; P < 0.02), and both PUFA and MUFA showed a lower net incremental glucose response (P < 0.02), although insulin concentrations were similar between meals. The pattern of the Apo E response was also different following the SFA meal (P < 0.02). There was a significant association between the net incremental NEFA (180-480 min) and glucose response (r(s)=0.409, P=0.025), and in multiple regression analysis the NEFA response accounted for 24 % of the variation in glucose response. Meal SFA have adverse effects on the postprandial glucose response that may be due to greater elevations in NEFA arising from differences in the metabolism of SFA- v. PUFA- and MUFA-rich lipoproteins. Elevated Apo E responses to high-SFA meals may have important implications for the hepatic metabolism of triacylglycerol-rich lipoproteins.