Anne Meynier

Volatile compounds of commercial Milano salami.

The relationship between extracted volatiles of Milano salami, one of the main dry-cured sausages produced in Italy, and their olfactory properties was studied. Volatile compounds were extracted by a purge-and-trap method, quantified using a flame ionisation detector and identified by mass spectrometry. Olfactory analysis was performed by sniffing the gas chromatographic effluent. Nearly 80 compounds were identified and quantified: most came from spices (60.5%), 18.9% from lipid oxidation, 11.8% from amino acid catabolism and 4.9% from fermentation processes. Panellists detected 19 odours by sniffing. These odours were associated with spices, lipid oxidation or fermentation and were in agreement with the contributions of each reaction to the overall aroma of the product.

Dietary oxidized n-3 PUFA induce oxidative stress and inflammation: role of intestinal absorption of 4-HHE and reactivity in intestinal cells

Dietary intake of long-chain n-3 PUFA is now widely advised for public health and in medical practice. However, PUFA are highly prone to oxidation, producing potentially deleterious 4-hydroxy-2-alkenals. Even so, the impact of consuming oxidized n-3 PUFA on metabolic oxidative stress and inflammation is poorly described. We therefore studied such effects and hypothesized the involvement of the intestinal absorption of 4-hydroxy-2-hexenal (4-HHE), an oxidized n-3 PUFA end-product. In vivo, four groups of mice were fed for 8 weeks high-fat diets containing moderately oxidized or unoxidized n-3 PUFA. Other mice were orally administered 4-HHE and euthanized postprandially versus baseline mice. In vitro, human intestinal Caco-2/TC7 cells were incubated with 4-hydroxy-2-alkenals. Oxidized diets increased 4-HHE plasma levels in mice (up to 5-fold, P < 0.01) compared with unoxidized diets. Oxidized diets enhanced plasma inflammatory markers and activation of nuclear factor kappaB (NF-κB) in the small intestine along with decreasing Paneth cell number (up to −19% in the duodenum). Both in vivo and in vitro, intestinal absorption of 4-HHE was associated with formation of 4-HHE-protein adducts and increased expression of glutathione peroxidase 2 (GPx2) and glucose-regulated protein 78 (GRP78). Consumption of oxidized n-3 PUFA results in 4-HHE accumulation in blood after its intestinal absorption and triggers oxidative stress and inflammation in the upper intestine.

The antioxidant activity of carnosine and its consequences on the volatile profiles of liposomes during iron/ascorbate induced phospholipid oxidation

Abstract The natural dipeptide L-carnosine (β-Ala-His) exhibits antioxidative properties and can be used as an antioxidant in food products. Its antioxidant activity and its effect on the volatile compounds produced during lipid oxidation was studied in a meat-related model system (liposomes of muscle phospholipids). Oxygen uptake, conjugated dienes, trienes and ketodienes, thiobarbituric acid reactive substances (TBARS) and volatile compounds were measured after induction of oxidation by equimolar Fe(III)/ascorbate (45 μM). Inclusion of carnosine (2–10 mM) lead to a decrease in all indices of lipid oxidation, except for the initial rate of oxygen uptake, which increased, and the rates of oxygen uptake 5 or more min after catalyst injection, which remained constant. The decrease varied as a function of carnosine concentration, method of measurement and incubation time. When carnosine was added to previously oxidised liposomes, TBARS, t-2-undecenal, total 2-alkenals and hexanol amounts decreased significantly. Carnosine antioxidant activity is multifunctional: it has a buffering effect; it interferes in the initiation step of oxidation; it decreases the amount of preformed peroxides; it reacts with some secondary products.

n-3 PUFA added to high-fat diets affect differently adiposity and inflammation when carried by phospholipids or triacylglycerols in mice

BackgroundDietary intake of n-3 polyunsaturated fatty acids (PUFA) is primarily recognized to protect against cardiovascular diseases, cognitive dysfunctions and the onset of obesity and associated metabolic disorders. However, some of their properties such as bioavailability can depend on their chemical carriers. The objective of our study was to test the hypothesis that the nature of n-3 PUFA carrier results in different metabolic effects related to adiposity, oxidative stress and inflammation.Methods4 groups of C57BL/6 mice were fed for 8 weeks low fat (LF) diet or high-fat (HF, 20%) diets. Two groups of high-fat diets were supplemented with long-chain n-3 PUFA either incorporated in the form of phospholipids (HF-ω3PL) or triacylglycerols (HF-ω3TG).ResultsBoth HF-ω3PL and HF-ω3TG diets reduced the plasma concentrations of (i) inflammatory markers such as monocyte chemoattractant protein-1 (MCP-1) and interleukin 6 (IL-6), (ii) leptin and (iii) 4-hydroxy-2-nonenal (4-HNE), a marker of n-6 PUFA-derived oxidative stress compared with the control HF diet. Moreover, in both HF-ω3PL and HF-ω3TG groups, MCP-1 and IL-6 gene expressions were decreased in epididymal adipose tissue and the mRNA level of gastrointestinal glutathione peroxidase GPx2, an antioxidant enzyme, was decreased in the jejunum compared with the control HF diet. The type of n-3 PUFA carrier affected other outcomes. The phospholipid form of n-3 PUFA increased the level of tocopherols in epididymal adipose tissue compared with HF-ω3TG and resulted in smaller adipocytes than the two others HF groups. Adipocytes in the HF-ω3PL and LF groups were similar in size distribution.ConclusionSupplementation of mice diet with long-chain n-3 PUFA during long-term consumption of high-fat diets had the same lowering effects on inflammation regardless of triacyglycerol or phospholipid carrier, whereas the location of these fatty acids on a PL carrier had a major effect on decreasing the size of adipocytes that was not observed with the triacyglycerol carrier. Altogether, these results would support the development functional foods containing LC n-3 PUFA in the form of PL in order to prevent some deleterious outcomes associated with the development of obesity.

Oxidation of muscle phospholipids in relation to their fatty acid composition with emphasis on volatile compounds

The impact of moderate changes of fatty acid (FA) composition of phospholipids (PL) on their oxidative stability and on volatile profiles remains largely unknown. PL of breast muscle of turkeys fed a diet containing 6% tallow, rapeseed oil or soya oil were purified and prepared as liposomes. After 24 h of incubation at 25 °C with iron/ascorbate, oxidation was quantified by measurement of thiobarbituric acid reactive substances (TBA-RS) and volatile compounds. TBA-RS level was the lowest (21.4 nmole eq MDA mg−1 PL) in PL from tallow-fed animals but was not significantly different (P > 0.05) in soya oil (30.9 nmole eq MDA mg−1 PL) and rapeseed oil (30.3 nmole eq MDA mg−1 PL) batches. ANOVA did not clearly distinguish between the three groups according to the quantities of individual volatiles except for Z,E-2,4-heptadienal. In contrast, principal component analysis (PCA) performed on standardised quantities of volatile compounds distinguished unambiguously the three groups. Axis 1 was positively correlated with volatile compounds arising from oxidation of n-6 fatty acids, and negatively with compounds of n-9 origin. Axis 2 was highly positively correlated with compounds from n-3 origin. Only a few compounds from each origin (n-6, n-3, n-9) had an atypical behaviour. A weak modification of the FA composition of PL led to concomitant modifications of the quantities of volatile compounds generated through oxidation, which were emphasised by multivariate analysis (PCA).

The initial characteristics of marine oil emulsions and the composition of the media inflect lipid oxidation during in vitro gastrointestinal digestion

This work aimed at evaluating the effect of simulated digestive fluids, interface and lipid droplet sizes on the oxidation of oil-in-water emulsions containing long chain n-3 fatty acyls. Emulsions stabilised by a protein or by phosphatidyl-choline/Tween 80 were submitted to gastro-intestinal in vitro conditions in presence of metmyoglobin. The gastric phase was characterised by a decrease of tocopherol amounts and moderate O2 uptake and aldehyde formation. Oxidation developed further during the intestinal phase, with tocopherols tending to zero, oxygen uptake and production of aldehydes at potentially toxic concentrations. The simulated digestive fluids reduced oxygen uptake and MDA formation only during the intestinal step of the phospholipid-stabilised emulsion. Quantitative losses of PUFA (e.g. EPA, DHA) were less than 10% even significant at the end of the digestion.

Stabilization of omega-3 oils and enriched foods using emulsifiers

Abstract: This chapter reviews the use of emulsifiers in delivery systems and foods enriched in omega-3 fatty acids. It begins by explaining the reasons why emulsifiers are required for formulation and stabilization of various multiphase systems, the focus being on oil-in-water emulsions, before going on to give an overview of the main classes of food-grade emulsifiers and their ability to stabilize emulsions and food formulations related to some of their molecular characteristics. The possible involvement of emulsifiers such as proteins and lecithins in delaying lipid oxidation is then presented, and the effects of emulsification and emulsifiers on flavour are also summarized. In conclusion, the potential for optimizing the bioavailability and the beneficial effects of polyunsaturated fatty acids through the control of lipid organization and the need for research in this area are underlined.

N-3 fatty acid enriched eggs and production of egg yolk powders: an increased risk of lipid oxidation?

Lipid oxidation is generally favoured by thermal processing and long-term storage. Oxidised lipids can alter nutritional and sensorial properties of foods. As eggs are widely used in food industries in dried powder form, our aim was to determine whether compositional or processing parameters have an impact on lipid oxidation from the shell eggs up to the dried powders and subsequent storage. Two batches of shell eggs were processed: one issued from hens fed with a standard diet and another receiving a diet enriched in extruded linseed, rich in linolenic acid. The extent of lipid oxidation was evaluated by quantification of conjugated dienes (CD) and malondialdehyde (MDA), but also by assessment of tocopherols, lutein and zeaxanthin losses. Results highlighted the remarkable oxidative stability of control and enriched yolk powders as revealed by a moderate increase of the quantities of CD and MDA, the lack of oxidised cholesterol and small loss of α-tocopherol.

n -3 PUFA prevent metabolic disturbances associated with obesity and improve endothelial function in golden Syrian hamsters fed with a high-fat diet

Glucose intolerance and dyslipidaemia are independent risk factors for endothelium dysfunction and CVD. The aim of the present study was to analyse the preventive effect of n-3 PUFA (EPA and DHA) on lipid and carbohydrate disturbances and endothelial dysfunction. Three groups of adult hamsters were studied for 20 weeks: (1) control diet (Control); (2) high-fat diet (HF); (3) high-fat diet enriched with n-3 PUFA (HFn-3) groups. The increase in body weight and fat mass in the HF compared to the Control group (P < 0.05) was not found in the HFn-3 group. Muscle TAG content was similar in the Control and HF groups, but significantly lower in the HFn-3 group (P = 0.008). Glucose tolerance was impaired in the HF compared to the Control group, but this impairment was prevented by n-3 PUFA in the HFn-3 group (P < 0.001). Plasma TAG and cholesterol were higher in the HF group compared to the Control group (P < 0.001), but lower in the HFn-3 group compared to the HF group (P < 0.001). HDL-cholesterol was lower in the HFn-3 group compared to the Control and HF groups (P < 0.0005). Hepatic secretion of TAG was lower in the HFn-3 group compared to the HF group (P < 0.005), but did not differ from the Control group. Hepatic gene expression of sterol regulatory element-binding protein-1c, diacylglycerol O-acyltransferase 2 and stearyl CoA desaturase 1 was lower in the HFn-3 group, whereas carnitine palmitoyl transferase 1 and scavenger receptor class B type 1 expression was higher (P < 0.05). In adipocytes and adipose macrophages, PPARγ and TNFα expression was higher in the HF and HFn-3 groups compared to the Control group. Endothelium relaxation was higher in the HFn-3 (P < 0.001) than in the HF and Control groups, and was correlated with glucose intolerance (P = 0.03) and cholesterol (P = 0.0003). In conclusion, n-3 PUFA prevent some metabolic disturbances induced by high-fat diet and improve endothelial function in hamsters.

Dynamic modeling of in vitro lipid digestion: individual fatty acid release and bioaccessibility kinetics.

The aim of this study was to gain knowledge about the role of triacylglycerol (TAG) composition in fatty acids (FA) of o/w emulsions on both the pancreatic lipolysis kinetics and the bioaccessibility of released products (i.e. contained within the bile salt micellar phase). A mathematical model was developed and its predictions were compared to a set of experimental data obtained during an in vitro digestion of a whey protein stabilized emulsion. Modeling results show that FA residues of TAG were hydrolyzed at specific rates, inducing different bioaccessibility kinetics. The estimated lipolysis rate constants of the studied FA (C8:0, C10:0≫C18:1 n-9≫C12:0>C14:0>C16:0≈C16:1 n-7>C22:6 n-3) were in close agreement with the available literature on the substrate specificity of pancreatic lipase. Results also suggest that lipolysis products are very rapidly solubilized in the bile salt mixed micelles with no fractionation according to the FA carbon chain.