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Background: Seaweed is an underutilised food source in Britain, despite being abundant on the surrounding shores, it is only found in localised dishes such as laverbread . Seaweed has been shown to be a source of basic nutrients such as protein and fibre as well as a source of vitamins and minerals. It has been identified as potential source of bioactive compounds including antioxidants. The seaweed Ascophylfum nodosum is an edible brown seaweed common to the British Isles. The main aims of this study were to evaluate if ultrasound-assisted extraction (UAE) was an efficient and environmentally friendly alternative to conventional solvent extraction for extracting antioxidants from of dried Ascophyllum nodosum; to analyse the effect of particle size, agitation and heat treatment on extraction; and to evaluate physical characteristics and consumer acceptability of a bakery product (crackers) containing different levels of the seaweed sample. Methods: The dried seaweed samples were treated at ultrasound amplitudes of 30, 70 and 100~m and compared against conventional solvent extraction. To evaluate impact of heat and time on extraction, samples were heated to 160°C, 180°C, 2000C and 220°C without ultrasound treatment and were treated for periods of 5,10,15 and 20 min. The bioactives were assessed by chemical assays . . To investigate feasibility of inclusion in the UK diet, the seaweed was incorporated into crackers at 5,10,15 and 20% levels with both particle sizes. Results: The investigation found particle size to have a significant impact on the antioxidant capacity with the fine grade (300 - 45~m) Ascophy/lum nodosum producing extracts with higher antioxidant capacity across all amplitudes. It was also observed that the addition of a shaking pre-treatment significantly improved the antioxidant capacity at all amplitudes and with both particle sizes (p<0.05). The use of water as a solvent compared to methanol was found to improve the antioxidant capacity; this was found to be significant across all tests at 70~m amplitude (p<0.05). In all the assays the ultrasound treated extracts showed a significant (p<0.05) improvement upon the control. The ultrasound treatment was shown to have a greater effect on the medium grade (355 - 850 ~m) Ascophyllum nodosum. The addition of heat decreased the antioxidant capacity at all time and temperatures when compared to the control. The colour of the seaweed was shown to change with the addition of heat over a period of time. The crackers produced with the fine grade Ascophyllum nodosum were considered unpalatable across all incorporations, the medium grade scored higher than the fine. The sample with 5% medium grade inclusion showed no significant difference to the control and was considered palatable. Conclusion: Ultrasound has shown to significantly improve the solid liquid extraction bioactive yield from Ascophyllum nodosum. The use of a shaking during the sol id liquid extraction and use of water as a solvent was shown to improve yield . Ascophyllum nodosum has shown potential to be used as an alternative ingredient in cracker production, producing a nutrient rich cracker with increased fibre content and potential bioactive effects. Crackers incorporating 5% Ascophyllum nodosum medium grade were found to be acceptable via sensory evaluation.

Background: Long chain omega-3 (n-3) polyunsaturated fatty acids (LC3PUFA) offer numerous health benefits throughout the life cycle, including improved cognititve and cardiovascular function. Currently, UK. intakes fall short of dietary guidelines. especially amongst vegetarians. Nanoemulsions are novel systems with small droplet sizes ti at can be used to enrich functional foods with LC3PUF A offering a vehicle to increase habitual intakes and bioavailability. Previous combinations of LC3PUFA and water I based emulsions have however been found to create problems with consumer acceptability and oxidative rancidity. This PhD set out to develop and analyse a novel, vegetarian, LC3PUF A nanoemulsion system for incorporation into a functional yogurt product. Methods: A nanoemulsion system was designed and used to create a strawberry yogurt drink, which was evaluated for consumer acceptability using sensory analysis. A full study assessed the oxidation stability of the nanoemulsion system and enriched yogurt. This was followed by a single blinded, randomised crossover intentention trial to compare the bioavailability of a vegetarian algae oil nanoemulsion with the same dose of the bulk algae oil as a control. Participants ingested 200g of yogurt enriched with bulk or nano-emulsified oil providing 1264mg DHA. Results: Droplet measurement results confirmed that nanoemulsion systems can be created using ultrasound with 7, 20 and 50 per cent oil loads in combination with lecithin and/or Tween 40 emulsifiers. Oxidation testing indicated that nanoemulsion of did not have a significant negative effect in terms of oxidation when products at 4°C and that sensory qualities improved after 16 days of storage (P < 0.001). oil the addition of the algae oil nanoemulsion had a significant adverse effect on cJ nsumer acceptability (P S 0.05). The affected attributes (aroma, flavour, texture, aftertaste and overall acceptability) were all significantly reduced when compared with a bulk oil enriched and control yogurt (P S 0.05). The addition of the algae oil nanoemulsion (4.29g1l00g yogurt, l264mg OHA) significantly increased the bioavailability of LC3PUF A compared to the same dosage of untreated bulk oil as indicated by under the curve calculation (AUC), (P < 0.05). Baseline adjusted omega-6 to n-3 ratios (n- 6: n-3) were also statistically significantly reduced by 4.52 per cent for the nanoemulsion I compared to 1.48 per cent for bulk oil (P < 0.05). Conclusions: The incorporation of vegetarian LC3PUFA oil nanoemulsions into functional foods offers a potential vehicle to improve omega-3 status within the general population. In comparison to untreated oils, increases were noted in the bioavailability of DHA. LC3PUFA and reductions in n-6:n-3 ratios. Further research is now needed to improve the consumer acceptability of the enriched yogurt and to study the bioavailability of vegetarian LC3PUF A nanoemulsions in the form of larger and longer randomised controlled trials.

Les accidents cardio-vasculaires représentent la première cause de décès en France. Parmi les facteurs de risque de ces pathologies figure la structure de l’apport lipidique, excédentaire en acides gras saturés, et déficitaire en acides gras polyinsaturés n-3. L’objectif de cette thèse est la mise au point d’un corps gras alimentaire, dont le profil lipidique permet de participer au rééquilibrage des apports en acides gras, avec comme cible la prévention des maladies cardio-vasculaires.Quatre études ont été réalisées pour répondre à cette problématique. Après la mise au point du profil en acides gras optimal, l’impact de la formulation de la phase concrète sur la texture du produit a été étudié afin de concilier les exigences nutritionnelles et les contraintes techniques de sa fabrication et de sa conservation.La mise au point de la formulation de la phase fluide a engendré une étude sur le développement de composés volatils délétères suite à l’addition d’une proportion importante d’huile de poisson dans la formule. Ce travail a mis en évidence deux phénomènes liés au dégagement de ces molécules, l’un attribué à l’oxydation des lipides, l’autre au contact avec l’eau.Le besoin de protéger les nutriments d’intérêt dans la matrice alimentaire a conduit à la mise au point d’une technologie de microencapsulation, originale de par son procédé de fabrication et sa finalité.Enfin, une étude de la biodisponibilité chez l’animal a montré que ce produit alimentaire est un vecteur efficace de ces nutriments d’intérêt que sont les acides gras polyinsaturés à longue chaîne. Apportés dans une telle matrice, ces composés ont modifié le profil lipidique des cellules circulantes et cérébrales, ce qui permet potentiellement d’améliorer le statut inflammatoire et coagulant des animaux / Cardiovascular events are the major cause of death in France. Among the known risk factors, lipid intake is of growing interest, saturated fatty acids being too much consumed, and n-3 polyunsaturated fatty acids not enough. The aim of this PhD study is to design a spread with a lipid profile that can improve the whole lipid intake, and with cardiovascular events prevention as main goal.Four studies were conducted regarding this issue. Following the design of the optimal fatty acid profile for the product, it appeared necessary to study the solid phase recipe impact on the product texture, to achieve both nutritional and technological restrains.The design of the liquid phase recipe generated a study on the development of deleterious volatile compounds following the addition of a high proportion of fish oil in the formula. This work highlighted two phenomena linked to the emission of these molecules, one related to lipid oxidation, and the other to a contact with water.A technology of microencapsulation, which is original because of its production process and aim, was designed to ensure the protection of the active nutrients in the product matrix.Finally, a bioavailability study in rats showed that this food product is a powerful way of providing these nutrients. Incorporated in such a matrix, these molecules modified the lipid profile of the circulating and cerebral cells membrane, potentially improving the inflammatory and clotting status of the animals