El presente trabajo se ha centrado en el desarrollo de emulsiones alimentarias aceite-en-agua estabilizadas con proteínas de atún. Específicamente, se ha analizado la influencia del método de conservación de las proteínas aisladas (liofilización, congelación) y de las condiciones de procesado seleccionadas sobre el comportamiento reológico y la microestructura de dichas emulsiones. Se han preparado emulsiones aceite en agua (con un contenido del 70% en peso de aceite) estabilizadas con proteínas de atún. La concentración de emulsionante usada ha sido 0,50% en peso. El comportamiento reológico de estas emulsiones no depende significativamente del método de conservación de la proteína empleado. Por otra parte, un aumento de la velocidad de agitación durante el proceso de manufactura de la emulsión da lugar a una disminución continua del tamaño medio de gota y a un aumento de las funciones viscoelásticas dinámicas, menos significativo a medida que aumenta dicha velocidad de agitación. | This work is focused on the development of o/w salad dressing-type emulsions stabilized by tuna proteins. The influence of protein conservation methods after the extraction process (freezing or liofilization) on the rheological properties and microstructure of these emulsions was analyzed. Processing variables during emulsification were also evaluated. Stable emulsions with adequate rheological and microstructural characteristics were prepared using 70% oil and 0.50% tuna proteins. From the experimental results obtained, we may conclude that emulsion rheological properties are not significantly affected by the protein conservation method selected. On the contrary, an increase in homogenization speed favours an increase in the values of the linear viscoelastic functions. Less significant is the fact that as agitation speed increases further, mean droplet size steadily decreases.

Water in oil emulsions would be prepared by silicones (SO), modified silicones (DC8500) and a food-grade stabilizer (starch 1). With increasing water contents, the emulsions turned from a liquid-like to gel-like behaviors with enhancing storage and loss modulus. When DC8500/SO was 1/17 with 10 wt% starch 1, a high internal phase emulsion can be obtained with 95 wt% water content. DC8500 and SO worked as efficient emulsifiers and possessed amphiphilic property to form emulsions with water in different ratios. A food-grade starch 1 was supplied as a stabilizer which can enhance both water content and strength of emulsion when added in a low concentration. Besides, it is indicated that the food-grade starches provided potential benefit on stabilizing emulsions in very low concentration.

In this paper we are concerned with adsorption, structure, topography, and dynamic properties (relaxation phenomena and surface dilatational rheology) of food dairy proteins (beta-casein, caseinate, and whey protein isolate, WPI), water-insoluble lipids (monopalmitin, monoolein, and monolaurin) and phospholipids (dipalmitoyl-phosphatidyl-choline, DPPC, and dioleoyl-phosphatidyl-choline, DOPC) at the air-water interface. Combined surface chemistry (surface film balance and static and dynamic tensiometry) and microscopy (Brewster angle microscopy, BAM) techniques have been used to determine the static and dynamic characteristics of these emulsifiers and their mixtures at the air-water interface. The derived information shows that biopolymer (proteins) and low-molecular-weight-emulsifier (LMWE, monoglycerides and phospholipids) type and their mixtures affect the interfacial characteristics of adsorbed and spread films. Important functional differences have been established between proteins, lipids and phospholipids. The static and dynamic characteristics of mixed films depend on the interfacial composition and the surface pressure (pi). At higher surface pressures, collapsed protein residues may be displaced from the interface by LMWE molecules with important repercussions on the interfacial characteristics of the mixed films.

This work deals with the manufacture of oil-in-water food emulsions stabilised by tuna proteins. The influence of protein and oil concentrations on the linear viscoelastic properties and microstructure of these emulsions was analysed. Stable emulsions with suitable linear viscoelastic response and microstructural characteristics were formulated with 70 wt.% oil and, at least, 0.25 wt.% tuna protein. Similarly, emulsions with oil concentrations between 45 and 70 wt.% were prepared using 0.50 wt.% protein. All these emulsions showed a predominantly elastic response in the linear viscoelastic region and a well-developed plateau region in its mechanical spectrum. Rheological and droplet size distribution results pointed out an extensive droplet flocculation, due to interactions among emulsifier molecules located at the oil–water interface of adjacent droplets. As a result, the linear viscoelastic behaviour was controlled by protein–protein interactions, allowing the use of the plateau modulus to successfully normalise both the storage and loss moduli as a function of frequency onto a master curve, irrespective of the selected emulsion formulation.

Thyme oil in water nanomulsion was prepared under subcritical water conditions using water and saponin, as solvent and emulsifier, respectively. Gas chromatography revealed that there were 44 bioactive components in the extracted thyme essential oil which, thymol and carvacrol were two mains of them. Experiments were designed based on central composite design and effects of amounts of saponin and thyme essential oil were evaluated on particle size, polydispersity index (PDI) and zeta potential of the prepared nanoemulsions using response surface methodology. Obtained results revealed that more desirable thyme oil nanoemulsions with minimum particle size (184.51 nm) and PDI (0.514), and maximum zeta potential (− 22.51 mV) were prepared using 0.94 g of saponin and 0.28 mL of thyme essential oil. Furthermore, results indicated that prepared nanoemulsion using obtained optimum production conditions had relatively high antioxidant activity (24%) and high antibacterial and antifungal activities against Staphylococcus aureus and Penicillium digitatum.

Gels are viscoelastic systems built up with a liquid phase entrapped in a three-dimensional network, which can behave as carriers for bioactive food ingredients. Many attempts have been made to design gel structures in the water phase (hydrogels, emulsion gels, bigels) or oil phase (organogels, bigels) in order to improve their delivery performances. Hydrogels are originated from proteins or polysaccharides, which are suitable for the delivery of hydrophilic ingredients. Organogels are mainly built up with the self-assembling of gelator molecules in the oil phase, and they offer good carriers for lipophilic ingredients. Emulsion gels and bigels, containing both aqueous and oil domains, can provide accommodations for lipophilic and hydrophilic ingredients simultaneously. Gel structures (e.g. rheology, texture, water holding capacity, swelling ratio) can be modulated by choosing different gelators, modifying gelation techniques, and the involvement of other ingredients (e.g. oils, emulsifiers, minerals, acids), which then alter the diffusion and release of the bioactive ingredients incorporated. Various studies have proved that gel-based delivery systems are able to improve the stability and bioavailability of many bioactive food ingredients. This review provides a state-to-art overview of different gel-based delivery systems, highlighting the significance of structure–functionality relationship, to provide advanced knowledge for the design of novel functional foods.

The microstructure and stability of oil-in-water emulsions, stabilized with non-protein emulsifiers (sorbitan esters), were analyzed as a function of emulsification time, rotor speed, hydrophilic-lipophilic balance (HLB), and ionic strength. Sauter average dia (D[3,2]) were determined from micrographs. Back-scattered light data were analyzed and a method to determine creaming rates of the systems was proposed. Creaming rates showed that the relationship between emulsion stability and HLB was non-linear. Addition of NaCl raised creaming rates, resulting in decreased stability, while micrographs showed the presence of flocs. Results were discussed taking account of interactions present in the system.

Global trends show that habitual omega-3 intakes are short of recommended guidelines, particularly among vegetarians and vegans. The potential health implications of low long chain omega-3 polyunsaturated fatty acid (LCω3PUFA) intakes coupled with concerns about sustainability of fish stocks call for innovative approaches to provide food based solutions to this problem. Nanoemulsions are systems with extremely small droplet sizes that could provide a solution while improving the bioavailability of LCω3PUFA. Oil in water nanoemulsion systems were successfully created using ultrasound with oil loads of up to 50% (w/w) using vegetarian LCω3PUFA oils (flaxseed and algae). Nanoemulsions of 50% (w/w) with mean droplet size measurements of 192 (flaxseed) and 182 nm (algae) using combinations of the emulsifiers Tween 40 and lecithin were prepared.This technique could be applied to create vegetarian LCω3PUFA nanoemulsions suitable for integration into enriched functional food products with the potential to increase LCω3PUFA intake and bioavailability.

The effect of esterification on hydrolyzed rice starch was analyzed, for this aim rice starch was hydrolyzed and subsequently esterified with lauroyl chloride at three modification levels. Starch derivatives were characterized regarding their degree of substitution (DS), water solubility index, z-potential, gelatinization, and digestibility properties. DS of derivatives of rice starch laurate ranged from 0.042 to 1.86. It was determined that after esterification the water solubility index increased from 3.44 to 53.61%, the z-potential decreased from −3.18 to −11.27, and the content of slowly digestible starch (SDS) decreased from 26.22 to 5.13%. Different emulsions with starch concentrations ranging from 6 to 30 wt% were evaluated. The most stable emulsions were those having 20 and 30 wt% of rice starch laurate.