Biomedical subjects

Nissim Garti

Publications and source records attributed to Nissim Garti.

4 recordsLinked to original sources

PubMed2003

Self-diffusion nuclear magnetic resonance, microstructure transitions, and solubilization capacity of phytosterols and cholesterol in Winsor IV food-grade microemulsions.

Microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. The incorporation of molecular phytosterols, cholesterol-lowering agents, in food products is of great interest to the food industry. In this work is demonstrated the use of water dilutable food-grade microemulsions consisting of ethoxylated sorbitan ester (Tween 60), water, R-(+)-limonene, ethanol, and propylene glycol as vehicles for enhancing the phytosterols solubilization. Phytosterols were solubilized up to 12 times more than the dissolution capacity of the oil [R-(+)-limonene] for the same compounds. The solubilization capacity of phytosterols and cholesterol along a dilution line in a pseudo-ternary phase diagram [on this dilution line the weight ratio of R-(+)-limonene/ethanol/Tween 60 is constant at 1:1:3] was correlated to the microstructure transitions along the dilution line. Structural aspects were studied by self-diffusion NMR spectroscopy. The ability of phytosterols to compete with cholesterol for penetration into bile salt micelles in the gut may be limited to rich aqueous systems (O/W microemulsion).

Cholesterol↗

PubMed2002

Food-grade microemulsions based on nonionic emulsifiers: media to enhance lycopene solubilization.

Water-dilutable food-grade microemulsions consisting of ethoxylated sorbitan esters, and in some cases blended with other emulsifiers, water, (R)-(+)-limonene, ethanol, and propylene glycol, have been prepared. These microemulsions are of growing interest to the food industry as vehicles for delivering and enhancing solubilization of natural food supplements with nutritional and health benefits. Lycopene, an active natural lipophilic antioxidant from tomato, has solubilized in water-in-oil, bicontinuous, and oil-in-water types of microemulsions up to 10 times the oil [(R)-(+)-limonene] dissolution capacity. The effects of aqueous-phase dilution, nature of surfactant (hydrophilic-lypophilic balance), and mixed surfactant on solubilization capacity and solubilization efficiency were studied. Structural aspects studied by self-diffusion NMR were correlated to the solubilization capacity, and transformational structural changes were identified.

Carotenoids↗

PubMed2002

Furfural-cysteine model reaction in food grade nonionic oil/water microemulsions for selective flavor formation.

The thermal reaction between cysteine and furfural was investigated at 65 degrees C in five-component food grade oil/water (O/W) microemulsions of R-(+)-limonene/ethanol, EtOH/water/propylene glycol, PG/Tween 60 as apart of a systematic study on the generation of aroma compounds by utilizing structured W/O and O/W fluids. The furfural-cysteine reaction led to the formation of unique aroma compounds such as 2-furfurylthiol (FFT), 2-(2-furanyl)thiazolidine (main reaction product), 2-(2-furanyl)thiazoline, and N-(2-mercaptovinyl)-2-(2-furanyl)thiazolidine. These products were determined and characterized by GC-MS. Enhancement in flavor formation is termed "microemulsion catalysis". The chemical reaction occurs preferably at the interfacial film, and therefore a pseudophase model was assumed to explain the enhanced flavor formation. The product internal composition is dictated by process conditions such as temperature, time, pH, and mainly the nature of the interface. Increasing water/PG ratio leads to a dramatic increase in the initial reaction rate (V(0)). V(0) increased linearly as a function of the aqueous phase content, which could be due to the increase in the interfacial concentration of furfural. Microemulsions offer a new reaction medium to produce selective aroma compounds and to optimize their formation.

Cyclohexenes↗

PubMed2001

Sugar-Ester Nonionic Microemulsion: Structural Characterization.

Surfactants containing sugar components and fatty acids satisfy the quality standards for food application. The food grade sugar ester in this study is a commercial sucrose monoester of stearic acid (abbreviated SES), the oil phase consists of a 1:1 mixture of n-tetradecane and l-butanol. The originally planned food grade oil, a medium chain triglyceride, is substituted by tetradecane because tetradecane is available as a fully deuterated product, which is necessary for some structural investigations. The investigated system is solid at room temperature, but liquefies and structures into a homogeneous microemulsion when heated to above 37 degrees C. The structural characterization of such microemulsions is the aim of this work. The established methods for this purpose are scattering methods, such as small-angle scattering of X-rays and neutrons and dynamic light scattering. These scattering techniques can be used to obtain valuable information on the size, shape, and internal structure of colloids and complex fluids. We started our investigation with the pseudobinary system SES, tetradecane and l-butanol, varying the SES content. The scattering results show that the sugar ester form inverse globular micelles in the oil phase. The size of these micelles is about 6 nm. While the size is nearly constant in a wide SES concentration regime (5 up to 40% surfactant), the volume or aggregation number increases significantly with SES. This is explained by an increasing replacement of l-butanol molecules by sugar-ester molecules in the micelles formed. Moreover, it can be shown that these micelles strongly overlap. Their center-to-center distance is about 3.8 nm at 40% SES at a micellar diameter of 6 nm. The micellar overlap leads to a highly reduced diffusion of the micelles as was found with dynamic light scattering. When incorporating water in the micellar core, the micelles swell up to about 10 nm and the shape of the aggregates becomes more and more elongated with higher water content. Copyright 2001 Academic Press.

Journal Article↗