Surface Modification of Okara Cellulose Crystals with Phenolic Acids to Prepare Multifunction Emulsifier with Antioxidant Capacity and Lipolysis Retardation Effect.

Emulsion-based foods are widely consumed, and their characteristics involving colloidal and oxidative stabilities should be considered. The fabrication of the interfaces by selecting the emulsifier may improve stability and trigger lipolysis, thereby reducing energy uptake from the emulsified food. The present work aimed to develop Okara cellulose crystals (OCs) as a multifunction emulsifier to preserve the physical and chemical stability of a Pickering emulsion via surface modification with phenolic acids. The modification of OC was performed by grafting with the selected phenolics to produce OC-gallic acid (OC-G) and OC-tannic acid (OC-T) complexes. There was a higher phenolic loading efficiency when the OC reacted with gallic acid (ca. 70%) than with tannic acid (ca. 50%). This trend was concomitant with better antioxidant activity of the OC-G than OC-T. Surface modification based on grafting with phenolic acids improved capability of the OC to enhance both the colloidal and oxidative stability of the emulsion. In addition, the cellulosic materials had a retardation effect on the in vitro lipolysis compared to a protein-stabilized emulsion. Surface modification by grafting with phenolic acids successfully provided OC as an innovative emulsifier to promote physico-chemical stability and lower lipolysis of the emulsion.

Emulsion stabilization mechanism of combination of esterified maltodextrin and Tween 80 in oil-in-water emulsions.

Esterified maltodextrins (EMs) were prepared using enzyme-catalyzed reaction of maltodextrin (DE of 16 and 9) and palmitic acid. The emulsion stabilization mechanism was investigated of a combination of Tween 80 and EM in oil-in-water emulsion to determine interfacial tension, ζ-potential, non-adsorbed Tween 80 in centrifuged-serum of emulsion, and fluoresced microstructure. The interfacial tension and non-adsorbed Tween 80 content of combination of Tween 80 and EM-stabilized oil-in-water emulsions were closed to those of sole Tween 80-stabilized emulsion. The ζ-potential of sole Tween 80-stabilzed emulsion had a small positive charge but ζ-potential changed to small negative charge as EM was added into Tween 80-stabilzed emulsion. Fluorescence microstructure confirmed that EM was adsorbed on oil droplet surface, stabilized by Tween 80. The mechanism of emulsion stabilization may conclude that Tween 80 was mainly adsorbed at oil surface and EM may interact with Tween 80 to form a double stabilization layer without competitive replacement.

Oil-in-water emulsions containing tamarind seed gum during in vitro gastrointestinal digestion: rheological properties, stability, and lipid digestibility.

BACKGROUND: Polysaccharides may enhance/inhibit lipid digestibility of oil-in-water (O/W) emulsions because of their emulsifying and/or stabilizing ability and can also affect the formation, stability, and viscosity of emulsions. Tamarind seed gum (TSG) was used as the sole emulsifier/stabilizer to stabilize an O/W emulsion prepared using high-speed homogenization. We investigated the effects of various TSG concentrations (50-150 g kg-1 ) on the lipid digestibility, rheological properties, and stability of O/W emulsions during in vitro gastrointestinal digestion. RESULTS: A low concentration (50 g kg-1 ) and a high concentration (150 g kg-1 ) of TSG reduced lipid digestibility by about 33% and 45%, respectively, compared to the control sample (without TSG). However, the emulsion containing the intermediate TSG concentration at 100 g kg-1 was the most efficient in the inhibition of lipid digestion, reducing lipid digestibility by about 70% compared to that of the control sample. The stability of emulsion tended to enhance as the concentration of TSG increased. The size of oil droplets before passing through the intestinal phase and the viscosity of the intestinal digested system may be important factors for enhancing/inhibiting lipid digestibility of emulsions. The destabilization of the emulsion during digestion was not clearly detected by rheological analysis because rheological characteristics (e.g. flow behavior index) were mainly driven by TSG. CONCLUSIONS: The addition of TSG in O/W emulsions inhibited lipid digestibility. TSG at a concentration of 100 g kg-1 was the most efficient in the inhibition of lipid digestibility, suggesting that TSG is an attractive alternative ingredient for control of lipid digestibility of emulsion foods. © 2020 Society of Chemical Industry.

Formulation and characterization of esterified xylo-oligosaccharides-stabilized oil-in-water emulsions using microchannel emulsification.

A series of amphiphilically esterified xylo-oligosaccharides (xylo esters) with different fatty acids residues - decanoic acid (C-10), lauric acid (C-12) and palmitic acid (C-16) - were enzymatically modified at 60°C for 4h. These xylo esters were used as emulsifiers to formulate oil-in-water (O/W) emulsions by microchannel emulsification (MCE). Grooved and straight-through MCE was used to investigate the droplet generation and/or emulsion stability. Xylo ester-stabilized oil droplets were generated smoothly from microchannels arranged linearly or two dimensionally, while xylo ester-stabilized emulsions were less monodispersed owing to low surface activity of the xylo esters. The combined use of xylo esters (2.5% (w/w)) and Tween series (0.1% (w/w)) in the continuous phase can improve the monodispersity of the resultant oil. Successful droplet generation was achieved with the straight-through MCE using 2.5% (w/w) xylo laurate and 0.1% (w/w) Tween 20. The optimized combination of xylo laurate and Tween 20 inhibited coalescence and oiling off more efficiently than the droplets solely stabilized by Tween 20 during 30days of storage.

Effect of esterified oligosaccharides on the formation and stability of oil-in-water emulsions.

Hydrophobically modified oligosaccharides were prepared by an enzyme-catalyzed reaction of maltodextrin/xylo-oligosaccharide and palmitic acid. Maltodextrin with dextrose equivalent (DE) of 16 palmitate (DE16_P) and 9 palmitate (DE9_P), as well as xylo-oligosaccharide palmitate (Xylo_P), were used. The effect of the concentration (10-50% (w/w)) and type of esterified oligosaccharides on the Sauter mean diameter and droplet-size distribution, the rate of coalescence (Kc), and the creaming properties of O/W emulsions were investigated. Esterified oligosaccharides (EO) adsorbed to the surface of the oil droplets. EO formed polydisperse O/W emulsions with particle sizes between 12 and 70 µm, depended on concentration of EO. The Sauter mean diameter, Kc, and the creaming index decreased markedly, with increasing concentration of EO. The type of ester minimally affected the Sauter mean diameter at each ester concentration. DE9_P inhibited coalescence and creaming more efficiently than other EO, mainly due to the higher viscosity of the continuous phase.

Esterified xylo-oligosaccharides for stabilization of Tween 80-stabilized oil-in-water emulsions: stabilization mechanism, rheological properties, and stability of emulsions.

BACKGROUND: Amphiphilic oligosaccharides have hydrophilic and hydrophobic subregions; therefore they can act like surfactants, while maintaining the viscous properties of the starting materials as stabilizers in emulsions. In the present work, xylo-oligosaccharides were modified by enzymatic esterification. Their emulsifying and stabilizing properties may improve the stability of emulsions, which could be explained by rheological properties. RESULTS: The degree of substitution (DS) of esterified xylo-oligosaccharide ranged between 0.042 and 0.066. The esterified xylo-oligosaccharide was adsorbed on to the surface of the oil droplets. The critical flocculation concentrations (CFCs) of Tween 80-stabilized emulsions containing native and esterified xylo-oligosaccharide were 140 and 190 g kg(-1) , respectively. At concentrations below CFC, no creaming or flocculation was observed and the flow behavior of emulsions was Newtonian. At concentrations above CFC, emulsions containing native and esterified xylo-oligosaccharide showed extensive flocculation of emulsion droplets; consequently, shear-thinning flow behavior was expressed. Further increases in the concentration improved the creaming stability. The concentration and type of esterified xylo-oligosaccharide influenced the rate of creaming, whereas flow behavior of emulsions containing esterified xylo-oligosaccharide was clearly induced by concentration. CONCLUSION: Esterified xylo-oligosaccharides have potential as emulsifiers and stabilizers, since they extended the CFC and were more effective in preventing creaming, compared with the native species.

Enzymatic esterification of tapioca maltodextrin fatty acid ester.

In this work new types of hydrophobically modified maltodextrin were prepared by enzyme-catalyzed reaction of maltodextrin and three fatty acids: decanoic acid (C-10), lauric acid (C-12) and palmitic acid (C-16). Lipase obtained from Thermomyces lanuginosus was found to be a useful biocatalyst in the maltodextrin esterification. Esterified maltodextrin with a degree of substitution (DS) 0.015-0.084 was prepared at the optimum conditions of 60 °C for 4 h. The DS was found to be at its highest when maltodextrin and fatty acids were taken in the ratio 1:0.5. The functional properties of these esterified maltodextrin were investigated. All esterified maltodextrin did not completely dissolve in water. Esterified maltodextrin at a concentration of 25% (w/w) exhibited Newtonian flow behavior similar to that of native maltodextrin. Esterified maltodextrin had a higher viscosity compare to native maltodextrin. X-ray diffraction pattern of esterified maltodextrin indicated crystallization of the fatty acid side chains. The thermal stability of esterified maltodextrin was checked by differential scanning calorimetry (DSC). Esterified maltodextrin was then used as an emulsifier to make n-hexadecane O/W emulsions. The emulsions were characterized according to their oil droplet characteristics and emulsification index.

Retrogradation of Waxy Rice Starch Gel in the Vicinity of the Glass Transition Temperature.

The retrogradation rate of waxy rice starch gel was investigated during storage at temperatures in the vicinity of the glass transition temperature of a maximally concentrated system (T g '), as it was hypothesized that such temperatures might cause different effects on retrogradation. The T g ' value of fully gelatinized waxy rice starch gel with 50% water content and the enthalpy of melting retrograded amylopectin in the gels were investigated using differential scanning calorimetry. Starch gels were frozen to -30°C and stored at 4, 0, -3, -5, and -8°C for 5 days. The results indicated that the T g ' value of gelatinized starch gel annealed at -7°C for 15 min was -3.5°C. Waxy rice starch gels retrograded significantly when stored at 4°C with a decrease in the enthalpy of melting retrograded starch in samples stored for 5 days at -3, -5, and -8°C, respectively, perhaps due to the more rigid glass matrix and less molecular mobility facilitating starch chain recrystallization at temperatures below T g '. This suggests that retardation of retrogradation of waxy rice starch gel can be achieved at temperature below T g '.