Shoichi Gohtani

EFFECT OF DROPLET SIZE ON OXIDATION OF DOCOSAHEXAENOIC ACID IN EMULSION SYSTEM

Abstract We investigated the effect of oil droplet size on the oxidation rate of DHA monodispersed emulsion with xanthan. Xanthan-free emulsions creamed rapidly but no creaming was observed in the emulsions containing xanthan over 8 weeks. While the peroxide value (POV) of the xanthan-free emulsion reached 10meq/ kg at 20 days, that of both emulsion systems containing xanthan changed little during the first 20 days. The POV for the emulsion with small droplet was higher than that for the emulsion with large droplet.

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.

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.

EFFECT OF SOME POLYSACCHAR1DES ON OXIDATIVE STABILITY OF METHYL LINOLEATE IN EMULSION

ABSTRACT In a model emulsion system consisting of 10% w/w of methyl linoleate and 0.5% w/v of Tween 20 as an emulsifier in a 0.05 M sodium acetate buffer (pH 4.0) with polysaccharide, locust bean gum, xanthan and glucomannan considerably inhibited oxidation, as proved by the change in peroxide value. Carrageenan and chitosan had no or only a small effect on oxidation. There was no evidence of organic radical scavenging activity as shown by ESR, but oxidation inhibiting polysaccharides manifested an iron binding activity.

ASYMMETRY IN LIPOSOME

ABSTRACT Asymmetry of phospholipid distribution along the vertical axis of the bimoiecular membrane in a liposome prepared with soybean phospholipids, PC and PE, was studied by using on ESR technique. From the difference in the values of the order parameter of doxylstearic acid radicals between the sample solutions into which the radicals were added before and after preparation of the liposome, it was concluded that PE is incorporated only in the inner layer of the liposome in the range of 0-30% of PE in mixed PC/PE systems and PE is incorporated in both layers of the liposome over about 30% of PE in the mixture.

Retrogradation of Rice Flour Gel and Dough: Plasticization Effects of Some Food Additives

Certain food additives commonly used in flour products also have a plasticization effect on product shelf life regarding retrogradation. Sucrose, sorbitol, glycerol, citric acid, and acetic acid at 25, 25, 25, 0.5, and 0.5%, respectively, were added to two different starch gel systems: slurry (high-amylose rice flour gel) and dough (waxy rice flour dough). All plasticizers increased gelatinization temperature, decreased enthalpy (ΔH), and promoted a more homogeneous system. Sucrose had the greatest effect on gelatinization increase. Rice dough was more susceptible to plasticizers, resulting in higher moisture content and a more amorphous structure. Retrogradation was highly positively correlated with amylose content, moisture retention, ratio of protons of water/starch, and previous occurrence of retrogradation. Moisture retention was increased in plasticizer-added samples, especially waxy rice dough. Over a longer storage period, sucrose and sorbitol showed an antiplasticization effect in waxy rice flour...

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.

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.

Dietary Protein Derived from Dried Bonito Fish Improves Type-2 Diabetes Mellitus-Induced Bone Frailty in Goto-Kakizaki Rats

Type-2 diabetes mellitus (T2DM) induces bone frailty. Protein and polyunsaturated fatty acids (PUFA) contained in fish can be effective in enhancing bone quality, but the bone developing effect of fish protein containing less PUFA has not been evaluated in young animals with T2DM. We prepared a bonito fish (BF) and defatted BF (DBF) and hypothesized that protein contained in BF and DBF would be effective for mitigating the effects of T2DM-induced bone frailty. We mainly evaluated the effect of dietary BF and DBF on bone and apparent calcium absorption in young Goto-Kakizaki (GK) rats with T2DM. GK rats were divided into 3 groups based on diets (casein, BF, and DBF) and fed with each diet for 6 wk. Wistar rats were fed with the casein diet as a non-T2DM control. Bone mass, bone strength, apparent calcium absorption, and serum biochemical parameters were determined. The dry weight and strength of the femurs were lower in the GK rats than in the Wistar rats fed with the casein diet. Dietary intake of the BF and DBF diets enhanced the maximum load and dry weight of the femurs and suppressed the serum alkaline phosphatase activity although the apparent calcium absorption was lower in the GK rats fed with the BF and DBF diets than in those fed with the casein diet. These parameters were not different between the rats fed with the BF and DBF diets. Our data suggest that protein contained in the BF and DBF diets improved T2DM-induced bone frailty.

Relationship Between Macroscopic and Microscopic Viscosities in Starch Gels

Abstract We investigated the relationship between the macroscopic viscosity lpar;ηN ), determined by creep measurement, and the microscopic viscosity, estimated by rotational correlation time (τc) of spin label determined by ESR method, for wheat and potato starch gels. Both ηNand τc. Of wheat starch gel increased linearly with an increase of starch concentration. Both ηN and τc of potato starch gel increased exponentially with an increase of starch concentration. The τc of wheat starch gel related linearly to the ηN of the gel at 30, 40 and 50°C. For potato starch gels, the τc.also related significantly to the ηN at 30, 40 and 50°C. The τc of free BrAcTEMPO was much smaller than that of spin-labeled AcTEMPO in wheat starch gel. It is concluded that the change in microscopic viscosity of starch gels agrees with their change in macroscopic viscosity.