Lipid oxidation processes were simulated for O/W emulsions with different oil-droplet sizes based on autocatalytic type rate expression in order to examine the effect of oil-droplet size on oxidation. Unoxidized lipid molecules were converted to oxidized ones momentarily or gradually, and the conversion occurred evenly or randomly in the droplets. When the oxidized molecules were formed momentarily, the droplet size scarcely affected the oxidation process, except for when the number of oxidized molecules was equal to or smaller than the number of oil droplets. In contrast, the oil droplet size significantly affected the oxidation process when the oxidized molecules were gradually and randomly formed at regular intervals. The oxidation was more retarded for the emulsions with smaller oil droplets. Because the latter case would be closer to a real system, the reduction in the oil droplet size in O/W emulsions is expected to increase the stability of lipids to protect against oxidation.
β-Carotene was encapsulated by self-aggregated caseinates, and the encapsulation efficiencies and storage stabilities of the resultant spray-dried powder were investigated. The pH of the sodium caseinate solution, which determined the degree of aggregation, tremendously affected the encapsulation yield and storage stability of β-carotene in the spray-dried powder. We found that at pH 6.0, the resultant powder showed excellent encapsulation property compared to other pH conditions (pH = 6.5, 5.5). Small angle X-ray scattering analysis revealed that the representative sizes of the aggregates in the sodium caseinate solution at pH 6.5, 6.0, and 5.5 were approximately 91, 111, and 166 nm, respectively. This analysis also clarified that our system represented fractal growth aggregation while the surface fractal dimension increased with decreasing pH. Apparently, the encapsulation property was affected by the physical properties of the aggregates, and there existed an optimal aggregation degree, which maximized the performance of an encapsulated system.
Protection of sensitive lipids such as oils against oxidation in foods is often a real challenge due to the heterogeneity of the food matrix and interactions of the matrix biopolymers with water present in the surroundings. Water-biopolymer interactions are important with regard to oxidation since oxygen dynamics is linked with water mobility, which in turn depends on the mobility of matrix molecules. Oils sensitive to oxidation can partly be protected by spray-drying of emulsions with oil as the dispersed phase. Spray-dried particles are also useful model systems to study the number of factors affecting oil oxidation in a bio-matrix and to elucidate the potential routes for improved oxidative stability via better control of oxygen dynamics.
Microsoft Excel® is most popularly used spreadsheet software. Although figures can be drawn using the software, their quality seems to be unsatisfactory for the use in scientific papers or reports. The quality can be improved using Microsoft PowerPoint®, which is also software in Microsoft Office® and is widely used as a presentation tool. A rough figure is prepared based on the data in the Excel, and it is modified to fine one using the PowerPoint. It will be explained how to draw fine figures using both the software of Office® 2013.
Commercially processed soybean, canola, high-oleic low-linoleic canola and palm olein oils were thermal-deteriorated at 180°C for 0, 40, 60, 80 hr, and evaluated odor compounds using Automatic Dynamic Head Space-GC/MS system and sensory score. Sensory score of overall odor was linear correlation with total area of odor compounds. The result in principal component analysis of sensory scores and the peak areas of odor compounds, gave that the odor compounds from linoleic acid were more effective for “rancid” and “pungent” odor than odor compounds from oleic acid and linolenic acid in thermal-deteriorated oils.
Nanoscale waxy rice starch particles were prepared in compressed hot water, and the effects of the concentration of waxy rice starch dispersion, the pressure and temperature of the compressed hot water on mean particle size and particle size distribution were investigated. Particle size and particle size distribution of the waxy rice starch nanoparticles were measured by dynamic light scattering. Mean particle size was found to depend on the preparation conditions. The smallest average particle size of 150.4 nm was obtained with a starch concentration of 0.1% (w/w), an initial pressure of 3.0 MPa, and a final temperature of 180°C. It is suggested that particle size can be controlled by the preparation conditions. In addition, any sample prepared in compressed hot water tends to have a particle size distribution spanning less than 100 nm. The use of compressed hot water is also effective for preparing waxy rice starch nanodispersion with nanoparticles smaller than 100 nm. Furthermore, we have attempted to determine the reaction field of compressed hot water by the ionic product.
Surface roughness of spaghetti depends on the die material used during production, and affects the momentarily rehydrated amount of water. The calculated average roughness of spaghetti surfaces, Ra, was evaluated for geometry measurements using a laser microscope. Smoothness of the spaghetti surface decreased, depending on the type of the die used during the preparation in the following order: Teflon, polypropylene, polycarbonate, aluminum, and bronze. For hypothetically smooth cylindrical spaghetti, the momentarily rehydrated amount of water per unit surface area was larger for spaghetti with larger Ra values. In contrast, the amount of water per surface area, which was estimated considering the roughness of the surface, did not affect the Ra value. This showed that the initial rehydration rate of spaghetti could be controlled by altering the surface roughness.
Isothermal drying rates and desorption isotherms of lemon juice were measured and compared with the data for a simulated lemon juice, sucrose, maltodextin and citric acid. The drying rates of lemon juice were much lower than the values for the simulated lemon juice and maltodextrin. Equilibrium water contents of lemon juice were much higher than those for other sugars, and similar to the values for the simulated lemon juice and citric acid.