Emulsions consist of two immiscible liquids, dispersed as small droplets of one in the other. In the field of food engineering, emulsions are widely used to incorporate food ingredients such as nutritional components, flavoring or coloring agents and antioxidants. The physicochemical environment in emulsion droplets is different from bulk phases, because of larger specific surface areas and compartmentalization effects. This results in particular phenomena in emulsion systems, for example decrease of lipid crystallization temperatures in small droplets. Recently, increased dispersion ability and physicochemical changes in the microenvironments of emulsion systems have been applied in development of novel food processing technologies. Given this background, a number of recent topics in research on food emulsions are presented in the special review “Developments in food emulsions contributing to the design of new functional influence”. One is recent progress in the preparation and characterization of micro-/nano-emulsions containing functional food components. A second focuses on retardation of lipid oxidation based on stochastic models, upon reducing emulsion droplet size. For the third topic, an overview of microchannel emulsification for preparing food-grade microdispersions, and improvement of their stability by layer-by-layer deposition is provided. Finally, the fourth topic concerns control of fat crystallization in emulsions.

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Emulsions are dispersions of at least two immiscible liquids, such as oil and water, where one of them is dispersed as droplets in the other, generally stabilized by an emulsifier. Different types of emulsions can be formulated, according to the application intended. For instance, single emulsions such as oil-in-water (O/W) and water-in-oil (W/O), or multiple emulsions such as water-in-oil-in-water (W/O/W) and oil-in-water-in-oil (O/ W/O) emulsions are the most common types. Droplets of different size and the size distribution patterns formed based on the different emulsification processes can affect the physicochemical properties. For example, the size of droplets in W/O food emulsions containing flavoring agents in the dispersed phase, can affect the flavor of the products. Hence, the average droplet size and the size distribution may determine the storage stability, rheological properties, color and taste of food emulsions.
Micro / nano-emulsions have been increasingly utilized in the food industry as delivery systems that can encapsulate, protect, and deliver functional food components, such as biologically active lipids (e.g., ω-3 fatty acids, conjugated linoleic acid) and oil-soluble flavors, vitamins, and nutraceuticals. The application of micro / nano-emulsions have potential advantages in increasing the bioavailability of lipophilic functional components, modulating the product texture and improving stability against droplet coalescence or phase separation.
This article provides an overview of the current status on the preparation and characterization of micro / nano emulsion containing functional food components, and presents their potential applications in the food industry.

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When oil-droplet size in an O/W emulsion is reduced to a certain point, the oxidation reaction itself becomes a rate-limiting step because of the necessity for a sufficient supply of oxygen through the oil-water interface. Therefore, it would be generally predicted that the lipid oxidation rate does not depend on further reduction in oil-droplet size. However, we propose two models, both of which predict that lipid oxidation is suppressed or retarded by reducing the oil-droplet size. In one, surfactants covering the oil-water interface anchor their hydrophobic moiety into the oil droplet to dilute the lipid to be oxidized. Decrease in the lipid concentration would bring about deceleration of lipid oxidation. In the other model, no influence of oxidized lipid in an oil droplet on lipid oxidation in other oil droplets is assumed. Under this condition, lipid oxidation is more retarded for smaller oil droplets. These two effects would synergistically operate to retard lipid oxidation with reduction of oil-droplet size in an O/W emulsion.
Also with microencapsulated lipids the surface-oil content would affect lipid oxidation behavior. The effects of oil-droplet size on this parameter was examined by two- and three-dimensional models based on the percolation theory. Both predicted that surface-oil content would be lower for smaller oil droplets. It was also shown that the distribution of ratios of size of oil droplets to microcapsules had only limited influence.
Therefore, stochastic models showed the possibility that lipid oxidation is suppressed or retarded by reducing the oil-droplet size in both O/W emulsions and microencapsulated lipid systems.

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This brief overview covers some important aspects of microchannel (MC) emulsification, especially for food-grade applications. We introduce typical MC emulsification systems, fundamental characteristics of their droplet generation, and preparation of food-grade monodisperse emulsions, microparticles, and microcapsules. Major advantages of grooved MC emulsification plates include detailed direct observation of droplet generation from parallel MCs and a wide droplet size range. Straight-through MC emulsification plates are advantageous for higher productivity of monodisperse emulsion droplets. The uniquely mild droplet generation for MC emulsification exploits interfacial tension dominant at the micron level, suppressing degradation and denaturation of heat- and shear-sensitive emulsion components. Information on devices and operating parameters affecting the resultant droplet size is summarized and effects of properties of MC array surfaces and emulsion components on droplet generation behavior are discussed. Layer-by-layer (LBL) deposition is applicable to improve stability of monodisperse oil-in-water (O/W) emulsion droplets prepared by MC emulsification. Featuring coating with a maximum seven layers of surface active components with positive or negative charges, the ζ-potential of the oil droplets alternatively changes, depending on the electrostatic property of the outer layer. Several combinations of differently charged surface active components have already been successfully applied for LBL deposition.

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The control of crystallization of fats and roles of emulsifiers for oil-in-water (O/W) emulsions are reviewed. First, the meaning of fat crystallization, one significant factor for demulsifying oil droplets in O/W emulsions is described. Secondly, the general mechanisms of fat crystallization in O/W emulsion are explained. Four types of nucleation occur in an oil droplet. The interfacial heterogeneous nucleation which is one of the four is a focus the present review. Two examples using emulsifiers as additives are documented. In the first case, when hexadecane, C16, was employed as the oil phase in O/W emulsions, a new polymorph crystallized when an emulsifier was added. This polymorph was identified to be odd-numbered alkanes such as heptadecane, C17, and even-numbered alkanes never appeared in the normal case. As the additive must be crystallized before oil crystallization, hexadecane crystallized on the surfaces of additive crystals. Since a so-called “template effect” occurred in this system, new crystallization occurred on the template; giving additive crystals. In the second case, when the palm-mid-fraction, PMF, was used as the oil phase, crystallization of PMF would be expected to occur at the oil-water interface. To check this phenomenon and also measure the polymorph of crystals on the interface, the synchrotron radiation microbeam X-ray diffraction (SR-μ-XRD) method was employed. The main result was that when the high melting emulsifier was added to the oil phase of an O/ W emulsion, the high melting fraction of PMF crystallized along the interface. On the other hand, no crystallization was noted without addition of the high melting emulsifier as an additive. Crystallization along the interface could be readily clarified using SR-μ-XRD. Finally, crystallization of the oil phase in oil droplets with no emulsifier was covered using a model sample of mayonnaise. As the oil phase, rapeseed oil and soybean oil were used as solvents. Two thermal thaw processes were performed; cooling from 20 ℃ to -15 ℃ and -30 ℃ , and heating to 20 ˚C after maintaining these temperatures for 10 min. The stability of both samples with cooling to -15 ℃ was retained because no ice crystallization occurred. On the other hand, different phenomena were apparent with cooling to -30 ℃ between the two samples; demulsification with rapeseed oil, and only limited coalescence in the case of the soybean oil sample. We believe that the high melting fraction of soybean oil crystallized along the oil-water interface, and then when the system was frozen during cooling to -30 ℃ , crystals along the interface of oil droplets were blocked from destroying oil droplets caused by volume expansion of frozen water.

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In 2003, Japan added risk analysis to its food safety system. Risk analysis comprises three interrelated processes: risk assessment, risk management, and risk communication. For the last ten years, there have been no serious errors in either risk assessment or risk management. However, the implementation of risk communication has not been successful. A sizeable amount of non-scientific information claims that food risk is still high. In particular, there seems to be some misunderstanding about food additives. As a result, when it comes to food safety, there is anxiety or distrust among members of the public. This paper attempts to examine the current status and problems related to risk communication.

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The saponin, esculeoside A, has been isolated as a predominant constituent from ripe fruits of the tomato, Solanum lycopersicum L., along with other minor ingredients. On the other hand, it has been established that esculeosides B-1 and B-2 are major constituents in processed canned tomatoes and juice. These are chemical isomers of tomato saponin obtained by refluxing with water. Since i) tomato saponin is partly converted into the pregnane glycoside during over-ripening, ii) the sapogenol of tomato saponin, esculeogenin A, is easily converted into the pregnane, and iii) metabolites including androstane derivatives are found in urine after consumption of large amounts of tomatoes, we hypothesize that orally administered steroidal glycosides such as spirostanol, furostanol and spirosolane glycosides are metabolized into pregnane derivatives. Tomato saponin is expected to be a constituent of health foods.

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Quinoa(Chenopodium quinoa Willd.) is the original food crop in the Central Andes area in South America. The major anatomical parts of the grain are the pericarp, the perisperm and the embryo. The pericarp usually contains saponins which are bitter anti-nutritional compounds. Therefore, the milled grain with the pericarp removed is used as food. The milled grain contains more protein, lipid and minerals than other cereals such as rice, wheat, barley, etc. Further the content ratio of protein, lipid and carbohydrate are excellent in nutritive quality. The carbohydrate content is 77.3 g/100 g dry milled grain, in which most is starch. Starch comprised over 50 % in the milled grain. The starch exists in a state of two kinds of particles whose sizes are about 20μm and 5μm in the perisperm. But all 20μm particles are split into 5μm particles by 0.1 % NaOH treatment. The median size of the starch particle is 0.90μm. The amylose content and the fine structure of amylose and amylopectin were investigated on four varieties of quinoa. The amylose content is between 4.7 and 13.8 %. Amylose of quinoa is a smaller molecule and contains more branched molecules than the amylose of other plant starches. The amylopectin of quinoa had the longest branched chains and showed a unique chain length distribution, compared with other plant starches.

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Dyeing has two meanings.
One is the color-driven phenomenon in which color stains an object, and the other one is human-driven conduct by which an individual dyes an object. Stains depend on different physical properties of the pigment and fiber, while color is expressed unexpectedly. For this reason, the expression “stain” is often used in a negative sense, meaning blemishes or color irregularities. On the other hand, dyeing is a technique that transforms these blemishes or color irregularities into positive meanings, such as coloring or patterns, by actively operative colors while controlling physical phenomena. We can observe the wisdom and creativity of humans in such a transformation with a sense of value.
Since ancient times, color has had a significant influence on the formation of societies and cultures while engaging with the activity of humans. The author considers that asking about familiar colors to explore the meaning of each color can clarify part of human desires. At the same time, by doing so we can question again what man really is.
The color red has various names. In the original Japanese version of this article, red is expressed using “紅(is called aka this paper).” This article focuses on this red, which particularly penetrates Japanese culture and society, so as to examine the invisible desires of humans (beauty and vitality) based on techniques that handle colors, through two different names that indicate red.

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