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Miso, a paste of salted fermented soybean, is a seasoning used extensively in traditional Japanese cuisine. Herein, pyroglutamyl peptides present in miso were identified by a liquid chromatography-tandem mass spectrometry (LC-MS/MS), detecting precursor ions, which generated immonium ion of pyroglutamyl residue. By using this method, 13 pyroglutamyl peptides were identified in four types of miso. Administration of the water extract prepared from 0.6 g soybean miso/kg body weight/day significantly suppressed high fat diet-induced weight gain. A similar effect was exerted by the hydrophobic pyroglutamyl peptide fraction, including pyroglutamyl proline (pEP), pEV, pEI, and pEL. Administration of a mixture of synthetic pEP, pEV, pEI, and pEL in a ratio to that in miso or pEL alone also suppressed the weight gain in a dose dependent manner. These results suggest that the short-chain hydrophobic pyroglutamyl peptides present in miso are effective in suppressing high fat diet-induced obesity.

The role of solid fat content (SFC) within fat particles was examined for its effects on adsorption behaviour at the air–water interface. Three kinds of vegetable oil with different SFC profiles were mixed with a sodium caseinate solution (2% w/w) to prepare the creams, whose fat contents were adjusted in the range of 0–40% w/w. The decrease of interfacial tension at the air–water interface was measured for creams and the sodium caseinate solution, and the ratio of the maximum decrease rate of creams (Δγmax)-to-the sodium caseinate solution (Δγ0max), Δγmax/Δγ0max, was calculated. The interfacial elastic modulus (E′) of creams and sodium caseinate solution was also measured and found to initially increase with time but decreased after the maximum value (E'max). Both Δγmax/Δγ0max and E'max were affected by the temperature, fat content of creams and SFC in fat particles. The largest increase for Δγmax/Δγ0max and E′max was observed when the SFC of creams was between 10 and 50% w/w. The microscopic structures of the air–water interface of creams after whipping were also affected by the SFC, such that fat particles containing 28.4% SFC were found to adsorb and aggregate at the air–water interface layer. These results suggest that the adsorption of fat particles onto the air–water interface and interfacial structure formation by adsorbed fat particles were promoted via partial coalescence.

Some components of bitterness make key flavor contributions to promote the palatability of foods, whereas other components are recognized as aversive signals to avoid consuming harmful substances. These contradictory behaviors suggest that humans tolerate tastes of bitterants based on certain criteria. Here, we investigated human taste tolerance and sensory cues leading to diverse taste tolerance of bitter compounds. Tolerance of eight bitter compounds, which are typically contained in foods, was evaluated by measuring detection and rejection thresholds. The results revealed that the level of tolerance of each compound was variable, and some compounds showed an acceptable concentration regarding the suprathreshold intensity. Tolerance did not depend on the nutritive value or attenuation and accumulation characteristics of bitterness and bitter taste receptors. These results suggest that the criteria controlling tolerance of bitter compounds may be derived from a complex relationship between the taste quality and cognitive process.

Soybeans (Glycine max (L,) Merr,) contain γ-glutamyl peptides and oligosaccharides, and these components play an important role in imparting the “kokumi” taste to foods. To gain insight into the genetic diversities and molecular mechanisms of accumulation of γ-glutamyl peptides and oligosaccharides in soybean, we measured the contents of these components using the Japan and World mini core collections. Similar to other previously reported traits, wide variations were detected among the accessions in the core collections with respect to the content of γ-glutamyl peptides and oligosaccharides. We found a positive relationship between the content of γ-glutamyl tyrosine and γ-glutamyl phenylalanine and between the content of raffinose and stachyose. Furthermore, there were unique accessions that included high levels of γ-glutamyl peptides and oligosaccharides. These accessions may be helpful in understanding the accumulation mechanism of γ-glutamyl peptides and oligosaccharides and to increase the “kokumi” taste components in soybean by performing a genetic analysis.

The whipped cream dispenser is a foaming tool that is an increasingly applied for on-site whipped cream consumption. It creates foams by incorporating nitrous oxide (N2O) or carbon dioxide (CO2) into protein dispersions, while other foaming methods such as agitation and aeration create foam by incorporating air and nitrogen (N2). In this study, a whipped cream dispenser was used to investigate the effects of different gases and proteins on the foaming properties of protein dispersions. Four gases (CO2, N2O, air, N2) and five proteins were used. The results show that a higher foaming capacity was obtained for all the protein dispersions that were prepared with more soluble gases (N2O and CO2). The foam that was prepared with the more soluble N2O was less stable than that prepared with air and N2. Although the impact of proteins on the foam stability was lower than that of gases, the applying different proteins also significantly changed the foam stability.

The aim of this study was to analyze changes in the surface structure and the inner microstructure of durum wheat pasta during the boiling process. Dried pasta was boiled for 1, 4, 7, or 10 min, and the structure of dried and boiled pasta was observed using polarizing light, laser, and fluorescence microscopy. The degree of gelatinization was measured by polarized light microscopy as well as the β-amylase-pullulanase method. The degree of gelatinization was shown to be larger when evaluated by polarized light microscopy. The surface roughness was evaluated by laser microscopy. The surface roughnesses of dried (non-boiled) pasta and boiled pasta showed different characteristics, and the calculation and analysis of parameters relating to surface roughness indicated that the surface of pasta becomes more uneven as boiling time increases. In principal component analysis of surface roughness, principal components 1 and 2 explained 71.7% of total variance. Principal component 1 mainly reflected the peak frequency and height, and principal component 2 mainly reflected the peak interval. We confirmed by fluorescence microscopy that starch granules began to swell from the outer periphery of the pasta during boiling, and the proportion of gluten network on the outer circumference structure clearly decreased.

The water extract of soybean seeds (Glycine max (L.) Merr.) is nearly tasteless, but “kokumi” taste sensation was confirmed upon addition of a basic umami solution containing glutamic acid, inosine monophosphate, and sodium chloride. To identify the key contributors to the “kokumi” taste sensation in soybean seeds, sensory-guided fractionation, taste sensory analyses, and LC–MS/MS analyses were utilized. γ-glutamyl-tyrosine and γ-glutamyl-phenylalanine were identified as contributors to “kokumi taste”; specifically, these γ-glutamyl peptides imparted the “kokumi” taste sensation at a low taste threshold in a basic umami solution. Raffinose and stachyose, which are sufficiently present in soybean seeds, exhibited a synergistic effect in regard to the enhanced “kokumi” taste sensation of γ-glutamyl peptides. This is the first report that the combined use of γ-glutamyl peptides and oligosaccharides can increase the “kokumi” intensity, which suggests that soybean extracts or soymilk can be used to enhance the “kokumi” taste sensation in food products.

Mayonnaise-like oil-in-water emulsions with different stabilities—evaluated from the degree of macroscopic defects, e.g., syneresis—were prepared by different formulations and processing conditions (egg yolk weight, homogenizer speed, and vegetable oil temperature). Emulsions prepared with lower egg yolk content were destabilized for shorter periods. The long-term stability of emulsions was weakly related to initial properties, e.g., oil droplet distribution and protein coverage at the interface. Protein aggregation between oil droplets was observed and would be responsible for the instability of emulsions exhibited by the appearance defects. SDS-PAGE results for adsorbed and unadsorbed proteins at the O/W interface suggested that predominant constituents adsorbed onto the interface were egg white proteins as compared with egg yolk components when the amount of added egg yolk was low. In present condition, egg white proteins adsorbed at the O/W interface could be a bridge of neighboring oil droplets thereby causing flocculation in emulsions.

Soybean oil bodies are natural and environment-friendly emulsifying agents from plant resources required as a substitute for emulsifiers such as low-molecular-weight one and animal proteins. The aim of this study was to reveal the interfacial properties and the emulsifying properties of two types of oil bodies extracted from soybean seeds at different pH conditions, that is purified oil bodies (OB) and crude oil bodies (OBC) including storage and other minor proteins. Particle size and zeta-potential measurements and SDS-PAGE revealed that the presence of the involved storage and other minor proteins promoted oil body aggregations and imparted the high zeta-potential to the oil bodies. OB adsorbed onto the oil-water (O/W) interface in closely packed state and formed more elastic adsorbed layer than OBC according to the results from tensiometry. Emulsions stabilized by OB (OB-E) were more stable against oil droplet coalescence than those by OBC (OBC-E) due to the absence of the involved proteins at the emulsion droplet surfaces. Cryo-SEM observation suggests that during emulsification most of the OB and OBC particles adsorbed onto the newly-created O/W interface and then rapidly ruptured.

The stability against solidification during storage and whippability of commercial cream products vary depending on the repetition of heat treatment and homogenization necessary for extended shelf-life. First, the two commercial creams subjected to different times of heat treatment and homogenization were investigated. Among several factors such as the colloidal properties, melting profiles of fat globules and protein content and composition, the amount of proteins present at the fat globule surfaces should play a major role in determining the cream quality probably in relation to the degree of expected partial coalescence of fat globules during transportation and whipping, while the composition of proteins adsorbed to the oil–water interface was not the critical factor affecting the quality of creams. A further step-wise preparation of cream samples in a laboratory scale revealed that the second homogenization significantly reduced the amount of proteins adsorbed to the surface of fat globules. There is a possibility that physical and colloidal macro-ordered properties of whipping creams can be controlled by appropriately managing the homogenization process.

Scope Dietary soy reportedly protects from diabetic nephropathy (DN), but its active components and mechanism of action remain unknown. Methods and results In this study, KKAy mice are fed three types of diet: Dietary soy isoflavones with soy protein (Soy-IP) diet, reduced isoflavones soy protein (RisoP), and oral administration of isoflavones aglycones (IsoAgc). Albuminuria and glycosuria are decreased only in the soy-IP group. The risoP group show reduced expansion of mesangial matrix and renal fibrosis, the IsoAgc group show renal anti-fibrotic and anti-inflammatory effects; however, these renal pathological changes are repressed in the soy-IP group, suggesting the distinct protective roles of soy protein or isoflavones in DN. The isoflavone genistein has a better inhibitory effect on the inflammatory response and cellular interactions in both mouse tubular cells and macrophages when exposed to high glucose and albumin (HGA). Genistein also represses HGA-induced activator protein 1 activation and reactive oxidases stress generation, accompanied by reduced NADPH oxidase (NOX) gene expression. Finally, diabetic mice show a decrease in lipid peroxidation levels in both plasma and urine, along with lower NOXs gene expression. Conclusion The data elucidate the detailed mechanism by which isoflavones inhibit renal inflammation and provide a potential practical adjunct therapy to restrict DN progression.

PyroGlu-Leu is present in certain food protein hydrolysates and traditional Japanese fermented foods. Our previous study demonstrated that the oral administration of pyroGlu-Leu (0.1 mg/kg body weight) attenuates dysbiosis in mice with experimental colitis. The objective of this study was to elucidate why such a low dose of pyroGlu-Leu attenuates dysbiosis in different animal models. High fat diet extensively increased the ratio of Firmicutes/Bacteroidetes in feces of rats compared to control diet. Oral administration of pyroGlu-Leu (1 mg/kg body weight) significantly attenuated high fat diet-induced dysbiosis. By focusing on the production of intestinal antimicrobial peptides, we found that pyroGlu-Leu significantly increased the level of 4962 Da peptides, which identified as the propeptide of rattusin or defensin alpha 9, in ileum. We also observed increased tryptic fragment peptides from rattusin in the lumen. Here, we report that orally administered pyroGlu-Leu attenuates dysbiosis by increasing in the host antimicrobial peptide, rattusin.

Japanese apricot and avocado powders without chemical modification or complicated processing were firstly applied for stabilizing food emulsions containing soybean oil as a source of clean label ingredients. In this work, Japanese apricot and avocado powders as fiber-rich and lipid-rich emulsifiers, respectively, were studied for evaluating emulsifying properties of the fruit powders. Each powder was dispersed in a water or an oil phase, followed by emulsifying with the other immiscible phase to produce emulsions. A more remarkable effect on emulsifying properties was found when fiber-rich powders were dispersed in a water phase and oil-rich powders were dispersed in an oil phase. In addition, avocado powder-based emulsions showed the high stability against creaming (no phase separation) for at least 24 h stored at 4 °C, and both Japanese apricot and avocado powder-based emulsions presented high stability against coalescence for 14-day storage. The results suggested high possibility that fruit powders can be used as food-grade emulsifiers to stabilize emulsions with high physical stability.

Soy lipophilic protein (LP) is considered to form a major fraction of soy protein isolate, in addition to β-conglycinin (7 S) and glycinin (11 S). LP consists of phospholipid-protein complex and phospholipid-free protein molecules. Surface and foaming properties of LP were compared to those of 7 S and 11 S. These soy protein samples were prepared under mild conditions in order to avoid thermal denaturation, which enabled us to study the effects of heat treatment on surface and foaming properties of the proteins. Without heat treatment, the surface and foaming properties of LP were superior to those of other soy protein fractions, suggesting the phospholipid-protein complex in LP can produce fine bubbles with high drainage stability. Despite low surface and foaming properties of non-heated 7 S and 11 S, heat treatment improved the surface and foaming properties of 7 S and 11 S dramatically, which could be relevant to heat-induced changes in particle size, zeta-potential and surface hydrophobicity of 7 S and 11 S molecules. On the other hand, the foaming ability of LP was declined, but the foam stability was increased to maintain the foam volume up to the final stage of observation, by heating. In the foam stabilized by heated LP, medium sized bubbles as well as fine bubbles were produced. The improved foam stability may be attributed to the combination effect of the delayed drainage from the lamellar phase of fine bubbles and the increased resistance to the bursting of medium sized bubble.

Soybean oil-storing organelles called oil bodies/oleosomes (OBs) are a potential eco-friendly plant-based emulsifier, whereas combinational effects of acid and salt addition on emulsifying properties of OBs were still unclear. This study aimed at investigating colloidal, interfacial, and emulsifying properties of OBs in the presence of acetic acid and NaCl. The purified OBs isolated from soybean seeds were dispersed into 10 mM acetate or phosphate buffer solutions at pH 4.0–7.0 with different NaCl concentrations between 0 and 100 mM. Without added NaCl, the purified OBs were finely dispersed at pH 4.0 and 4.5 by electrostatic repulsion, whereas they aggregated at pH 5.0 and 5.5 probably due to small net charge. The NaCl addition caused screening of the electrostatic interaction between OBs and induced salting-in of OBs. Interfacial tension and interfacial viscoelasticity analyses showed that strongly-charged OBs tended to more slowly sparsely adsorb onto oil-water interface to form less elastic adsorbed layer; this tendency might result from electrostatic adsorption energy barrier between the adsorbed- and non-adsorbed OBs. The OB-stabilized emulsions slightly coalesced under at pH 4.0 and 4.5 without added NaCl probably due to a relatively small amount of the surface protein load. Under all the other tested pH (4.0–7.0) and NaCl (0–100 mM) conditions, the OB-stabilized emulsions were stable against coalescence because of the improved surface load. These results suggest that OBs can be widely applicable for various food emulsions as a potential eco-friendly emulsifier with the appropriate formulation of acid and salt.

This study was aimed at characterizing the physicochemical properties of whey protein isolate (WPI)-xanthan gum (XG) complexes and the oil-in-water (O/W) type emulsions stabilized with the complexes. The WPI-XG complexes were fabricated under acidic conditions (pH 4.0) by changing the XG content (0.05–0.2%) of the complexes, and the O/W emulsions were prepared at 20% oil content at pH 4.0. In addition to the physicochemical properties, the assembly of the complexes and the interfacial microstructures of the emulsions were also explored by cryo-SEM to determine the stabilization mechanism of the emulsions. The results revealed that the WPI-XG complexes were around 100 nm in diameter and had a lower isoelectric point (≈pH 2.0) compared to un-complexed WPI (≈pH 4.5). The droplet size of the emulsions did not change during storage at 25 °C for 28 days when the XG content was over 0.12%. Cryo-SEM showed that the WPI-XG complexes (or WPI globules) adsorbed onto the surface of oil droplets with XG fibrils extending from WPI, contributing to the emulsion stability. It was suggested that these structural features of the complexes contributed to enhancing the emulsion stability. The findings of this study will be useful for the development of emulsified foods with novel functionality, by using natural ingredients.

The alkaline extract of Enoki mushroom (Flammulina velutipes) has been shown to have ice crystal growth inhibiting activity, and its beneficial effect on the quality preservation of frozen foods is highly expected. The purpose of this study was to investigate the effect of Enoki mushroom extract which has an ice recrystallization inhibiting activity on the quality of frozen whipped creams. Whipping creams with different milk/vegetable fat compositions were prepared. The proportion of % milk fat and % vegetable fat was given as follows; 0:37, 10:28, 20:20 and 40:0, respectively. Whipped foam samples were frozen and stored at −20 °C, then the effect of adding 0.1% Enoki mushroom extract was tested. Fresh dairy flavor and smooth melt in mouth texture was deteriorated during the course of frozen storage for 37 days, and the frequency is higher in whipped creams with high milk fat content. Addition of 0.1% Enoki mushroom extract ameliorated these quality changes and significantly retained moisture content. Microscopic observation of the internal structure of frozen foam samples by cryo-SEM revealed that the ice crystal aggregates grown in the emulsified solid phase were reduced by adding Enoki mushroom extract. GC/MS analysis of the flavor components revealed that the content of furan compounds (furfural and 2-furanmethanol) was increased by 1.7 times in control foam samples during frozen storage, whereas the furan compounds in whipped foam sample containing Enoki mushroom extract did not increase after frozen storage. Based on these findings, it is proposed that ice crystal growth at the emulsified solid phase causes the sublimation of water on the surface of frozen whipped cream and destruction of the network structure of fat globules results in the quality changes after thawing. Enoki mushroom extract was found to retard ice crystal growth in whipped cream, thus supposed to reduce the quality changes during frozen storage.

Pancakes served as a dessert with creams and fruits toppings nowadays stored under refrigerated conditions are often subjected to significant changes in physical properties recognized as quality deterioration, which is efficiently prevented by including small molecule emulsifiers into commercial pancakes formulations. In order to reveal these molecular prevention mechanisms in the real multicomponent wheat-based products, small molecule emulsifiers with various HLB values and head group size were formulated into pancake samples and their physical properties evaluated. Starch retrogradation, emulsifier-starch inclusion complex formation and gelatinization behaviors were followed by the texture profile analysis, differential scanning calorimetry, iodine colorimetry and confocal laser scanning microscopy. Hardening of the pancake samples varied with the type of emulsifiers, which in general reduced the retrogradation of starch. This reduction was dominantly attributed to the emulsifier-starch complex formation, particularly with amylose molecules, probably leading to less leaching of the starch molecules from the starch granules. These findings are of practical use in selecting effective emulsifiers that prevent hardening of pancakes. The degree of complexation was partially explained by the HLB and head group size of the emulsifiers, while it can be also significantly affected by interactions between the emulsifier and other components in the pancake mixture, like milk and eggs.

The effects of autoclave and microwave heating on the protein and oil in soybean seeds were investigated under low moisture conditions. The nitrogen solubility index (NSI) decreased on heating. The reduction in the NSI was accompanied by an increase in the size and deformation of the oil bodies in the cellular tissue of soybean seeds. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis revealed that lipoxygenase was susceptible to heat denaturation, but 7S and 11S globulins were only partially denatured. The partial denaturation of the proteins was confirmed by Fourier transform infrared spectroscopy measurements. The ratio of oil to protein peaks increased with increasing heating, suggesting the exudation of oil to the surface or outside of oil bodies. Microwave heating is more efficient in changing the oil distribution in soybean seeds than autoclave heating. On the other hand, the degree of protein denaturation is lower after microwave heating.

This paper reports the effects of adding talc particles on the physical properties of palm oil (PO)-based shortening formed by working refined PO (RPO) after rapid cooling. We examined the thermal and viscoelastic behavior of RPO in bulk fat systems, and the polymorphism and hardness of the shortening in the presence and absence of talc particles. In addition, the microstructure of fat crystals formed was observed. The effects of talc addition are summarized as follows: (i) When RPO was cooled at a rate of 5°C/min, crystallization of the high-melting fraction, including tripalmitoylglycerol (PPP) and 1,3-dipalmitoyl-2-oleoyl glycerol (POP), was preferentially promoted to form small-sized microcrystals. During cooling, the increase in the viscoelasticity of RPO was suppressed at low temperatures. (ii) When the shortening was stored at 5°C, β′-crystallization of 1-palmitoyl-2,3-dioleoyl glycerol (POO) and β-crystallization, probably of a molecular compound (MC) of POP and 1,2-dipalmitoyl-3-oleoyl glycerol (PPO), were delayed compared to β′-crystallization of PPP and POP. During storage, the homogeneity of the fat crystal dispersion improved and the hardness of the shortening decreased. These results indicate that talc improved the physical properties of the PO-based shortening by changing the crystallization kinetics and the networking processes of the fat crystals. Practical applications: The present study showed that adding talc particles effectively improved the physical properties of palm oil (PO)-based shortening during storage. This is considered beneficial for resolving problems in the quality control of PO-based products, such as post-hardening and the formation of granular crystals due to low rates of crystallization. Storage modulus (G′) of refined palm oil (RPO) with and without talc particles in bulk fat systems, obtained from dynamic viscoelasticity measurements during cooling at a rate of 5°C/min. Adding talc particles drastically changed the three-stage increases in G′ of pure RPO, promoting the first-stage increase but suppressing subsequent increases at low temperatures.

In order to impart emulsifying ability to gel-forming polysaccharides that have not been used as emulsifying agents, three kinds of polysaccharides, agar, curdlan, and gellan gum were converted to microgels by different gelation methods via the bottom-up and top-down approaches. We clearly demonstrated that agar and curdlan acquired the ability to emulsify an edible oil by microgel formation. Among the colloidal properties of microgel suspensions such as microstructure, particle size, zeta-potential, viscosity, and surface hydrophobicity, we pointed out the importance of particle size on the emulsifying ability of polysaccharide-based microgels. The creaming behavior of the microgel-stabilized emulsions depended on the polysaccharide types and microgel preparation methods. The emulsion stability against oil droplet coalescence was extremely high for agar and curdlan microgel-stabilized emulsions during storage in the static condition, whereas different stability was observed for both the emulsions, that is, the curdlan microgel-based ones were more resistant to dynamic forcible destabilization by centrifugation than the agar ones, which can be attributed to the surface hydrophobicity of the microgels., Food Emulsion: Microgelation turns polysaccharides into emulsifying agents Polysaccharides are widely recognized as gelling agents while rarely used alone as emulsifying agents due to their surface inactiveness. Now Kentaro Matsumiya and coworkers from Kyoto University report the microgelated polysaccharide particles can emulsify soybean oil, forming so-called microgel-based Mickering emulsions. It was found that large microgels formed by agar and curdlan exhibited better emulsifying abilities compared to small gellan gum microgels, regardless of the preparation methods. The creaming behaviors varied with the changing polysaccharide types and microgel preparation methods. The static stability was quite high for all emulsions while their dynamic stability was different, which can be attributed to the surface hydrophobicity difference. It is noteworthy that the microgelation turned surface-inactive polysaccharides into effective emulsifying agents. The low-allergenic polysaccharide food emulsions might find usage practically soon.

This chapter focuses on recent developments in the understanding of the structure and functionality relationships of soy proteins. Seed proteins play an important role in food consumption worldwide. Soy proteins have been utilized for many kinds of traditional foods. The use of soy protein products as functional ingredients is gaining increasing acceptance in food manufacturing from the standpoints of human nutrition and health. The seed proteins of legumes, including soybeans, are albumins and globulins. Globulins, the dominant storage proteins, account for about 50–90% of seed proteins. Storage globulins are grouped into two types according to their sedimentation coefficients: 7S globulins and 11S globulin. The ratio of 11S to 7S globulins varies among cultivars. It is about 0.5–1.7 in soybean. The 11S globulins, legumin-type proteins, are widely distributed in many legume and nonlegume seeds and are generally simple proteins, although there are some exceptions; for example, lupin 11S globulin is a glycosylated protein.

Diglycerol ester of mono-oleic acid (DO), a bacteriostatic emulsifier causes severe coalescence of oil droplets stabilized by milk proteins and phase separation between oil and aqueous phase under agitating conditions. In order to clarify the destabilizing mechanism of the emulsifier, physicochemical and colloidal properties of the emulsifier were compared to similar emulsifiers without destabilizing effects. DO, that is dispersible both in oil and water, adsorbed to the oil–water interface to reduce the interfacial tension, and migrated from oil phase to aqueous phase and vice versa in a plane interface system. Experiments performed in an emulsion system revealed that DO had little ability to emulsify food-grade oil, but displaced milk proteins from the oil droplet surface. These data indicate that DO with little emulsifying ability predominantly occupies the oil droplet surfaces via emulsifier–protein competitive interactions to promote severe coalescence of emulsion oil droplets probably because DO actively migrates between oil and aqueous phase and it favors to form the planar oil–water interface.

Long-term stability of milk-based emulsions in canned coffee or tea varies with the formulation of small-molecule emulsifiers aiming at bacteriostatic effects or stability-enhancing effects. To predict the long-term stability of the emulsions in short-time period, we developed a novel method for rapid determination of aggregation forces between colloidal particles using model emulsions and suspensions with different stability to aggregation for the first step. The novel method was based on an idea that particles with stronger aggregation forces tend to form aggregates and cannot be readily redispersed. While the milk-based emulsions were subjected to long-term storage test with coffee extract, the same emulsions, but not including coffee extract, were rapidly evaluated by both the novel method and a common method, Turbiscan analysis often applied to the evaluation of emulsion stability. Statistical regression analysis according to the datasets obtained by the two rapid assays revealed that the long-term stability of the milk-based emulsions can be better predicted by the aggregation forces evaluated by the newly developed method than the initial aggregating process evaluated by Turbiscan method. We named the novel method “vibration-redispersion method”.

There are 2 types of soybean soluble polysaccharide (SSPS); an ordinary type with low molecular weight (SSPS-LMW; molecular weight = 550 kg/mol), and a new type with high molecular weight (SSPS-HMW; molecular weight = 2850 kg/mol). In the current study, the protein stabilizing ability of both types of SSPS was investigated in model acidified milk. We prepared model acidified milk drinks that were composed of 3.0% skimmed milk and 0.4% SSPS-HMW or SSPS-LMW. Model acidified milk was centrifuged at several centrifugal accelerations. The centrifuged samples were visually observed, and the measurement of precipitate weight and turbidity of the upper layer confirmed that SSPS-HMW stabilized proteins better than SSPS-LMW. The model mixture of SSPS-HMW had smaller particle sizes and a larger zeta-potential. In addition, The surface concentration of SSPS-HMW was about 2 times that of SSPS-LMW, indicating that the thicker SSPS-HMW layer produces larger steric repulsion to protein particles. These results clearly demonstrate that SSPS-HMW has a greater ability to disperse milk proteins because of the larger electrostatic repulsive force of polysaccharide chains and the steric repulsive force of the thicker layer that forms on the surface of particles.

Effect of the polysaccharide from leaves of Corchorus olitorius L. (PLC) on the freeze-thaw (FT) stability of corn starch gel was studied. PLC was incorporated into the starch gel at 0.7% and total solid was adjusted to 6.0%. The syneresis was measured by the centrifugal-filtration method and, as a result, addition of PLC reduced effectively the syneresis of the starch gel even after 5 FT cycles, which was less than one third that of the normal starch gel. The rheological changes of the starch/PLC gel during the FT treatments were evaluated while the gel remained on the rheometer plate. The starch/PLC gel had less significant changes in the rheological parameters during the FT cycles than starch/guar gum or xanthan gum gel systems. SEM images showed that PLC stabilized the gel matrix surrounding pores, which would contribute to both a lower syneresis production and a higher stability in the rheological behavior at FT.

It is widely accepted that aromas from plant essential oils show some mental and physiological effects that are often called "aromachology" effects. However, there are few reports exhibiting the clear scientific evidence on aromachology effects of essential oil. In this study, we tested aromachology effects of essential oils from two lavenders (Lavandula angustifolia (called "true lavender") and L. hybrid (called "lavandin")). Lavender essential oil is believed to have relaxing effects. POMS (Profile of Mood States) test was tried to reveal the mental effects of the oils on human volunteers. Some relaxing effects such as decrease of "fatigue" feeling were observed by giving aroma of both the lavender essential oils. Power spectral analysis on R-R intervals of heartbeat was used for evaluating the physiological effects of the lavender oils on human autonomic activity. Aroma of the lavender oil from L. angustifolia (called "true lavender") caused an increase of human parasympathetic nerve activity, but the oil from L. hybrid did not show such an effect. To reveal key compounds causing such a difference in the physiological effect, volatile compounds of the essential oils were analyzed by GC and GC-MS. The similar contents of linalool and linalyl acetate were included in both the essential oils, but the content of camphor was higher in the oil of lavandin. Since camphor is believed to have the ability of increasing sympathetic nerve activity, this compound may offset the relaxing effects of linalool and linalyl acetate.

Destabilizing effects of diglycerol mono-esters of different saturated or one mono-unsaturated fatty acids (DF) on protein-based emulsions prepared with various types of oil were examined by visual observations and particle size analyses. By diglycerol esters of oleic acid (DO), a hexadecane-in-water emulsion was more obviously destabilized than an octadecane-in-water emulsion or food oil-in-water emulsions. Interfacial tension measurements indicated that the adsorbed protein on oil droplet surfaces of hydrocarbon emulsions can be more easily displaced by DO compared to the case of food oil emulsions. The degree of hydrocarbon emulsion destabilization by DO varied with the chain length of hydrocarbon molecules. From the results of combination tests of five hydrocarbons varying in chain length in oil phase and five DF having different mono-fatty acid residue, we described a possibility that DF could effectively destabilize the hydrocarbon emulsion when the chain length of fatty acid residue of DF was similar to that of hydrocarbon molecules.

For milk-based emulsion products such as canned coffee or tea, the addition of bacteriostatic emulsifiers is necessary to inhibiting the growth of heat-resistant sporeformers. Since bacteriostatic emulsifiers often cause the destabilization of emulsions, other type of emulsifiers, such as stability-enhancing ones, are necessary for the long-term stability of emulsions. Four milk-based emulsions were prepared from powdered milk combined with several types of emulsifiers. The long-term stability of emulsions, which was detected by the occurrence of a creaming layer after 3 months of storage, differed according to the composition of emulsifiers. To understand the reason for the differences in the stability of emulsions, particle size, distribution, ζ-potential, and the amount of proteins and phospholipids present in the cream layer (separated oil droplets) in the emulsions were measured. Only the amount of proteins adsorbed onto oil droplets was found to be closely related to the difference in emulsion stability, that is, the more proteins adsorbed, the higher the emulsion stability. SDS–PAGE analyses revealed that κ-casein and β-lactoglobulin play an important role in emulsion stability by adsorbing onto the oil droplet surface.

Viscous hydrocolloid from leaves of Corchorus olitorius L. was fractionated with ammonium sulfate solution (50%, w/v) followed by the stepwise extraction with distilled water. The yield of the hydrocolloid was 4.5% (w/w) based on dry material. Ash, protein, moisture and total sugars were 3.4, 5.3, 12.3 and 83.8% based on dry-material, respectively. The hydrocolloid consisted of mainly uronic acid and the weight ratio was approximately 90% of total sugars. When the molecular weight distribution was checked by size-exclusion chromatography, the hydrocolloid showed a wide uronic acid peak with a molecular weight of 940 kDa. The viscoelastic properties of the hydrocolloid were examined by low-amplitude oscillatory measurements and the hydrocolloid exhibited gel-like character at the concentration higher than 0.5% (w/w). Viscosity of the hydrocolloid surpassed other food hydrocolloids such as guar gum and locust bean gum at the same condition (0.25∼1.0% [w/w], 25 °C). When the hydrocolloid was heated over 60 °C (∼100 °C), an irreversible increase in viscosity was observed, suggesting the conformational change of the polysaccharide molecule.

Hydrocolloid from leaves of Corchorus olitorius was fractionated with ammonium sulfate (50%, w/v) and extracted with distilled water. The yield of the hydrocolloid was 6.0% (w/w) based on dry material. The contents of total carbohydrate, anhydrouronic acid, ash, protein, and moisture of the hydrocolloids were 62.2%, 35.3%, 13.3%, 5.5%, and 16.1% (w/w), respectively. Degree of esterification of 19.4% was calculated assuming that the methoxyl groups were attached to only anhydrouronic acid. When the molecular weight distribution was checked by size-exclusion chromatography on Sepharose CL-4B, the hydrocolloid gave a single peak with a molecular weight of 1860 kDa. The rheological behavior of mixed gels made from κ -carrageenan and the hydrocolloid at a total hydrocolloids concentration of 1% (w/w) was investigated by gel strength measurement. Then it was found that the hydrocolloid exhibited synergy with κ -carrageenan in relation to gel strength.

The effects of addition of an oil-soluble emulsifier on cream solidification after the thermal treatment, in which the cream was temporarily heated and then cooled, were investigated. Thirteen oil-soluble emulsifiers were tested for the ability to retard the cream solidification. Two emulsifiers, namely the sucrose esters of fatty acids that have low hydrophilic-lipophilic balance (HLB) values (SE-L) and the citric acid esters of monoglyceride (CMG), showed an inhibitory effect on the cream solidification. The increase in solid fat content (SFC) in cream was delayed by SE-L addition during the recooling process in the thermal treatment. SE-L inhibited the cream solidification presumably by modifying the fat crystallisation behaviour in oil droplets. On the other hand, the SFC changing pattern of the cream containing CMG during the recooling process was not different from that of solidified cream, suggesting that a mechanism other than fat crystallisation was involved in the inhibition of the cream solidification by this emulsifier.

The inhibitory effects of polysaccharides on lipid oxidation in emulsions were investigated. Methyl linoleate was emulsified by β-casein or surfactants to prepare emulsions, and the oxidation was induced by an azo-compound or FeSO4 addition. The initial oxidation was followed by measuring the oxygen consumption in the emulsions for 30 min, and the extent of the lipid oxidation over a long time (∼48 h) was evaluated by the determination of the unoxidized lipid by gas chromatography and the thiobarbituric acid test. Peptide-bound polysaccharides, such as gum arabic and soluble soybean polysaccharides (SSPS), showed an ability to inhibit lipid oxidation, whereas maltodextrin and pullulan exhibited no inhibitory effects. Especially, SSPS almost perfectly suppressed the lipid oxidation from the initial to the late stages, irrespective of the emulsifiers and oxidation-inducing reagents. The mechanism whereby the peptide-bound polysaccharides inhibited the lipid oxidation in the emulsions is considered in terms of the chemical composition and other properties of the polysaccharides.

Maltodextrins and a highly branched cyclic dextrin (HBCD) were tested for their ability to serve as wall materials for microcapsules with proteins. HBCD or a maltodextrin of DE18 with sodium caseinate (SC) improved the oxidative stability of encapsulated fish oil; however, the DE18/SC wall system had 2 disadvantages: browning induced by the Maillard reaction and agglomeration. The oil load level and the selection of dextrin strongly affected the outer topography and the inner structure, as well as the ratio of the oil to dextrin on the surface of the microcapsules. It is stated that drying speeds of dextrin and oil load levels were shown to be likely related to the structural difference in the microcapsules.

Heat-induced gels were prepared from glycinins of various soybean cultivars at protein concentrations of 18 to 20%. Textural properties of the gels measured by a compression-decompression test were evaluated by the three-dimensional representation of the gels through factor analysis of the instrumental data and calculation of factor scores for each gel. Differences in gel texture were clearly observed among the soybean cultivars,with Shirotsurunoko gel being the most fracturable and Yamabe-A3 gel the most unfracturable. The most elastic was the gel from Hill and Matsuura gel exhibited the lowest elasticity. The existence of A4 polypeptide also contributed to the textural features of the gels. The gels of A4-containing cultivars were more unfracturable and less elastic compared to those of A4-lacking cultivars. Physical properties of the gels, gel network structure, and polypeptide composition of the glycinin were related each other to some extent. The compressibility which corresponded to the textural attribute of fracturability was related to regularity and/or pore size of network structure of the gels. The acidic polypeptide of A4 seemed to be responsible for whether the gel network was aggregate or strand type, thereby relating to the physical properties of compressibility and resiliency of the gels. The results obtained here suggest that polypeptide composition of the glycinin affects the properties of gel networks and thereby contributes to different physical and textural properties of the gels.