Sucrose Fatty Acid Esters Research Articles

Effect of sucrose fatty acid ester on crystal growth of carbon dioxide hydrate in aqueous fructose solution

CO2 hydrate is a remarkable candidate for novel solid carbonated foods because of its large gas capacity. This paper reports the effect of surfactants, essential additives in food production, on hydrate crystal growth by visually observing the CO2 hydrate crystal growth in aqueous fructose + sucrose fatty acid ester solution + gaseous CO2 system. Under all thermodynamic conditions, the surfactants affected the crystal growth of CO2 hydrates at liquid/gas interface, while not influencing growth in the liquid bulk phase. Porous hydrate crystals were formed at the liquid/CO2 interface and grew continuously along the reactor wall. The hydrate crystal morphology in liquid bulk phase was not affected by surfactants, changing from polyhedral and polygonal to dendritic shapes as temperature decreased. Discussion is provided on how the observation results can be specifically applied to intensification of hydrate formation process design and evaluation of hydrated food texture.

Effects of compound emulsifiers on the characteristics and stability of nano-emulsions from pollock bones

To improve the stability of pollock bone broth, compound emulsifiers were employed and evaluated in nano-emulsions from pollock bones (PBNs). The microstructure, creaming index, particle size, zeta potential, and viscosity of PBNs were characterized and the stability of PBNs was investigated. It revealed that the concentration of compound emulsifiers is one of the principal factors for particle size, zeta potential, and viscosity of PBNs, and 0.9% of sodium caseinate and sucrose fatty acid ester (CS-SE) can make the PBN display good stability. Its particle size changed from 81.17 ± 1.33 nm to 19.62 ± 0.21 nm when the temperature ranged from 40 °C to 80 °C, and its creaming index could reach a maximum (90.83%) among all PBNs in 4 months of freeze-thaw assays. PBN stability could be improved by the compound emulsifier (CS-SE), which offers a theoretical basis for the application of pollock bone broth.

Common dietary emulsifiers promote metabolic disorders and intestinal microbiota dysbiosis in mice

Dietary emulsifiers are linked to various diseases. The recent discovery of the role of gut microbiota–host interactions on health and disease warrants the safety reassessment of dietary emulsifiers through the lens of gut microbiota. Lecithin, sucrose fatty acid esters, carboxymethylcellulose (CMC), and mono- and diglycerides (MDG) emulsifiers are common dietary emulsifiers with high exposure levels in the population. This study demonstrates that sucrose fatty acid esters and carboxymethylcellulose induce hyperglycemia and hyperinsulinemia in a mouse model. Lecithin, sucrose fatty acid esters, and CMC disrupt glucose homeostasis in the in vitro insulin-resistance model. MDG impairs circulating lipid and glucose metabolism. All emulsifiers change the intestinal microbiota diversity and induce gut microbiota dysbiosis. Lecithin, sucrose fatty acid esters, and CMC do not impact mucus–bacterial interactions, whereas MDG tends to cause bacterial encroachment into the inner mucus layer and enhance inflammation potential by raising circulating lipopolysaccharide. Our findings demonstrate the safety concerns associated with using dietary emulsifiers, suggesting that they could lead to metabolic syndromes.

Efficient Synthesis of Mannopyranoside-based Fatty Acyl Esters: Effects of Acyl Groups on Antimicrobial Potential.

The approval of Sucrose Fatty Acid Esters (SFAEs) as food additives/ preservatives with antimicrobial potential has triggered enormous interest in discovering new biological applications. Accordingly, many researchers reported that SFAEs consist of various sugar moieties, and hydrophobic side chains are highly active against certain fungal species. This study aimed to conduct aregioselective synthesis of SAFE and check the effect of chain length and site of acylation (i.e., C-6 vs. C-2, C-3, C-4, and long-chain vs. short-chain) on antimicrobial potency. A direct acylation method maintaining several conditions was used for esterification. In vitro tests, molecular docking, and in silico studies were conducted using standard procedures. In vitro tests revealed that the fatty acid chain length in mannopyranoside esters significantly affects the antifungal activity, where C12 chains are more potent against Aspergillus species. In terms of acylation site, mannopyranoside esters with a C8 chain substituted at the C-6 position are more active in antifungal inhibition. Molecular docking also revealed that these mannopyranoside esters had comparatively better stable binding energy and hence better inhibition, with the fungal enzymes lanosterol 14-alpha-demethylase (3LD6), urate oxidase (1R51), and glucoamylase (1KUL) than the standard antifungal drug fluconazole. Additionally, the thermodynamic, orbital, drug-likeness, and safety profiles of these mannopyranoside esters were calculated and discussed, along with the Structure-Activity Relationships (SAR). This study thus highlights the importance of the acylation site and lipid-like fatty acid chain length that govern the antimicrobial activity of mannopyranoside-based SFAE.

Effect of glycerol incorporation on the liquid crystal structure of sucrose fatty acid ester in aqueous solution

A series of homogeneous samples with high sugar-surfactant content (sucrose fatty acid ester/water and sucrose fatty acid ester/glycerol/water systems) were prepared with well-controlled processes and investigated by DSC, polarized microscopy, X-ray scattering and rheology. Meanwhile the accuracy of the preparation process is confirmed gas chromatography. The polarized microscopy indicates that the ordering degree of the network structure composed of the liquid crystals may be reduced by the glycerol addition. The results of DSC revealed that 50% glycerol solution could significantly inhibit the crystallization of sucrose fatty acid ester and resulted in a significant widening of the temperature interval for the transformation of the liquid crystal phase into the gel phase. In order to further evaluate the effect of glycerol molecules versus water molecules on the liquid crystal structure of sucrose fatty acid ester, we comparatively analyzed the X-ray scattering data from two perspectives: the mass fraction and molar fraction. It was found that 50% glycerol solution could inhibit the crystallization of sucrose fatty acid ester through changing the water-head group interaction of surfactant, facilitates the integration of sucrose fatty acid ester with different alkyl chain length and may reduce the regularity of liquid crystal, both from the perspective of surfactant mass and molar fraction. Furthermore, the addition of 50% glycerol (w/w) does not significantly impede the liquid crystal formation of sucrose fatty acid ester in aqueous solution. However, from the perspective of surfactant mass fraction, glycerol incorporation could reduce the effective cross-sectional areas of the hydrophilic part of sucrose fatty acid ester in aqueous solution and induce the phase transition of hexagonal liquid crystals to aggregates with less positive curvature, while an opposite tendency could be obtained from the perspective of surfactant molar fraction. The conclusions are also confirmed by subsequent rheological test. Moreover, the results of rheological measurements reveals that the interactions among cylindrical units of the hexagonal liquid crystalline phase become weaker and the surfactant molecules aggregate more loosely in the cylindrical unit with the glycerol incorporation. Moreover, the above-mentioned influence of glycerol on the liquid crystal structure of sucrose fatty acid ester in aqueous solution would be similar but more prominent from the perspective of the molar fraction.

Molecular formula assignment of dissolved organic matter by ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry using two non-targeted data processing approaches: A case study from recirculating aquaculture systems

BackgroundThe accumulation of dissolved organic matter (DOM) poses an issue in the management of the water quality from recirculating aquaculture systems (RAS), but its characterization is often not detailed enough to understand the DOM transformations in RAS. In this study, we investigated the application of two distinct non-targeted data processing approaches using ultra-performance liquid chromatography (UPLC) with quadrupole time-of-flight mass spectrometry (QTOF-MS) and two software with different algorithmic designs: PetroOrg and Progenesis QI to accurately characterize the molecular composition of DOM in RAS by UPLC-QTOF-MS. ResultsThe UPLC-QTOF-MS resolution in combination with PetroOrg and Progenesis QI software successfully assigned 912 and 106 unique elemental compositions, respectively, including compounds containing carbon, hydrogen, and oxygen (CHO) and nitrogen-containing CHO compounds (CHON), in the DOM samples from RAS. The results of these two distinct data processing approaches were consistent with the list of DOM formulas from RAS identified by higher resolution mass spectrometry techniques confirming their reliability. PetroOrg approach revealed only compositional information in the DOM samples from RAS, while Progenesis QI in addition to identifying new elemental compositions, increased their chemical space by giving information about their polarity and their possible key structures. DOM samples from RAS were found to be rich in unsaturated CHO compounds, with tentatively key structures of terpenoids with medium polarity indicating natural origins in their composition. The analysis also revealed probable structures of sucrose fatty acid esters and polyethylene glycol, indicating anthropogenic sources. Significance and NoveltyThe combination of these two non-targeted data processing approaches significantly improves the characterization of the complex mixture of DOM from RAS by UPLC-QTOF-MS reporting for the first time accurate DOM results in terms of its composition, while proposing its key structures. The presented methods can also be used to analyze different DOM samples with other HRMS techniques and software.

Improvement of 3D white chocolate printing molding effect with oleogels

This study used oleogels to resolve unsolidified white chocolate in 3D printing. Because white chocolate cannot be shaped during 3D printing, the oleogel system is used to solve this problem. The printing parameters and accuracy in a 3D printing system were investigated by using different oleogels added to white chocolate as a material to enhance chocolate extrusion solidification, monoglycerides (MAG), sucrose fatty acid ester (SE) and hydroxypropyl methylcellulose (HPMC), and their effects on rheological characterization, bridging experiments, and optimal print parameters (material formulation, nozzle height, layer height and print speed) were compared. In the rheological analysis, the viscosity recovery was more than 80% for the HPMC group and less than 80% for the MAG and SE groups. In the bridging experiment, when MAG and SE were added at more than 2%, the white chocolate could be effectively extruded and solidified, and the bridging distance could be stretched to 10 mm. The suitable printing parameters are a nozzle height of 3 mm, a layer height of 3 mm, and a printing speed of 10 mm/s. This study provides a future solution to solve the problem of extruded unsolidified chocolate.

Re-evaluation of sucrose esters of fatty acids (E 473) as a food additive in foods for infants below 16 weeks of age and follow-up of its previous evaluations as food additive for uses in foods for all population groups.

Sucrose esters of fatty acids (E 473) was re-evaluated in 2004 by the former EFSA Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (AFC Panel). In addition, the former EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS Panel) issued scientific opinions on the safety of sucrose esters of fatty acids (E 473) in 2010, 2012 and 2018. As a follow-up to these assessments, the Panel on Food Additives and Flavourings (FAF) was requested to assess the safety of sucrose esters of fatty acids (E 473) for its uses as food additive in food for infants below 16 weeks of age. In addition, the FAF Panel was requested to address the issues already identified by the EFSA AFC and ANS Panels when used in food for the general population. The process involved the publication of calls for data to allow the interested business operators to provide the requested information to complete the risk assessment. The Panel concluded that the technical data provided by the interested business operators support an amendment of the specifications for sucrose esters of fatty acids (E 473) laid down in Commission Regulation (EU) No 231/2012. According to the available information, E 473 is not used in food categories (FCs) 13.1.1 and 13.1.5.1, including all types of food for infants below 16 weeks of age, and in FC 13.1.5.2. As a consequence, an assessment of the safety for the uses of E473 as food additive in these FCs and age group was not performed. When the updated exposure estimates considering the provided use levels for some food categories are taken into account the estimates of exposure to sucrose esters of fatty acids (E 473) exceeded the group acceptable daily intake (ADI) of 40 mg/kg body weight (bw) per day for many population groups.

Biodegradable Nanofibrillated Cellulose/Poly-(butylene adipate-co-terephthalate) Composite Film with Enhanced Barrier Properties for Food Packaging.

Biodegradable composites consisting of Poly-(butylene adipate-co-terephthalate) (PBAT), thermoplastic starch, hydrophobically modified nanofibrillated cellulose (HMNC), and green surfactant (sucrose fatty acid ester) were prepared via the melt-mixing and film-blowing process (PBAT-HMNC). The composites were characterized using the Fourier transform infrared spectroscope (FT-IR), scanning electron microscope (SEM), and thermogravimetric analyzer (TGA). The mechanical and barrier properties were systematically studied. The results indicated that PBAT-HMNC composites exhibited excellent mechanical and barrier properties. The tensile strength reached the maximum value (over 13 MPa) when the HMNC content was 0.6% and the thermal decomposition temperature decreased by 1 to 2 °C. The lowest values of the water vapor transmission rate (WVTR) and the oxygen transmission rate (OTR) were obtained from the composite with 0.6 wt% HMNC, prepared via the film-bowing process with the values of 389 g/(m2·day) and 782 cc/(m2·day), which decreased by 51.3% and 42.1%, respectively. The Agaricus mushrooms still had a commodity value after 11 days of preservation using the film with 0.6 wt% HMNC. PBAT-HMNC composites have been proven to be promising nanocomposite materials for packaging.

Inhibition of Tolaasin Cytotoxicity Causing Brown Blotch Disease in Cultivated Mushrooms Using Tolaasin Inhibitory Factors.

Tolaasin, a pore-forming bacterial peptide toxin secreted by Pseudomonas tolaasii, causes brown blotch disease in cultivated mushrooms by forming membrane pores and collapsing the membrane structures. Tolaasin is a lipodepsipeptide, MW 1985, and pore formation by tolaasin molecules is accomplished by hydrophobic interactions and multimerizations. Compounds that inhibit tolaasin toxicity have been isolated from various food additives. Food detergents, sucrose esters of fatty acids, and polyglycerol esters of fatty acids can effectively inhibit tolaasin cytotoxicity. These chemicals, named tolaasin-inhibitory factors (TIF), were effective at concentrations ranging from 10-4 to 10-5 M. The most effective compound, TIF 16, inhibited tolaasin-induced hemolysis independent of temperature and pH, while tolaasin toxicity increased at higher temperatures. When TIF 16 was added to tolaasin-pretreated erythrocytes, the cytotoxic activity of tolaasin immediately stopped, and no further hemolysis was observed. In the artificial lipid bilayer, the single-channel activity of the tolaasin channel was completely and irreversibly blocked by TIF 16. When TIF 16 was sprayed onto pathogen-treated oyster mushrooms growing on the shelves of cultivation houses, the development of disease was completely suppressed, and normal growth of oyster mushrooms was observed. Furthermore, the treatment with TIF 16 did not show any adverse effect on the growth of oyster mushrooms. These results indicate that TIF 16 is a good candidate for the biochemical control of brown blotch disease.

Retrospective analysis on the immunopotentiating mechanism of an emulsion-based vaccine adjuvant on human antigen presenting cells.

We retrospectively analyzed the immunopotentiating mechanism of an oil-in-water (O/W) emulsion-based vaccine adjuvant LiteVax™ Adjuvant (LVA) that contains CMS (Maltose 4'-monosulphate 1,2,3,6,2',3',6'-heptadecanoic acid ester), squalane, Tween 80 in phosphate buffered saline. Despite being effective in animal models, the immunological mechanisms by which LVA exerts adjuvant function are not known. As dendritic cells (DC) are key for initiating and propagating the immune response, we have investigated the effect of LVA and of its components on the DC function. We show that CMS but not LVA significantly enhances the expression of DC activation-associated markers, cytokine secretion, and CD4+ T cell responses. On the other hand, CMS ZERO [non-sulphated sucrose fatty acid esters (ZERO)], used as a control, had no such activity. Our data identified the unique nature of CMS in LVA, and propose that LVA acts as a delivery system, and CMS acts as an immunostimulatory agent.

Synchronous pressing and refining after solid-phase preadsorption technology as a new method for rapeseed oil preparation

A new method for rapeseed oil preparation named synchronous pressing and refining after solid-phase preadsorption technology was investigated. Rapeseed and adsorbents were first mixed evenly to form premixes, and the product oils were then obtained by direct pressing and filtering. The phospholipid content, acid value, a* value, chlorophyll, carotene, polyphenol contents of crude oil increased, while L* and b* values decreased with increasing squeezing chamber temperature. A moderate adsorbent dosage and temperature could improve the refining effects. Silicon dioxide had the highest dephosphorization and deacidification rates of 95% and 42%, respectively, when the dosage was 30 g/kg at 130 °C. Activated clay decreased the chlorophyll and carotene contents by 75% and 38%, respectively. Sucrose fatty acid ester had dephosphorization and deacidification rates of 67s% and 41%, respectively. Ascorbic palmitate had a dephosphorization rate of 74% and retained polyphenols intactly. This technology would not affect the oil yield and could decrease the peroxide value of rapeseed oil. It realized the simultaneous completion of pressing and refining with the advantages of a short preparation time and environmental sustainability.

Preparation of dyeing, flame retardant and anti-dripping polyethylene terephthalate fibers based on natural sodium copper chlorophyll dyeing and intercalation of phosphorylated sucrose fatty acid ester

As the largest synthetic fibers in the world, polyethylene terephthalate (PET) fibers have a wide range of applications. However, PET fibers are flammable fibers with serious droplet phenomenon during combustion, which has great potential safety hazards. To solve the issue, multifunctional PET fibers with dyeing, flame retardant and anti-dripping were developed in this work. First, dyed PET fibers (DY-PET) were prepared by directly dyeing of PET fibers with sodium copper chlorophyllin (SCC). Then, DY-PET was intercalated with ammonium phosphate of sucrose fatty acid ester (APSFA) to obtain the flame retardant PET fibers (FR-PET). Compared with the original samples, the peak heat release rate (PHRR) and total heat release rate (THR) of DY-PET and FR-PET were significantly reduced. Meanwhile, the limiting oxygen index (LOI) of DY-PET and FR-PET was also improved, indicating the improved flame retardant properties of DY-PET and FR-PET. In addition, the anti-dripping performance was excellent, which was mainly due to the high temperature self-crosslinking, high temperature ionic aggregation and hydrogen bond & π-π stacking effect. The improved flame retardant performance of FR-PET was attributed to the blocking effect of the generated char layer catalyzed by APSFA under high temperature and the dilution effect of incombustible gas resulting from the thermal decomposition of APSFA. This work provided a scalable strategy for the design of dyeing, flame retardant and anti-dripping PET fibers, and endowed PET with great potential application in the field of functional polymer materials.

Preparation of Highly Stable Z‐Isomer‐Rich Lycopene Nanodispersions via a Continuous‐Flow System with Selected Emulsifiers

AbstractAs a potent antioxidant with numerous health benefits, lycopene finds multiple applications. Among the geometric isomers of lycopene, the Z‐isomers have greater bioavailability than the all‐E‐isomer but are less stable and hence, less suitable for practical applications. Herein, highly stable Z‐isomer‐rich lycopene nanodispersions are produced through the thermal isomerization of (all‐E)‐lycopene in a flow reactor followed by continuous dispersion in an aqueous emulsifier (Tween 20, sucrose fatty acid ester, or polyglycerol fatty acid ester [PFAE]) solution upon agitation with an in‐line swirl mixer. The effects of emulsifier type and other processing conditions (flow rate, pressure, temperature, lycopene Z‐isomer ratio) on dispersion efficiency and properties are examined in detail, and finally, Z‐isomer‐rich lycopene nanodispersions (>60% of total Z‐isomer ratio and <10 nm of mean particle size) are successfully obtained. Moreover, it is found that lycopene Z‐isomers have greater encapsulation efficiency for dispersions with emulsifiers than that of the all‐E‐isomer. The storage test of the resulting dispersions clearly shows that the highest storage stability is achieved in the case of using PFAE, which effectively inhibits lycopene degradation and reverse (Z‐ to all‐E) isomerization.Practical applications: To practical use of lycopene Z‐isomers, it is essential to improve their storage stability as well as usability (i.e., dispersibility in water). The present study reveals that when producing the lycopene dispersions, the use of PFAE as an emulsifier allows to improve the stability of lycopene isomers and inhibit the Z‐ to all‐E‐isomerization during storage. Given the high demand for stable Z‐isomer‐rich lycopene formulations, the obtained results promote the practical use of lycopene Z‐isomers in diverse (e.g., food and cosmetic) industries.

Ionic liquid as dual-function catalyst and solvent for efficient synthesis of sucrose fatty acid esters

Carbohydrate fatty acid esters are important bio-based, non-ionic surfactants. Their synthesis confronts the challenge of reacting substrates of vastly different polarity. Here, we show imidazolium-based ionic liquids with basic anions (dicyanamide, acetate) as dual-function catalysts and solvents for an efficient C4-C18 fatty acid esterification of sucrose. The conversion proceeds from the anhydride, the vinyl ester, and the free fatty acid in that order of reactivity. It benefits ≥ 3-fold from a moderately polar, protic co-solvent (2-methyl-2-butanol, tert‑butanol) in ∼1:1 vol ratio with the ionic liquid. Optimized synthesis from vinyl palmitate (C16; ≤ 3-fold excess over 50 mM sucrose; 60 °C) was unexpectedly selective, giving the 6-O-mono-acyl product (∼70%) in quantitative yield. The ionic liquid-promoted conversion gains efficiency from the imidazolium cation aiding in sucrose solubilization and the basic anion providing catalytic facilitation to the esterification. By virtue of high reactivity at mild conditions and useful product selectivity, it advances the current repertoire of synthetic methods, including biocatalytic transformations, for sucrose palmitate ester production.

Continuous production of Z-isomer-rich astaxanthin nanodispersions with stabilized Z-structures using selected ester-based nonionic emulsifiers

The multiple beneficial biological activities of astaxanthin show promise for the application of ​nutritional supplements and cosmetics, but the industrial use of this carotenoid is hindered by its high crystallinity and poor solubility, which result in low oral bioavailability and percutaneous absorbability. These drawbacks are inherent to many carotenoids and are typically addressed through their formulation as aqueous dispersions. Given that carotenoid Z-isomers have greater bioavailability than the corresponding all-E-isomers, we herein realized the continuous production of Z-isomer-rich astaxanthin nanodispersions and determined the optimal conditions for Z-isomer stabilization. The thermal isomerization of (all-E)-astaxanthin was performed in a flow reactor using subcritical ethyl acetate as a solvent, and a total Z-isomer ratio of >60% was achieved in only 15 s. The mixture of isomers was dispersed in an aqueous solution of an ester-based nonionic emulsifier using an in-line swirl mixer, and the properties of these dispersions were investigated as functions of emulsifier type. The best performance was observed for sucrose fatty acid ester, which promoted the formation of fine dispersions (average particle size of <10 nm) and stabilized astaxanthin Z-isomers. Thus, the Z-isomer-rich fine dispersions are expected to increase the bioavailability of astaxanthin and hold great promise for its industrial applications.

Comparative Study on Inhibition of Pancreatic Cancer Cells by Resveratrol Gold Nanoparticles and a Resveratrol Nanoemulsion Prepared from Grape Skin.

Resveratrol, a phenolic compound possessing vital biological activities such as anti-cancer, is present abundantly in grape skin, a waste produced during the processing of grape juice. The objectives of this study were to prepare resveratrol-gold nanoparticles and a resveratrol nanoemulsion from grape skin and study their inhibition effects on pancreatic cancer cells BxPC-3. The spherical-shaped citrate gold nanoparticles (GNPs) and resveratrol-gold nanoparticles (R-GNPs) were, respectively, prepared with a surface plasmon resonance peak at 528 and 538 nm, mean particle size of 20.8 and 11.9 nm, and zeta-potential at −32.7 and −66.7 mV, by controlling an appropriate concentration of citrate/resveratrol and gold chloride as well as stirring time and temperature. The resveratrol nanoemulsion, composed of soybean oil, Tween 80, and sucrose fatty acid ester in glycerol and water, possessed a high storage stability with a mean particle size of 14.1 nm, zeta-potential of −49.7 mV, and encapsulation efficiency of 95.5%. An antiproliferation study revealed that both R-GNPs and resveratrol nanoemulsion could effectively inhibit the growth of pancreatic cancer cells BxPC-3, with the latter showing a higher inhibition effect. Western blot analysis implied that both can down-regulate expressions of cyclin A, cyclin B, CDK1, and CDK2 and up-regulate expressions of p53 and p21, accompanied by enhancing cytochrome C expression, decreasing BcL-2 expression, increasing Bax expression, and leading to the elevation of caspase-8, caspase-9, and caspase-3 activities for cell apoptosis execution. Future research is needed to study the inhibition of pancreatic tumors in vivo by R-GNPs and resveratrol nanoemulsions.

Effect of emulsifiers on the discoloration of chlorophyll and their potential for use in green beverages.

The discoloration of chlorophyll (Chl) by light is an ongoing issue for green beverages in the food industry. To suppress the discoloration of Chl in aqueous solution, the effects of different emulsifiers were investigated on the discoloration of Chl under ultraviolet (UV) irradiation to determine their potential application for use as food additives. Sucrose fatty acid ester (SE), sorbitan fatty acid ester (TW), and quillaja saponin (QS) were used as emulsifiers, while Triton X-100 (TX) was used for reference. The discoloration of Chl was measured using a color difference meter. The species of Chl in solution were determined using ultraviolet-visible (UV-Vis), fluorescence, and circular dichroism (CD) spectroscopy, and the particle size of Chl in solution was determined using dynamic light scattering. The Chl aggregates were observed by the observation of increased peak areas at longer wavelengths in the UV spectra of Chl, in addition to a reduced fluorescence intensity. The CD spectra showed that the Chl aggregates were arranged in a random structure. Furthermore, the average particle size of the Chl aggregates was determined to be approximately 100nm. SE and QS were found to significantly enhance the formation of self-aggregates due to their high hydrophilicities compared to those of TW and TX. As a result, SE and QS protect themselves from light to suppress the discoloration of Chl. The present results therefore suggest that SE and QS are suitable emulsifiers to address the problem of Chl discoloration in beverages, such as green tea and vegetable juices. PRACTICAL APPLICATION: Chlorophyll (Chl), a green pigment present in vegetables and green tea, is discolored by light. In this study, it was found that emulsifiers (sucrose fatty acid ester and quillaja saponin) suppress the discoloration of Chl. The implementation of these emulsifiers as food additives would enable green tea or green vegetable juices to maintain their colors for long periods and could contribute significantly to the beverage industry.

Autolysis-mediated membrane vesicle formation in Bacillus subtilis.

It is known that Bacillus subtilis releases membrane vesicles (MVs) during the SOS response, which is associated with cell lysis triggered by the PBSX prophage-encoded cell-lytic enzymes XhlAB and XlyA. In this study, we demonstrate that MVs are released under various stress conditions: sucrose fatty acid ester (SFE; surfactant) treatment, cold shock, starvation, and oxygen deficiency. B. subtilis possesses four major host-encoded cell wall-lytic enzymes (autolysins; LytC, LytD, LytE, and LytF). Deletions of the autolysin genes abolished autolysis and the consequent MV production under these stress conditions. In contrast, deletions of xhlAB and xlyA had no effect on autolysis-triggered MV biogenesis, indicating that autolysis is a novel and prophage-independent pathway for MV production in B. subtilis. Moreover, we found that the cell lysis induced by the surfactant treatment was effectively neutralized by the addition of exogenous purified MVs. This result suggests that the MVs can serve as a decoy for the cellular membrane to protect the living cells in the culture from membrane damage by the surfactant. Our results indicate a positive effect of B. subtilis MVs on cell viability and provide new insight into the biological importance of the autolysis phenomenon in B. subtilis.

Kinetic stability of the oil-in-water emulsions and dynamic interfacial properties of mixtures of sucrose esters and polysaccharides

This article presents a study of the interfacial properties of oil-in-water emulsions containing sugar esters and polysaccharides. Sucrose fatty acid esters were synthesized using immobilized Candida antarctica lipase B. A yield of 53.4% was obtained using 2-methyl-2-butanol and 1:3 M ratio of sucrose:stearic acid. Equilibrium surface tension was 45 mN/m and low critical micellar concentration (CMC) value was obtained (ca. 10 mg/mL), characteristic of non-ionic surfactant. The interfacial properties of mixtures of sucrose esters and polysaccharides, at the oil–water interface were determined using a pendant drop tensiometer. Addition of polysaccharides increased the interfacial tension. Studies of interfacial viscoelasticity showed that the films were predominantly elastic. The presence of polysaccharides in emulsions resulted in flocculated droplets. All the emulsions presented great stability along 28 days with no creaming formation.