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Effect of spent brewer's yeast β-D-glucan incorporation (0.25–2.00%, w/w wheat flour) on the characteristics of wheat flour dough and bread during chilled storage at 4 °C for 8 days was investigated. The dough containing 0.75% yeast β-D-glucan had the highest strength, work of adhesion, and stickiness. The addition of yeast β-D-glucan up to 0.75% yielded the breads with an appearance comparable to the control bread (without yeast β-D-glucan). The staling of bread was retarded by the addition of yeast β-D-glucan up to 0.75% as evidenced by the higher retained moisture content and cohesiveness and the lower L* value and hardness of the bread crumb during chilled storage compared to the control and the 1.00–2.00% yeast β-D-glucan breads. The 0.75% yeast β-D-glucan bread exhibited the lowest melting enthalpy of retrograded starch (ΔHret), the lowest B-type- and total crystallinities, the least microstructure change of the crumb matrix, and the highest consumer acceptance after 4 days chilled storage. These results suggested that the incorporation of an appropriate amount of yeast β-D-glucan could improve the quality and shelf life of bread or other starch-based food products during chilled storage.

Riceberry brown rice is regarded as a source of various nutrients; often richer than white rice. Non-thermal plasma has recently been gaining a role for improving properties of cereal grains, especially brown rice. A number of methods of plasma treatment has been proposed including discharges as capacitive coupled plasma (CCP) and inductive coupled plasma (ICP). ICP has two operation modes as capacitive (E-mode) and inductive (H-mode) discharge with rather distinct characters. In this study we have focused on using ICP Ar/O2 plasma in both E-and H mode for plasma treatment on riceberry brown rice. The input power for plasma generation were set to 50 and 250 W for E-and H-mode, respectively. Plasma in H-mode was having higher plasma density than that in E-mode, as observed in the optical emission spectrum. The surface morphology of riceberry brown rice before and after Ar/O2 plasma treatment was evaluated using a scanning electron microscope without or with an energy dispersive spectroscopy (SEM and SEM/EDS). It has been found that the bran layer was richer in elemental compositions than the endosperm. The surface of rice sample was found to be etched and more porous after plasma treatment. The Ar/O2 plasma in H-mode was observed to offer higher effect. The surface contact angle was found to decrease from 120.1o ± 0.9o in untreated samples to 79.3o ± 0.6o and 99.2o ± 0.8o in plasma treated samples on E-and H-mode, respectively.

Astaxanthin (AX) is one of the major bioactives that has been found to have strong antioxidant properties. However, AX tends to degrade due to its highly unsaturated structure. To overcome this problem, a Pickering O/W emulsion using nanofibrillated cellulose (NFC) as an emulsifier was investigated. NFC was used because it is renewable, biodegradable, and nontoxic. The 10 wt% O/W emulsions with 0.05 wt% AX were prepared with different concentrations of NFC (0.3–0.7 wt%). After 30 days of storage, droplet size, ζ-potential values, viscosity, encapsulation efficiency (EE), and color were determined. The results show that more stable emulsions are formed with increasing NFC concentrations, which can be attributed to the formulation of the NFC network in the aqueous phase. Notably, the stability of the 0.7 wt% NFC-stabilized emulsion was high, indicating that NFC can improve the emulsion’s stability. Moreover, it was found that fat digestibility and AX bioaccessibility decreased with increasing NFC concentrations, which was due to the limitation of lipase accessibility. In contrast, the stability of AX increased with increasing NFC concentrations, which was due to the formation of an NFC layer that acted as a barrier and prevented the degradation of AX during in vitro digestion. Therefore, high concentrations of NFC are useful for functional foods delivering satiety instead of oil-soluble bioactives.

In this study, the effect of hydrocolloids with different electrostatic characteristics, namely negatively charged xanthan gum (XG), positively charged chitosan (CH), and non-ionic guar gum (GG), on the physicochemical properties, stability, and lipid digestibility of 10% (w/w) soybean oil-in-water Pickering emulsions stabilized by nanofibrillated cellulose (NFC) was investigated. Addition of XG and CH to the NFC-stabilized emulsions significantly increased the oil droplet sizes and apparent viscosity at high shear rates as compared with the addition of GG. The XG added emulsion showed the lowest rate and extent of creaming, whereas the CH added emulsion gave the highest extent of creaming. The addition of XG and CH led to a more pronounced effect on

Native cassava starch (NCS) was chemically modified by cross-linking (CL), octenylsuccinylation (OS), CL followed by OS, and OS followed by CL. The modified cassava starches (MCS) were determined for physicochemical, in-vitro digestibility, and emulsifying properties. For the dual modifications, the functional groups introduced in the first modification were partially replaced by the ones that introduced in the second modification. The X-ray diffraction pattern and relative crystallinity of cassava starch did not change by both modifications, indicating that both reactions occurred predominantly in amorphous regions as well as on the surface of starch granules and did not alter the crystalline pattern in the granules. The physicochemical and emulsifying properties of the dual MCS were predominantly affected by the functional groups introduced in the second modification. For the in-vitro digestibility, the dual MCS exhibited the highest resistant starch content of 19.48-22.00% in comparison with the NCS (6.05%) and the single MCS (10.76-14.49%), possibly due to a synergistic effect of the functional groups introduced in the first and second modifications.

Vitamin D3 was encapsulated in 10% wt soybean oil-in-water (O/W) Pickering emulsions stabilized by either nanofibrillated cellulose (NFC) or whey protein isolate (WPI) at 0.3%, 0.5%, and 0.7% w/w. The vitamin D3 -enriched emulsions were tested for their stability against temperature (30 °C to 90 °C), pH (2 to 8), and ionic strength (0 to 500 mM NaCl). The mean particle diameter (d32 ), ζ-potential, and creaming stability of the oil droplets in the emulsions were measured, as well as their vitamin D3 encapsulation efficiency (EE). After preparation, the oil droplet size (d32 ) of the emulsions stabilized by NFC increased with increasing emulsifier concentration, whereas the droplet size of emulsions stabilized by WPI decreased. NFC provided good stability to the emulsions through a combination of steric and electrostatic repulsion. The EE of vitamin D3 increased with increasing emulsifier concentration. Heating or ionic strength did not significantly (P < 0.05) affect the emulsions properties and EE. On the other hand, the NFC-stabilized emulsions were sensitive to highly acidic conditions (pH 2), with an increase in particle size and decrease in EE. The WPI-stabilized emulsions aggregated around the isoelectric point of the adsorbed proteins (pI ≈ 4.8). Increasing NFC or WPI concentration improved the stability and EE of the emulsions against environmental stresses. NFC-stabilized emulsions had good long-term stability. The results show that NFC can be used as an effective emulsifier for creating vitamin-enriched emulsions with good stability. PRACTICAL APPLICATION: This study can be used to develop more effective encapsulation technologies for fat-soluble vitamins in emulsion-based food products. Encapsulation using nanofibrillated cellulose effectively protected the encapsulated vitamins against environmental stresses which occur in industrial food production (such as pH changes, salt addition, and thermal processing). Moreover, nanofibrillated cellulose extracted from mangosteen rind is a nature-derived emulsifier that is environmental friendly.

Flour and starch from four Thai pigmented rice cultivars, i.e., Riceberry (RB), Hom Nil (HN), Niaw Dang (ND), and Kum Pleuak Khao (KP) were compared for their physicochemical and rheological properties. Amylose content of all rice starches decreased in the following order: RB (12.09%) > HN (8.14%) > KP (2.87%) ~ ND (2.77%). The HN starch had the lowest proportion of amylopectin short A chains, while the KP starch showed the highest. Pasting temperature, setback, and final viscosity increased, while breakdown and swelling power decreased with increasing amylose content for both flour and starch samples. The flours and starches from the RB and HN showed greater onset and peak temperatures and enthalpy change (ΔH) of gelatinization than those from the ND and KP. Moreover, the gelatinization temperatures of all starches were significantly lower, but ΔH was higher than their flour counterparts. Dynamic viscoelastic tests revealed weak-gel like behavior of all flour and starch gels as evidenced by their G′ > G″ and tan δ values were smaller than unity.

In this study, rice starch was modified by different modifications that included debranching (DB), esterification with octenyl succinic anhydride (OSA), debranching followed by OSA modification (DBOS) and OSA modification followed by debranching (OSDB). Following modification, the resistant starch content and emulsifying properties of the modified starches markedly increased in comparison with the native starch with the DBOS starch having the highest resistant starch content and the best emulsifying properties. This can be attributed to its higher degree of OSA substitution resulting in an enhanced amphiphilic character and better emulsion stability. Microstructure, physical stability and rheological properties of oil-in-water emulsions using these modified rice starches were also investigated and it was observed that emulsions stabilized by OSA and DBOS starches exhibited smaller oil droplets, were more stable to creaming and possessed stronger three-dimensional structure when compared with the other modified starch-based emulsions. Since the DBOS starch was found to demonstrate the highest resistant starch content and better emulsifying properties than the other starches, it was then chosen for optimization of its concentration to give the best emulsion characteristics and stability. The emulsions stabilized by the DBOS starch at a concentration of 4% or 5% (w/w) were found to be more stable and very little phase separation was observed after a storage period of 30 days.

This research aimed to investigate the optimum levels of yeast β-glucan and additional water, and chilled storage time for producing chilled bread using response surface methodology. Yeast β-glucan, a natural hydrocolloid extracted from yeast cell wall, possesses not only functional properties but also human health benefits to be used in food products. A Box–Behnken design with three independent variables (yeast β-glucan, additional water, and chilled storage time) and three levels was used to develop models for the different characteristic responses. Superimposition of contour plots of the significant responses (spread ratio, crumb color L* and b* values, crumb hardness and cohesiveness, and moisture content) was performed to obtain the optimum chilled bread formula. Using the qualities of one-day-on-shelf commercial bread as a reference, the optimum chilled bread contained 0.28% yeast β-glucan and 11.69% additional water (wheat flour basis) with 4 days chilled storage. The optimum chilled bread had superior qualities to the basic formula bread at 4 days of chilled storage. The bread staling during chilling can be retarded by incorporating yeast β-glucan and additional water in the bread formula.

Hydroxypropyl methylcellulose (HPMC) was used as a co-emulsifier with chitosan and the whole cells of bacteriocin-producing Lactococcus lactis IO-1 (L. lactis IO-1) for the preparation of bacteria interface Pickering emulsion. The obtained emulsion exhibited a high stability against centrifugation force, ionic strength and low temperature, with the whole cells of L. lactis IO-1 located at the oil/water interface. Because L.lactis IO-1 was found to produce peptide lantibiotic against several strains of Gram-positive food pathogen, the highly stable emulsion demonstrated in this study exhibited high potential as an antimicrobial emulsion with several health benefits of chitosan and HPLC useful for food industry.

The influence of pH (3–7) and ionic strength (0–250 mM NaCl) on the physical and rheological properties and stability of soybean oil-in-water emulsions containing whey protein isolate (WPI) as an emulsifier and anionic polysaccharide (xanthan gum, XG) as a stabilizer was studied. The influence of ionic strength was found to be dependent on whether the pH was below or above the isoelectric point (pI ≈ 4.6) of the emulsion droplets. At pH below the pI, the ζ-potential of the emulsions increased from negative to positive values with increasing ionic strength. The emulsions exhibited more extensive droplet flocculation, more viscous, and more structured, but less creaming stability at low ionic strength than at high ionic strength. At pH above the pI, the ζ-potential of the emulsions was always negative and its magnitude decreased with increasing ionic strength. The emulsions exhibited a slight increase in droplet flocculation, decrease in viscosity, viscoelasticity, and creaming stability with increasing ionic strength. This study could potentially serve for applications in the food industry to design the emulsion-based food products with improved physical and rheological properties and stability over a wide range of pH and ionic strength conditions.

Benzene, toluene, ethylbenzene and (p-, m- and o-) xylene (BTEX) are classified as main pollutants by several environmental protection agencies. In this study, a non-pathogenic, Gram-positive rod-shape bacterium with an ability to degrade all six BTEX compounds, employed as an individual substrate or as a mixture, was isolated. The bacterial isolate was identified as Bacillus amyloliquefaciens subsp. plantarum strain W1. An overall BTEX biodegradation (as individual substrates) by strain W1 could be ranked as: toluene > benzene, ethylbenzene, p-xylene > m-xylene > o-xylene. When presented in a BTEX mixture, m-xylene and o-xylene biodegradation was slightly improved suggesting an induction effect by other BTEX components. BTEX biodegradation pathways of strain W1 were proposed based on analyses of its metabolic intermediates identified by LC–MS/MS. Detected activity of several putative monooxygenases and dioxygenases suggested the versatility of strain W1. Thus far, this is the first report of biodegradation pathways for all of the six BTEX compounds by a unique bacterium of the genus Bacillus. Moreover, B. amyloliquefaciens subsp. plantarum W1 could be a good candidate for an in situ bioremediation considering its Generally Recognized as Safe (GRAS) status and a possibility to serve as a plant growth-promoting rhizobacterium (PGPR).

Oil-in-water Pickering emulsions stabilized by nanofibrillated cellulose (NFC) were used to encapsulate and deliver vitamin D3. NFC was extracted from a waste product of the food industry, mangosteen (Garcinia mangostana L.) rind, using dissolution in a hot sodium hydroxide solution, bleaching using hydrogen peroxide, and shearing using a high-pressure homogenizer. This yielded cellulose fibers with a diameter of around 60 nm and a length of several micrometers. Emulsions containing 10% w/w oil (0.01% w/w vitamin D3 and 9.99% w/w soybean oil), 0.10–0.70% w/w NFC as emulsifier, and phosphate buffer (pH 7) were prepared. The effect of NFC on lipid digestion and vitamin bioaccessibility was investigated using a simulated gastrointestinal tract (GIT) model, which included mouth, stomach and small intestine phases. The rate and extent of lipid digestion, as well as the vitamin bioaccessibility, decreased with increasing NFC concentration. Numerous physicochemical phenomena may account for this effect, including the ability of NFC to: act as a physical barrier at the lipid droplet surfaces; to promote droplet flocculation in the gastric phase; and, to increase the viscosity of the aqueous phase. The slight decrease in vitamin D3 bioaccessibility at higher NFC levels, was probably due to the lower level of lipid digestion. Our results indicate that mangosteen fiber can be used to stabilize oil-in-water emulsions, and only has a minor effect on lipid digestion and vitamin bioaccessibility when used at relatively low levels. This information may be useful for the rational design of functional foods from natural waste-products, such as mangosteen rind.

In the present study, a fixed-film bioscrubber (FFBS) of BTEX-degrading bacterium Microbacterium esteraromaticum SBS1–7 with ‘AQUAPOROUSGEL® or APG’ supporting material was continuously fed with toluene- or styrene-contaminated gas stream for 172 days. Response Surface Methodology (RSM) was used to optimize the biofilm formation on APG as well as the toluene biodegradation in mineral salt medium (MM). The results suggested that 1000 ppm of yeast extract (YE) was necessary for biofilm formation of SBS1–7. The optimized combination of YE and toluene concentration exhibiting the highest biofilm formation and toluene removal was further employed in an up-scale FFBS operation. The maximum Elimination Capacity (ECmax) of 203 g·m−3·h−1 was obtained at the toluene Inlet Loading Rate (ILR) of 295 g·m−3·h−1. FFBS of SBS1–7 was able to withstand a 5-day shutdown and required only 24 h to recover. Moreover, when the inlet Volatile Organic Compound was shifted to styrene, FFBS required only 24 h for adaptation and the system was able to efficiently remove ~95% of styrene after that. Finally, the performance of the bioscrubber when operated in 2 different modes of operation (FFBS vs Biotricking Filter or BTF) were compared. This study evidently demonstrated the robustness and stability of FFBS with M. esteraromaticum SBS1–7.

In this study, a non-pathogenic, BTEX-degrading Microbacterium esteraromaticum SBS1-7 was isolated from estuarine sediment in Thailand via an enrichment technique. M. esteraromaticum SBS1-7 was able to degrade all six BTEX components, in both liquid medium and soil slurry system, when BTEX was supplied as an individual component or a mixture. It exhibited a high level of tolerance towards a wide range of hydrocarbons and also utilized alkanes and naphthalene. Detection of metabolites produced during BTEX and naphthalene degradation revealed highly extensive biodegradation pathways used by M. esteraromaticum SBS1-7. Toluene was metabolized via activities of both monooxygenase (toluene 4-monooxygenase or T4MO) and dioxygenases (toluene dioxygenase or TDO and naphthalene 1,2-dioxygenase or NDO). Benzene was metabolized via phenol, possibly by an activity of T4MO. Ethylbenzene was converted into styrene and 1-phenethyl alcohol by a well-documented activity of NDO. Dioxidation of ethylbenzene, possibly by ethylbenzene dioxygenase or EBDO, was also found. All xylene isomers were converted into their corresponding alcohols via an activity of NDO while naphthalene was metabolized via dioxidation reaction by the same enzyme. This study is, by far, the first direct evidence of BTEX biodegradation by a non-pathogenic, rhizosphere bacterium M. esteraromaticum.

Native rice starch was modified using different methods which included debranching (DB), octenyl succinylation (OSA), debranching followed by octenyl succinylation (DBOS) and octenyl succinylation followed by debranching (OSDB). The effect of different modifications and the impact of modified starch properties (resistant starch content (RS) and degree of substitution (DS)) on the gastrointestinal fate of emulsified lipids are elucidated using an in vitro digestion model that included the mouth, stomach, and small intestine phases in order to understand their functionality for further applications. The effect of the different modified rice starches on the particle size distribution of the lipid droplets, surface charge (ζ-potential), microstructure, lipid digestion (free fatty acid (FFA) release), and starch hydrolysis was also assessed. The OSA-modified starch and DBOS starch-based emulsions were found stable during the mouth phase and were also found to demonstrate lesser flocculation and coalescence in comparison with the other emulsions due to the presence of more OSA groups that provide greater steric hindrance and better protection from the gastrointestinal conditions. Furthermore, the DBOS starch was found to form emulsions that were more resistant to digestion with a degree of FFA release like dietary fibers and a lower extent of starch digestion that can be attributed to their higher resistant starch content (RS). Thus, the DBOS starch-based emulsions were found to be suitable for further applications such as developing functional foods to control satiety or for designing delivery systems for the sustained release of bioactive compounds.

Vitamin D

To develop a novel modification process of tapioca starch using low-pressure argon plasma treatment in a large-scale production, a semi-continuous downer reactor was designed to provide a production rate of 0.1–0.5 kg per cycle. Physicochemical and rheological properties of plasma-treated starch were investigated in order to predict the phenomena occurred during the plasma treatment. Native tapioca starch (NTS) was plasma-treated for 1, 3, or 6 cycles, which were referred to as PTS-1, PTS-3, or PTS-6 samples, respectively. Plasma treatment of the NTS resulted in a significant decrease (P

The application of lycopene, a potent antioxidant, is limited because of its hydrophobic nature and low chemical stability. To overcome this, different delivery systems, i.e. oil-in-water emulsions and alginate beads, have been synthesized in this study using modified rice starch for improving the stability of lycopene. Lycopene solution (in oil) was used as a control. Modified rice starch was used as it is cheap, GRAS, has better adsorption at the oil-water interface and provides higher resistance to the encapsulated lycopene against the harsh environment of the gastrointestinal tract. During storage at different temperatures (4–70 °C) for 15 days, the lycopene degradation rate was found to increase with increasing storage temperature for all delivery systems and with the type of delivery systems in the following order: solution > emulsion > alginate beads. Further, the delivery systems were passed through a simulated gastrointestinal tract (GIT) model to study the extent of lipid digestion and lycopene bioaccessibility. A positive correlation was observed between the rate and extent of lipid digestion and lycopene bioaccessibility. A significantly higher bioaccessibility of lycopene was observed for the emulsions (20.2%) over the beads (15.6%), whereas the chemical stability of lycopene was found to be significantly higher in the alginate beads (35.6%) than in the emulsions (29.5%). Overall, the results obtained suggest that the modified rice starch can be used as an innovative food-grade material for the design of different delivery systems to improve the chemical stability of lycopene and its controlled release in the gastrointestinal tract.

The influence of starch type (resistant starch (RS) versus native (NS) starch) and concentration (10 and 35wt.%) on the potential gastrointestinal fate of digestible lipid (corn oil) droplets encapsulated within starch hydrogels was studied using a simulated gastrointestinal tract (GIT). The NS used was a normal corn starch, whereas the RS used was a high amylose corn starch. Changes in morphology, organization, size, and charge of the particles in the delivery systems were measured as they passed through each stage of the GIT model: mouth, stomach, and small intestine. The GIT fates of three types of delivery system were compared: free lipid droplets; lipid droplets in RS-hydrogels; and, lipid droplets in NS-hydrogels. Encapsulation of the lipid droplets in the hydrogels had a pronounced influence on their GIT behavior, with the effect depending strongly on starch type. The starch granules in the RS-hydrogels remained intact throughout the simulated GIT because their compact structure makes them resistant to enzyme digestion. The initial rate of lipid digestion in the small intestine phase also depended on delivery system type: emulsion>RS-hydrogels>NS-hydrogels. However, the lipid phase appeared to be fully digested at the end of the digestion period for all samples. These results provide useful information for designing functional foods for improved health. For example, food matrices could be developed that slowdown the rate of lipid digestion, and therefore prevent a spike in serum triacylglycerols in the blood, which may be advantageous for developing functional foods to tackle diabetes.

The aim of this research was to investigate the extraction yield and physicochemical properties of sago starch extracted after enzymatic pretreatment. Sago pith was enzymatic-pretreated by varying enzyme (cellulase enzyme complex) concentration, pretreatment time, and sago pith slurry concentration. The extracted sago starch was analyzed for its properties, e.g., extraction yield, pasting and thermal properties, and in vitro starch digestibility. Sago pith contained 82% (db) starch. The extraction yield and reducing sugar released increased with enzyme concentration and pretreatment time. The optimum enzymatic pretreatment conditions were 10% (w/w) sago pith slurry, enzyme concentration of 0.25 mL (618 carboxymethylcellulose unit and 139 p-nitrophenyl-β-d-glucopyranoside unit)/g substrate, and 24 h pretreatment time, providing the highest extraction yield of 71.36% (w/w sago pith, db), while control method, without enzymatic pretreatment, provided 61.01% extraction yield. Results from pasting and thermal properties confirmed that the granular stability, resistance to shear, and crystalline perfection of sago starch were improved due to hydrothermal effect of annealing during enzymatic pretreatment. The enzymatic-pretreated sago starch also had lower retrogradation but higher starch digestibility than the control sago starch. The enzymatic pretreatment enhanced the extraction yield of sago starch and also improved its quality by the effect of annealing.

The influence of concentration of microfibrillated cellulose (MFC) extracted from mangosteen ( Garcinia mangostana L.) rind on the properties and stability of 10% w/w soybean oil-in-water (o/w) Pickering emulsions (pH ≈ 7.0) was examined. The MFC concentration in the aqueous phase was varied from 0.05 to 0.70% w/w. The mean droplet size and the color intensity of the emulsions increased with increasing MFC concentration. Microscopic observations revealed that the MFC particles mainly adsorbed at the oil-water interface of the emulsion droplets, whereas the amount of excess non-adsorbing MFC particles present in the continuous aqueous phase increased with increasing MFC concentration. The rheological data provided evidence for network formation in the emulsions with increasing MFC concentration. Such a gel-like behavior was attributed to an inter-droplet network structure and the formation of an MFC network in the continuous phase. All the emulsions were stable to coalescence for a period of 80 days whatever the MFC concentration but the stability to creaming decreased progressively with decreasing MFC concentration. These results have important implication for the rational design and production of particle-stabilized food emulsions.

The use of bacterial cell or biocatalyst for industrial synthetic chemistry is on the way of significant growth since the biocatalyst requires low energy input compared to the chemical synthesis and can be considered as a green technology. However, majority of natural bacterial cell surface is hydrophilic which allows poor access to the hydrophobic substrate or product. In this study, Escherichia coli (E. coli) as a representative of hydrophilic bacterial cells were accumulated at the oil–water interface after association with chitosan at a concentration range of 0.75–750 mg/L. After association with negatively charged E coli having a ζ potential of −19.9 mV, a neutralization of positively charged chitosan occurred as evidenced by an increase in the ζ potential value of the mixtures with increasing chitosan concentration up to +3.5 mV at 750 mg/L chitosan. Both emulsification index and droplet size analysis revealed that chitosan-E. coli system is an excellent emulsion stabilizer to date because the threshold concentration was as low as 7.5 mg/L or 0.00075 % w/v. A dramatic increase in the surface hydrophobicity of the E. coli as evidenced by an increase in contact angle from 19 to 88° with increasing chitosan concentration from 0 to 750 mg/L, respectively, resulted in an increase in the stability of oil-in-water emulsions stabilized by chitosan-E. coli system. The emulsion was highly stable even the emulsification was performed under 20 % salt condition, or temperature ranged between 20 and 50 °C. Emulsification was failed when the oil volume fraction was higher than 0.5, indicating that no phase inversion occurred. The basic investigation presented in this study is a crucial platform for its application in biocatalyst industry and bioremediation of oil spill.

Response surface methodology (RSM) was used to analyze effects of hydroxypropylmethylcellulose (HPMC), yeast β-glucan, and whey protein isolate (WPI) on physical properties of gluten-free bread baked from formulas based on rice starch. A Box–Behnken design with three independent variables (HPMC, yeast β-glucan, and WPI) and three levels was used to develop models for the different responses (physical properties). Individual contour plots of the different responses produced from the models were compared to the corresponding reference wheat bread data and were superimposed to locate gluten-free bread formulations that met the wheat bread standards for spread ratio, specific volume, hardness, cohesiveness, chewiness, and crumb color L∗ value. The optimal formulation, determined from the data, contained 4.35 g/100 g HPMC, 1 g/100 g β-glucan, and 0.37 g/100 g WPI, rice starch basis. Predicted values of the optimized bread were experimentally tested and compared with the experimental wheat bread data. A good agreement among these data was observed. Moreover, the optimized rice starch bread was found to be acceptable according to the results of sensory analysis.

The impact of biological surfactants (bile salts) on the protein (β-lactoglobulin) corona surrounding gold nanoparticles (200 nm) was studied using a variety of analytical techniques at pH 7: dynamic light scattering (DLS); particle electrophoresis (ζ-potential); UV–visible (UV) spectroscopy; transmission electron microscopy (TEM); and surface-enhanced Raman scattering (SERS). The bile salts adsorbed to the protein-coated nanoparticle surfaces and altered their interfacial composition, charge, and structure. SERS spectra of protein-coated nanoparticles after bile salt addition contained bands from both protein and bile salts, indicating that the protein was not fully displaced by the bile salts. UV, DLS and TEM techniques also indicated that the protein coating was not fully displaced from the nanoparticle surfaces. The impact of bile salts could be described by an orogenic mechanism: mixed interfaces were formed that consisted of islands of aggregated proteins surrounded by a sea of bile salts. This knowledge is useful for understanding the interactions of bile salts with protein-coated colloidal particles, which may be important for controlling the fate of colloidal delivery systems in the human gastrointestinal tract, or the gastrointestinal fate of ingested inorganic nanoparticles.

Aqueous microfibrillated cellulose (MFC) suspensions were prepared by extraction of ground mangosteen ( Garcinia mangostana L.) rind with hot aqueous sodium hydroxide, bleaching with hydrogen peroxide, and subsequent shearing in a high pressure homogenizer. The cellulose content of the material markedly increased after the alkali and bleaching pre-treatments. The influences of number of passes through the homogenizer on characteristics of the resulting MFC were investigated. Results show that crystallinity index, degree of polymerization, viscoelaticity, and viscosity of the MFC suspensions decreased as the number of homogenization passes increased, indicating that fiber degradation occurred during homogenization. The emulsion stabilizing properties of MFC, on the other hand, were improved when the number of homogenization passes was increased. The oil-in-water emulsions stabilized by MFC (30% w/w soybean oil, 0.7% w/w MFC in aqueous phase, emulsion pH range = 6.8–7.2) obtained at the higher number of homogenization passes exhibited smaller oil droplets, stronger three-dimensional network structures, and more stable to creaming than those stabilized by MFC obtained at the lower number of homogenization passes. The creaming stability of the MFC-stabilized emulsions was reduced at low pH or high salt concentration due to electrostatic screening of the negatively charged MFC particles. Thermal treatment had little influence on the creaming stability of these emulsions. These results should improve understanding of the relationships between processing and characteristics of MFC from a novel lignocellulosic material, i.e. mangosteen rind, and lead to a potential application as an emulsion stabilizer.

Effects of salts on pasting, thermal, and rheological properties of rice starch (RS) in the presence of non-ionic (guar gum; GG) or ionic (xanthan; XT) hydrocolloid were studied. Rapid visco-analysis (RVA) showed that addition of salts significantly increased peak, breakdown, and final viscosities, and pasting temperatures of RS/XT blends, whereas those of RS/GG blends were varied depending on the type of salts added. Differential scanning calorimetry (DSC) demonstrated that salt addition significantly increased gelatinization temperatures of either RS/GG or RS/XT blend, whereas gelatinization enthalpy was less affected. Dynamic viscoelastic tests revealed that addition of salts had a more pronounced effect on enhancing structure formation of RS/XT gels than that of RS/GG gels. The steady shear viscosity was generally in line with the values of final viscosity obtained during pasting. These results would be used as a guideline for developing starch-based food products containing salts.

A two-step autolysis process was proposed to enhance amino acid production from spent brewer's yeast. The technique was developed based on comparative study of the dynamics of production and release of proteins and amino acids during the autolysis of a concentrated suspension (22 wt.%) and a dilute yeast cell suspension (11.25 wt.%). The results suggest that, in the concentrated yeast suspension, proteins are more effectively broken down into amino acids, but the product release rate was lower due to a lower concentration gradient across the cell membrane. Thus, a two-step process, in which a high protein conversion occurred in a concentrated cell suspension during the first 13 h period, followed by a 26 h autolysis process within a dilute cell suspension, provided a higher overall yield of amino acids compared than the single-step process. The two-step process was found to result in a 25% higher amino acid yield with a weight fraction increase from 0.4 to 0.5 g/g dry wt. Other than these findings, the ef...

The objective of this study was to obtain additional information on the influence of different @b-glucan preparations, i.e. curdlan (CL), barley (BG), oat (OG), and yeast (YG) @b-glucans, on the physical and rheological properties of egg yolk stabilized oil-in-water emulsions containing 20% oil. The emulsion without @b-glucan (REF) was also prepared as a reference. Addition of CL and OG increased emulsion oil droplet sizes, whereas BG and YG showed no effect. Emulsion microstructures revealed that @b-glucans induced flocculation of the oil droplet in the following order: CL>BG~OG>YG. Dynamic oscillatory shear tests indicated that all emulsions exhibited weak gel-like characteristics which were enhanced by @b-glucans addition as evidenced by an increase in G' and a decrease in tan@d values. Flow tests showed that @b-glucans enhanced thixotropy and yield stress of the emulsions. Stability tests demonstrated that @b-glucans addition improved creaming stability of the emulsions during storage possibly due to an increase in viscosity of the continuous phase and/or a formation of a three-dimensional droplet network. CL exhibited the most pronounced effects on the aforementioned properties of emulsions compared to the other @b-glucans tested. YG gave emulsion with higher viscoelastic properties and yield stress but lower stability than those made with BG or OG, indicating complex relationship between rheology and stability of these emulsion systems.

Four β-glucan preparations, i.e., curdlan (CL), oat (OG), barley (BG) and yeast (YG) β-glucans, were compared for their effects on the gelatinisation and retrogradation of rice starch (RS). Rapid visco-analysis (RVA) showed that addition of any of these β-glucans significantly increased the peak, breakdown, final, and setback viscosities of RS, whereas the pasting temperatures were significantly decreased by OG or CL addition, but were unaffected by BG or YG addition. Differential scanning calorimetry (DSC) demonstrated that all the β-glucans had a negligible effect on the onset ( T o ), peak ( T p ), and conclusion ( T c ) temperatures but slightly decreased the gelatinisation enthalpy (△ H 1 ) of RS. Storage of all the gels at 4 °C resulted in a marked decrease in the T o , T p , T c , and melting enthalpy (△ H 2 ) values. The retrogradation ratio (△ H 2 /△ H 1 ) and the phase transition temperature range ( T c – T o ) of all the gels increased with storage time. Dynamic viscoelastic measurements revealed weak gel-like behaviour of all the gels, in which their storage modulus ( G ′) increased and their loss tangent (tan δ ) decreased during storage. Steady flow tests illustrated time-dependent shear-thinning (thixotropic) behaviour of all the gels. The hysteresis loop area and the gel hardness increased with storage time. However, the rate and extent of retrogradation and the rheological and textural changes of the RS gels were reduced by addition of any of these β-glucans. The extent of the aforementioned effects differed among the different β-glucan preparations, generally in the order OG ≈ BG > CL ≈ YG.

Effects of molecular weight ( M w ) of xanthan (XG) and salts (0.1 M NaCl or CaCl 2 ) on the pasting, thermal, and rheological properties of rice starch (RS) were studied. A series of five XG samples, having various M w , was prepared by homogenization of native XG solutions in the presence or absence of salts. The presence of salts greatly reduced the intrinsic viscosities, [ η ], of all XG solutions. Rapid visco-analysis (RVA) data showed that XG addition increased the peak, breakdown, final, and setback viscosities of RS, either in the presence or absence of salts, whereas the pasting temperatures were unaffected. Differential scanning calorimetry (DSC) demonstrated that the gelatinization temperatures of RS were unaffected by XG addition but slightly increased by CaCl 2 addition, whereas the gelatinization enthalpies (Δ H ) were significantly decreased by additions of XG and salts. Dynamic shear data revealed weak gel-like behaviour in all paste samples in which their rigidity was decreased by XG addition. Flow tests showed that all pastes exhibited time-dependent shear-thinning (thixotropic) with yield stress behaviour in which the hysteresis loop areas were significantly decreased by XG addition, whereas the other rheological parameters varied differently among the samples, with and without added salt. In general, the effects of XG addition on the pasting and rheological properties of RS were more pronounced with increasing M w of XG and these effects depended on salts added.

Effects of different cellulose derivatives and carrageenans on the pasting, rheological, and textural properties of normal (NRS) and waxy (WRS) rice starches were investigated. When suspensions of both NRS and WRS were heated in a Rapid Visco Analyser (RVA) in the presence of the hydrocolloids, increases in apparent pasting temperatures and peak and final viscosities in the following decreasing order were observed: methylcellulose (MC) > carboxymethylcellulose (CMC) for cellulose derivatives and λ- > i- > κ-carregeenan for carrageenans. Slight decreases in peak and final viscosities were observed when hydroxypropylmethylcellulose (HPMC) was the hydrocolloid. Dynamic viscoelasticity measurements indicated that NRS–hydrocolloid pastes were less solid-like than the control, as evidenced by their higher tan δ values, whereas tan δ values of WRS–hydrocolloid pastes were the same as that of the control. Steady shear rheological measurements showed that addition of the different hydrocolloids used increased the apparent viscosity ( η a,100 ) and consistency coefficient ( K ) values of both starches with the same trend as that observed during pasting, whereas the opposite trend was observed for the flow behavior index ( n ) values. The hardness and adhesiveness of NRS pastes were significantly increased by addition of κ- and i-carrageenans, but were unaffected by the other hydrocolloids. A similar effect was observed for WRS, with the exception of κ-carregeenan, in which the hardness of the mixed paste was decreased. The starch–hydrocolloid pastes exhibited a phase-separated microstructure in which amylose- and amylopectin-rich domains were dispersed in a hydrocolloid-rich continuous phase.

The purpose of this study was to produce and characterize core-shell biopolymer particles based on electrostatic deposition of an anionic polysaccharide (beet pectin) onto amphoteric protein aggregates (heat-denatured beta-lactoglobulin [beta-lg]). Initially, the optimum conditions for forming stable protein particles were established by thermal treatment (80 degrees C for 15 min) of 0.5 wt% beta-lg solutions at different pH values (3 to 7). After heating, stable submicron-sized (d=100 to 300 nm) protein aggregates could be formed in the pH range from 5.6 to 6. Core-shell biopolymer particles were formed by mixing a suspension of protein aggregates (formed by heating at pH 5.8) with a beet pectin solution at pH 7 and then adjusting the pH to values where the beet pectin is adsorbed (< pH 6). The impact of pH (3 to 7) and salt concentration (0 to 250 mM NaCl) on the properties of the core-shell biopolymer particles formed was then established. The biopolymer particles were stable to aggregation from pH 4 to 6, but aggregated at lower pH values because they had a relatively small -potential. The biopolymer particles remained intact and stable to aggregation up to 250 mM NaCl at pH 4, indicating that they had good salt stability. The core-shell biopolymer particles prepared in this study may be useful for encapsulation and delivery of bioactive food components or as substitutes for lipid droplets.

The formation of coatings on hydrogel surfaces due to adsorption of lipid droplets is important in a number of natural and industrial processes, e.g., foods, cosmetics, and pharmaceuticals. The adsorption of cationic protein-coated lipid droplets to the surfaces of anionic hydrogels was examined in this study. An oil-in-water emulsion containing cationic β-lactoglobulin-coated lipid droplets was prepared (d4,3 = 0.3 μm, ζ = +67 mV, pH 3.0). An anionic hydrogel consisting of 1 wt% gellan gum (pH 3.0) was prepared. Emulsions containing different lipid droplet concentrations (0.1–10 wt%) were brought into contact with the hydrogel surfaces for different times (0–24 h). The adsorption of lipid droplets to the hydrogel surfaces could not be explained by a typical adsorption isotherm. We found that the electrical charge on the non-adsorbed lipid droplets became less positive or even became negative in the presence of the hydrogel, and that extensive droplet aggregation occurred, which was attributed to the ability of gellan molecules released from the hydrogels to interact with the lipid droplets. These results may have important consequences for understanding certain industrial and biological processes, as well as for the design of controlled or triggered release systems.

Effects of guar (GG) and xanthan (XG) gums (0.35–1.0% w/w) on pasting and rheological properties of waxy corn starch (WCS) (6.0% w/w) were studied. GG had a higher molecular weight but lower intrinsic viscosity than did XG, indicating that the GG chain was more flexible. RVA results indicated that viscosity and pasting temperature of the WCS dispersion during pasting increased with increasing GG or XG concentration. Dynamic viscoelasticity measurements indicated that the WCS/XG mixed pastes exhibited slightly superior viscoelastic properties to the WCS/GG pastes as evidenced by their higher G′ and lower tan δ values. Flow tests showed that the WCS/GG pastes exhibited mainly thixotropic hysteresis loops during a full shear cycle, whereas the WCS/XG pastes showed much less thixotropic and eventually became antithixotropic at high XG concentrations. In-shear structural recovery of the pastes increased more with increasing XG concentrations than did pastes with increasing GG concentrations. The differences in molecular characteristics of the GG and XG chains are hypothesized to be responsible for the above mentioned effects.

Production of instant soymilk powders was completed in three stages - ultrafiltration, spray drying, and fluidized bed agglomeration. Ultrafiltration increased total solids, protein, and fat contents, but decreased carbohydrate and ash contents of soymilk, leading to an increase in particle size, wettability, and dispersibility of the resultant spray-dried powders. However, all the spray-dried soymilk powders were very small (