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The in vitro hypoglycemic properties of three different sulfuric acid (H 2 SO 4 ) modified rice bran insoluble fibers (SMRBIFs) produced using 0.2% (0.2%-SMRBIF), 1.25% (1.25%-SMRBIF), 2.0% (2.0%-SMRBIF) (w/v) H 2 SO 4 in combination with 1.25% potassium hydroxide (KOH) respectively, were investigated. The results revealed that all the three RBIFs have strong glucose adsorption capacity and α-amylase inhibition activity, with 1.25%-SMRBIF being the most effective one. The glucose adsorption capacity increased with increasing porosity and specific surface area of the SMRBIFs, and the maximum glucose bound amount increased by 2–3 folds for acid-alkaline treated RBIFs compared to untreated material. The α-amylase inhibition activity of RBIF was associated with the formation of amylase-RBIF complex as confirmed by fluorescence spectroscopy, with the highest amylase activity inhibitory (24.72%) for 1.25%-SMRBIF. However, the glucose diffusion was retarded a bit stronger by these RBIFs compared to the untreated rice bran, which might be attributed to their larger specific surface area. Therefore, it was suggested that the concentration of postprandial serum glucose lowered by RBIF was mainly ascribed to binding glucose and retarding α-amylase action.

Physicochemical stability and thermal degradation of vitamin E (VE) in nanoemulsions fabricated by low energy emulsification method known as Emulsion Phase Inversion: catastrophic phase inversion (EPI) with different carrier oils (short-chain, medium-chain and long-chain triglycerides) and Tween 80 were investigated. Although nanoemulsions made with VE and the 3 carrier oils showed physical stability to heat shock (30–90 °C, 30 min), ionic strength (0–500 mM), pH (2.0–8.5) and long term storage (60 days, under light and darkness, 4, 25 and 40 °C), there was significant VE degradation in heat processed and long-term storage samples. The VE degradation in long-term storage fitted well with Weibull model, while heat degradation followed the first order kinetics, with medium-chain triglyceride (MCT) based nanoemulsions held at 90 °C showing the greatest degradation rate ( k = 0.1526 × 10 −3 min −1 ) and lowest half-life of 4.54 min. The lack of droplets aggregation or coalescence was associated with absence of electrostatic screening and ion-binding effects. The nanoemulsions stored at 4 °C were more stable than those at 40 °C. The short-chain triglyceride (SCT) based nanoemulsions did not physically withstand the high temperatures (>25 °C) while long-chain triglyceride (LCT) showed good retention in all studied conditions. The VE retention was increased when nanoemulsions were stored in the dark. This study might be helpful to food and pharmaceutical industries in choosing better processing and storage conditions of VE delivery systems.

Negative aromas such as rancid, fusty, winey-vinegary and frozen are sensory attributes of defective virgin olive oil recognized by the International Olive Council. Solid phase microextraction-gas chromatography/mass spectrometery (SPME-GC/MS) was employed to establish a flavour profile for each defective oil. The potential contribution of the identified compounds to the overall aromas of oil samples was assessed by calculating the ratio relative area/odour threshold in air – Relative Area over Threshold (RAOT). The relevant compounds of each defective sensory attributes were suggested: a series of C7-C12 unsaturated aldehydes, such as 2, 4-heptadienal, E-2-nonenal and E-2-octenal, were found to be responsible for rancidity, Z-3-hexenyl acetate and nonanoic acid were related to fusty defects, acetic acid and butyric acid were responsible for winey-vinegary defects, and limonene was found as a relevant compound in frozen oil. Copyright © 2015 John Wiley & Sons, Ltd.

Recently there has been an increased interest towards the biological activities of essential oils (EOs). However, EOs are unstable and susceptible to degradation when exposed to environmental stresses like oxygen, temperature, and light. Therefore, attempts have been made to preserve them through encapsulation in various colloidal systems such as microcapsules, nanospheres, nanoemulsions, liposomes, and molecular inclusion complexes. This review focuses on various techniques used for the encapsulation of EOs, potential applications in food, and their behaviours/trends after encapsulation. The encapsulation efficiency, particle size, and physical stability of EOs encapsulated in colloidal systems is dependent on the kind of technique and the type and concentration/ratio of emulsifier/wall material used. Moreover, the benefits associated after encapsulation, namely bioavailability, controlled release, and protection of EOs against environmental stresses are discussed. The applications of encapsulated EOs are also summarized in this review. Encapsulated EOs are promising agents that can be used to increase the anti-microbial, antifungal, antiviral, and pesticidal activities of EOs in real food systems, to study their action mechanism, and to provide nonlethal therapeutic agents to treat several diseases.

Brasenia schreberi (蓴菜 chún cài) is an invasive aquatic weed found in the USA, but the plant has economic value in Asia where it is cultivated for food. The young leaves of B. schreberi are coated with gelatinous water-insoluble mucilage. This mucilage is a polysaccharide composed of galactose, mannose, fucose, and other monosaccharides. Because some carbohydrate gels are hypocholesterolemic, we evaluated their cholesterol-lowering properties in male hamsters fed hypercholesterolemic diets containing 2% gel coat from B. schreberi (GEL), or 1% cholestyramine (CA), or 5% hydroxypropyl methylcellulose (HPMC), and compared them to 5% microcrystalline cellulose (control) for 3 weeks. We found that very-low-density lipoprotein-, low-density lipoprotein-, and total-cholesterol concentrations in plasma were significantly lowered by GEL, CA, and HPMC compared to control. High-density lipoprotein-cholesterol concentration was lowered by CA and HPMC. Body weights and abdominal adipose tissue weight of GEL and control group animals were greater than those of the CA and HPMC groups. Fecal lipid excretion was greater in the CA and HPMC groups than in the control group. Expression of hepatic CYP51 and CYP7A1 mRNA was upregulated by CA, HPMC, and GEL, indicating increased hepatic cholesterol and bile acid synthesis. Expression of low-density lipoprotein receptor mRNA was upregulated by all treatments. These results suggest that modulation of hepatic expression of cholesterol and bile acid metabolism-regulated genes contributes to the cholesterol-lowering effects of GEL., Graphical abstract

In this work, conformational structures of glycinin and β-conglycinin were characterized in aqueous solvents containing different urea concentrations and pH values in order to find industrially processable denatured conformations. The results revealed that both proteins possess thermoset behaviors without melting points. Dynamic light scattering and circular dichroism of the solutions were measured. Structural dissociation of the proteins into subunits occurred at high concentrations of urea in protein solutions under either very acidic or very alkaline conditions. Hydrodynamic radii of the protein subunits gradually increased with increasing urea concentrations, but the hydrodynamic radii and polydispersity indexes of the subunits in very alkaline solutions decreased. Both proteins were denatured by 6–8 M urea solutions through a two-step denaturation mechanism. However, some structural transitions were detected by changing the pH of solutions. Solubilities of glycinin and β-conglycinin are significantly...

The volatile profiles of virgin olive oils originating from the USA were first studied: 71 volatile compounds were identified in 21 monovarietal virgin olive oils using solid-phase microextraction–gas chromatography/mass spectrometry, representing 100 % of the headspace composition. Principal component analysis (PCA) allowed for the grouping of olive oils based on geographical origin, and also the distinguishing of olive oil varieties by their relative positions in the group; 17 distinguishable volatile compounds that significantly contributed to the olive oil classification were found to be distributed on a PCA plot according to their sensory attributes. Moreover, the major volatile components were compared among varieties and origins to clarify the genetic and geographic influences. Our results indicate the significant effects of both origin and cultivar on the volatile composition of olive oil as well as the dominant role of the geographic effect compared to the genetic effect on applied samples.

Flow cytometry exactly discriminated three subpopulations, i.e., viable, damage and sublethal cells of L. monocytogenes, S. aureus and E. coli when treated at their MIC values. Purity gum ultra (PGU) a large molecule surfactant-based CO nanoemulsion exerted significant impact on cellular subpopulations of L. monocytogenes and S. aureus, with more membrane-damaged cells. On the other hand, when compared with bulk CO the results showed minimum membrane damage and more viable cells, whereas PGU CO nanoemulsion showed minimum effect on cellular subpopulation and represented more viable than damaged cells in case of E. coli. Similarly, Tween 80 a small molecule surfactant-based CO nanoemulsion showed limited overall activity against three tested microorganisms with more viable cells. We conclude that it was due to sequestration of CO constituents in interfaces, less availability in aqueous phase and finally inhibit bactericidal activity. Moreover, both CO and CO nanoemulsions showed membrane damage as primary inactivation mechanism of tested bacterial cells.

This study was conducted to elucidate the inter-relationships between the classical compression–extension test and the dynamic rheological test to analyze the texture of cooked rice with two different water ratios. The classical compression–extension test evaluated firmness and adhesiveness, after which the modified balance was calculated. Concurrently, a rheological test, tanδ and |G*| were used to analyze the data. The compression–extension test revealed that the firmness and modified balance increased, while adhesiveness was less affected as the water to rice ratio increased. The modified balances generally increased as grains became shorter, while, |G*| increased and tanδ decreased as the grain became longer. These results were also closely related to the amylose content of each rice variant. Waxy rice (few amylose content) was least firm and highest modified balance, lowest |G*| and highest tanδ, while the results of rice with the highest amylose content showed the opposite results. Principal component analysis revealed that the modified balance, tanδ, firmness and |G*| were located in similar ordinates, indicating that the variables of the two different tests were closely related. Overall, these results demonstrate that some variables in the two different tests provide the same type of information and complementary explanation.

Storage conditions can affect the stability and quality of extra virgin olive oil (EVOO). While many studies have reported the influence of high temperature and light exposure during storage, little is known on the influence of the cold storage. The aim of this study was to evaluate the effect of different storage conditions (25, 4.5 and −27 °C) on the various compositions of EVOO and to determine if cold storage will prolong shelf-life by retarding hydrolysis and oxidation. The changes of quality indices (FFA, PV, and UV) and natural antioxidants such as α-tocopherol and phenolic compounds were evaluated periodically during storage. The characterization and quantification of phenolics were achieved by ultra-performance liquid chromatography—diode array detector (UPLC-DAD). In addition, 1, 2-diacylglycerols (DAGs), pyropheophytin A (PPP) were measured to indicate thermal degradation during storage.

Volatile constituents of commercial black-ripe table olives (Olea europaea) from the United States, Spain, Egypt and Morocco were analysed by gas chromatography and gas chromatography-mass spectrometry (GC-MS). Dynamic headspace sampling was used to isolate a variety of aldehydes, alcohols, esters, ketones, phenols, terpenes, norisoprenoids, and pyridines. Odour unit values, calculated from concentration and odour threshold data, indicate that the following compounds are major contributors to black-ripe table olive aroma: β-damascenone, nonanal, (E)-dec-2-enal, 3-methylbutanal, ethyl benzoate, octanal, 2-methoxyphenol, 2-methylbutanal and 2-methoxy-4-methylphenol. Imported olives contained a variety of fermentation derived volatiles that were not detected in domestic olives. Constituents such as ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, 3-methylbutyl acetate, oct-1-en-3-one, ethyl hexanoate, (Z)-hex-3-enyl acetate, hexyl acetate, ethyl cyclohexanecarboxylate, benzyl acetate and 4-ethylphenol contributed to the odour of imported olives but were not detected in domestic olives.

In order to overcome the limitations of liquid-base emulsion system, beta-carotene nanoemulsions stabilized by modified starch were spray-dried to powders after the emulsification process. The powders showed a good dissolution in water and the reconstituted emulsions had similar particle sizes with the fresh nanoemulsions. A 30 days storage test was carried out to investigate the effect of relative humility (RH) on the storage stability of beta-carotene powders at 25.0 °C. The beta-carotene degradation profiles over time were found to fit well with a Weibull model and also closely related to the film property of the matrix, moisture sorption property and glass transition temperature of the powder. The results showed that modified starches with lower film oxygen permeability had a higher retention of beta-carotene during storage. The glass transition temperature of powder in different RH also affected the rate of beta-carotene degradation. Overall these results provide useful information for choosing wall materials and storage conditions to protect nutraceuticals in delivery systems.

Verifying the authenticity of edible oils is of international concern. A new quality control standard for olive oil has been proposed that relates the ratio of 1,2-diacylglycerol (DAG) to 1,3-DAG to sensory aspects of olive oil. DAGs and their isomers are difficult to quantitate and characterize by Flame Ionization Gas Chromatography (GC-FID) due to the lack of suitable standards. Mass detectors offer the advantage of providing structural detail to the eluding DAG(s), thus removing ambiguity to the identification of both resolved and unresolved DAGs in GC chromatograms. In this study, a GC Electron Ionization Mass Spectrometry (GC-EI-MS) method was developed to determine the fatty acid composition and molecular structure of trimethylsilyl (TMS) derivatized DAGs present in edible oils. Twenty-two species of DAG isomers were identified in refined coconut oil and unrefined olive oil utilizing signature fragment ions, [M-15](+), [M-89](+), [M-RCO2](+), [RCO2+58](+) and [M-RCO2CH2](+). The [M-RCO2CH2](+) ion is considered the key diagnostic ion to distinguish between DAG positional isomers. MS/MS spectra of [M-RCO2](+) and [M-15](+) ions obtained from commercial standards containing both 1,2- and 1,3-DAG isomers were used as a model system to confirm the identification of DAG isomers in natural products. Furthermore, a number of reaction mechanisms are proposed to explain the formation of the most abundant mass fragments of DAGs and their isomers.

Waxy rice starch was impregnated with xanthan and heat-treated in a dry state. The effects on the pasting and rheological properties of the treated starch–xanthan mixture were evaluated. Swelling of the granule was restricted, and a continuous rise of the viscosity during pasting was provided for the treated sample. After pasting, the gel forming ability of the treated starch was strengthened, as both storage and loss modulus increased and tan δ decreased. The paste also owned the highest zero order Newtonian viscosity and yield stress. An increase in starch particle size of the dry heated starch–xanthan mixture suggested a cross linking of the starch granules by the xanthan polymers. An increase of crystallinity was observed for the starch after dry heat treatment, but with the addition of xanthan the amorphous region of the granule became more resistant to dry-heating. The melting enthalpy was found to be correlated with the crystallinity.

Oil-in-water nanoemulsions stabilized by food-grade biopolymer emulsifiers (modified starches) were fabricated using high-pressure homogenization in an effort to improve the stability and bioaccessibility of β-carotene. Physicochemical and biological properties of β-carotene nanoemulsions were investigated considering the particle size, β-carotene retention, and in vitro digestion. During 30 days of storage at different conditions, the mean diameters of the emulsion systems were increased by 30-85%. The retention of β-carotene in nanoemulsions was significantly higher compared to that of the β-carotene dispersed in bulk oil. After in vitro digestion, the bioaccessibility of β-carotene was increased from 3.1% to 35.6% through nanoencapsulation. The results also indicated that modified starch with high dispersed molecular density led to a higher retention but lower bioaccessibility of β-carotene in nanoemulsions. This could be due to the thick and dense interfacial layer around the oil droplets. This result provides useful information for developing protection and delivery systems for carotenoids.

The characteristics of pullulan–chitosan and pullulan–carboxymethyl chitosan (CMCH) blended films were investigated. The viscosity of the film-forming solutions, mechanical properties, barrier properties (water and oxygen), water solubility, and color are reported. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) measurements were used to study the interactions and compatibility between the polysaccharides. The addition of the chitosan or CMCH to pullulan effectively modified the mechanical and oxygen barrier property of the film. The improvements in the film properties have been related to strong interactions between chitosan/CMCH and pullulan polymers, which were observed with FTIR spectroscopy. The ratio of pullulan and chitosan to achieve films with optimum mechanical properties, oxygen and water barrier properties was identified to be 1:1. Increased concentrations of chitosan lead to the formation of inter-molecular hydrogen bonds rather than the intra-molecular hydrogen bonds which were suggested from XRD measurements.

The Maillard reaction was carried out under wet reaction conditions using rice protein product from limited hydrolysis to conjugate with various mono-, oligo- and polysaccharides. The Maillard reaction products (MRPs) prepared with rice protein hydrolysates at 5% degree (hydrolysed by Protease N) and dextran T20 (20 min at 100 °C) showed the greatest improvement in functionality. The solubility, emulsification activity (EA), and emulsification stability (ES) of the MRPs increased by factors of 3.5, 5.3 and 7.3 times, respectively as compared to MRPs formed with native rice proteins and dextran T20. Amino acid analysis indicated that lysine and arginine decreased significantly in the MRPs. Formation of MRPs reduced the surface hydrophobicity, which was in agreement with the change of solubility. However, further decreasing of the surface hydrophobicity resulted in lower EA and ES during the late stage of the reaction. Fluorescence analysis suggested that formation of late stage MRPs occurred after 20 min of the Maillard reaction. The molecular weight distributions showed that the functional properties of MRPs and the mechanisms of formation were affected by the peptide chain length.

This paper describes how long chains of AP affect the measurement of AM content and also investigates the rheological properties of purified starches from 14 rice cultivars. The AM content of each rice starch was determined by two different methods: the colorimetric iodine method and the Concanavalin A method. A high-performance size exclusion chromatograph equipped with multi-angle laser-light scattering and RI detectors was used to determine the molecular weight of long chains of AP. Iodine blue values overestimated the AM content because iodine interacts with long chains of AP. However, long chains of AP with molecular weight under 0.89 × 104 g/mol (Calmochi101) did not affect the measurement of AM content by the iodine calorimetric method. Peak temperature correlated positively with AM content and negatively with the number of long chains of AP. Peak viscosity correlated negatively with AM content and molecular weight of long chains of AP. The difference between final viscosity and peak viscosity was larger in long, medium, and short grain rice varieties than in wx grain varieties.

The effects of engineering higher levels of the High Molecular Weight Glutenin Dx5 subunit on starch characteristics in transgenic wheat (Triticum aestivum L.) grain were evaluated. This is important because of the interrelationship between starch and protein accumulation in grain, the strong biotechnological interest in modulating Dx5 levels and the increasing likelihood that transgenic wheat will be commercialized in the U.S. Unintended effects of Dx5 overexpression on starch could affect wheat marketability and therefore should be examined. Two controls with native levels of Dx5 were used: (i) the nontransformed Bobwhite cultivar, and (ii) a transgenic line (Bar-D) expressing a herbicide resistant (bar) gene, and they were compared with 2 transgenic lines (Dx5G and Dx5J) containing bar and additional copies of Dx5. There were few changes between Bar-D and Dx5G compared to Bobwhite. However, Dx5J, the line with the highest Dx5 protein (×3.5) accumulated 140% more hexose, 25% less starch and the starch had a higher frequency of longer amylopectin chains. These differences were not of sufficient magnitude to influence starch functionality, because granule morphology, crystallinity, amylose-to-amylopectin ratio, and the enthalpy of starch gelatinization and the amylose–lipid complex melting were similar to the control (P > 0.05). This overall similarity was borne out by Partial Least Squares-Discriminant Function Analysis, which could not distinguish among genotypes. Collectively our data imply that higher Dx5 can affect starch accumulation and some aspects of starch molecular structure but that the starches of the Dx5 transgenic wheat lines are substantially equivalent to the controls. Practical Application: Transgenic manipulation of biochemical pathways is an effective way to enhance food sensory quality, but it can also lead to unintended effects. These spurious changes are a concern to Government Regulatory Agencies and to those Industries that market the product. In this study we examined if making “specific” changes to the composition of gluten proteins in wheat seeds would simultaneously alter starch, as their synthesis is interrelated and the molecular structure of both determine f lour functionality. This information may be used to address issues of “substantial equivalence” and to inform Industrial End-Users of possible changes in product performance.

Roux made from three wheat flours and cornstarch and cooked to six different temperatures were tested for gelatinization onset temperatures and thickening power. All roux showed an increase in thickening power on moderate heating. Cooking to higher temperatures greatly reduced thickening power. Bread flour and all-purpose flour showed increasing gelatinization onset temperatures on heating, whereas pastry flour and cornstarch showed the opposite trend. Only roux made with wheat flours developed color during cooking. These results suggest that the browning during roux cooking is due to Maillard reactions and that caramelization is only a minor contributor to color change.

The effect of an acid protease hydrolysis on protein from ribbonfish backbone to produce peptides with angiotensin I-converting enzyme inhibitory activity (ACEIP) was studied and optimized using response surface methodology (RSM). To optimize the hydrolysis reaction, a three-step design was used which included fractional factorial design, steepest ascent design and central composite design (CCD). The results showed that the optimal conditions of ribbonfish backbone protein hydrolysis to produce ACEIP were: pH of 2.67, temperature of 45C, enzyme to substrate ratio of 1/150 (g/g protein), substrate to water ratio of 1:4.38 (g/mL) and hydrolysis time period of 7.0 h. With these conditions, the hydrolyzate concentration (mg/mL) that inhibited 50% angiotensin I-converting enzyme activity (ACEIC50) was 1.054 ± 0.016 mg/mL, which compared well with the predicted value (1.050 mg/mL) by RSM model. PRACTICAL APPLICATIONS Ribbonfish is one of the principle catches from the China Sea. It is processed into various fish products in many factories in the China coastal areas. However, significant amounts of the ribbonfish backbone (12% protein, wet weight) are by-products or waste from the processing, which are not fully utilized. It is often used as animal feedstuff. This study presents a use of the ribbonfish backbone to produce bioactive peptides with angiotensin I-converting enzyme inhibitory activity, through optimizing an acid protease hydrolysis on protein from ribbonfish backbone using response surface methodology.

The aim of this work was to determine if the molecular structure of starch from tomato ( Solanum lycopersicum L.) is influenced by fruit physiology and carbohydrate metabolism. The effect of fruit size, fruit ripening behavior, and assimilate availability on starch granule accumulation was examined in nine tomato samples. The percentage of (14)C-glucose partitioning to starch was similar among samples, but starch contents varied 10-fold, suggesting differences in metabolism. In contrast, granule size (10-20 microm), amylose content (19-23%), degree of crystallinity (26-31%), and enthalpy of gelatinization (14.8-17.2 degrees C) were similar. Some differences in structure were detected in starch from the largest and smallest fruit using more sensitive analyses such as thermal properties, chain length distribution of amylopectin, and susceptibility to in vitro alpha-amylase digestion. However, overall, our results suggest that granule characteristics are highly conserved in tomato fruit, and we conclude that this is likely due to inherent metabolic constraints.

The glycation of rice proteins with reducing sugars was investigated in an attempt to improve their solubility and functionality. Rice proteins isolated from a Chinese milled medium-grain rice were glycated with glucose, lactose, maltodextrin, or dextran in 2% aqueous dispersions. The sugar that provided the most improvement of the solubility, emulsification activity ( EA ) and emulsification stability ( ES ) of the Maillard reaction products was glucose. The optimum reaction conditions were at pH 11, 100 °C, and reaction time 15 min, which increased the solubility, EA and ES of rice protein from 20%, 0.46 and 11.1 to 92%, 0.64 and 18.2, respectively. Extending the reaction time beyond 15 min continued the development of latter-stage Maillard browning products without improvements in the functional properties of the Maillard reaction products. SEC–HPLC analysis with light scattering detection showed a decrease of the weight-averaged molecular weight from 500 to 100 K during the initial 15 min.

Preparation and characterisation of microemulsions (ME) with mint oil (MO) as the oil phase were conducted to find a system which could provide a controlled, sustained, and prolonged delivery of MO. The influence of surfactant type and processing parameters on the formation of MO-ME’s was studied by comparing the areas of the monophase ME regions in pseudoternary phase diagrams. A 1:1 mixture of the surfactants, AOT and CrEL, was found to be the most effective, and it produced a ME monophase area of about 70%. The monophase regions were analysed by conductivity measurements; the results suggested that O/W regions within the ME phases were formed when the water content was higher than 60–65%. As tested with dynamic light scattering (DLS) and head space (HS) GC analysis, the particle size of O/W ME, with 60% water and AOT/CrEL = 1:1 as surfactants, was 20.0 nm and the encapsulation efficiency was 78.4%. The results indicated that a ME of MO/AOT and CrEL/ethanol/water, may be a promising dispersion for the protection of MO in food products.

The effects of different protease treatments on rice starches and their properties were studied. The rice starches produced from protease N exhibited higher pasting viscosities than those produced from alcalase. The hot pastes of the starches produced from protease N also showed higher elastic moduli, zero-order Newtonian viscosities and yield stresses than those produced from alcalase. No differences were found in the crystalline pattern, thermal properties, granules appearance, and average molecular weight ( M w ) of the rice starches between the two protease treatments. But the M w of the pasted starch produced from protease N was higher than that produced from alcalase. When additional protease was added to the isolated starches and the mixture pasted, the M w of the starches pasted with added alcalase was significant lower than that of the starches pasted with added protease N. The reduction in molecular weight suggested that alcalase had modified the starch molecules during pasting.

The effect of rice variety and starch isolation method on the pasting and rheological properties of rice starches was evaluated. One waxy and three non-waxy rice varieties from California with a range of amylose contents of 1.6–26.5% and four methods of isolation were evaluated. A rotational rheometer (RR) was used to measure the pasting and rheological properties of starch dispersions (8% w/w). The RR pasting curves had similar shapes to those from a rapid visco-analyzer (RVA). The four treatments used for isolating starch were a protease, NaOH (0.1% and 0.4%), or sodium dodecyl sulfate (SDS) (1.0%). The NaOH (0.4%) and SDS treatments were found to reduce the peak pasting temperatures of the non-waxy starches as compared with the protease and NaOH (0.1%) treatments. The same trend of the treatments was found with the elastic moduli, low shear viscosities, and yield stresses of the non-waxy starch pastes measured at 65 °C, immediately after pasting. The elastic moduli of the waxy starch pastes appeared to be least affected by method of starch isolation, but the low shear viscosity and yield stress of the protease starch paste was significantly higher than the paste from the other three treatments. Overall, the method of rice starch isolation was found to affect the gelatinization and rheological characteristics of hot rice starch paste.

Starch modified by combination with sodium carboxymethylcellulose (CMC) has been reported to have improved film properties. In this study, rice starches with different amylose content were heat-treated in a dry state after being impregnated with low or medium-viscosity CMC. Noticeable change was found in pasting properties of the starches after dry heat treatment with CMC. It indicated that crosslinkage occurred between the starch and CMC. The waxy starch showed significant change in viscosity throughout pasting after dry heating with CMC, suggesting that the ester bonds were mostly formed between the hydroxyl groups in amylopectin branches of rice starch and carboxylate acid groups of CMC. Particle size also increased after heat treatment with CMC. The modified starch-based films showed improvement in the tensile strength. Both water vapor and oxygen permeability reduced for the modified starch-based films. Dynamic mechanical analysis (DMA) study showed that the values of G ′ of modified starch-based film were higher than those of native starch-based film over the temperature range −40 to 60 °C. The heating process with CMC could be used as a modification method for starch and provide desirable properties of starch-based films.

The efficiency of starch isolations from milled rice with six food-grade protease preparations and combinations with ellulase, high-intensity ultrasound or defatting treatments were investigated. Alcalase and protease N `Amano' (Protease N) were found to provide for a better separation of the rice starch from protein. Protease hydrolysis of the rice flour proteins combined with cellulase and defatting treatments lower residual protein content further to values which were similar to the conventional alkaline steeping method. Protein removal by hydrolysis with the two proteases was found to be most enhanced with a Cellulase pretreatment followed by initial pH adjustments of 10.5 for the alkaline protease Alcalase, and 8.5 for the neutral protease N. There were differences between the trough to final viscosities of the starches prepared with alcalase and protease N. There were no notable differences among different treatments of the isolated starches from the differential scanning calorimetry measurements. Most rice starch granules treated with protease showed no apparent surface damage as observed from scanning electron micrographs. Particle size distribution analysis revealed that the flour displayed bi-model size distribution. The higher sized fraction (10 to 100 μm) decreased rapidly when protease treatments were applied. The isolation of rice starch with proteases combined with other treatments could produce rice starch with native structure, limit the waste products from the separation process and provide a prospective for the design of a commercial process.

Gelatinization and pasting properties of diverse rice types grown in two locations were examined by differential scanning calorimetry (DSC) and rotational rheometry, respectively. The data were compared to previously reported molecular starch properties for these samples: specifically, amylose content, starch molecular weight (Mw), and amylopectin side-chain-length distributions. Significant correlations were observed between amylose content, starch Mw, and the weight degree of polymerization of the long side chains of amylopectin F1(DPw) and many of the gelatinization and pasting properties measured. Higher amylose content corresponded with increased gelatinization onset (To) and peak temperatures (Tp), pasting onset and peak temperatures, and decreased peak and trough viscosity. Starch Mw correlated negatively with To, Tp, pasting onset, and peak temperature and positively with peak, trough, final, and breakdown viscosity. Amylopectin with DPw 59-78 of F1(DPw) correlated with increased To, Tp, pasting onset and peak temperature, and decreased peak, trough, final and breakdown viscosity. Pasting properties were also somewhat related to DPw 21 of shorter side chains of amylopectin (F2(DPw)). Significant correlations between F2(DPw) and peak, final, and breakdown viscosity were observed (r = −0.447*, −0.391*, −0.388*, peak, final, and breakdown viscosity, respectively).

Physicochemistry and structural studies of two types of japonica rice, low amylose Calmochi-101 (CM101) and intermediate amylose M-202 (M202), were conducted to determine similarities and differences between the rices perhaps attributable to amylose content differences. The rheological behavior of the gelation and pasting processes of flours and starches was determined with high accuracy and precision using a controlled stress rheometer. Fat and protein, although minor constituents of milled rice, were shown to have significant effects on the physicochemical and pasting properties of starches and flours. Removal of protein and lipids with aqueous alkaline or detergent solutions caused lower pasting temperatures and higher overall viscosity in both starches, compared with their respective flours. There was less viscosity difference between M202 flour and its starch when isolated by enzymatic hydrolysis of protein. The protease did not reduce internally bound lipids, suggesting that fats help to determine pasting properties of rice flours and their respective starches. Structural integrity differences in individual granules of waxy and nonwaxy rice flours, starches, and whole raw, soaked, and cooked milled grain were revealed by fracture analysis and scanning electron microscopy. Calmochi 101 and M202 did not differ in weight-averaged molar mass (M w ) and root-mean-square radii (R z ) between flours and starches, as determined by high-performance size exclusion chromatography (HPSEC) and multiple-angle laser light scattering (MALLS) (Park, I.; Ibanez, A. M.; Shoemaker, C. F. Starch 2007, 59, 69-77).

The yield and in vitro hypocholesterolemic activity of low-molecular weight soy protein hydrolysates were studied. The yield and cholesterol micellar solubility inhibitory rate (CMSIR) were higher for soy protein Alcalase hydrolysates (SAPH) than soy protein AS1398 hydrolysates (SNPH). The highest CMSIR of 48.6% was found with SAPH with a degree of hydrolysis (DH) of 18%. Optimal parameters for desalting SAPH with macroporous adsorption resin DA201-C were decided to be pH 4.5, SAPH dispersion to resin ration 75:100, and a loading rate 1 BV/h, at which the adsorption rate of the peptide was 89.7%. Only a 4% decrease in CMSIR was found with SPAH (DH 18%) after gastrointestinal protease digestion. In a mice feeding study for 30 d, the serum level of LDL-C + VLDL-C in the SAPH diet group with 0.5 and 2.5 g/kg BW SAPH decreased by 34% and 45% respectively compared to the mice fed only the hypercholesterolemia diet.

A novel hypocholesterolemic peptide was fractionated by gradient ethanol elution from a macroporous adsorption resin (MAR DA201-C), and then separated on Sephadex G-15 and RP-HPLC from a soy protein hydrolysate (SAPH DH 18%). Identification of the hypocholesterolemic peptide structure was accomplished with HPLC-MS. The peptide with the highest hypocholesterolemic activity was found in 75% ethanol fraction among the four fractions from gradient ethanol elution with MAR DA201-C. The calculated average hydrophobicity by amino acid composition of each ethanol eluted fraction suggested that the peptides could be separated in terms of hydrophobicity with MAR DA201-C. Four peaks were obtained with further fractionation on Sephadex G-15, the highest cholesterol micellar solubility inhibition rate, 81.3%, was obtained in Peak 2, corresponding to the molecular weight fraction of 300-800 Da. Fifteen main peaks were obtained with RP-HPLC fractionation, the highest cholesterol micellar solubility inhibition rate (94.3%) was in Peak 7. The amino acid sequence of this peptide was identified as WGAPSL with LC-MS and amino acid composition analysis.

The composition and starch molecular structure of eight rice varieties were studied. Waxy and non-waxy (long-, medium-, and short-grain) rice varieties from California and Texas were used. The amylose contents were measured using the Concanavalin A method and were found to be related to the type of rice: waxy 11.0%, short and medium grain 8.7-15.4%, and long grain 17.1-19.9%. The weight-average molar masses (M w ) of the starches varied from 0.52 to 1.96 x 10 8 g/mol. As would be expected, a higher M w of rice starch correlated to lower amylose content. The range of M w of amylopectin was 0.82 to 2.50 x 10 8 g/mol, and there was also a negative correlation of amylopectin M w with amylose content. Amylose M w ranged from 2.20 to 8.31 x 10 5 g/ mol. After debranching the amylopectin with isoamylase, the weight-average degree of polymerization (DP w ) for the long-chain fraction correlated positively with a higher amylose content. California and Texas varieties were significantly different in their amylose content, starch M w (short- and medium-grain only), and amylopectin M w (p < 0.05).

The ability of different proteases to induce the gelation of soy protein isolate dispersions (5.33% w/w) was studied. The coagulation time and gel firmness were determined using dynamic viscoelastic measurements. Among the six protease tested, papain was the most effective coagulant in terms of gel strength and coagulation speed; the second was alcalase. Degree of hydrolysis (DH), pH and viscosity profiles of soy proteins were tested during the coagulation with different proteases. The result suggested that strong interactions, other than electrostatic interaction, existed between peptides in papain and alcalase induced coagulation. Thermal and pH stability tests indicated that papain was more stable than alcalase in the temperature (60–90 °C) and pH (5.8–7.0) ranges studied. Higher papain dosages within the range of 5–13.3 U/ml resulted in firmer soy protein gels, but concentrations higher than 13.3 U/ml produced weaker gels. With the addition of 0.625 mM cysteine, the soy protein coagulation ability of papain was improved. A soy protein gel formed with 0.025% papain in the presence of 0.625 mM cysteine had about the same strength as that induced by 0.133% papain without cysteine.

The flow behavior of commercially available, aseptically packaged vanilla pudding was measured using a Thermo Haake RheoStress rheometer (RS1, Thermo Electron Corporation, Waltham, MA) with a concentric cylinder system. Six different shear rates, ranging from 1 to 100/s, and three reasonable serving temperatures were investigated using constant shear rate tests. A time-dependent, Herschel-Bulkley model characterized the thixotropic nature of pudding. The model's five parameters were related to temperature. The model was validated at three constant shear rates and at two different temperatures, and was found to predict viscosity well as a function of time, shear rate and temperature.

The gelation of soy peptides produced by the action of papain enzymes on soy glycinin (11S) dispersions (4.7% w/v) was investigated. Cation-exchange chromatography was used to fractionate crude papain. The nonbinding fraction showed no gel-forming activity on the 11S dispersion. Two binding fractions showed gel-forming activity, and the gel strength of both 11S gels was similar. The activity of the crude papain on 11S dispersions produced a slightly stronger gel than one formed with either of the 2 binding fractions. With the crude papain, the rate of gel formation appeared to be strongly influenced by the enzyme concentration, but the maximum gel strength was independent of enzyme concentration. When the temperature was increased, the papain treatment of 11S soy protein produced weaker gels when the measurement was made at the temperature of formation. This dependence of maximum gel strength on temperature was found to be a function of only the measurement temperature and not the gel formation temperature. The degree of protein hydrolysis at maximum gel strength was similar (∼6%) for the gels formed at different temperatures. When the temperature was increased, the elastic modulus G′, the viscous modulus G″, and the degree of viscoelasticity (G″/G′) decreased. This suggested that the gels were formed the by hydrophobic interactions among the peptides. This observation was supported by particle size measurements on samples of gels which were mixed with reagents known for their ability to disrupt hydrophilic/electrostatic, hydrophobic, or disulfide interactions.

Dimethyl sulfoxide (DMSO), with either 50 mM LiBr, 10% water, or both, was used as solvent for multi-angle laser-light scattering (MALLS) batch mode analysis of rice starch, and amylopectin and amylose weight-average molecular weight (Mw). DMSO/50 mM LiBr was a better solvent for these measurements than was DMSO/10% water, based on this solvent's ability to dissolve starch and to reduce the size of starch aggregates. Starch concentration decreased and amylose:amylopectin ratio increased when starch suspended in DMSO was centrifuged or filtered prior to size-exclusion chromatography (SEC)-MALLS analysis. A higher amylose:amylopectin ratio made starch more soluble, and the higher this ratio, the lower the Mw of eluted amylopectin. For SEC analysis of Mw, fractions of starch amylopectin and amylose dispersed in DMSO-based solvents yielded better results than starch dispersed directly into the solvents, because dispersion of these fractions decreased starch aggregation. When these two starch components were fractionated and then dissolved separately in DMSO/50 mM LiBr, the Mw of dispersed amylopectin ranged from 40 to 50 million, and that of amylose was ca. 3 million, whereas starch from three rice varieties of varying amylose content ranged from 60 to 130 million. We recommend that SEC evaluation of amylopectin and amylose be accomplished with fractionated samples as in this study; such evaluations were superior to evaluations of natural mixtures of amylopectin and amylose.

Properties of composite gels with 13% protein consisting of 0:1-to-1:0 α-lactalbumin (α-Lac) to β-lactoglobulin (β-Lg) and 10 or 30% filler consisting of fractionated milk fat as well as properties of matrix-only gels with 10–15% proteins were investigated at 4–50 °C. Maximum compressive force and elastic modulus of the composites were proportionately related to the proportion of β-Lg and proportion of solid lipids included in the matrix and filler, respectively. Details of the compressive behavior, microstructure and extent to which filler affected the mechanical properties were significantly influenced by protein composition. Results obtained with matrix-only gels indicated a protein composition-specific power law relationship ( n =2) between protein content and mechanical properties of the gels.

© 2015 American Chemical Society. The aim of this work was to examine agronomic, compositional, and functional changes in rice (Oryza sativa L. cv. Nipponbare) grains from plants grown under low-to-moderate salinity stress in the greenhouse. Plants were grown in sodium chloride-containing soil (2 or 4 dS/m2electrical conductivity), which was imposed 4-weeks after transplant (called Seedling EC2 and EC4) or after the appearance of the anthers (called Anthesis EC2 and EC4). The former simulates field conditions while the latter permits observation of the isolated effect of salt on grain filling processes. Key findings of this study are the following: (i) Plants showed adaptive responses to prolonged salt treatment with no negative effects on grain weight or fertility. Seedling EC2 plants had more panicles and enhanced caryopsis dimensions, while surprisingly, Seedling EC4 plants did not differ from the control group in the agronomic parameters measured. (ii) Grain starch increased in Seedling EC4 (32.6%) and Anthesis EC2 (39%), respectively, suggesting a stimulatory effect of salt on starch accumulation. (iii) The salinity treatment of 2 dS/m2was better tolerated at anthesis than the 4 dS/m2treatment as the latter led to reduced grain weight (28.8%) and seed fertility (19.4%) and compensatory increases in protein (20.1%) and nitrogen (19.8%) contents. (iv) Although some salinity treatments led to changes in starch content, these did not alter starch fine structure, morphology, or composition. We observed no differences in reducing sugar and amylose content or starch granule size distribution among any of the treatments. The only alterations in starch were limited to small changes in thermal properties and glucan chain distribution, which were only seen in the Anthesis EC4 treatment. This similarity of compositional and functional features was supported by multivariate analysis of all variables measured, which suggested that differences due to treatments were minimal. Overall, this study documents the specific response of rice under defined conditions, and illustrates that the plasticity of plant response to mild stress is complex and highly context-dependent, even under greenhouse conditions in which other potential environmental stress impacts are minimized.

Compressive properties of composite gels consisting of 13% whey protein isolate (WPI) and 10% to 30% selected milkfat fractions were investigated at different temperatures. Compressive properties of gels were significantly affected by melting properties of the filler. Maximum compressive strength of composite gels was proportional to filler load and proportion of solid lipids. Compressive strength of composite gels was higher than that of WPI-only gels, and the relative increase in hardness ranged from about 5% to 91%. Results indicated that compressive properties of gels were affected by a combined effect of filler load and temperature-dependent influence on compressive properties of matrix, interface, and filler particles.

Fundamental dynamic rheological tests were used to mea-sure the rigidity (|G*|) and viscoelasticity (tan d ) of gels madefrom skim milk samples that were (1) never cooled, (2) storedat 48 C, or 3) stored at 48 C and then rewarmed to 258 C. Milkcooled and held at 48 C prior to gel formation produced gelswith lower |G*| and higher tan( d ) than fresh milk gels. Chilledmilk samples that were rewarmed to 25 8 C for 16h prior to gelformation produced gels with rheological properties similarto fresh milk gels. The solubilization of b -casein during coldstorage was hypothesized to be the cause of observed dif-ferences in gel rheology.Key words: milk gels, rheology, b -casein, rigidity, vis-coelasticity INTRODUCTION T HE STORAGE HISTORY OF MILK IS VITAL TO THE SUCCESS mL) was added to some samples to inhibit plasmin activity. OF cheese making. Storing milk for extended times at 48C decreasescheese yield, increases coagulation time, and in some cases, producescheese with less desirable texture attributes (Ali et al.,1980; Pyne andMcGann, 1960). Such changes result in increased costs to processorsand consumers.Milk is typically cooled to 4 8C immediately after milking and storedat or near 48C until further processing. Downey and Murphy (1970)reported on the dissociation of b-casein from casein milk micellesbetween 48 and 308C using high-speed centrifugation and gel filtra-tion. They found that soluble casein increased after lowering the tem-perature of milk. Murphy and Fox (1991) successfully fractionated b-casein from sodium caseinate for further processing using ultrafiltra-tion at 48C. Ali et al. (1980) investigated the partial dissociation ofmicellular caseins into the soluble phase during storage at 4 to 7 8C. Amaximum dissociation of casein was found after storing milk for 48hat 4 8C. b-Casein accounted for most of the increase in soluble casein.In the same study, using empirical measurements, they reported thatcurd structure was weaker and cheese yields were lower in milk withelevated soluble phase casein.Curd firmness is influenced by many factors in addition to milkstorage time and temperature. Other important parameters include pHand heat treatment as well as calcium, phosphate and protein concen-tration (Kowalchyk and Olson, 1979; McMahon et al., 1984; Ustunoland Hicks, 1990). Enriching milk with up to 10 mM calcium also wasreported to increase gel strength (Schultz and Ashworth, 1974; Rametet al., 1981; Marshall et al., 1982; Storry and Ford, 1982; McMahonet al., 1984; Zoon et al., 1988). However, adding high amounts ofcalcium ( .10 mM) decreased gel strength (Murphy and Fox, 1991).Studies on the structure and mechanical properties of milk gelshave been conducted using instruments that measured dynamic rheo-logical properties. Dejmek (1987) used a Bohlin universal viscometerto study aged chymosin gels at various temperatures, strains and strainrates. Halim and Shoemaker (1990) used controlled stress rheometryto study the firmness of gels from milk enriched with purified caseins.Our objective was to determine the influence of milk storage time andtemperature on the firmness and viscoelasticity of chymosin-inducedskim milk gels.

Three methods were used to characterize seven purified endo-1,4-β- d -glucanases derived from different microbial sources (Trichoderma reesei, Thermomonospora fusca, and Acidothermus cellulolyticus) on carboxymethylcellulose (CMC). The methods included capillary viscometry, reducing end-group analysis, and high performance size exclusion chromatography combined with multi-angle laser light scattering (HPSEC-MALLS). The investigation was performed with the objective of comparative evaluation of the different methods for characterizing endoglucanases, particularly in relation to their endo- and exomode of action. The measurement of the initial rate of reducing end-group formation using disodium 2,2′-bicinchoninate (BCA) was found to be the most accurate method for determination of endoglucanase activity. The BCA method was highly sensitive, simple to perform, and directly gave the number of bonds broken, thus allowing for expression of endoglucanase activity in international units (μmol of β-1,4-glucosidic bonds hydrolyzed in 1 min during the initial period of hydrolysis). The viscometric method was simple to perform and highly sensitive for the internal bonds cleaved, but did not account for the hydrolysis of CMC near the chain end, and thus only allowed for expression of endoglucanase activity in arbitrary viscometric units. The HPSEC-MALLS technique provided the number-average molecular weight (Mn) of CMC, thus allowing the quantification of the number of the bonds broken during degradation of CMC; however, reproducibility of the method was low, especially for the high-molecular weight fragments of CMC at the beginning of hydrolysis. As hydrolysis proceeded to the more advanced stages, the HPSEC-MALLS method gave an overestimated (compared to the reducing end-group analysis) values for Mn, probably due to insufficient sensitivity of the light-scattering detector for the low-molecular weight products of CMC degradation. The combined use of the three methods allowed characterization of endoglucanases according to their selectivity for hydrolysis of internal bonds within a CMC molecule which was expressed as the ratio of the initial rate of viscosity decrease to the initial rate of glucosidic bonds broken. This ratio was found to be unique for each endoglucanase, and, therefore, no universal equation could be established for all endoglucanases for conversion of arbitrary viscometric units to international units of activity.

A transducer to directly measure lethality rates during thermal processing was designed and tested. The transducer consisted of a double-legged thermocouple, thermocouple conditioner, and an antilog amplifier. Lethality rates measured real-time during thermal process experiments compared well with those calculated after-wards. A microcomputer data acquisition system was designed to evaluate this transducer. This data system was a general purpose system and can be easily modified to meet the data recording needs of similar experiments and routine processing operations.

A simple and efficient method for the synthesis of lactose-based homopolymers from lactose O-(p-vinylbenzyl)oxime (4) is described. Free radical polymerization of the new oxime monomers proceeded smoothly in an aqueous solution using potassium persulfate (KPS) and N,N,N‘,N‘-tetramethylethylenediamine (TMEDA) as the initiating system and gave water-soluble homopolymers in good yields. These synthetic lactose-based polymers had high molecular weights and narrow polydispersities (Mw/Mn: 1.20−1.35) as determined by size exclusion chromatography, in conjunction with multiangle laser light scattering (SEC−MALLS). The Mark−Houwink equation was obtained as [η] = 2.15 × 10-4Mv0.73. When the monomer was copolymerized with the cross-linking reagent N,N‘-methylenebis(acrylamide) (BisA) (16% mol), hydrogels were formed which swelled as much as 21-fold in deionized water. These gels have potential applications as biocompatible materials.

Low-pressure propoxylation of reduced whey permeate (RWP) with different water contents (12.7 and 33.4%) under alkaline conditions afforded polyether polyols (PEP) which have been characterized by their 1H-NMR, HPLC, hydroxyl number, viscosity, unsaturation content, and alpha color. The results were compared with those from lactitol- and sucrose-based polyether polyols (LPEP and SPEP, respectively). Compared with LPEP and SPEP, polyether polyols from reduced whey permeate (RWP-PEP) showed relatively higher hydroxyl number, lower viscosity, and a similar degree of unsaturation. RWP-PEP was generally darker in color. In addition, polyurethane rigid foams (PURFs) from RWP-PEP, LPEP, and commercial sucrose−glycerin-based polyols (Voranol-PEP) were prepared and characterized. All PURFs made from RWP-PEP have low densities (from 28 to 29 kg/m3) and high closed cell contents (>73%). Compressive strength ranged from 13 to 17 kg × 1000/m2 at 10% deformation. These foams have similar thermal stability as the commer...