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The effects of mung bean starch (MS) on physicochemical properties of rice flour (RF) and the quality of extruded rice noodles were investigated. Results showed that the amylose content, retrogradation degree, storage modulus (G′) and loss modulus (G″) increased gradually as addition levels of MS increased, while the solubility, swelling power and pasting viscosities decreased with increasing MS content. Acceptable cooking quality and textural properties in the extruded rice noodles were obtained when MS content was up to 5 g/100 g. Sensory evaluation results showed that the scores of firmness, elasticity, slipperiness and chewiness increased gradually as addition levels of MS increased. Scanning electron micrographs of raw extruded rice noodles showed that the surface was smoother and the network of cross-section was more compacted for noodles made from blends of 95 g/100 g RF and 5 g/100 g MS than those from pure RF. This study provides a crucial basis for understanding the interaction between MS and RF and the quality improvement in the extruded rice noodles. [ABSTRACT FROM AUTHOR]

Effective fermentation monitoring is a growing need during the manufacture of wine due to the rapid pace of change in the wine industry. Ethanol and reducing sugar are two most important process variables indicating the status of Chinese rice wine (CRW) fermentation process. In this study, the potentials of Raman spectroscopy (RS) as a rapid process analytical technique to monitor the evolution of these two chemical parameters involved in CRW fermentation process and to group samples according to different fermentation stages were investigated. The results demonstrated that compared with the PLS model using all wavelengths of Raman spectra, the prediction precision of model based on the spectral variables selected by competitive adaptive reweighted sampling (Cars) was significantly improved. In addition, nonlinear models outperformed linear models in predicting fermentation parameters. After systemically comparison and discussion, it was found that for both ethanol and glucose, Cars-support vector machine (Cars-SVM) models gave the best results with the highest prediction precisions. Moreover, the results obtained from discriminant partial least squares analysis (DPLS) showed that good performances were obtained with an average correct classification rate of 94.9% for different fermentation stages. The overall results indicated that RS combined with efficient variable selection algorithm and nonlinear regression tool could be utilized as a rapid method to monitor CRW fermentation process. [ABSTRACT FROM AUTHOR]

In order to investigate the effect of thermostable α-amylase on the rice physicochemical properties, free/bound phenolics, and antioxidant capacities during extrusion, seven different gradients of enzyme concentration from 0 to 6 ‰ (db of starch) were used for both hulled and whole rice. For rice treated with the same extrusion conditions, special mechanical energy (SME) input changed slightly in the presence of fiber fraction (bran/husk), while decreased greatly with increasing α-amylase levels due to the reduced viscosity and friction between mechanical elements and materials. Huge physicochemical modifications were achieved in expansion ratio (ER), bulk density (BD), water absorption/solubility indices (WAI/WSI), and viscosity via enzymatic liquefaction. The total phenolic content (TPC) retention increased dramatically (93.06 and 86.33 % for hulled and whole rice, respectively) with increasing enzyme concentrations to 6 ‰, indicating that a milder reaction environment was created with less thermal-mechanical impact on phenolics. By linear analysis, the TPC of extruded rice hulled or not was strongly and positively related with BD ( R = 0.9185 or 0.9719) and WSI ( R = 0.9719 or 0.8857), whereas negatively related with SME ( R = −0.9460 or −0.8906). Besides, the free/bound phenolics combined with antioxidant activities (1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and ferric reducing antioxidant power (FRAP)) were all improved significantly by the separate/synergetic addition of enzyme and bran/husk used as, respectively, the 'special protective agent' and rich source of bioactive compounds. In summary, thermostable α-amylase could achieve many beneficial effects on both physicochemical properties and antioxidant activities of rice extruded with/without fiber for promoting the development of cake making, wine brewing, infant food industries, or animal husbandry. [ABSTRACT FROM AUTHOR]

Microgels composed of carboxymethyl cellulose (CMC) polymers via chemical crosslinking with sodium trimetaphosphate were synthesized and characterized using thermogravimetric analysis (TGA), swelling, and rheological analysis. The effects of pH, ionic strength, and crosslinking density on lysozyme loading in microgels were also studied. The microgel particle size ranged primarily from 10 to 20 μm. TGA revealed that the crosslinking increased the thermal stability of CMC. The swelling degree increased as pH increased from 3 to 5, and remained almost constant from pH 5 to 8. However, the swelling degree decreased with increasing ionic strength. The rheological analysis was in good agreement with the results of swelling degree. The protein uptake decreased with increasing ionic strength and crosslinking density. The pH 6 was the optimal pH for lysozyme absorption at ionic strength 0.05 M. The lysozyme–microgel complex was identified by confocal laser scanning microscopy, and the lysozyme distribution in the microgel was observed to be rather homogeneous. [ABSTRACT FROM AUTHOR]

The high content of amino acids of Chinese rice wine (CRW), especially essential amino acids makes it a food increasingly demanded by consumers. Rapid detection technique of amino acid content, which is an important quality and function index of CRW, is highly desirable for consumers, producers as well as administrative authorities. In this study, the potential of Fourier transform infrared spectroscopy (FT-IR) as a novel and rapid analytical technique to determine 17 free amino acids in CRW were investigated. Genetic algorithms (GA) and synergy interval partial least squares (SiPLS) were used to select the most efficient spectral variables to improve the prediction precision of the classic partial least squares (PLS) model constructed on the full-spectrum. The results demonstrated that compared with the PLS model using all wavelengths of FT-IR spectra, the prediction precision of model based on the spectral variables selected by GA and SiPLS was significantly improved, especially for arginine and proline. After systemic comparison and discussion, it was found that GA-SiPLS model achieved the best performance, with the correlation coefficient in calibration ( R2 (cal)) higher than 0.80 and the residual predictive deviation higher than 2.00 for all of the free amino acids analyzed in this study. The overall results confirmed that FT-IR combined with efficient variable selection algorithms is a method that may be useful to replace the traditional methods for routine analysis of free amino acids in CRW. [ABSTRACT FROM AUTHOR]

Superheated steam treatment (SST) can improve cereal-based foodstuff quality by altering the gluten properties. In the current study we investigate the effect of SST on the polymerization behavior, conformational rearrangement and microscopic characteristics of gluten, which contribute to determining the molecular mechanisms of SST that impact the gluten properties. Compared with native wheat gluten, SST was observed to induce an increase in sodium dodecyl sulfate (SDS) insoluble gluten. This indicates that SST promoted the polymerization behavior of gluten via the cross-linking of disulfide (SS) bonds. In addition, hydrogen bonds were observed to develop from the micro-environment variation of tryptophan (Trp) residue in the gluten. This consequently had a synergistic effect on the secondary structure, increasing the proportion of intermolecular β-sheets and α-helices. Furthermore, SST enhanced the molecular surface roughness and weakened the gluten network structure. This study could contribute to insight into the improvement of flour quality following SST. • Conformational rearrangement and microscopic properties of gluten were studied. • Superheated steam treatment buried the tryptophan residue and tyrosine doublet. • Superheated steam treatment rearranged disulfide conformation. • Superheated steam treatment roughened the surface micro-structure of gluten. [ABSTRACT FROM AUTHOR]

• Evolution of volatiles and quality of Chinese steamed bread during storage were investigated. • Esters and 2-pentylfuran rapidly decreased during storage of Chinese steamed bread. • Relative soft crumb was observed during Chinese steamed bread storage at 25 °C. • Storage at 4 °C was beneficial to remain volatiles in Chinese steamed bread. The aim of this work is to investigate the evolution of volatiles and quality of CSB during 4 d of storage at 4 °C and 25 °C, respectively. Rapidly increasing hardness and decreasing resilience were observed in CSB after 1 d of storage at 4 °C. However, relative soft CSB was found after 1 d of storage at 25 °C as a result of the lower rate of retrogradation. Volatiles were monitored by gas chromatography-mass spectrometer. Significant (P < 0.05) decrease of 4 esters and 2-pentylfuran were observed with prolonged storage time for CSB stored at both 4 °C and 25 °C. PCA analysis indicated that the storage temperature of 4 °C was beneficial to remain CSB volatiles during long storage time (2–4 d). These findings might be beneficial to retain more volatiles and quality and finally extend shelf-life of CSB. [ABSTRACT FROM AUTHOR]

[Display omitted] • 2-Acetyl-1-pyrroline was only detected in aromatic varieties and decreased upon cooking. • Great losses of esters and long-chain ketones were exhibited after cooking. • Products of lipid oxidation and phenolic acid degradation increased upon cooking. • Volatiles most significantly influenced by cooking were selected. The aim of this study was to scientifically investigate the impact of optimal-water boiling cooking on the volatile profile of 26 japonica rice varieties. A modified direct solvent extraction combined with gas chromatography-mass spectrometry was applied to analyze the volatiles in raw and cooked samples. 2-Acetyl-1-pyrroline (2AP) was only detected in aromatic varieties and decreased after cooking (-81.94% – −43.97%). Great losses of esters and long-chain ketones were exhibited after cooking. Cooking accelerated lipid oxidation and degradation of phenolic acids, thus volatiles originate from lipid oxidation and several benzenoid compounds showed increase trends in majority of the samples. Increases of 3 saturated aldehydes including hexanal (48.01% – 306.02%), octanal and nonanal (67.03% – 544.15%) could be observed in all samples. Acetophenone, 2-methoxy-4-vinylphenol (11.95% – 297.61%) and vanillin (14.29% – 319.25%) were also enhanced upon cooking. Correlations existed in volatiles with common precursors or involved in same pathways. According to multivariate and univariate statistical analysis, 18 volatiles most greatly influenced by cooking were selected. This study will facilitate the aroma improvement of cooked rice in the future. [ABSTRACT FROM AUTHOR]

Enzymatic extrusion, instead of traditional steam cooking, to treat rice is an efficient and alternative pretreatment for Chinese rice wine fermentation. In order to determine the formation of volatiles in enzymatic extrusion-processed rice wine (EE), and to confirm its characteristic flavor compounds, headspace solid-phase micro-extraction followed by GC-MS was used. A total of 66 volatile compounds were identified in EE. During fermentation, most volatiles generated from enzymatic extruded rice had the similar trends with those from steam-cooked rice, but the differences in the concentration of volatiles indicated a changed balance of flavors release caused by enzymatic extrusion. Besides, the concentrations and sorts of volatiles in EEs fermented from different rice particle sizes, were not dramatically different. By principal component analysis, EE could be distinctly separated from other traditional Chinese rice wines according to its characteristic volatiles, namely, 2-heptanol, 1-octen-3-ol, ethyl 4-hydroxybenzoate, methylpentyl 2-propenoate, γ-hexalactone, and 4-vinylguaiacol. [ABSTRACT FROM AUTHOR]

The thermal degradation behavior of hypochlorite-oxidized starch nanocrystals (OSNCs) was evaluated in this study. Carbonyl and carboxyl groups in OSNCs increased from 0.006 and 0.091 mmol/g to 0.033 and 0.129 mmol/g, respectively, as the active chlorine concentration increased from 1% to 4% (w/w). Compared with starch nanocrystals (SNCs), the initial degradation temperature of OSNCs with 4% oxidization decreased from 273 °C to 253 °C. Two degradation processes were detected using differential thermal analysis. The activation energy of the low-temperature process increased with increasing oxidization level because of removal of sulfate esters and reduction of the decomposition products of H 2 O during oxidation. With increasing temperature, the H 2 O generating from decarboxylation and decomposition of the carboxyl groups may catalyze SNCs depolymerization, leading to decrease in the activation energy of the high-temperature process. OSNCs (4% oxidized level) can be used in dry process below 253 °C to avoid degradation. [ABSTRACT FROM AUTHOR]

Microgels synthesized with different crosslinking densities were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetry analysis (TGA), swelling, and rheological analyses. The lysozyme uptake capacity of these microgels was evaluated through the effects of lysozyme concentration, pH, and ionic strength. The microgel particle size mostly ranged within 25 μm to 45 μm. FT-IR analysis results suggested that sodium trimetaphosphate reacted with the hydroxyl groups of carboxymethyl starch (CMS), thereby forming ester linkages. TGA data indicated that crosslinking increased the thermal stability of CMS. Swelling degree increased with increasing pH before pH 5, and then remained almost constant. However, swelling degree decreased with increasing ionic strength and crosslinking density. The microgels behaved as viscoelastic solids because the storage modulus was higher than the loss modulus over the entire frequency range of dispersions with polymer concentrations of 3% (W/W) at 25 °C. The data for the uptake of lysozyme by microgels demonstrated that the protein uptake increased with increasing pH and lysozyme concentration, as well as with decreasing ionic strength and crosslinking density. The lysozyme–microgels complex was identified by CLSM, and the distribution of lysozyme in microgels with low crosslinking density was rather homogeneous. [ABSTRACT FROM AUTHOR]

This study was aimed to establish a detecting system based on transformer method to evaluate moisture content and conductivity of egg albumen and yolks during storage. Results showed that the decrease in impedance of albumen and yolk resulted in the increase in the secondary terminal voltage during the eggs’ storage. Terminal voltage positively correlated with electric conductivity, regardless of frequency. The highest linear coefficient of determination (0.9955) between moisture content of yolk and terminal voltage at 50 Hz was observed. Exponential correlations emerged between the eggs’ conductivity and terminal voltage, with highest coefficient of determination ( R 2 = 0.8311 for albumen, R 2 = 0.9772 for yolk) at 200 Hz and 400 Hz, respectively. The correlations obtained in frequencies ranging from 50 to 400 Hz at 10 V laid the foundation for a method of evaluating moisture content and conductivity in albumen and yolks. Results facilitate an alternative application of the technique for rapid evaluation of the quality indices of liquid food products. [ABSTRACT FROM AUTHOR]

Large-ring cyclodextrins (LR-CDs) have a number of intriguing properties for potential use in pharmaceutical and food industry. To date, no colorimetric method has been reported for LR-CD content quantification. In this study, triple wavelength colorimetry (TWC) and orthogonal-function spectrophotometry (OFS) have been successfully applied to determine ingredient concentrations in a mixture of amylose and LR-CDs. Both TWC and OFS yielded precise amylose content data in good agreement with expected values. For quantification of LR-CD content, OFS provided a higher accuracy than TWC, which resulted in a slight over-determination. As a comparison, single-wavelength colorimetry performed at the corresponding absorption maximum led to a significant over-determination of both amylose and LR-CD contents. The validity of TWC and OFS allowed their application for discriminative detection of the cyclization and total activity of a 4-α-glucanotransferase (4αGTase) from Thermus aquaticus regarding the synthesis of LR-CDs and the conversion of amylose to small molecules, respectively. High pressure size exclusion chromatography analysis of the post-reaction mixtures following 4αGTase-catalyzed conversion of amylose revealed the presence of linear malto-oligosaccharides in the LR-CD fraction. By introduction of a correction factor, the interference caused by linear malto-oligosaccharides was eliminated for a more accurate determination of LR-CD cyclization activity. [ABSTRACT FROM AUTHOR]

Magnetic chitosan/Fe 3 O 4 nanoparticles prepared by in situ mineralization of Fe 3 O 4 in chitosan hydrogel were first modified by 3-aminopropyltriethoxysilane (3-APTES) and then tested for the possibility of being used as carriers for the immobilization of pullulanase. It was found that the immobilized enzyme showed high activity retention (>70%) and the affinity between enzyme and substrate was improved. However, compared to the enzyme immobilized by electrostatic adsorption (87% of its initial activity lost after 10 consecutive reuses), the enzyme immobilized by crosslinking was more stable and there was less loss of activity. The improvement of activity retention and stability was further studied from the view of surface amino concentration of nanoparticles at the function of the amount of 3-APTES added, and crosslinker concentration in the activation process. The highest activity retention (89%) and operation stability (61% residual activity after 10 consecutive reuses) were obtained under the condition of 1.6 amino groups per nm 2 and 15% glutaraldehyde (v/v, dimmer of glutaraldehyde). Therefore, the magnetic chitosan/Fe 3 O 4 nanoparticle prepared by in situ mineralization was proved to be a suitable carrier. In addition, immobilized pullulanase exhibited good resistance to metal ions and detergents. [ABSTRACT FROM AUTHOR]

A linear dextrin (LD)-conjugated linoleic acid (CLA) inclusion complex was prepared using LD obtained from debranched waxy corn starch as an encapsulation wall material. The aim was to prepare a nontoxic CLA product with improved water solubility and controlled release in small intestine by encapsulating CLA with the water-soluble LD. The optimal complexation temperature, volume of ethanol used to dissolve CLA, and mass ratio of LD to CLA were 30°C, 1 mL, 12:1, respectively. Thermogravimetric analysis and Fourier transform infrared spectroscopy showed that CLA was successfully encapsulated by LD. The solubility of the LD-CLA complex greatly improved from 62.64 to 91.05% when the temperature was increased from 20 to 90°C. A total of 34.1% CLA of the LD-CLA complex was released into a simulated small intestine environment. Therefore, LD can improve the solubility of the complex and enable the targeted delivery of functional lipids and other bioactive components to the small intestine. [ABSTRACT FROM AUTHOR]

The structural and functional properties of non-gelatinized waxy rice starch were investigated after 1, 3, 7, and 10 freezing/thawing cycles. Freezing caused an increasing damaged starch from 1.36% in native waxy rice starch to 5.77% in 10 freezing/thawing-treated starch (FTS), as evidenced by the cracking surface on starch granules. More dry matter concentration was leached, which was characterized by high amylopectin concentration (4.34 mg/mL). The leaching was accompanied by a decrease in relative crystallinity from 35.19% in native starch to 31.34% in 10 FTS. Freezing treatment also led to significant deviations in the functional characteristics, for instance decreased gelatinization temperature range, enthalpy, and pasting viscosities. The resistant starch content of 10FTS significantly decreased from 58.9% to 19%, whereas the slowly digested starch content greatly increased from 23.8% in native starch to 50.3%. The increase in susceptibility to enzyme hydrolysis may be attributed to porous granular surface, amylopectin leaching, and the decrease in the relative crystallinity caused by freezing water. [ABSTRACT FROM AUTHOR]

The gluten polymerization behavior, water content, starch crystallinity and firmness of Chinese steamed bread made from frozen dough were investigated and their correlations were also established in this study. The decreased degree of gluten polymerization in steamed bread was observed by the enhanced SDS-extractable proteins (SDSEPs) upon frozen storage. Less incorporation of glutenin in the glutenin–gliadin crosslinking of steamed bread mainly contributed to the decreased degree of gluten polymerization. The decreased moisture of steamed bread had a significant negative correlation with the sublimated water in frozen dough ( r = −0.8850, P < 0.01). Frozen storage also induced an increase in starch crystallinity and bread firmness. A multiple linear regression model with SDS-extractable proteins, water content and melting enthalpy of starch crystals of steamed bread accounted for 86% of the variance in the natural logarithm of firmness and further revealed that starch crystallinity mainly contributed to bread firmness. [ABSTRACT FROM AUTHOR]

Salt content and soluble solid content are important test indicators of quality in pickled products according to commercial standards. Pickled cucumber contains many organic compounds and free ions, and its juice, acting as the secondary coil under alternating magnetic flux, shows specific electrical characteristics during pickling. This study applied a detection system based on the o-core transformer to determine the NaCl content ( N) and soluble solid content ( SSC) of pickled cucumber in the extreme low-frequency range of 50 to 400 Hz at room temperature. It is interesting to note that the changes in electrical properties during pickling resulted in impedance changes in the coils of cucumber juice. Results showed that the terminal voltage ( U) in the secondary circuit was positively correlated with NaCl content and SSC, due to the increase of conductivity in the coil. The inductive current was the ratio of the inductive voltage to the total impedance in the secondary circuit, which increased according to Ohm's law, resulting in an increase of terminal voltages ( U) related to the physicochemical properties of the samples, particularly the amount of free ions. The λ value was found to be more effective than U in evaluating the NaCl content ( N), while the most effective regression model for predicting SSC was obtained at a primary voltage of 30 V and a frequency of 120 Hz based on U value. The proposed method laid the foundation to investigate the response characteristics of food materials by combing magnetic flux with transformer properties. [ABSTRACT FROM AUTHOR]

There is a growing need for the effective fermentation monitoring during the manufacture of wine due to the rapid pace of change in the industry. In this study, the potential of attenuated total reflectance mid-infrared (ATR-MIR) spectroscopy to monitor time-related changes during Chinese rice wine (CRW) fermentation was investigated. Interval partial least-squares (i-PLS) and support vector machine (SVM) were used to improve the performances of partial least-squares (PLS) models. In total, four different calibration models, namely PLS, i-PLS, SVM and interval support vector machine (i-SVM), were established. It was observed that the performances of models based on the efficient spectra intervals selected by i-PLS were much better than those based on the full spectrum. In addition, nonlinear models outperformed linear models in predicting fermentation parameters. After systemically comparison and discussion, it was found that i-SVM model gave the best result with excellent prediction accuracy. The correlation coefficients ( R 2 (pre)), root mean square error (RMSEP (%)) and the residual predictive deviation (RPD) for the prediction set were 0.96, 6.92 and 14.34 for total sugar, 0.97, 3.32 and 12.64 for ethanol, 0.93, 3.24 and 9.3 for total acid and 0.95, 6.33 and 8.46 for amino nitrogen, respectively. The results demonstrated that ATR-MIR combined with efficient variable selection algorithm and nonlinear regression tool as a rapid method to monitor and control CRW fermentation process was feasible. [ABSTRACT FROM AUTHOR]

To better understand how high-shear extrusion combined with enzymatic hydrolysis affects the rice properties and subsequent fermentation, a twin screw extruder incorporated with rice treatment with thermostable α-amylase was used for simultaneous saccharification and fermentation (SSF) of Chinese rice wine. Seven pretreatment methods for rice were compared, and their impacts on rice properties and quality indices of final wine were studied. Enzymatic extruded rice had higher water solubility index (WSI), extent of gelatinization (GE), but lower water absorption index (WAI) and viscosity than those of other treated rice due to a strong synergy of shear action and enzymatic hydrolysis on the degradation and gelatinization of starch. The modification of enzymatic autoclaved rice was smaller than that of enzymatic extruded rice mainly for the lack of mechanical shearing force. Although extrusion with smaller particle size tended to have higher susceptibility to enzyme, the effect was not dramatic. This implied that manipulating particle size had limited effect on the modification of rice properties. Correlation analysis showed that the ethanol yield (EY), fermentation efficiency (FE), amino acid (AA), and soluble solid content (SSC) of finished rice wine increased as rice properties improved by enzymatic extrusion. Overall, simultaneous high-shear extrusion and enzymatic hydrolysis can be an attractive alternative to obtain modified rice with desirable properties for manufacturing Chinese rice wine or other fermentation products. [ABSTRACT FROM AUTHOR]

Normal maize starch was hydrolyzed by the glucan 1,4-alpha-maltotriohydrolase (AMTS), and the changes in molecular characteristics and digestibility of starch were evaluated. Upon hydrolysis, maltotriose purity could be modified via controlled AMTS action. The transglycosylation of AMTS possibly happened during the extensive hydrolysis of starch. No single linear association between the z -average radius of gyration ( R z ), conformation exponent ( ν ), apparent molecular density ( ρ ) and weight average molar mass ( M w ) of the starch molecules could be established in the entire process of AMTS hydrolysis. Under mild hydrolysis (≤240 min), R z and ρ displayed linear relationships with M w . However, transitions of ν , R z and ρ appeared after extensive hydrolysis (>240 min), due to the increase in the amount of short chains [degree of polymerization (DP) ≤ 5]. The spherical starch molecule tends toward less compact and a structure between sphere and random coil after extensive hydrolysis. And the increase in the amount of DP ≤ 12 chains and reduction of molecular dimension after AMTS hydrolysis restrict the digestibility of starch. The results of this study suggest that normal maize starch can be modulated by AMTS to produce the desired maltotriose syrup, starch molecular characteristics, and starch digestibility. [ABSTRACT FROM AUTHOR]

In the present study, gluten samples varied in different glutenin to gliadin ratios were used to study the depolymerization behavior of glutenin macropolymers (GMP) during the frozen storage. The depolymerization degree of GMP increased with the enhanced frozen storage time for all the gluten samples, and also increased with enhanced gliadin content at each frozen storage period. Moreover, the depolymerization degree showed linear-law dependence on the frozen storage time and the gliadin content. A multiple linear regression model with frozen storage time and gliadin content as variables accounts for 94% of the variance of depolymerization degree. This study also rationalized the important effect of gliadin content on the depolymerization degree of GMP. [ABSTRACT FROM AUTHOR]

Discrimination of Chinese rice wines from four geographical origins ('Zhejiang', 'Jiangsu', 'Shanghai' and 'Fujian') in China was investigated according to their UV-vis spectra. The UV-vis absorption spectra of 112 samples in the wavelength range of 190-800 nm were collected. Then the absorption data was subjected to principal component analysis to reveal differences between samples and the potential possibility of using multivariate methods to distinguish differences. Classification models were developed by soft independent modelling of class analogy, linear discriminate analysis (LDA), discriminant partial least squares and support vector machine. Seven mathematical pre-treatments were applied to improve the performance of the multivariate classification models. Among the seven pre-treatments, standard normal transformation (SNV) was superior to the other six methods. The results showed that, compared with other models, SNV-treated LDA models achieved better performances with an average correct classification rate of 98.96% in the training set and 100% in the testing set. The results demonstrate that UV spectroscopy combined with chemometric data analysis, as a rapid method to classify Chinese rice wines according to their geographical origins, is feasible. Copyright © 2015 The Institute of Brewing & Distilling [ABSTRACT FROM AUTHOR]

A method for determining the total solids and fat content of liquid whole egg products based on the principle of transformer was developed. The electrical parameters (terminal voltage and λ value) in the secondary circuit, where the sample acted as the coil, were investigated under the action of alternating magnetic flux in the frequency range from 60 to 400 Hz. Findings indicated that subtle changes of quality indices could be detected by electrical parameters based on the transformer properties that relate to the amount of free ions in the samples. As the inductive voltage was fixed, terminal voltage was negatively correlated with quality indices of total solids and fat content. Therefore the decrement of impedance in the secondary circuit caused the increment of inductive current according to Ohm's law. Linear prediction models for the aforementioned quality indices based on these electrical parameters were also established. Judging from coefficients of determination ( R 2 ) and the root mean square error of prediction (RMSEP) of these models, the λ value was found to be a better predictor for quality indices of liquid whole egg products than terminal voltage. It is believed that this method has the potential to evaluate the quality of liquid food materials over a wider frequency and temperature range. [ABSTRACT FROM AUTHOR]

The combined effect of a gelatin-derived cryoprotective peptide (Pro–Ala–Gly–Tyr) and a non-peptide antioxidant (caffeic acid) in a fish mince model system was investigated. The physicochemical properties (peroxide value, thiobarbituric acid-reactive substances, total sulfhydryl group content and protein carbonyl content), water distribution and thermal properties of Japanese sea bass mince were determined before and after 6 freeze-thaw cycles. Mince supplemented with a combination of a cryoprotective tetrapeptide (12.5 ppm) and 50 ppm caffeic acid had the lowest peroxide value and comparable thiobarbituric acid-reactive substances to 100 ppm caffeic acid. The cryoprotective tetrapeptide at 12.5 ppm also showed the greatest effect when combined with caffeic acid in lowering protein oxidation, in protecting the total sulfhydryl group content and in having the lowest protein carbonylation, which led to least myosin heavy chain denaturation. The state of water was studied using low-field nuclear magnetic resonance. The tetrapeptide reduced the formation of free water in the mince, especially in conjunction with caffeic acid. Thus, the cryoprotective tetrapeptide worked with caffeic acid in retarding the quality losses in the mince induced by freezing and thawing. [ABSTRACT FROM AUTHOR]

Volatile compounds in enzymatic extruded rice, produced under different conditions of varying barrel temperature (BT), α-amylase concentration (AC) and moisture content (MC), were extracted and identified by headspace solid phase microextraction (HS-SPME) and gas chromatography-linked mass spectrometry (GC-MS). Statistical analyses reflected that the Maillard reaction could be inhibited both by the mild extrusion conditions and the enhanced hydrolysis caused by thermostable α-amylase. Relative amounts of total volatiles in enzymatic extruded rice were far less than those in severe processed extruded rice. Reverse-phase high-performance liquid chromatography (RP-HPLC) showed that the amino acids (AAs) involved in Maillrad reaction were utmostly preserved in extruded rice with highest amylase concentration by comparison of total AA content of different extrudates. These results suggest that enzymatic extrusion liquefaction is an effective way to control the generation of volatiles from extruded rice for Chinese rice wine production. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine 1-buatnol–hydrochloric acid (1-butanol–HCl) hydrolysis process of starch. Normal rice starch was hydrolyzed by 0.36% HCl in anhydrous 1-butanol at 40 °C from 4 h to 7 days. The changes in starch granule, crystalline, and molecular weight during the 1-butanol–HCl hydrolysis were determined using SEM, particle size analyzer, XRD, HPSEC–MALLS–RI, and iodine staining. SEM and particle size analyzer analysis showed that the granule morphology significantly changed and the granule size decreased from 5.47 μm to 5.07 μm after the hydrolysis by 1-butanol–HCl for 7 days. XRD results indicated that amorphous areas of normal rice starch were firstly hydrolyzed followed by the ordered areas during 1-butanol–HCl hydrolysis. The peak (2θ) of V-type crystallinity was detected at around 20° in the XRD curves of 1-butanol–HCl-hydrolyzed starches. This peak confirmed the formation of amylose–1-butanol complex. HPSEC–MALLS–RI and iodine staining analysis demonstrated that the weight-average molecular weight of normal rice starch sharply decreased from 2.4 × 107 Da to 4.9 × 105 Da after 1-butanol–HCl hydrolysis for 4 h, then gradually decreased, and finally stabilized at about 2.6 × 104 Da after hydrolysis for 4 days. These results suggest that the attack of 1-butanol–HCl on normal rice starch preferentially occurred in the amylopectin molecules of amorphous areas. [ABSTRACT FROM AUTHOR]

A carboxymethyl starch (CMS) microgel system was prepared for the control of uptaking and releasing proteins (lysozyme). The physicochemical properties of microgels in various degrees of substitution (DS) were determined by thermal gravimetric analysis (TGA), swelling degree, and rheological analysis. The microgel particle size mostly ranged from 25 µm to 45 µm. The result obtained from the TGA studies indicated that carboxymethylation decreased the thermal stability of starch, but crosslinking increased the thermal stability of CMS. The CMS microgels showed typical pH sensitivity, and the swelling degree of microgel increased with the increasing of DS and pH, because of the large amounts of carboxyl group ionization. The samples (2.25%) could behave as viscoelastic solids since the storage modulus was larger than the loss modulus over the entire frequency range. The protein uptake increased with increasing pH and DS at low salt concentration. The optimal pH shifted to lower pH with increasing ionic strength. The saturated protein uptake decreased with increasing ionic strength at each pH. The protein was easily released from the microgel with high pH and high salt concentration. [ABSTRACT FROM AUTHOR]

A novel immobilization of pullulanase has been developed by using magnetic chitosan/Fe 3 O 4 nanoparticles (CS-MNPs). The CS-MNPs were synthesized by in situ mineralization of Fe 3 O 4 in chitosan hydrogel and characterized by transmission electron microscopy, vibrating sample magnetometer, Fourier transform infrared spectroscopy, thermogravimetric analyzer and X-ray diffractometer. The resultant material (CS-MNPs) was used as support for the covalent immobilization of pullulanase with glutaraldehyde as cross-linker. In the process of pullulanase immobilization, both the amount (g) of immobilized pullulanase and the activity retention(%) increased with enzyme concentration increasing (15–60 μg/ml), and the optimum activity retention (93.5%) was obtained at pH 3.5. In enzymatic properties, the immobilized enzyme exhibited a broadened pH profiles and higher thermal stability than the free enzyme. The optimum pH of immobilized pullulanase (3.5) was lower than that of the free enzyme (4.4), and the immobilized enzymes could retain about 84% of their initial activity after incubated for 5 h at 60 °C in contrast with 58% of free enzyme. Furthermore, the immobilized pullulanase retained more than 56% of its initial activity after eight consecutive reuses. These results prove that the CS-MNPs are an effective support for the immobilization of pullulanase. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the effect of frozen storage on chemical and physical properties of wheat gluten-, glutenin- and gliadin-rich fractions was evaluated. Chemical changes were studied by size-exclusion (SE) and reversed-phase (RP) high-performance liquid chromatography (HPLC), thiol (SH) measurement, sodium dodecyl sulphate poly-acrylamide gel electrophoresis (SDS-PAGE), circular dichroism (CD) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Physical properties were determined by dynamic rheological measurements. During the frozen storage, depolymerization of glutenin macropolymer (GMP) was observed by SE-HPLC in gluten- and glutenin-rich fractions with a higher depolymerization rate of GMP in gluten-rich fraction, this further suggested that gliadin might have the potential to disaggregate the GMP. The depolymerization effects led to the major variation of thiol content. The results of SE-HPLC were also in accordance with that of the SDS-PAGE profiles of gluten and glutenin-rich fractions. No aggregation behavior was observed for α-gliadin and γ-gliadin containing cysteine in gluten- and gliadin-rich fractions, leading to the constant content of thiol content of gliadin during the frozen storage. The results of combined CD spectroscopy and FTIR spectroscopy indicated non-covalent interactions were also affected. Significant loss of elastic modulus (G′) and viscous modulus (G″) to gluten- and glutenin-rich fractions were detected with the increasing storage except that no apparent changes occurred in gliadin-rich fractions, suggesting that variation of glutenin functionality was quite important for that of gluten. Moreover, highly significant negative correlations between the content of SDS-soluble glutenin and data of G′ were found in gluten- and glutenin-rich fractions suggested depolymerization of GMP was the main indicator of deterioration of gluten and glutenin during the frozen storage. [Copyright &y& Elsevier]

Abstract: The effect of branched limited dextrin (BLD) on starch retrogradation was investigated to explain the anti-firming mechanism of α-amylase. The influence of BLD on the gelatinized wheat and waxy rice starch retrogradation was characterized by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WXRD). DSC and WXRD results showed that retrogradation of wheat and waxy rice starch gels were reduced with the addition of branched limit dextrins (F75 and F88). Avrami equation was used to analyze the enthalpies of retrograde wheat starch gels, and the value of k indicated that F75 and F88 reduced the kinetics of starch retrogradation. In addition, molecular dynamic (MD) simulation was adapted to predict the interaction of BLD and starch fraction, and the results showed that the BLD reduced starch retrogradation by the interplay between starch and BLD. [Copyright &y& Elsevier]

Abstract: Phosvitin (Pv) from hen egg yolk was conjugated to dextran (Dex) through the initial stage of Maillard reaction in an aqueous system (Pv:Dex, 1:4 (w/w); Mw of Dex, 40 kDa) at 100 °C for 6 h. The red shift of λ ma x occurred to Pv after the conjugation reaction from 355 to 362 nm and from 510 to 520 nm of intrinsic and extrinsic fluorescence emission spectra respectively. Circular dichroism spectra demonstrated that partial unordered secondary structure of Pv transformed into α-helix and β-turn after conjugating with Dex. The solubility of Pv–Dex conjugates represented an increase from 53.0% to 79.3% at pH 4.0. The zeta-potential of all tested emulsions decreased with lowering pH from 7.0 to 4.0. The interfacial thickness of Pv (1.0 mg/ml) absorbed onto latex particles at pH 4.0 was prominently increased by conjugation with Dex. Both the highest ESI and the slight fluctuation of D[4,3] of Pv–Dex conjugates illustrated that conjugation of Pv with Dex would be an effective method to improve its emulsion stability against more acidic pH environment. [Copyright &y& Elsevier]

Egg yolk-derived phosvitin phosphopeptides (PPPs) are considered to have a huge potential in nutraceutical and cosmetic industries for their high Ca2+ binding capacity and antioxidant activity. This work aimed to obtain information on effect of fertilization on conformation of phosvitin (PSV) and bioactivities of PPPs. After 12days of incubation, a significant decrease was seen in phosphorus content of PSV. The conformational and thermal analyses indicated that PSV underwent a conformational change during incubation, and the PSV on day 12 possessed a much more unfolded structure. Correspondingly, the PPPs derived from fertilized egg PSV exhibited stronger Ca2+ binding capacity (18.4ppm at 600mg/L) and antioxidant activities against DPPH radical, hydroxyl radical and lipid peroxidation than that of PPPs from unfertilized egg PSV. These results suggested that fertilized egg could be explored as a potential source of bioactive phosphopeptides. [ABSTRACT FROM AUTHOR]

Flavourzyme is a commercial peptidase, mainly with exopeptidase activity. In this study, effects of Flavourzyme addition (0–0.16 g/100 g) on properties of wheat dough and bread were systematically studied. Bread with a low concentration (0.01–0.08 g/100 g) of Flavourzyme addition had a large specific volume and soft texture with a uniform cell structure. The optimal Flavourzyme content was 0.04 g/100 g and the specific volume increased from 3.9 mL/g to 4.4 mL/g, the hardness decreased from 21.7 N to 13.3 N. The gas production capacity of yeast increased with low concentrations of Flavourzyme addition, promoting dough expansion. Flavourzyme had a clear hydrolysis effect on wheat gluten in dough and caused the depolymerization and unfolding of gluten structure, thus decreasing the strength and viscoelasticity of dough. Confocal laser scanning microscopy and scanning electron microscopy results further revealed that a low concentration of Flavourzyme had a slight effect on gluten. However, the gluten structure became discontinuous and open, which made the dough easily collapsed during fermentation, resulting in poor bread quality with high Flavourzyme content. The positive effects of appropriate amount of Flavourzyme addition on dough and bread properties indicated the potential of Flavourzyme as a bread improver by substituting chemical additives. • Moderate amount of Flavourzyme addition improved the quality of bread significantly. • The optimal addition of Flavourzyme is 0.04 g/100 g (based on wheat flour). • Dough expansion was enhanced with moderate Flavourzyme addition. • Moderate Flavourzyme addition did not cause obvious damage to gluten network. [ABSTRACT FROM AUTHOR]

Nowadays, new snacks using alternative raw materials and ingredients are the critical driving forces for the snack food industry development. Wheat is an abundant cereal resource with the potential for chips making. In the present study, protease-treated wheat flour improved the quality of wheat chips by weakening the gluten strength of dough and reducing the chips' hardness from 6019 ± 306 N to 785 ± 200 N. The optimal enzymatic hydrolysis parameters were established as 1.44 × 104 U bromelain/100 g flour at 50 °C for 60 min. Bromelain significantly reduced the polymeric proteins content (from 15.81 ± 0.52% to 0.82 ± 0.03%) and glutenin macropolymer (GMP, from 14.95 ± 0.23% to 2.06 ± 0.05%), swelling power, gelatinization enthalpy (from 8.82 ± 0.39 to 7.31 ± 0.27 J/g), and viscosities, but increased the solubility (from 3.9 ± 0.1% to 12.8 ± 0.7%) of wheat flour. Moreover, protease hydrolysis significantly decreased the elastic modulus and viscous modulus (P < 0.05); values and the gluten network in the protease-treated dough showed different degradation degrees. The reconstituted wheat chips proved that GMP was the main factor affecting the chip hardness. The present study suggests that protease hydrolysis, especially bromelain, has great potential as a flour modification technology for producing baked wheat chips. • Wheat flour treated with protease improved the quality of wheat chips. • The optimal enzymatic hydrolysis parameters were: 1.44 × 104 U/100 g flour at 50 °C for 60 min. • Protease hydrolysis weakened the gluten strength and changed the starch properties. • Bromelain showed stronger hydrolytic effect on wheat proteins and rheological properties. • Glutenin macropolymer played a key role in the hardness of wheat chips. [ABSTRACT FROM AUTHOR]

Corn oil and Lactococcus lactis (L. lactis) were selected for improving the sourdough bread aroma, and their effect on bread flavor was studied. Volatile compounds (VOCs) in sourdough and bread crumbs were determined by gas chromatography−mass spectrometry. The results demonstrated that the VOC profiles appeared mainly dominated by alcohols, aldehydes, ketones, acids, esters, and heterocyclic compounds. Principal component analysis and cluster analysis showed that the formation of most alcohols were promoted by L. lactis , while corn oil addition yielded more aldehydes, ketones, and furans. Further analysis of odor-active components in bread was characterized by aroma extract dilution analysis and odor activity value (OAV). In the sourdough bread obtained with the addition of corn oil and lipase, (E,E)-2,4-decadienal, 2-pentylfuran, 1-octen-3-ol, 3-methylthio-1-propanol, and (E)-2-nonenal had higher flavor dilution factors and OAV, which were the key aroma compounds distinguished from other varieties of breads. • The formation of alcohols were promoted by Lactococcus lactis fermentation. • Corn oil had a positive effect on the concentrations of aldehydes, ketones, and furans. • The synergistic effect of Lactococcus lactis , lipase, and corn oil contributed to creating more volatile compounds. [ABSTRACT FROM AUTHOR]

Abstract: In this study, a glucose oxidase (GOX), papain and xylanase combination was developed for fresh whole wheat dough for both browning inhibition and rheological improvement. Measurements of carotenoids extracted from enzyme-treated doughs showed that 0.001% (w/w) GOX could catalyze the oxidization of 40.0% carotenoids and thus cause a decrease of browning index (BI) by 5.20 during dough preparation. For 24 h browning inhibition, 0.010% (w/w) xylanase and papain individuals were able to separately act on the phenolic compounds and polyphenol oxidase, leading to lower BI rises (5.36 and 7.04, respectively) of doughs as compared to the BI rise (13.53) of the control dough; however, 0.020% GOX caused a higher BI rise (16.60) than control although it made BI decrease by 6.34 at 0 h. Rheological investigations on enzyme-treated doughs revealed that both xylanase and papain led to decreases of elastic (G′) and viscous modulus (G″) of doughs while GOX caused increases of G′ and G″. Therefore, an optimal combination composed of 0.010% (w/w) xylanase, 0.005% (w/w) papain and 0.002% (w/w) GOX was carried out using orthogonal experimental design by comparing BI rises in 24 h, which was also proved as a rheological improver for fresh whole wheat dough. [Copyright &y& Elsevier]

Highlights: [•] HHP improves the percentage of slowly digestible starch. [•] HHP increases the imperfect crystallites in the HHP-gelatinized starch. [•] HHP reduces the retrogradation of rice starch. [•] Enthalpy change of retrogradation is not positively correlated with the SDS percentage. [Copyright &y& Elsevier]

Abstract: The effect of different dispersion pHs on zeta potentials, size distribution, and aggregation behavior of starch nanocrystals (SNC) prepared by sulfuric acid hydrolysis was examined in this study. The results showed that zeta potential of starch nanocrystals decreased from −6.7 mV to −34.5 mV as the dispersion pH increased from 2.07 to 11.96. Smaller starch nanocrystals and wider distribution peaks were observed with the increase of dispersion pH. The data obtained from field emission scanning electron microscopy (FE-SEM) also indicated that the aggregated parallelepiped nanoplatelets (1.5 μm) changed to monodispersed spherical-like nanoparticles (50 nm) with increasing of dispersion pH from 2.07 to 11.96. Considering these findings, the stable SNC suspension could be obtained by adjusting the dispersion pH to the range of 7.44–9.45. [Copyright &y& Elsevier]

Highlights: [•] Enzymatic extrusion of broken rice was applied to manufacture rice wine. [•] Response surface methodology was used to optimise the ethanol yield of rice wine. [•] Fermentation processes were monitored for novel and traditional rice wine. [•] Fermentation recovery and efficiency of these two rice wine were also compared. [ABSTRACT FROM AUTHOR]

Abstract: The effect of frozen storage on the water sorption capability, water mobility, secondary structure, thermal and microscopic properties of gluten-, glutenin- and gliadin-rich fractions were investigated. Lower water sorption capability was observed for samples after frozen storage, suggesting that more hydrophobic moieties were exposed. Conversions of α-helix structure to β-turn structures and specific β-sheet structures were observed in the secondary structure analysis of gluten- and gliadin-rich fractions. Frozen storage induced higher water mobility in hydrated gluten proteins. Similar changes were observed in gluten-water and gliadin-water systems, implying that the changes were primarily attributed to subdued gliadin-water interactions and gliadin can stabilize glutenin network to confine the water mobility. Meanwhile, thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that thermal degradation temperature decreased while thermal denaturation stability increased in gluten- and glutenin-rich fractions with the increasing time of frozen storage. However, the enthalpies of all the gluten proteins decreased, indicating more disordered structures in the aged gluten proteins. The micrographs of scanning electron microscopy (SEM) also confirmed more disordered and weak structures in gluten- and glutenin-rich fractions induced by frozen storage. Furthermore, consistent changes in gluten-, glutenin- and gliadin-rich fractions indicated that the variations in conformational, thermal and microscopic properties of gluten might originate from glutenin and gliadin upon frozen storage. [Copyright &y& Elsevier]

Highlights: [•] Cycloamylose (CA) was prepared by combined treatment of isoamylase and TA 4αGTase. [•] The maximum yield of CA increased from 24.6% to 45.6% after debranching of amylomaize. [•] The minimum DP of CA produced by TA 4αGTase was 5 despite reaction conditions. [•] The larger CA molecules (DP>22) were main constitutes after 24h of reaction. [Copyright &y& Elsevier]

Abstract: Fertilized hen eggs are traditionally considered as dietary supplements in many Asian countries. This work aimed to obtain information on antioxidant peptides derived from fertilized eggs. Antioxidant activities were evaluated by measuring reducing power, DPPH radical scavenging activity and inhibition of pyrogallol autoxidation. During 15days of incubation, the antioxidant activity of peptides increased with increasing incubation time. The peptides on day 15 were employed for isolation of antioxidant peptide. An antioxidant peptide, HLFGPPGKKDPV (MW: 1291.51Da), was purified by consecutive chromatographic methods. The purified peptide was a novel peptide corresponding to the fragment 302–313 of ovotransferrin. The conformational prediction and Fourier transform infrared spectroscopy suggested that the peptide existed in β-sheet. Furthermore, the peptide showed an inhibition ratio of 60.20% on linoleic acid autoxidation and an inhibitory effect on ABTS radicals (IC50: 312μM). These results suggested that fertilized eggs could be explored as a source of antioxidant peptides. [Copyright &y& Elsevier]

Highlights: [•] Glucan 1,4-α-maltotriohydrolase (AMTS) is an enzyme that catalyzes transglycosylation reactions. [•] AMTS transfers maltotriosyl units. [•] The smallest donor of transglycosylation reactions by AMTS is maltotetraose. [•] Maltotriose production is controlled by starch structure and hydrolysis time. [ABSTRACT FROM AUTHOR]

Abstract: The hydration of rice grain and the quality of cooked rice with the different pressure soaking treatments were estimated using Chroma meter (CM), Texture Profile Analysis (TPA), Scanning electron microscopy (SEM), and Differential Scanning Calorimetry (DSC). The results showed that the vacuum soaking and the high hydrostatic pressure (HHP) soaking increased the hydration degree of normal rice, while the hydration effect in waxy rice was increased only by the HHP treatment. The lightness (L*) and the color intensity (B) of cooked normal rice and waxy rice were significantly improved by the two treatments. The HHP soaking also generated the lower hardness, while the higher springiness and cohesiveness for cooked normal and waxy rice samples. These highlights were mainly attributed to the less amylose leaching and the smaller network channels formed between starch granules and other connection parts. Furthermore, the retrogradation of cooked normal and waxy rice was reduced by the HHP treatment. These findings suggest that the HHP soaking could be used for producing high-quality of cooked rice. [Copyright &y& Elsevier]

Highlights: [•] The effect of US/HHP on enzymatic activity of dextranase was investigated. [•] US/HHP treatment increased the dextranase activity by 163.79% compared with the control. [•] V max, K M and k cat values of dextranase increased under US/HHP treatment compared with the control. [•] US/HHP treatments could be an effective method for improving enzyme activity in many industries. [ABSTRACT FROM AUTHOR]

Abstract: The influence of spring dextrin (SD) on the gelatinized starch retrogradation was investigated by wide X-ray diffraction (WXRD), differential scanning calorimetry (DSC) and molecular dynamic (MD) simulation. Different wheat and corn starch gels were prepared with the addition of SD3, SD5, SD7 or SD9. WXRD results showed that recrystallinity of wheat and corn starch gels was reduced with the addition of SD7 or SD9. Alternatively, SD3 or SD5 accelerated recrystallinity. Enthalpies of retrograde wheat and corn starch gels were analyzed using the Avrami equation and confirmed the WXRD results. Finally, MD simulation was adapted to predict the interaction of SD and starch fraction in water, and the results showed that the SD disturbed starch retrogradation by altering starch fraction–starch fraction interaction. Based on the obtained results of WXRD, DSC and MD, it was concluded that the addition of SDs significantly influences starch long-term retrogradation. [Copyright &y& Elsevier]

Abstract: The effect of defatting on the physiochemical properties and the acid hydrolysis rate of maize starch with different amylose contents was evaluated in this study. The increase in the number of pores and the stripping of starch surface layers were observed after defatting by scanning electron microscopy. X-ray diffraction spectrum showed that the peaks attributing to the amylose–lipid complex disappeared. The relative crystallinity increased by 19% for high-amylose maize starch (HMS) on defatting, while the other tested starches virtually unchanged. Differential scanning calorimetry study indicated an increase in the thermal stability for the defatted starches. Compared with native waxy maize starch, the acid hydrolysis rate of the defatted one increased by 6% after 10 days. For normal maize starch (NMS) and HMS, the higher rate of hydrolysis was observed during the first 5 days. Thereafter, the hydrolysis rate was lower than that of their native counterpart. The increase in susceptibility to acid hydrolysis (in the first 5 days) was mainly attributed to the defective and porous structures formed during defatting process, while the decrease of hydrolysis rate for NMS and HMS samples (after the first 5 days) probably resulted from the increase in the relative crystallinity. [Copyright &y& Elsevier]

Abstract: The aim of this study was to examine the interaction between amylose and 1-butanol during the 1-butanol-hydrochloric acid (1-butanol-HCl) hydrolysis of normal rice starch. The interaction model between amylose and 1-butanol was proposed using gas chromatography–mass spectrometry (GC–MS), 13C cross polarization and magic angle spinning NMR analysis (13C CP/MAS NMR), differential scanning calorimetry (DSC), and thermalgravimetric analysis (TGA). GC–MS data showed that another form of 1-butanol existed in 1-butanol-HCl-hydrolyzed normal rice starch, except in the form of free molecules absorbed on the starch granules. The signal of 1-butanol-HCl-hydrolyzed starch at 100.1ppm appeared in the 13C CP/MAS NMR spectrum, indicating that the amylose-1-butanol complex was formed. DSC and TGA data also demonstrated the formation of the complex, which significantly affected the thermal properties of normal rice starch. These findings revealed that less dextrin with low molecular weight formed might be attributed to resistance of this complex to acid during 1-butanol-HCl hydrolysis. [Copyright &y& Elsevier]

Abstract: The present work was designed to obtain information on the effect of germination time on the selected physicochemical properties of brown rice flour and starch prepared from three different rice cultivars. Changes in total starch, amylose and amylopectin contents of flour, amylopectin/amylose ratio and molecular weight of starch, gelatinization, pasting, rheological, and morphological properties of flour and starch during 5 days of germination were investigated. Significant changes of pasting and rheological properties of brown rice flour were found during germination, but only small changes of these properties could be found in isolated starch. Scanning electron micrographs of flour showed that the continuous matrix structure of flour was highly destroyed after germination and scanning electron micrographs of isolated starch showed that after three days of germination, pits and holes were discovered on the surface of some starch granules. Germination had little effect on the average molecular weight of starch, but the polydispersity value in germinated brown rice (2–5 days germination) was higher than that in non-germinated brown rice. The changes observed in physicochemical properties of brown rice flour and starch after germination provided a crucial basis for understanding flour and starch modification mechanisms with potential applications for an industrial scale. [Copyright &y& Elsevier]