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Zhao Q.,Nanchang University | Xiong H.,Nanchang University | Selomulya C.,Monash University | Chen X.D.,Monash University | And 5 more authors.
Food Chemistry | Year: 2012

The effects of various proteases on the formation and characteristics of rice dreg protein hydrolysates (RDPHs) were investigated. Enzymatic hydrolysis of often under-utilised rice dreg protein (RDP) with different enzymes studied here was found to significantly improve protein content and solubility. RDPHs prepared by alkaline protease showed better protein recovery, producing higher protein content with much smaller peptides, while hydrolysates generated by Protamex showed the highest antioxidant activities with more than 80% solubility over a wide pH range. The results indicated that the type of protease greatly influenced the molecular weight and amino acid residue composition of RDPH. The enzyme type also determined the functional properties and antioxidant activity of the recovered proteins. It was found that an optimum allocation of alkaline protease in addition to the Neutrase enzyme could be an appropriate strategy to produce RDPH with desirable functionalities, antioxidant properties, and low salt content. © 2012 Elsevier Ltd. All rights reserved.


Cui F.,Jiangsu University | Cui F.,Jiangxi Provincial Engineering and Technology Center for Food Additives Bio Production | Li X.,Jiangsu University | Zhou Y.,China Agricultural University | And 5 more authors.
Chinese Journal of Environmental Engineering | Year: 2013

The present paper focused on the effect of NaOH pretreatment on anaerobic digestion (AD) of corn stover. NaOH solution with the concentrations of 1.0%, 2.5%, 5.0%, 7.5%(M/V) was used for pretreating corn stover with 24-soaked or no-soaked status, and the biogas production effeciency was determined during the AD process. The obtained data showed that lignin of corn stover was degraded up to 38.54% by 5.0% NaOH pretreatment for 24 h. The total gas yield was 226.75 L/kg VS, which was 38.54% higher than the group without NaOH pretreatment. All the results indicated that the pretreatment of corn stover by 5.0% NaOH for 24 h was preferred for further study due to its significant improvement of biogas prodution and efficiency of anaerobic digestion.


Zhao Q.,Nanchang University | Selomulya C.,Monash University | Xiong H.,Nanchang University | Chen X.D.,Monash University | And 7 more authors.
Journal of Cereal Science | Year: 2012

Rice proteins, as a cheap plant protein source from the by-products of rice dreg processing, could potentially replace commonly used proteins such as soy and whey proteins in selected food products. In this study, the functional properties, surface hydrophobicity (H 0), sulfhydryl and disulfide bond contents, thermal properties, as well as secondary structures of native rice endosperm protein (REP) and processed rice dreg protein (RDP) extracted from long-grain indica rice, were compared. RDP was found to have a higher solubility associated with its relatively higher emulsifying and foaming properties than REP, as well as its water/oil holding capacity, although it was a denatured protein. The emulsifying properties were dependent on the solubility and H 0, while solubility was also related to the disulfide bond contents. Distinct differences in H 0, thermal properties, and disulfide bond contents between REP and RDP could be due to the conformational changes, as the industrial processing steps in the production of rice syrups caused an increase in β-turns at the expense of β-sheets and random coils of REP, leading to the unfolding of β-sheets into higher-ordered supramolecular structures for RDP, which could be responsible for its better functional properties. © 2012 Elsevier Ltd.


Zhao Q.,Nanchang University | Xiong H.,Nanchang University | Selomulya C.,Monash University | Chen X.D.,Monash University | And 5 more authors.
Food and Bioprocess Technology | Year: 2013

This work was done to investigate the effects of different drying methods in the preparation of rice protein isolates (RPIs), as the understanding could provide useful information regarding applications of plant proteins in the food industry. RPI from rice dreg protein, a cheap by-product from the production of rice syrups, was extracted using an alkali solution along with isoelectric precipitation, and subsequently dried by freeze drying (FD-RPI) or spray drying (SD-RPI). The differences in biochemical, physical, and structural characteristics were observed for the dried proteins. SD-RPI had higher protein solubility and emulsifying activity at the pH values between 5 and 11, with higher foaming capacities (127.08 ± 2.25 % compared to 118.83 ± 2.71 %) than FD-RPI. However, FD-RPI had larger mean diameter (2,114.2 ± 79.6 nm compared to 490.4 ± 44.8 nm of SD-RPI), higher water/oil holding capacity (p < 0.05), and thermal stability. In addition, FD-RPI contained more β-turn structures (43.04 % compared to 25.81 %), and less β-sheet and random coils than SD-RPI, indicating that the more compact and ordered conformations of FD-RPI might be related to their physicochemical and functional properties. The choice of drying method could significantly influence physicochemical and conformational properties of RPIs, consequently determining their specific functional properties. The understanding of drying effects on their properties could assist in selecting the appropriate drying method to optimize the utilization of RPIs in the food industry. © 2012 Springer Science+Business Media, LLC.


Zhao Q.,Nanchang University | Selomulya C.,Monash University | Wang S.,Nanchang University | Xiong H.,Nanchang University | And 7 more authors.
Food Research International | Year: 2012

Rice dreg protein hydrolysates (RDPH) can potentially be used as natural antioxidants for a variety of emulsion-type food systems. They contained 89.9% protein, 934.2. mg/g total amino acids with 517.7. mg/g total hydrophilic amino acids, and 78% peptides smaller than 5. kDa. Here, the physical and oxidative stabilities of corn oil-in-water emulsions (10. wt.% lipid) containing RDPH (0-20. mg/mL) and stabilized by Tween-20 were investigated as a function of RDPH concentration and pH. The results showed that emulsions with RDPH and Tween-20 emulsions did not experience coalescence (when RDPH concentration < 20. mg/mL), and were more stable than emulsions prepared by either emulsifier alone (RDPH or Tween-20). RDPH and Tween-20 could not prevent coalescence, because when RDPH = 20. mg/mL, competitive adsorption existed at the interface between high concentrations RDPH and Tween-20. The negatively charged emulsion stabilized with 5. mg/mL RDPH and Tween-20 was found to be more stable at pH 5. RDPH was able to inhibit lipid oxidation, reducing the formation of lipid hydroperoxides and TBARS with increasing RDPH concentrations. Similarly the increase in pH also reduced oxidation, possibly by scavenging free radicals and chelating pro-oxidant metals. The antioxidant properties of RDPH at the interface of emulsion droplets would render them suitable as natural antioxidants in some food products. © 2012 Elsevier Ltd.


PubMed | Nanchang University, Monash University, Parchn Sodium Isovitamin C Co. and Xiamen University
Type: Journal Article | Journal: Food chemistry | Year: 2014

The effects of various proteases on the formation and characteristics of rice dreg protein hydrolysates (RDPHs) were investigated. Enzymatic hydrolysis of often under-utilised rice dreg protein (RDP) with different enzymes studied here was found to significantly improve protein content and solubility. RDPHs prepared by alkaline protease showed better protein recovery, producing higher protein content with much smaller peptides, while hydrolysates generated by Protamex showed the highest antioxidant activities with more than 80% solubility over a wide pH range. The results indicated that the type of protease greatly influenced the molecular weight and amino acid residue composition of RDPH. The enzyme type also determined the functional properties and antioxidant activity of the recovered proteins. It was found that an optimum allocation of alkaline protease in addition to the Neutrase enzyme could be an appropriate strategy to produce RDPH with desirable functionalities, antioxidant properties, and low salt content.


Sun W.-J.,Jiangsu University | Sun W.-J.,Parchn Sodium Isovitamin C Co. | Liu C.-F.,Jiangsu University | Yu L.,Jiangsu University | And 5 more authors.
BMC Microbiology | Year: 2012

Background: Bacteriophages have the destructive damage on the industrial bioprocess. 2-Keto-gluconic acid (2KGA) producing bacteria had also been attacked and lysed by bacteriophages which lowered the glucose consumption and 2KGA yield and even stopped the fermentation process. In this study, we presented the characteristics of a novel virulent bacteriophage specifically infecting Pseudomonas fluorescens K1005 and proposed an efficient remedial action for this phage infection to reduce the production loss. Results: The phage KSL-1 of Pseudomonas fluorescens K1005 was isolated from abnormal 2KGA fermentation broth. It belonged to the Siphoviridae family with a hexagonal head diameter of about 99 nm and a non-contractile tail of about 103 nm × 39 nm. The genome size of phage KSL-1 was estimated to be approximately 53 kbp. Its optimal MOI to infect P. fluorescens K1005 was about 0.001. One-step growth curve gave its latent and burst periods of 90 min and 75 min with a burst size of 52 phage particles per infected cell. This phage was stable with a pH range of 7.0-10.0, and sensitive to thermal treatment. Finally, a simple remedial action was proposed by feeding fresh seed culture. Compared with the infected 2KGA fermentation, the remedial experiments restored 2KGA fermentation performance by increasing the produced 2KGA concentration to 159.89 g/L and shortening the total fermentation time of 80 h with the productivity and yield of 2.0 g/L.h and 0.89 g/g. The obtained data proved that this method was effective to combat the phage infections problems during the 2KGA fermentation. Conclusion: The phage KSL-1 was a novel bacteriophage specifically infecting Pseudomonas fluorescens K1005. The remedial action of feeding fresh seed culture to the infected broth was an easily-operating and effective method to maintain a high 2KGA yield and avoid the draft of infected broth. © 2012 Sun et al.; licensee BioMed Central Ltd.


Du Y.,Nanchang University | Jiang Y.,Nanchang University | Zhu X.,Nanchang University | Xiong H.,Nanchang University | And 6 more authors.
Food Chemistry | Year: 2012

The physicochemical and functional properties of protein isolate (API) and major protein fractions prepared from Akebia trifoliata var. australis seed were investigated. The seed contained 38.83% of oil and 17.23% of protein. Albumin (51.65%) and glutelin (46.40%) were the predominant fractions in the protein component of the seed. The major amino acids were found to be glutamic acid and aspartic acid, while the contents of sulphur-containing amino acids and threonine were very low. One to eight distinct bands with molecular weight (MW) ranging from 12.0 to 50.0 kDa were displayed by SDS-PAGE. The solubilities of API, albumin and glutelin from seeds of the A. trifoliata var. australis were the lowest at pH 4.0-5.0. The high surface hydrophobicity indices of these three proteins were observed at pH 7.0, while the excellent emulsifying properties were displayed at pH 9.0. Circular dichroism measurements indicated that API, albumin and glutelin were rich in β-strand and random coil structures. © 2012 Elsevier Ltd. All rights reserved.


Sun W.-J.,Jiangsu University | Sun W.-J.,Parchn Sodium Isovitamin C Co. | Zhou Y.-Z.,Jiangsu University | Zhou Y.-Z.,Parchn Sodium Isovitamin C Co. | And 5 more authors.
Bioresource Technology | Year: 2012

2-Keto-gluconic acid (2KGA) was produced in a semi-continuous process using Pseudomonas fluorescens AR4 and rice starch hydrolysate (RSH). The bacterium was cultured in medium with an initial glucose concentration of 170. g/L supplied as RSH. Once the glucose level had dropped to 20. g/L, 60% of the culture volume was replaced with fresh medium containing 190. g/L of glucose in the form of RSH. After an additional two cycles of growth and media replacement, a total of 476.88. g/L of glucose was consumed and 444.96. g/L of 2KGA was produced. A total productivity of 6.74. g/L and a yield of 0.93. g/g were obtained. These findings suggest that P. fluorescens AR4 is suitable for the production of commercially acceptable levels of 2KGA in semi-continuous culture. © 2012 Elsevier Ltd.


Cui F.,Jiangsu University | Cui F.,Jiangxi Provincial Engineering and Technology Center for Food Additives Bio production | Zan X.,Jiangsu University | Li Y.,Jiangsu University | And 9 more authors.
International Journal of Biological Macromolecules | Year: 2013

A novel glycoprotein GFG-3a with the molecular weight of 88.01. kDa and potent anti-tumor activity was isolated from the cultured mycelia of Grifola frondosa GF9801. GFG-3a was heat-sensitive with the decreasing anti-proliferative activity after treated from 56. °C to 100. °C for 10-120. min. GFG-3a was a glycoprotein with O-glycosylation and contained 6.20% carbohydrate composed of d-arabinose, d-fructose, d-mannose, and d-glucose with a molar ratio of 1.33:4.51:2.46:1.00. FT-IR and NMR spectra proved that GFG-3a contained protein and carbohydrate portions with 3-O-methyl-galactose residues, (1→4)-linked β-galactose residues, and β-linked glucose residues. Circular dichroism (CD) revealed that GFG-3a was a predominantly β-sheet glycoprotein with a relatively small α-helical content. Protein sequencing and 3D model of GFG-3a were finally predicted by using MALDI-TOF-MS, NCBI blast search and online SWISS-MODLE Workspace service. Our findings will be a reference for the further structure-activity relationship analysis of the mushroom glycoproteins. © 2013 Elsevier B.V.

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