Publications by authors named "Shaotong Jiang"

66 Publications

Controlled Release of Flavor Substances from Sesame-Oil-Based Oleogels Prepared Using Biological Waxes or Monoglycerides.

Foods 2021 Aug 7;10(8). Epub 2021 Aug 7.

School of Food Science and Bioengineering, Hefei University of Technology, Hefei 230009, China.

The flavor substances in sesame oil (SO) are volatile and unstable, which causes a decrease in the flavor characteristics and quality of SO during storage. In this study, the effect of gelation on the release of flavor substances in SO was investigated by preparing biological waxes and monoglycerides oleogels. The results showed that the release of flavor substances in SO in an open environment is in accordance with the Weibull equation kinetics. The oleogels were found to retard the release of volatiles with high saturated vapor pressures and low hydrophobic constants in SO. The release rate constant k value of 2-methylpyazine in BW oleogel is 0.0022, showing the best retention effect. In contrast, the addition of gelling agents had no significant retention effect on the release of volatiles with low saturated vapor pressures or high hydrophobic constants in SO, and even promoted the release of these compounds to some extent. This may be due to the hydrophilic structural domains formed by the self-assembly of gelling agents, which reduces the hydrophobicity of SO. This work provides a novel approach for retaining volatile compounds in flavored vegetable oils. As a new type of flavor delivery system, oleogels can realize the controlled release of volatile compounds.
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http://dx.doi.org/10.3390/foods10081828DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8392103PMC
August 2021

Comparative analysis of the microbial community and nutritional quality of sufu.

Food Sci Nutr 2021 Aug 23;9(8):4117-4126. Epub 2021 Jun 23.

Key Laboratory for Agricultural Products Processing of Anhui Province School of Food and Biological Engineering Hefei University of Technology Hefei, Anhui Province China.

Sufu is a type of fermented food with abundant nutrients and delicious taste. It is made from the fermentation of tofu by various microorganisms. In this study, three types of sufu were prepared through natural fermentation: (NF), single-strain fermentation (SF), and mixed-strain fermentation (MF). Microbial species, amino acids, and fatty acids were identified to investigate dynamic changes in nutritional quality and microbial flora in sufu. The results showed that the number of microbial species in NF sufu was the highest ( = 284), whereas that in SF sufu was the lowest ( = 194). Overall, 153 microbial species were found in all three types of sufu. Relative abundance analysis also revealed that , , , and were the main bacteria in sufu. However, there was a large number of harmful bacteria such as  in NF sufu. The levels of various nutrients were low in SF sufu, whereas the contents of protein and soy isoflavones were higher in NF and MF sufu. Seventeen kinds of amino acids were detected, comprising seven essential amino acids and ten other amino acids. The contents of essential amino acids and essential fatty acids were higher in MF sufu than the other two types, resulting in its high nutritional value. The sufu produced through the three fermentation methods differed significantly ( < .05) in terms of microbial flora and nutritional quality.
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http://dx.doi.org/10.1002/fsn3.2372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8358361PMC
August 2021

pH-responsive antibacterial film based polyvinyl alcohol/poly (acrylic acid) incorporated with aminoethyl-phloretin and application to pork preservation.

Food Res Int 2021 09 17;147:110532. Epub 2021 Jun 17.

School of Food and Biological Engineering, Hefei University of Technology, 230009 Hefei, Anhui, PR China; Anhui Institute of Agro-Products Intensive Processing Technology, 230009 Hefei, Anhui, PR China.

This study demonstrates a pH-responsive antibacterial film based on polyvinyl alcohol/poly (acrylic acid) incorporated with aminoethyl-phloretin (PVA/PAA-AEP) for intelligent food packaging. The thermal, mechanical, barrier and light transmittance properties of PVA/PAA are enhanced by PAA presence of ≤6%. The interactions between PVA and PAA were hydrogen and ester bonds. The pH-responsive characteristic is dependent on the protonation/deprotonation tendency of the carboxylic groups on PAA in acidic/alkaline environment. The PVA/PAA3 is selected for the incorporation of AEP and its pH-responsive swelling follows Ritger-Peppas and Schott second-order models. The AEP is hydrogen bonded with the matrix of PVA/PAA3 and the release of AEP is pH-responsive and a rate-limiting step following the First-order model. With pH decrease, the predominant release control was gradually changing from polymer relaxation to Fick diffusion. The PVA/PAA3-AEP films demonstrate AEP content dependent antioxidant and antimicrobial activities. Furthermore, the antibacterial efficiency against Listeria monocytogenes and Staphylococcus aureus is significantly better than Escherichia coli. The target film PVA/PAA3-AEP3 can effectively prolong the shelf-life of pork (TVB-N < 25 mg/100 g) by 4 days at 25 °C, suggesting its great potential in intelligent food packaging.
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http://dx.doi.org/10.1016/j.foodres.2021.110532DOI Listing
September 2021

Functional effectiveness of double essential [email protected] starch/microcrystalline cellulose as active antibacterial packaging.

Int J Biol Macromol 2021 Sep 19;186:873-885. Epub 2021 Jul 19.

School of Food and Biological Engineering, Hefei University of Technology, 230009 Hefei, Anhui, PR China; Anhui Institute of Agro-Products Intensive Processing Technology, 230009 Hefei, Anhui, PR China.

In this work, two combinations of double EOs, i.e., α-terpineol: eugenol (α-T:Eu) and carvacrol:eugenol (CA:Eu), are used to develop the active antibacterial films of double [email protected] starch/microcrystalline cellulose ([email protected]). The hydrogen-bonded networks in SC matrix are conducive to thermostability enhancement and the film of SC25 is determined for EO incorporation. The interactions between EOs and SC matrix are also hydrogen bonds and the double [email protected] are smooth at ratio of ≤2:2 for α-T:Eu or CA:Eu. The ultimate film properties are dependent on the incorporated EOs. The release of EOs is well controlled by two mechanisms of diffusion (predominant) and swelling (secondary). Synergetic antibacterial activity occurs on double [email protected] The shelf life of pork can be extended by 1 day at 25 °C by the two typical films of α-T:[email protected] and CA:[email protected] Moreover, [email protected] can be well degraded in humus soil. Thereby, the target films will have great potential in active packaging to extend the shelf life of food.
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http://dx.doi.org/10.1016/j.ijbiomac.2021.07.094DOI Listing
September 2021

Recombinant Expression of Aflatoxin B-Degrading Enzyme (TV-AFBD) in Engineering GS115 and Application in AFB Degradation in AFB-Contaminated Peanuts.

Toxins (Basel) 2021 05 13;13(5). Epub 2021 May 13.

Anhui Key Laboratory of Intensive Processing of Agricultural Products, College of Food and Biological Engineering, Hefei University of Technology, 420 Feicui Road, Shushan District, Hefei 230601, China.

Aflatoxins seriously threaten the health of humans and animals due to their potential carcinogenic properties. Enzymatic degradation approach is an effective and environmentally friendly alternative that involves changing the structure of aflatoxins. In this study, aflatoxin B-degrading enzyme gene (TV-AFBD) was integrated into the genome of GS115 by homologous recombination approach. The recombinant TV-AFBD was expressed in engineering with a size of approximately 77 kDa under the induction of methanol. The maximum activity of TV-AFBD reached 17.5 U/mL after the induction of 0.8% ethanol (/) for 84 h at 28 °C. The AFB proportion of 75.9% was degraded using AFB standard sample after catalysis for 12 h. In addition, the AFB proportion was 48.5% using AFB-contaminated peanuts after the catalysis for 18 h at 34 °C. The recombinant TV-AFBD would have good practical application value in AFB degradation in food crops. This study provides an alternative degrading enzyme for the degradation of AFB in aflatoxin-contaminated grain and feed via enzymatic degradation approach.
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http://dx.doi.org/10.3390/toxins13050349DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8153001PMC
May 2021

Antibacterial Activity of Polyvinyl Alcohol/WO Films Assisted by Near-Infrared Light and Its Application in Freshness Monitoring.

J Agric Food Chem 2021 Jan 15;69(3):1068-1078. Epub 2021 Jan 15.

School of Food and Biological Engineering, Hefei University of Technology, Hefei, 230009 Anhui, P. R. China.

Nowadays, films with antibacterial activity and applied for freshness monitoring by colorimetric response have been drawing growing attention in food packaging. However, the development of versatile antibacterial and colorimetric agents is still highly desirable. Herein, WO nanorods are incorporated in a polyvinyl alcohol (PVA) matrix to develop a novel composite film with photothermal antibacterial activity and freshness monitoring faculty. The interaction between WO nanorods and PVA is due to hydrogen bonds. Compared with the PVA film, the presence of WO nanorods can significantly enhance the mechanical and barrier properties; typically, the target film (WO/PVA) shows an increase in tensile strength by 52.7% and Young's modulus by 400.0% and a decrease in oxygen permeability by 72.4% and water vapor permeability by 66.9%. The films demonstrate a WO content-dependent antibacterial activity. Under irradiation of near-infrared light (NIR808), the synergistic effect of physical damage, oxidative stress, and temperature increase markedly improves the antibacterial activity of (WO/PVA), showing an antibacterial efficiency of ∼90% against or beyond 90% against . The incorporated WO nanorods demonstrate lower cytotoxicity toward the model cells of human colon cancer cell line HT-29. The (WO/PVA) film exhibits colorimetric response to HS and can also be used for pork freshness monitoring as an indicator.
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http://dx.doi.org/10.1021/acs.jafc.0c06961DOI Listing
January 2021

Gel properties of transglutaminase-induced soy protein isolate-polyphenol complex: influence of epigallocatechin-3-gallate.

J Sci Food Agric 2021 Jul 19;101(9):3870-3879. Epub 2021 Jan 19.

School of Food and Biological Engineering, Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China.

Background: Traditional soy protein isolate (SPI)-based gel products, such as tofu, are generally produced by heating and by addition of metal salt ions to adjust the hydrophobicity and electrostatic force of soybean protein to facilitate the formation of a uniform network structure. However, the gelation rate of the soy protein gel network structure is difficult to control. Theoretically, epigallocatechin-3-gallate (EGCG) could be used to alter the surface hydrophobicity of thermally induced SPI to improve its gelation rate and form a more uniform network structure, thus improving SPI-based gel properties (hardness, water holding capacity and rheological properties).

Results: An SPI-EGCG complex (SPIE) was prepared, and properties of the resulting gel, following induction of transglutaminase (TG), were evaluated. Results showed that EGCG is bound to thermally induced SPI primarily via hydrophobic and hydrogen bonding, thus altering the secondary structure composition and reducing surface hydrophobicity of proteins in thermally induced SPI. Furthermore, the optimum amount of EGCG required to improve the gel strength, water holding capacity and rheological properties was ≤0.04:1 (SPI 1 g L ; EGCG:SPI, w/w). Thermal stability analysis further indicated that EGCG in SPIE was more stable than free EGCG after heating.

Conclusion: This study demonstrated that EGCG can improve the gel properties of TG-crosslinked SPIE, while EGCG in SPIE exhibits enhanced thermal stability. Additionally, the results of this study provide a novel strategy for the development of SPI-based gel foods with improved gel properties and that are enriched with bioactive compounds. © 2020 Society of Chemical Industry.
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http://dx.doi.org/10.1002/jsfa.11025DOI Listing
July 2021

Review on -Allulose: Metabolism, Catalytic Mechanism, Engineering Strain Construction, Bio-Production Technology.

Front Bioeng Biotechnol 2020 3;8:26. Epub 2020 Feb 3.

Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, United States.

Rare sugar -allulose as a substitute sweetener is produced through the isomerization of -fructose by -tagatose 3-epimerases (DTEases) or -allulose 3-epimerases (DAEases). -Allulose is a kind of low energy monosaccharide sugar naturally existing in some fruits in very small quantities. -Allulose not only possesses high value as a food ingredient and dietary supplement, but also exhibits a variety of physiological functions serving as improving insulin resistance, antioxidant enhancement, and hypoglycemic controls, and so forth. Thus, -allulose has an important development value as an alternative to high-energy sugars. This review provided a systematic analysis of -allulose characters, application, enzymatic characteristics and molecular modification, engineered strain construction, and processing technologies. The existing problems and its proposed solutions for -allulose production are also discussed. More importantly, a green and recycling process technology for -allulose production is proposed for low waste formation, low energy consumption, and high sugar yield.
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http://dx.doi.org/10.3389/fbioe.2020.00026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7008614PMC
February 2020

Preparation and Characterization of Emulsion-based Peony Seed Oil Microcapsule.

J Oleo Sci 2020 ;69(3):219-226

School of Food Science and Bioengineering, Hefei University of Technology.

Microcapsules were constructed with starch sodium octenyl succinate (SSOS), β-cyclodextrin (β-CD), and pectin walls and peony seed oil cores. A rheological phenomenon occurred in which the emulsion initially behaved like a shear-thickening fluid and then a shear-thinning fluid within a shear range. The emulsion exhibited good stability under low amplitude stress; however, as amplitude increased the concentration of pectin played an important role in maintaining the stability of the emulsion system. The optimum embedding yield of peony seed oil (92.5%) was achieved with a ratio of 70% SSOS, 22.5% β-CD, and 7.5% pectin. This ratio produced 4.521 μm particles with the lowest surface-oil content (2.60%) and moisture content (1.76%). The peony seed oil microcapsules were spherical with smooth surfaces and a synchronous thermogravimetric analysis showed they possessed good thermal stability. Encapsulation increased the induction period to 5-7 times that of unencapsulated peony seed oil.
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http://dx.doi.org/10.5650/jos.ess19235DOI Listing
September 2020

Radical scavenging activities of peptide from Asian clam (Corbicula fluminea) and its protective effects on oxidative damage induced by hydrogen peroxide in HepG2 cells.

J Food Biochem 2020 03 15;44(3):e13146. Epub 2020 Jan 15.

School of Food and Biological Engineering, Hefei University of Technology, Hefei, China.

The soft part of Asian clam (Corbicula fluminea) was hydrolyzed using trypsin and the hydrolysates were separated by ultrafiltration using the membrane with molecular weight cutoff of 10 and 5 kDa. Three fractions (F10000, F10000-5000, and F5000) were obtained. The F5000 showed the strongest scavenging abilities to DPPH (2,2-diphenyl-1-picrylhydrazyl), superoxide anion, and hydroxyl radicals, and was further fractionated into four fractions (component I, II, III, and IV) by gel chromatography. The protective effects of these components on oxidative damage induced by hydrogen peroxide (H O ) in HepG2 cells were evaluated. Meanwhile, component I separated from F5000 had more positive effects on increasing the activity of catalase, decreasing lipid peroxidation, inhibiting H O -induced apoptosis, and higher yield. The component I was further separated using anion exchange chromatography and reversed phase high-performance liquid chromatography, and the peptide sequence of Lys-Gly-Pro-Ala- Pro-Phe-Tyr-Pro-Leu was identified by mass with molecular weight of 988.3 Da. PRACTICAL APPLICATIONS: Asian clam (C. fluminea) is used for liver protection in traditional Chinese medicine. The present study investigated the radical scavenging activity of the hydrolysates from C. fluminea and the protective effects of the hydrolysate fractions on oxidative damage induced by H O in HepG2 cells. In addition, a peptide was purified from the hydrolysate and the amino acid sequence of it was identified. Although chemical antioxidant has some side effects on health, the peptide with antioxidant activity obtained from C. fluminea would have more extensive application in food and nutraceutical.
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http://dx.doi.org/10.1111/jfbc.13146DOI Listing
March 2020

Colorimetric film based on polyvinyl alcohol/okra mucilage polysaccharide incorporated with rose anthocyanins for shrimp freshness monitoring.

Carbohydr Polym 2020 Feb 13;229:115402. Epub 2019 Oct 13.

School of Food and Biological Engineering, Hefei University of Technology, 230009, Hefei, Anhui, PR China; Anhui Institute of Agro-Products Intensive Processing Technology, 230009, Hefei, Anhui, PR China.

In this work, a colorimetric film was designed for shrimp freshness monitoring by incorporating rose anthocyanins (RAs) in polyvinyl alcohol/okra mucilage polysaccharide (PVA/OMP) composite film. The presence of OMP changed the film-forming solution from Newtonian to non-Newtonian fluid. The addition of OMP and RAs decreased the crystalline of PVA due to the hydrogen bonds among RAs, OMP and PVA. An appropriate content of RAs and OMP could improve the film mechanical and barrier properties. The colorimetric film showed distinguishable color changes at pH 2-12 and was high sensitive to volatile ammonia. The target film of PVA/OMP-RAs could effectively monitor shrimp freshness in real time and the color changes were easily distinguished by naked eye, suggesting its potential in intelligent packaging for freshness monitoring of aquatic products and meat foods.
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http://dx.doi.org/10.1016/j.carbpol.2019.115402DOI Listing
February 2020

Comparison of Lipids Extracted by Different Methods from Chinese Mitten Crab (Eriocheir sinensis) Hepatopancreas.

J Food Sci 2019 Dec 24;84(12):3594-3600. Epub 2019 Nov 24.

School of Food and Biological Engineering, Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei Univ. of Technology, 193 Tunxi Rd, Hefei, 230009, Anhui, China.

The effects of four different extraction methods (Folch, Soxhlet, two-step, and enzyme-assisted aqueous extraction) on the yields, lipid class, fatty acids (FAs) composition, minor components (including carotenoid, cholesterol), and thiobarbituric acid reactive substances values of lipids in the hepatopancreas of Chinese mitten crab (Eriocheir sinensis) were investigated. The C16:0, C18:1, and C18:2 were identified to be the dominant FAs in crab lipids, and the FAs were present in the form of triglycerides. The Soxhlet and enzyme-assisted extraction were more suitable for crab lipids extraction, showing higher extraction rates and oxidative stability. Especially, the lipid extracted by enzyme-assisted extraction has high carotenoids content. The components of crab lipids extracted by enzyme-assisted aqueous extraction were further identified using untargeted metabolomics methods. The polyunsaturated fatty acid, sterols, amino acids, products of lipid β-oxidation and ATP degradation, phosphatidyl ethanolamine, and astaxanthin were founded in crab oil. PRACTICAL APPLICATION: The Chinese mitten crab (Eriocheir sinensis) is a popular aquatic food in China. The hepatopancreas is the major lipid storage organ of crab, and the distinctive flavor of crab is mainly from it. To compare the different extraction methods on yield, composition and properties of crab lipids can be helpful for lipids production from crab hepatopancreas. Meanwhile, the crab hepatopancreas lipids are rich in polyunsaturated fatty acids and astaxanthin, and have potential to be as a functional component and a crab flavor additive in food industry.
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http://dx.doi.org/10.1111/1750-3841.14946DOI Listing
December 2019

Secretion of γ-Glutamyltranspeptidase from and Its Application in Enzymatic Synthesis of l-Theanine.

J Agric Food Chem 2019 Dec 10;67(51):14129-14136. Epub 2019 Dec 10.

School of Food and Biological Engineering, Key Laboratory for Agricultural Products Processing of Anhui Province , Hefei University of Technology , Hefei 230009 , China.

In this study, the gene of γ-glutamyltranspeptidase (GGT) from (BaGGT) controlled by the P promoter was cloned into to construct two recombinant vectors with either one or two signal peptides to drive extracellular secretion. After optimization, 90 ± 0.2 mg/L BaGGT was obtained when the inducing conditions were 24 h and 80 μM (IPTG). The properties of BaGGT were measured, showing that the optimal reaction conditions were 40 °C and pH 9.0 with 55.0 ± 0.5 U/mg enzymatic activity. and were 0.214 mM and 88.13 μmol/min/mg. BaGGT could be stored for 72 h with 90% of the initial activity at 40 °C and retained more than 50% of the initial activity after being maintained at different pH values for 24 h. Finally, enzymatic synthesis of l-theanine was performed with the optimal conditions: 20 mM l-Gln, 100 mM ethylamine HCl, 0.5 U/mL BaGGT, incubated at 40 °C for 6 h, 200 rpm.
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http://dx.doi.org/10.1021/acs.jafc.9b06140DOI Listing
December 2019

Effective Expression of the Phospholipase A1 Gene in BL21(DE3), Enzyme Characterization, and Crude Rapeseed Oil Degumming via a Free Enzyme Approach.

Front Bioeng Biotechnol 2019 17;7:272. Epub 2019 Oct 17.

Department of Biological Engineering, College of Engineering, Konkuk University, Seoul, South Korea.

Crude oil degumming by phospholipid removal is crucial to guarantee oil quality. Phospholipase degumming could produce green vegetable oil by reducing energy consumption and protecting the environment. To develop a novel phospholipase for oil degumming, we cloned the outer membrane phospholipase A gene () and expressed its 33 KDa protein in engineered BL21(DE3). OM-PLA1 activity reached 18.9 U mL with the induction of 0.6 mM isopropyl β-D-1-thiogalactopyranoside for 4 h. The optimum temperature and pH were 50°C and 7.5, respectively. Mg, Ca, Co, and Mn at 0.1 mM L significantly increased OM-PLA1 activity. The kinetic equations of OM-PLA1 and Lecitase Ultra were = 13.7+0.74 (K = 18.53 mM, V = 1.35 mM min) and = 24.42+0.58 (K = 42.1 mM, V = 1.72 mM min), respectively. The phosphorus content decreased from 22.6 to 9.3 mg kg with the addition of 15 units of free recombinant OM-PLA1 into 150 g of crude rapeseed oil. OM-PLA1 has the close degumming efficiency with Lecitase Ultra. The outer membrane phospholipase gene (OM-PLA1) possessed higher substrate affinity and catalytic efficiency than Lecitase Ultra. This study provides an alternative approach to achieve crude vegetable oil degumming with enzymatic technology.
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http://dx.doi.org/10.3389/fbioe.2019.00272DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6811509PMC
October 2019

Microwave-Assisted Extraction Combined with Ultra-High-Performance Liquid Chromatography and Quadrupole/Q-Exactive High-Resolution Mass Spectrometry for the Determination of Main Flavor Substances in Green Tea.

J AOAC Int 2020 Apr;103(2):428-432

Beijing University of Chemical Technology, College of Life Science and Technology, No. 15 East Beisanhuan Rd, Beijing 100029, P.R. China.

Background: In order to make up for the efficacy of sensory assessment of green tea quality and taste, main flavor substances should be quantitatively characterized based on efficient extraction and frontier determination scheme.

Methods: A new, relatively simple sample preparation and detection workflow has been developed for the quantification and confirmation of flavor substances in green tea by microwave-assisted extraction combined with ultra-high-performance LC and quadrupole/Q-Exactive high-resolution MS system. The method identified main flavor substances (i.e., catechins, free amino acids, and caffeine) that were the main components in the formation of tea taste. After crushing pretreatment, tea was extracted and purified simultaneously in a microwave extraction jar by matrix-dispersed solid-phase extraction. The extracting solution was determined by LC coupled to high-resolution Orbitrap mass spectrometry.

Results: In this study, extraction solvent and purification materials were selected, extraction temperature and time were optimized, and the amount and proportion of solid-phase extraction packing were optimized.

Conclusions: The method enabled detection of multiple catechins, amino acids, and caffeine in tea by LC coupled to high-resolution Orbitrap MS, and a database of tea flavor substances was established.

Highlights: The method could be used for screening and confirmation of the main flavor substances in tea as well as assisting the sensory evaluation to grade the quality of tea.
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http://dx.doi.org/10.5740/jaoacint.19-0265DOI Listing
April 2020

Evaluation of Orchid-Like Aroma Between Different Grades of Taiping Houkui Tea by Solid-Phase Microextraction and Comprehensive Two-Dimensional Gas Chromatography Coupled with Time-of-Fight Mass Spectrometry.

J AOAC Int 2020 Apr;103(2):433-438

Beijing University of Chemical Technology, College of Life Science and Technology, No. 15 East Beisanhuan Rd, Beijing 100029, P.R. China.

Background: Taiping houkui tea won the title of "the King of Green Tea" at the International Tea Exposition in 2004, which had an orchid fragrance but the material basis of the orchid fragrance had not been revealed yet.

Objective: To investigate the material basis of the orchid fragrance and identify the quality grade of Taiping houkui tea.

Methods: A method was developed for evaluating orchid-like aroma between different grades Taiping houkui tea by solid-phase micro extraction (SPME) and comprehensive two-dimensional gas chromatography coupled with time-of-fight mass spectrometry (GC×GC-TOFMS). The crushed tea sample in a 25 mL headspace bottle was incubated at 90°C for 10 min. Then the gaseous sample was extracted by SPME divinylbenzene/polydimethylsiloxane fiber for 50 min and thermally desorpted at 250°C for 2 min.

Results: In total, 735 volatile compounds were determined by SPME- GC×GC-TOFMS and 15 compounds were related to orchid-like aroma.

Conclusions: The high-quality Taiping houkui tea has the orchid fragrance and the low-grade one does not; thus orchid-like aroma can be used as a reference of grades of Taiping houkui tea.

Highlights: Thirty different grades of Taiping houkui tea samples were compared and analyzed experimentally, and the results showed that the special aroma substances, which played a key role in grade discrimination of Taiping houkui tea, were found by the statistical method.
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http://dx.doi.org/10.5740/jaoacint.19-0266DOI Listing
April 2020

The Secretion of Transglutaminase From and Immobilization on Porous Magnetic Nanoparticles.

Front Microbiol 2019 6;10:1675. Epub 2019 Aug 6.

School of Food and Biological Engineering, Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China.

Microbial transglutaminase (MTG) from is an important enzyme widely applied in food processing for the improvement of protein properties by catalyzing the cross-linking of proteins. In this work we aimed at improving the production and enabling an easy and efficient purification process from culture supernatants. Thus, recombinant vectors, with either a constitutive promoter (P ) or an inducible promoter (P ), controlling the expression of the MTG gene fused to the signal peptide of Usp45 (SP ) were constructed and then expressed in . After purification, 43.5 ± 0.4 mg/L mature MTG-6His was obtained. It displayed 27.6 ± 0.5 U/mg enzymatic activity cross-linking soy protein isolate effectively. The purified mature MTG was immobilized with magnetic porous FeO nanoparticles, which improved its activity up to 29.1 ± 0.4 U/mg. The immobilized MTG maintained 67.2% of the initial activity after being recycled for 10 times. The high production and secretion of functional MTG from and the magnetic immobilized MTG-6His onto FeO nanoparticles reported in this study would have potential industrial applications.
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http://dx.doi.org/10.3389/fmicb.2019.01675DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6691175PMC
August 2019

Effects of mixed cultures of and aromatizing yeast in alcoholic fermentation on the quality of apple vinegar.

3 Biotech 2019 Apr 6;9(4):128. Epub 2019 Mar 6.

1School of Food Science and Engineering, Hefei University of Technology, No. 193 Tunxi Road, 230009 Hefei, Anhui People's Republic of China.

There are two steps (alcoholic fermentation and acetic acid fermentation) in the production of fruit vinegar by liquid fermentation. The yeast alcoholic fermentation step plays an important role in the quality of apple vinegar. In this work, and aromatizing yeast were used in mixed alcoholic fermentation to improve the flavor of the apple vinegar. The total organic acid contents of apple cider and vinegar in mixed cultures were all higher than those in pure culture (). Umami and sweet free amino acid levels in mixed-culture apple vinegar (MCAV; 1236.71 and 858.25 mg/L, respectively) were significantly higher than those in pure-culture apple vinegar (PCAV; 1214.69 and 820.37 mg/L, respectively). The total esters, total alcohols, and total phenolics were also significantly increased in MCAV (282.36 g/L, 254.22 g/L and 47.49 g/L, respectively), fruit flavor and floral aromas in MCAV were higher than that in PCAV. In the principal component analysis (PCA), the integrative score for MCAV was higher than that for PCAV. Therefore, mixed cultures of and aromatizing yeast in alcoholic fermentation can effectively improve the flavor and quality of apple cider vinegar; more details about the mixed culture need to be investigated in the future.
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http://dx.doi.org/10.1007/s13205-019-1662-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6403275PMC
April 2019

Recombinant Expression of Outer Membrane Phospholipase A (A1) in and Immobilization With Graphene Oxide-Based FeO Nanoparticles for Rapeseed Oil Degumming.

Front Microbiol 2019 21;10:334. Epub 2019 Feb 21.

Anhui Key Laboratory of Intensive Processing of Agricultural Products, College of Food and Biological Engineering, Hefei University of Technology, Hefei, China.

Enzymatic degumming is an effective approach to produce nutritional, safe, and healthy refined oil. However, the high cost and low efficiency of phospholipase limit the application of enzymatic degumming. In this study, an 879 bp outer membrane phospholipase A (A1) (OM-PLA1) gene encoding 292 amino acid residues was isolated from the genome of . The recombinant OM-PLA1 profile of appropriately 33 KDa was expressed by the engineered GS115. The OM-PLA1 activity was 21.2 U/mL with the induction of 1 mM methanol for 72 h. The expression efficiencies of OM-PLA1 were 0.29 U/mL/h and 1.06 U/mL/OD600. A complex of magnetic graphene oxide (MGO) and OM-PLA1 (MGO-OM-PLA1) was prepared by immobilizing OM-PLA1 with graphene oxide-based FeO nanoparticles by cross-linking with glutaraldehyde. The content of phosphorus decreased to 5.1 mg/kg rapeseed oil from 55.6 mg/kg rapeseed oil with 0.02% MGO-OM-PLA1 (w/w) at 50°C for 4 h. MGO-OM-PLA1 retained 51.7% of the initial activity after 13 times of continuous recycling for the enzymatic degumming of rapeseed oil. This study provided an effective approach for the enzymatic degumming of crude vegetable oil by developing a novel phospholipase and improving the degumming technology.
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http://dx.doi.org/10.3389/fmicb.2019.00334DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6393389PMC
February 2019

Physicochemical Properties, Crystallization Behavior and Oxidative Stabilities of Enzymatic Interesterified Fats of Beef Tallow, Palm Stearin and Camellia Oil Blends.

J Oleo Sci 2019 Feb 17;68(2):131-139. Epub 2019 Jan 17.

School of Food and Bioengineering, Hefei University of Technology.

Properties, crystallization behavior and oxidative stabilities of enzymatically catalyzed interesterified fats were investigated in this study. Interesterified fats were catalyzed by Lipase Lipozyme RM IM, through reaction from beef tallow (BT), palm stearin (PS) and camellia oil (CO)under the mass ratio of 7.55: 2.45: 4 (BT: CO: PS) using 3.65% (w/w) of Lipozyme RM IM at 72.6°C for 3.85 h. After reaction, interesterified fats with 36.8°C sliding melting point (SMP) was obtained. Physicochemical properties (fatty acid profile, triacylglycerol profile, solid fat content (SFC), melting and crystallization curve, polymorphic forms) of interesterified fats were characterized. Results proved that interesterified fats blends after interesterification were improved with desirable β' type crystals and preferable SFC. Triacylglycerol constituent of interesterified fats displayed a decrease in OOO, PSS/SPS, LLL, SSS and increased in PSO/POS/SPO, POO/OPO, POP/PPO, PLO/PLP/PPL by comparison of physical blends without interesterification. Additionally, it is estimated that interesterified fats have a moderate antioxidative stability about 352 days-shelf life at 20°C through the traditional accelerated oxidation test. In conclusion, interesterified fats with desirable properties could be suitable for plastic fats use.
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http://dx.doi.org/10.5650/jos.ess18201DOI Listing
February 2019

Study of polycyclic aromatic hydrocarbons generated from fatty acids by a model system.

J Sci Food Agric 2019 May 6;99(7):3548-3554. Epub 2019 Mar 6.

Key Laboratory for Agricultural Products Processing of Anhui Province, School of Food and Biological Engineering, Hefei University of Technology, Hefei, China.

Background: The characteristics of carcinogenic polycyclic aromatic hydrocarbons (PAHs) produced from various fatty acids, as important components of fats and oils, at high temperature are still little known. The reason is because the existing data are from experiments conducted in complex food systems. In this study, 12 PAHs produced from nine fatty acids, representing saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs), were investigated in a model system heated at 98, 165 and 240 °C.

Results: SFAs can with difficulty be pyrolyzed to generate PAHs at 98 °C, but small amounts of PAHs were determined in MUFAs (44.97 µg kg ) and PUFAs (177.73 µg kg ). When the temperature reached 165 °C, there were totals of 27.59, 142.8 and 449.68 µg kg PAHs assayed in SFAs, MUFAs and PUFAs, respectively. The amounts of PAHs generated from SFAs, MUFAs and PUFAs at 240 °C were higher when compared with those of the 165 °C group (P < 0.05). With an increase of heating temperature, the proportion of PAHs with four to five rings increased. Under the same heating conditions, the concentration of PAHs in fatty acids increased with an increase in the number of double bonds.

Conclusions: More PAHs, especially carcinogenic ones with four to five rings, will be produced in fatty acids heated at higher temperature. The content of PAHs generated from fatty acids increased with an increase in the number of double bonds. This study will increase the understanding of the production characteristics of PAHs from various fatty acids under heating condition. © 2019 Society of Chemical Industry.
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http://dx.doi.org/10.1002/jsfa.9575DOI Listing
May 2019

Ethylene-vinyl Alcohol Copolymer-Montmorillonite Multilayer Barrier Film Coated with Mulberry Anthocyanin for Freshness Monitoring.

J Agric Food Chem 2018 Dec 7;66(50):13268-13276. Epub 2018 Dec 7.

Anhui Institute of Agro-Products Intensive Processing Technology , 230009 Hefei , Anhui , PR China.

Colorimetric films incorporated with anthocyanins as an indicator for freshness monitoring have aroused growing interest recently. However, the application of the films is limited by the easily oxidizable nature of anthocyanins. In this work, we developed a novel colorimetric film with a barrier by coating mulberry anthocyanin (MBA) on the internal side of an ethylene-vinyl alcohol copolymer-montmorillonite (EVOH-MMT) multilayer film. A facile layer-by-layer (LBL) assembly was employed under a parallel electric field to build the EVOH-MMT multilayer structure, in which the exfoliated MMT nanosheets were well-oriented and assembled on the EVOH matrix to form a tightly stacked layer between two EVOH layers. The interlayer of MMT significantly enhanced the barrier and mechanical properties of the films (below 40 layers). The interactions between EVOH and MMT and between EVOH and MBA were confirmed to be intermolecular hydrogen bonds. The colorimetric response of (EVOH-MMT)-MBA to volatile ammonia and pH was sensitive, and the color change could be easily distinguished by the naked eye. The successful application of (EVOH-MMT)-MBA to shrimp-freshness monitoring confirms its high potential for the freshness monitoring of packaged food.
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http://dx.doi.org/10.1021/acs.jafc.8b05189DOI Listing
December 2018

Effect of Partial Hydrolysis with Papain on the Characteristics of Transglutaminase-Crosslinked Tofu Gel.

J Food Sci 2018 Dec 21;83(12):3092-3098. Epub 2018 Nov 21.

School of Food Science and Engineering, Hefei Univ. of Technology, Hefei, 230009, China.

The effects of partial enzymatic hydrolysis of soymilk on the characteristics of transglutaminase (TG)-crosslinked tofu gel were studied. SDS-PAGE showed that the molecular weight of the partially hydrolyzed soybean protein was reduced to that of a digested peptide (less than 43.0 kDa) when papain was added at more than 50 μL/100 mL soymilk. The content of free sulfhydryls, β-sheets, and random coils in papain-treated soymilk increased. When TG was added to soy milk after papain treatment and tofu gel was formed, its storage modulus increased from 957.44 to 1241.39 Pa. The gel strength, water-holding capacity, and nonfreezing water content of the tofu gel were greater than those without enzyme treatment. Scanning electron microscopy revealed that limited papain hydrolysis stimulated TG-catalyzed cross-linking of soymilk to form a dense gel network structure, whereas an extended enzymatic hydrolysis of soymilk did not promote crosslinking by TG. PRACTICAL APPLICATION: This work investigated the effect of partial hydrolysis on TG cross-linked tofu gel. Partial hydrolysis of soybean protein with papain can promote TG cross-linking reaction, thus form a dense network structure, increase gel strength, and water-holding capacity. Therefore, it can be used to produce a good gel product with higher gel strength, springiness, water-holding capacity, and a more dense microstructure.
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http://dx.doi.org/10.1111/1750-3841.14403DOI Listing
December 2018

Antibacterial activity and cytotoxicity of l‑phenylalanine-oxidized starch-coordinated zinc (II).

Int J Biol Macromol 2019 Feb 12;123:133-139. Epub 2018 Nov 12.

School of Food Science and Engineering, Hefei University of Technology, 230009 Hefei, Anhui, PR China; Anhui Institute of Agro-Products Intensive Processing Technology, 230009 Hefei, Anhui, PR China.

Zn (II) coordination compounds have aroused growing attentions as antibacterial entities. In the present work, we fabricated a new antibacterial complex of l‑phenylalanine‑oxidized starch-coordinated zinc (II) (l‑Phe-OSt→Zn (II)) by successive reactions of oxidization, Maillard and coordination. Maillard reaction occurred between l‑Phe and OSt to form l‑Phe-OSt, which was then coordinated with Zn (II) by carboxyl groups for l‑Phe-OSt→Zn (II). The complex showed good antibacterial activity and the antibacterial activity against E. coli was slightly poorer than B. subtilis. The presence of complex favored the generation of reactive oxygen species (ROS) in bacteria and the ROS level in B. subtilis was higher than that in E. coli. Furthermore, the toxicity of l‑Phe-OSt→Zn (II) towards HT-29 cells was very low. The characteristics of better antibacterial activity and less cytotoxicity endow l‑Phe-OSt→Zn (II) a great potential of application as a food additive.
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http://dx.doi.org/10.1016/j.ijbiomac.2018.11.057DOI Listing
February 2019

CRISPR-Cas9 Approach Constructing Cellulase Engineered for the Production of Orange Peel Ethanol.

Front Microbiol 2018 10;9:2436. Epub 2018 Oct 10.

College of Food and Biological Engineering, Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Hefei, China.

The development of lignocellulosic bioethanol plays an important role in the substitution of petrochemical energy and high-value utilization of agricultural wastes. The safe and stable expression of cellulase gene was achieved by applying the clustered regularly interspaced short palindromic repeats-Cas9 approach to the integration of expression cassette containing glyceraldehyde-3-phosphate-dehydrogenase gene () promoter in the chromosome. The target insertion site was found to be located in the hexokinase 2 by designing a gRNA expression vector. The recombinant SESTC protein exhibited a size of approximately 44 kDa in the engineered . By using orange peel as the fermentation substrate, the filter paper, endo-1,4-β-glucanase, exo-1,4-β-glucanase activities of the transformants were 1.06, 337.42, and 1.36 U/mL, which were 35.3-fold, 23.03-fold, and 17-fold higher than those from wild-type , respectively. After 6 h treatment, approximately 20 g/L glucose was obtained. Under anaerobic conditions the highest ethanol concentration reached 7.53 g/L after 48 h fermentation and was 37.7-fold higher than that of wild-type (0.2 g/L). The engineered strains may provide a valuable material for the development of lignocellulosic ethanol.
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http://dx.doi.org/10.3389/fmicb.2018.02436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6191481PMC
October 2018

Butylated hydroxyanisole encapsulated in gelatin fiber mats: Volatile release kinetics, functional effectiveness and application to strawberry preservation.

Food Chem 2018 Dec 2;269:142-149. Epub 2018 Jul 2.

School of Food Science and Engineering, Hefei University of Technology, 230009 Hefei, Anhui, PR China.

Butylated hydroxyanisole (BHA) encapsulated in gelatin (GA) (GA-BHA) fiber mats were fabricated via electrospinning technique and applied to strawberry preservation. The volatile release kinetics and functional effectiveness of the mats were investigated. BHA was high efficiently encapsulated in GA fibers and the antioxidant activity of BHA could be well protected. The encapsulation of BHA enhanced the stability of GA and favored structure transition of GA from random coil and β-turns to α-helix and β-sheet. The GA-BHA mats showed good antibacterial activity against Staphylococcus aureus, and the predominant volatile release mechanism of BHA from mats was Fickian diffusion. Furthermore, the mats also showed broad-spectrum antifungal activity against four mould genera (Rhizopus sp., Mucor sp., Aspergillus sp. and Penicillium sp.). The shelf-life of strawberry can be prolonged effectively in the presence of GA-BHA mats during storage. Results suggested that the GA-BHA mats may have a great potential in active food packaging.
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http://dx.doi.org/10.1016/j.foodchem.2018.06.150DOI Listing
December 2018

Heterologous signal peptides-directing secretion of Streptomyces mobaraensis transglutaminase by Bacillus subtilis.

Appl Microbiol Biotechnol 2018 Jul 25;102(13):5533-5543. Epub 2018 Apr 25.

School of Food Science and Engineering, Key Laboratory for Agricultural Products Processing of Anhui Province, Hefei University of Technology, Hefei, China.

Microbial transglutaminase (MTG) from Streptomyces mobaraensis has been widely used for crosslinking proteins in order to acquire products with improved properties. To improve the yield and enable a facile and efficient purification process, recombinant vectors, harboring various heterologous signal peptide-encoding fragments fused to the mtg gene, were constructed in Escherichia coli and then expressed in Bacillus subtilis. Signal peptides of both WapA and AmyQ (SP and SP ) were able to direct the secretion of pre-pro-MTG into the medium. A constitutive promoter (P ) was used for the expression of SP -mtg, while an inducible promoter (P ) was used for SP -mtg. After purification from the supernatant of the culture by immobilized metal affinity chromatography and proteolysis by trypsin, 63.0 ± 0.6 mg/L mature MTG was released, demonstrated to have 29.6 ± 0.9 U/mg enzymatic activity and shown to crosslink soy protein properly. This is the first report on secretion of S. mobaraensis MTG from B. subtilis, with similar enzymatic activities and yields to that produced from Escherichia coli, but enabling a much easier purification process.
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http://dx.doi.org/10.1007/s00253-018-9000-yDOI Listing
July 2018

Cell regeneration and cyclic catalysis of engineered Kluyveromyces marxianus of a D-psicose-3-epimerase gene from Agrobacterium tumefaciens for D-allulose production.

World J Microbiol Biotechnol 2018 Apr 23;34(5):65. Epub 2018 Apr 23.

College of Food Science and Engineering, Anhui Key Laboratory of Intensive Processing of Agricultural Products, Hefei University of Technology, Tunxi Road 193, Hefei, 230009, Anhui, China.

D-Allulose as a low-energy and special bioactive monosaccharide sugar is essential for human health. In this study, the D-psicose-3-epimerase gene (DPEase) of Agrobacterium tumefaciens was transferred into thermotolerant Kluyveromyces marxianus to decrease the production cost of D-allulose and reduce the number of manufacturing procedures. The cell regeneration of K. marxianus and cyclic catalysis via whole-cell reaction were investigated to achieve the sustainable application of K. marxianus and the consumption of residual D-fructose. Results showed that DPEase, encoding a 33 kDa protein, could be effectively expressed in thermotolerant K. marxianus. The engineered K. marxianus produced 190 g L D-allulose with 750 g L D-fructose as a substrate at 55 °C within 12 h. Approximately 100 g of residual D-fructose was converted into 34 g of ethanol, and 15 g of the engineered K. marxianus cells was regenerated after fermentation at 37 °C for 21 h. The purity of D-allulose of more than 90% could be obtained without isolating it from D-allulose and D-fructose mixture through residual D-fructose consumption. This study provided a valuable pathway to regenerate engineered K. marxianus cells and achieve cyclic catalysis for D-allulose production.
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http://dx.doi.org/10.1007/s11274-018-2451-6DOI Listing
April 2018

Producing Acetic Acid of Acetobacter pasteurianus by Fermentation Characteristics and Metabolic Flux Analysis.

Appl Biochem Biotechnol 2018 Sep 19;186(1):217-232. Epub 2018 Mar 19.

School of Food Science and Engineering, Hefei University of Technology, No.193 Tunxi Road, Hefei City, 230009, Anhui Province, People's Republic of China.

The acetic acid bacterium Acetobacter pasteurianus plays an important role in acetic acid fermentation, which involves oxidation of ethanol to acetic acid through the ethanol respiratory chain under specific conditions. In order to obtain more suitable bacteria for the acetic acid industry, A. pasteurianus JST-S screened in this laboratory was compared with A. pasteurianus CICC 20001, a current industrial strain in China, to determine optimal fermentation parameters under different environmental stresses. The maximum total acid content of A. pasteurianus JST-S was 57.14 ± 1.09 g/L, whereas that of A. pasteurianus CICC 20001 reached 48.24 ± 1.15 g/L in a 15-L stir stank. Metabolic flux analysis was also performed to compare the reaction byproducts. Our findings revealed the potential value of the strain in improvement of industrial vinegar fermentation.
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http://dx.doi.org/10.1007/s12010-018-2732-4DOI Listing
September 2018

Antibacterial [2-(Methacryloyloxy) ethyl] Trimethylammonium Chloride Functionalized Reduced Graphene Oxide/Poly(ethylene-co-vinyl alcohol) Multilayer Barrier Film for Food Packaging.

J Agric Food Chem 2018 Jan 10;66(3):732-739. Epub 2018 Jan 10.

Anhui Institute of Agro-Products Intensive Processing Technology , 230009, Hefei, Anhui P. R. China.

The objective of present work was to construct antibacterial [2-(methacryloyloxy) ethyl] trimethylammonium chloride functionalized reduced graphene oxide/poly(ethylene-co-vinyl alcohol) (MTAC-rGO/EVOH) multilayer barrier films by using layer-by-layer assembly under a parallel electric field. Besides barrier and mechanical properties, the antibacterial activities of the film and cytotoxicity of MTAC-rGO nanosheets were extensively investigated. The functionalization of rGO was achieved by grafting MTAC onto a graphene framework through C (sp)-C bonds. The assembly of MTAC-rGO on the EVOH matrix not only significantly improved film mechanical strength, but also endowed the targeting film with outstanding moisture barrier even under a relative humidity of 99% (e.g., 0.019 g m s atm for (MTAC-rGO/EVOH)) besides good oxygen barrier (e.g., 0.07 cm m d atm for (MTAC-rGO/EVOH)). Among the testing films, MTAC-rGO/EVOH film had the best antibacterial activity, and the activity against S. aureus was better than E. coli. Meanwhile, the cytotoxicity of MTAC-rGO nanosheets was very low. Results suggest that MTAC-rGO/EVOH film may have great potential in food active packaging.
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http://dx.doi.org/10.1021/acs.jafc.7b04784DOI Listing
January 2018
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