Yonghong Meng

Interactions between polyphenols in thinned young apples and porcine pancreatic α-amylase: Inhibition, detailed kinetics and fluorescence quenching

Young apple polyphenols (YAP) and nine types of phenolic compounds were investigated regarding the inhibitory activity against porcine pancreatic α-amylase (PPA) in vitro. Tannic acid, chlorogenic acid and caffeic acid in YAP showed relatively high inhibition with the IC50 values of 0.30, 1.96 and 3.69mg/mL, respectively. A detailed kinetics of inhibition study revealed that YAP and tannic acid were competitive inhibitors of PPA, whereas chlorogenic acid and caffeic acid were mixed inhibitors, exhibiting both competitive and uncompetitive characteristics. The fluorescence of PPA could be significantly quenched by YAP and the three polyphenols, and their quenching constants were determined. The results showed that for the polyphenols investigated, the order of the apparent static quenching constants (KFQ) was in agreement with that of the reciprocal competitive inhibition constants (1/Kic) (tannic acid>chlorogenic acid>caffeic acid>epicatechin); both of the parameters were contrary to the order of the IC50 values. Thus, combining detailed kinetics and fluorescence quenching studies can be applied to characterise the interactions between polyphenols in young apples and α-amylase.

Metabolic and phylogenetic analyses based on nitrogen in a new poly-γ-glutamic acid-producing strain of Bacillus subtilis

ObjectivesNitrogen metabolism was investigated during poly-γ-glutamic acid (γ-PGA) synthesis and phylogenetic analyses was used to explore glutamate dependency in Bacillus subtilis HSF1410.ResultsBacillus subtilis HSF1410 was cultured with 15NH4+ in the medium, and the γ-PGA synthesized was then analyzed using 15N-NMR. The γ-PGA framework was partially labeled with 15N, indicating that γ-PGA was synthesized from inorganic nitrogen and carbohydrate. Assay of glutamate synthetase and glutamine synthetase activities also revealed that ammonium can be used to synthesize γ-PGA in HSF1410. Phylogenetic trees based on γ-PGA synthesis genes (pgsBCA) and 16S rRNA showed that HSF1410 falls within a cluster of glutamate-dependent strains, versus glutamate-independent strains, which is confirmed by HSF1410 being unable to produce γ-PGA without glutamate in its mediumConclusionwe classify B. subtilis HSF1410 as a glutamate-dependent strain that can use exogenous inorganic nitrogen sources to synthesize γ-PGA.

A novel formulation of thiamine dilaurylsulphate and its preservative effect on apple juice and sterilised milk

Thiamine dilaurylsulphate (TLS), synthesised by a new method, was developed for a formulation with a wide antimicrobial spectrum and evaluated in apple juice and milk. The result of a disc diffusion method showed that TLS, which was synthesised from sodium lauryl sulphate and thiamine hydrochloride, had strong growth-inhibitory effects on Gram-positive bacteria, yeasts, and moulds, but had weak inhibitory effects on Gram-negative bacteria such as Escherichia coli. Moreover, the TLS antibacterial spectrum could be broadened to all microbes by formulation with organic acids, such as gluconic acid or acetic acid, since organic acids have synergistic effects on TLS bacteriostasis. Compared to TLS, the formulation had a better preservation in milk (pH 6.64) by viable microbial counting, although the antibacterial effect of the formulation with TLS showed no significant difference in apple juice (pH 3.98). Therefore, the TLS formulation has wide application and better potential, as a preservative, to enhance food safety.

Effect of Different Drying Processes on the Physicochemical and Antioxidant Properties of Thinned Young Apple

Abstract In China, there are about 1.6 million tons of thinned young apples (TYAs) every year after blossoming and fruit thinning. These resulting fruits, in reality, could be utilized as agricultural and food resource. This study was undertaken to evaluate the influence on physical properties, bioactive attributes of TYAs that were subjected to chosen drying techniques. In general, significant differences (p < 0.05) exist in physical appearance and polyphenol. Antioxidant capacity was also investigated on the basis of assay for Trolox equivalent antioxidant capacity (TEAC) by 2,2ʹ-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), reducing power and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability. Judging from the results, it was concluded that hot air drying at 60℃ is appropriate for large-scale production; furthermore, vacuum freeze drying tends to manufacture high-value up-market TYA products that are available to give the best results for dehydrated fruits. It is suggested that TYA has great potential in the food industry as functional ingredient.

Antioxidant activities of young apple polyphenols and its preservative effects on lipids and proteins in grass carp (Ctenopharyngodon idellus) fillets

ABSTRACT The aim of this study was to study the antioxidant and antibacterial activities of young apple polyphenols (YAP) and to investigate the application of YAP in grass carp fillets (GCF) stored at 4°C for retarding lipid and protein degradation. The results indicated that YAP had high antioxidant activities in vitro, and the addition of YAP to GCF during low-temperature storage could significantly inhibit the microbial growth; retard the decrease in contents of fatty acids for both unsaturated and saturated ones; and minimize the degradation of salt-soluble myofibrillar protein and sulfhydryl group. The profiles of GCF in the presence and absence of YAP under a scanning electron microscope indicated that YAP could protect GCF from destruction that was resulted from fish deterioration. Therefore, YAP may be developed as natural antioxidants to control lipid and protein degradation and to extend shelf life of freshwater fish fillets.

Metabolic Redesign of Rhodobacter sphaeroides for Lycopene Production

Lycopene plays an important role as an antioxidative and anticancer agent, and is an increasingly valuable commodity in the global market. Rhodobacter sphaeroides, a carotenogenic and phototrophic bacterium, is an efficient and practical host for carotenoid production. Herein, we explored the potential of metabolically engineered Rb. sphaeroides as a novel platform to produce lycopene. The basal lycopene-producing strain was generated by introducing an exogenous crtI4 from Rhodospirillum rubrum to replace the native crtI3 and deleting crtC in Rb. sphaeroides. Furthermore, knocking out zwf blocked the competitive pentose phosphate pathway and improved the lycopene content by 88%. Finally, the methylerythritol phosphate pathway was reinforced by integration of dxs combined with zwf deletion, which further increased the lycopene content. The final engineered strain produced lycopene to 10.32 mg/g dry cell weight. This study describes a new lycopene producer and provides insight into a photosynthetic bacterium as a host for lycopene biosynthesis.

Corrigendum to “Interactions between polyphenols in thinned young apples and porcine pancreatic α-amylase: Inhibition, detailed kinetics and fluorescence quenching” [Food Chem. 208 (2016) 51–60]

We declare that the key method, inhibition kinetics used in this paper is originally trained and instructed by Dr. Frederick J. Warren who is at Quadram Institute and Prof. Michael J. Gidley who is at The University of Queensland. As both the scientists made an intelligent contribution to this work, they are specially acknowledged. Their contacts are shown above.

Purification, Characterization, Antioxidant and Antitumour Activities of Polysaccharides from Apple Peel Pomace Obtained by Pre-pressing Separation

Abstract Purification, characterization, in vitro antioxidant and antitumour activities of polysaccharides from apple peel pomace obtained by pre-pressing separation were investigated. Apple peel polysaccharides (APP) were obtained by water extraction and ethanol precipitation. They were further purified by chromatography of Cellulose DEAE-52 and Sephadex G-150 to obtain three fractions (APP-1, APP-2 and APP-3). Both GC-MS and HPLC analysis showed that galactose and arabinose were two main components in the three fractions with an average molecular weight of 197 kDa, 395 kDa and 303 kDa, respectively. Uronic acids were only presented in APP-2 and APP-3, which were further confirmed by Fourier transform infrared spectroscopy. Besides, the results showed that the antioxidant activity measured by ferric-reducing power and scavenging of O2•−, DPPH• and OH• and the antitumour activity examined by HepG2 cells were connected with the content of uronic acids. These findings provide scientific basis for comprehensive utilization of apple peel pomace.

Characterization, antioxidant activities and hepatoprotective effects of polysaccharides from pre-pressing separation Fuji apple peel

ABSTRACT Characterization, antioxidant activities and hepatoprotective effects of polysaccharides from pre-pressing separation apple (Fuji) peel pomace were investigated in this study. Gel permeation chromatography indicated that apple peel polysaccharides (APPs) were a kind of heteropolysaccharides composed of three fractions with homogenous polarity. Both GC–MS and HPLC analysis showed that arabinose, galactose and galacturonic acid were the main monosaccharides in APP. In vitro antioxidant activities of APP were characterized. Furthermore, administration of APP (450 mg/kg bw) in mice significantly decreased the CCl4-induced elevations of serum alanine aminotransferase, asparate aminotransferase and lactic dehydrogenase activities, and hepatic malondialdehyde level and inhibited the decreases in superoxide dismutase and glutathione peroxidase activities caused by CCl4. Histopathological observation further confirmed that APP could protect the liver tissues from CCl4-induced histological alternation. These findings indicate that APP has the antioxidant and hepatoprotective potentials and provide a scientific basis for comprehensive utilization of pre-pressing separation apple peel pomace.

Draft Genome Sequence of Bacillus subtilis subsp. natto Strain CGMCC 2108, a High Producer of Poly-γ-Glutamic Acid

ABSTRACT Here, we report the 4.1-Mb draft genome sequence of Bacillus subtilis subsp. natto strain CGMCC 2108, a high producer of poly-γ-glutamic acid (γ-PGA). This sequence will provide further help for the biosynthesis of γ-PGA and will greatly facilitate research efforts in metabolic engineering of B. subtilis subsp. natto strain CGMCC 2108.