Yurong Guo

Preparation and characterization of chitosan film incorporated with thinned young apple polyphenols as an active packaging material

The objective of this study was to characterize the physical, mechanical and bioactive properties of chitosan film incorporated with thinned young apple polyphenols (YAP). The results indicated that the addition of YAP resulted in a significant increase in the thickness, density, swelling degree, solubility and opacity of chitosan film, but the water content, water vapor permeability and mechanical properties of the film were decreased. Besides, the antioxidant and antimicrobial properties of chitosan film were significantly enhanced by YAP. Both the NMR and FTIR spectra indicated the interactions between YAP and chitosan were likely to be non-covalent. Furthermore, the thermal stability of the film was decreased by YAP addition, suggested by DSC. Interestingly, the changing tendency of crystalline degree indicated by X-ray kept pace with that of thermal stability for YAP-chitosan films. Overall, YAP-chitosan film was shown a potential as a bioactive packaging material to extend food shelf-life.

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.

Characterization of citrus pectin films integrated with clove bud essential oil: Physical, thermal, barrier, antioxidant and antibacterial properties

The increasing demand for bio-based materials to be used in food packaging has stimulated the development of novel, environmentally-friendly edible films. Antimicrobial films were developed by incorporating different levels of clove bud essential oil (0.5%, 1.0%, and 1.5%) into the citrus pectin in order to modify the functional properties of the films. Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry analysis (DSC) and X-ray diffraction (XRD) were performed, together with the determination of physical, optical, mechanical, antioxidant and antimicrobial properties of pectin emulsified films. The inclusion of oil significantly enhanced the water barrier properties of the films. Addition of oil leads to more opaque films with relatively heterogeneous microstructure, resulting in an increase in film opacity. The composite films were more resistant to breakage and more flexible than the control films. Differential scanning calorimetry (DSC) demonstrated that films incorporating CEO exhibited improved heat stability with slightly higher degradation temperature, compared with control films. The inhibitory effect of pectin films with CEO was also evaluated on three common foodborne bacteria. These results revealed that clove oil has a good potential to be incorporated into citrus pectin to make antimicrobial edible films or coatings for various food applications.

Effects of thinned young apple polyphenols on the quality of grass carp (Ctenopharyngodon idellus) surimi during cold storage

The aim of this study was to investigate the effects of young apple polyphenols (YAP) on the quality of grass cap surimi (GCS) during storage at 4°C. The addition of YAP into GCS was found to be effective in delaying lipid oxidation, soluble myofibrillar protein (SMP) degradation and changes of L∗, a∗ and b∗ values of GCS. Chlorogenic acid was screened to be the primary component showing preservative effects. YAP was shown to protect the functional properties of SMP during cold storage, retarding both the decrease in emulsifying activity and stability, and the increase in surface hydrophobicity of SMP. Additionally, the loss of gel strength and texture of GCS with YAP were significantly (P<0.05) lower than that of GCS without YAP during cold storage. Therefore, YAP may be developed as a natural antioxidant to maintain the quality and to extend the shelf life of freshwater fish surimi.

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.

Simultaneous separation and purification of chlorogenic acid, epicatechin, hyperoside and phlorizin from thinned young Qinguan apples by successive use of polyethylene and polyamide resins

The method for separating and purifying chlorogenic acid (CA), epicatechin (EC), hyperoside (HY) and phlorizin (PH) simutaneously from young Qinguan apples by successive use of X-5 and polyamide resins has been developed in this study. The order of adsorption capacities of X-5 for the four phenolics was PH>HY>EC>CA, and the adsorption equilibriums of the four phenolics onto X-5 resin conformed to Langmuir isotherms preferentially. The adsorption kinetics of EC and CA onto X-5 conformed to the pseudo-first-order model, while that of HY and PH accorded with the pseudo-second-order model. Interestingly, the values of equilibrium adsorption capacities (Qe) calculated in the preferential kinetics models were closer to that of theoretical maximum adsorption capacities (Q0) calculated by Langmuir isotherms. Through dynamic adsorption and desorption using X-5 and polyamide resins with ethanol solution as strippant, CA, EC, HY and PH were obtained with purities of 96.21%, 95.34%, 95.36% and 97.36%, respectively.

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.

Innovation and Practice of Separation Pre-Pressing Technology and WholeApple Utilization

Apple and apple products are one kind of popular fruit and fruit products among the world. The planting acreage, output and trade quantity of the apples in the world are keeping increasing. At present, China has become the biggest apple producing and trading country. However, Chinese companies of concentrated apple juice suffer a serious deficit since the global financial crisis. The most important reasons are the rising cost of raw materials, less utilization and the single products. In order to solve these problems, pressing pre-peeled apple and the whole apple utilization were proposed, which not only solved the less processing quality, discoloration, pesticide residues and other issues, but also processed apples based on the nutrients of different parts (juice, flesh, peel and seeds). It may extend juice processing chain and achieve zero waste of processing apples which will be the future direction of the juice industry.

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.