Dr Quan Vuong

© 2019 International Society for Horticultural Science. All rights reserved. Ethylene, hydrogen sulphide (H2S) and nitric oxide (NO) are signaling molecules that affect plant metabolism. Postharvest fumigations with these gases have been shown to interfere with a range of factors associated with postharvest senescence. This study reports on postharvest studies with pak choy (Brassica rapa subsp. chinensis) that examined the effect of fumigation with hydrogen sulphide and nitric oxide and subsequent storage at 10°C in air with and without the addition of 0.1 µL L-1 ethylene. The results showed that treatment with nitric oxide increased the shelf life and decreased respiration rates for the pak choy heads during the storage. However, fumigation with H2S alone or in combination with NO resulted in greater inhibition of respiration rate and extension in market life, and this effect was more pronounced in the presence of 0.1 µL L-1 ethylene.

© 2017 Olive pomace is a waste produced by the olive oil industry in massive quantities each year. Disposal of olive pomace is difficult due to high concentrations of phenolic compounds, which is an environmental concern. However, phenolic compounds have applications in the health industry. Therefore, extraction of phenolic compounds from olive pomace has the potential to remove an environmentally hazardous portion of pomace while creating an additional source of income for farmers and producers. Using advanced technologies including Ultrasound Assisted Extraction (UAE), combined with water as an extraction solvent, has recently gained popularity. The present study outlines the optimal UAE conditions for the extraction of phenolic compounds with high antioxidant activity from olive pomace. Optimal conditions were developed using RSM for parameters power, time and sample-to-solvent ratio. Total phenolic compounds determined by Folin Ciocalteu method and total major bioactive compounds determined by HPLC as well as antioxidant capacity (DPPH and CUPRAC) were investigated. The optimal conditions for the extraction of phenolic compounds with high antioxidant activity were 2 g of dried pomace/100 mL of water at 250 W power for 75 min. UAE improved the extraction efficiency of water and yielded extracts with high levels of phenolic compounds and strong antioxidant activity.

© 2017, © 2017 Har Krishan Bhalla & Sons. The aim of this study was to compare phytochemical and antioxidant properties of different parts of Salacia chinensis L. The root of S. chinensis had the highest content of phenolics, flavonoids, proanthocyanidins and saponins (64.4 mg gallic acid equivalent /g dried weight (DW), 106 mg catechin equivalent (CE)/g DW, 43.5 mg CE/g DW and 799.9 mg escin equivalent /g DW, respectively), followed by the stem and leaf. Similarly, results from the four antioxidant assays (ABTS, DPPH, FRAP and CUPRAC) showed that the root of S. chinensis had the highest antioxidant capacity (632.2, 577.1, 443.3 and 365.0 µM trolox equivalent/g DW, respectively), followed by the stem while the leaf had the lowest antioxidant capacity. From HPLC chromatograms, three major compounds were detected from the root and stem of S. chinensis, while more major individual compounds in lower quantities were seen in the leaf. As the root contained high phytochemical and antioxidant properties, future studies are recommended to isolate and identify the major bioactive compounds from the root for further industrial utilization.

© 2016 Elsevier B.V. The influence of process variables (pea starch, guar gum and glycerol) on the viscosity (V), solubility (SOL), moisture content (MC), transparency (TR), Hunter parameters (L, a, and b), total color difference (dE), yellowness index (YI), and whiteness index (WI) of the pea starch based edible films was studied using three factors with three level Box-Behnken response surface design. The individual linear effect of pea starch, guar and glycerol was significant (p < 0.05) on all the responses. However, a value was only significantly (p < 0.05) affected by pea starch and guar gum in a positive and negative linear term, respectively. The effect of interaction of starch × glycerol was also significant (p < 0.05) on TR of edible films. Interaction between independent variables starch × guar gum had a significant impact on the b and YI values. The quadratic regression coefficient of pea starch showed a significant effect (p < 0.05) on V, MC, L, b, dE, YI, and WI; glycerol level on dE and WI; and guar gum on dE and SOL value. The results were analyzed by Pareto analysis of variance (ANOVA) and the second order polynomial models were developed from the experimental design with reliable and satisfactory fit with the corresponding experimental data and high coefficient of determination (R2) values (>0.93). Three-dimensional response surface plots were established to investigate the relationship between process variables and the responses. The optimized conditions with the goal of maximizing TR and minimizing SOL, YI and MC were 2.5 g pea starch, 25% glycerol and 0.3 g guar gum. Results revealed that pea starch/guar gum edible films with appropriate physical and optical characteristics can be effectively produced and successfully applied in the food packaging industry.

© 2016 Elsevier Ltd Background Sweet cherries (Prunus avium L.) are a nutritious fruit which are rich in polyphenols and have high antioxidant potential. Most sweet cherries are consumed fresh and a small proportion of the total sweet cherries production is value added to make processed food products. Sweet cherries are highly perishable fruit with a short harvest season, therefore extensive preservation and processing methods have been developed for the extension of their shelf-life and distribution of their products. Scope and approach In this review, the main physicochemical properties of sweet cherries, as well as bioactive components and their determination methods are described. The study emphasises the recent progress of postharvest technology, such as controlled/modified atmosphere storage, edible coatings, irradiation, and biological control agents, to maintain sweet cherries for the fresh market. Valorisations of second-grade sweet cherries, as well as trends for the diversification of cherry products for future studies are also discussed. Key findings and conclusions Sweet cherry fruit have a short harvest period and marketing window. The major loss in quality after harvest include moisture loss, softening, decay and stem browning. Without compromising their eating quality, the extension in fruit quality and shelf-life for sweet cherries is feasible by means of combination of good handling practice and applications of appropriate postharvest technology. With the drive of health-food sector, the potential of using second class cherries including cherry stems as a source of bioactive compound extraction is high, as cherry fruit is well-known for being rich in health-promoting components.

© 2016, Taylor & Francis Group, LLC. Xao tam phan (Paramignya trimera (Oliv.) Guillaum) has been used as an herbal medicine for the treatment of cancer or cancer-like diseases in recent years, particularly in Vietnam. Drying is an important step for preparation of dried materials for storage and further investigation; however, the effects of drying must be taken into account when processing samples, because this can have profound effects on the stability of phytochemical compounds and the biological activity of the dried P. trimera root. As such, this study assessed the effects of four different drying methods (conventional, hot air, vacuum, and microwave) on phytochemical retention and antioxidant capacity of P. trimera root, to identify an optimal drying method for P. trimera root. The results showed that the drying methods significantly affected phytochemical levels and antioxidant capacity of P. trimera root and that among the four drying methods tested, microwave drying (400¿W) had the highest levels of phytochemical compounds, with total phenolic, total flavonoid, proanthocyanidin, and saponin contents of 11.27¿mg GAE, 19.88¿mg RE, 3.98¿mg CE, and 267.15¿mg EE/gram of dried sample, respectively. Dried sample prepared using this method had antioxidant capacity comparable to that of other drying methods. In addition, this method had the shortest drying time (0.28¿h) and consumed the least energy (0.28¿kWh). Therefore, microwave drying should be considered for drying P. trimera root for further investigation and utilization.

© 2016, The Korean Society of Food Science and Technology and Springer Science+Business Media Dordrecht. The effects of different solvents on the recovery of (i) extractable solids (ES), (ii) total phenolic compounds (TPC), (iii) total flavonoid content (TFC), (iv) vitamin C, and (v) antioxidant activity from lemon pomace waste were investigated. The results revealed that solvents significantly affected the recovery of ES, TPC, TFC, and antioxidant properties. Absolute methanol and 50% acetone resulted in the highest extraction yields of TPC, whereas absolute methanol resulted in the highest extraction of TFC, and water had the highest recovery of vitamin C. 50% ethanol, and 50% acetone had higher extraction yields for TPC, and TFC, as well as higher antioxidant activity compared with their absolute solvents and water. TPC and TFC were shown to be the major components contributing to the antioxidant activity of lemon pomace.

© 2014 Institute of Food Science and Technology. Summary: The papaya (Carica papaya) leaf (PL) contains high levels of saponins and polyphenolic compounds, and historically, it has been used as a folk medicine for numerous ailments, including cancer. PL is traditionally prepared by hot water extraction; however, optimised extraction conditions have not been assessed. This study optimised conditions for the extraction of saponins from PL and assessed their antioxidant capacity and antipancreatic cancer activity. Optimisation was achieved using response surface methodology. Saponins and total phenolic compounds were assessed for their antioxidant, free radical scavenging, ion-reducing capacity, and antipancreatic cancer activity. Optimal aqueous extraction conditions were 85 °C, 25 min. and a water-to-leaf ratio of 20:1 mL g-1. Ethanol extracts demonstrated higher antioxidant, free radical scavenging and ion-reducing capacity, as well as antipancreatic cancer activity. This study revealed that the PL contains numerous bioactive compounds, with significant anticancer activity warranting further studies on the isolation and characterisation of individual bioactive compounds from the PL.

© 2015 Elsevier B.V. Xao tam phan (. Paramignya trimera (Oliv.) Guillaum) is a Vietnamese traditionally medicinal plant used in the treatment of numerous cancers. The preparation of Xao tam phan extracts including solvent type and extraction method have significant effects on extraction efficiency, phytochemical profile and biological activity. This study aimed to investigate the effects of five various solvents (water, acetonitrile, methanol, ethyl acetate and hexane) and three different extraction methods (conventional, ultrasound-assisted and microwave-assisted) on phytochemical yield and antioxidant capacity of P. trimera root from Vietnam. The results indicate that methanol extracted the maximal yield of phytochemicals from P. trimera and exhibited the greatest antioxidant capacity, with eleven compounds were identified and quantified. Microwave-assisted extraction produced the maximal phytochemical yields (except for total flavonoids) and antioxidant capacity, when compared to conventional and ultrasound-assisted extractions. These data reveal that the use of methanol and microwave-assisted extraction are recommended for extraction of biologically active phytochemicals from P. trimera root for application in the nutraceutical and/or pharmaceutical industries.

© 2015, The Korean Society of Food Science and Technology and Springer Science+Business Media Dordrecht. Far-infrared (FIR) vacuum is an advanced drying technique that has recently been applied in food processing. Optimal drying conditions for processing tea from Miang leaves using FIR vacuum drying were investigated. Response surface methodology with a central composite design was used to design, analyze, and predict the optimal time and temperature conditions for FIR vacuum drying, taking into account the physicochemical properties of Miang leaves. When the temperature increased from 50 to 65°C and the time from 60 to 120 min, the amount of epicatechin, epicatechin gallate, epigallocatechin gallate, and total catechins significantly (p<0.05) increased while the moisture content and water activity significantly (p<0.05) decreased, compared with controls. The physicochemical properties of dried Miang leaves were significantly (p>0.05) influenced by time and temperature, compared with controls. Drying conditions of 65°C for 120 min are recommended for optimization of drying.

© 2015 Wiley Periodicals, Inc. Vitex agnus-castus (VitexAC) leaves have been used for medicinal purposes for many years. Drying is important to prepare starting materials for further processing, as it is associated with production cost and quality of the materials. Herein, the effects of five different drying conditions on the physical, chemical and antioxidant properties of VitexAC were evaluated. The results showed that 30% of dried leaves with moisture content of less than 7% could be produced from fresh leaves. VitexAC leaves dried by freeze and vacuum drying at 65C had higher levels of bioactive compounds as well as higher antioxidant capacity in comparison with other drying conditions, revealing that these drying conditions are more suitable for drying VitexAC leaves. However, freeze drying is costly and time-consuming; thus, vacuum drying at 65C is suggested for drying the VitexAC leaves as the starting materials for further processing steps. Practical Applications: As drying is an important process to prepare starting materials for further processing steps, it is important to compare different drying methods to identify the most suitable method with low cost and less effect on material quality. The results showed that inappropriate drying conditions resulted in big loss of bioactive compounds and antioxidant capacity. Vacuum drying at 65C was found to be the most suitable method, which can be easily applied for drying Vitex agnus-castus leaves in the industrial scale.

Copyright © 2015 Verlag Helvetica Chimica Acta AG, Zürich. The genus Eucalyptus (Myrtaceae) is mainly native to Australia; however, some species are now distributed globally. Eucalyptus has been used in indigenous Australian medicines for the treatment of a range of aliments including colds, flu, fever, muscular aches, sores, internal pains, and inflammation. Eucalyptus oils containing volatile compounds have been widely used in the pharmaceutical and cosmetics industries for a multitude of purposes. In addition, Eucalyptus extracts containing nonvolatile compounds are also an important source of key bioactive compounds, and several studies have linked Eucalyptus extracts with anticancer properties. With the increasing research interest in Eucalyptus and its health properties, this review briefly outlines the botanical features of Eucalyptus, discusses its traditional use as medicine, and comprehensively reviews its phytochemical and anticancer properties and, finally, proposes trends for future studies.

© 2015 American Chemical Society. In this paper we present a new method for finding the optimal path for pulling a ligand from the binding pocket using steered molecular dynamics (SMD). Scoring function is defined as the steric hindrance caused by a receptor to ligand movement. Then the optimal path corresponds to the minimum of this scoring function. We call the new method MSH (Minimal Steric Hindrance). Contrary to existing navigation methods, our approach takes into account the geometry of the ligand while other methods including CAVER only consider the ligand as a sphere with a given radius. Using three different target + receptor sets, we have shown that the rupture force Fmax and nonequilibrium work Wpull obtained based on the MSH method show a much higher correlation with experimental data on binding free energies compared to CAVER. Furthermore, Wpull was found to be a better indicator for binding affinity than Fmax. Thus, the new MSH method is a reliable tool for obtaining the best direction for ligand exiting from the binding site. Its combination with the standard SMD technique can provide reasonable results for ranking binding affinities using Wpull as a scoring function.

Bitter melon, Momordica charantia L. (Cucurbitaceae), aqueous extracts are proposed to have health-promoting properties due to their content of saponins and their antioxidant activity. However, the optimal conditions for the aqueous extraction of saponins from bitter melon and the effects of spray drying have not been established. Therefore, this study aimed to optimize the aqueous extraction of the saponins from bitter melon, using response surface methodology, prepare a powder using spray drying, and compare the powder's physical properties, components, and antioxidant capacity with aqueous and ethanol freeze-dried bitter melon powders and a commercial powder. The optimal aqueous extraction conditions were determined to be 40 °C for 15 min and the water-to-sample ratio was chosen to be 20:1 mL/g. For many of its physical properties, components, and antioxidant capacity, the aqueous spray-dried powder was comparable to the aqueous and ethanol freeze-dried bitter melon powders and the commercial powder. The optimal conditions for the aqueous extraction of saponins from bitter melon followed by spray drying gave a high quality powder in terms of saponins and antioxidant activity. © 2014 Institute of Food Technologists®.

Lilly pilly (LP) fruit (Syzygium paniculatum Gaertn.) is widely grown in eastern Australia and has been used as food by indigenous Australians. However, there is limited information on its bioactivity. This study investigated the physicochemical and antioxidant properties of the crude fruit extract, identified its bioactive compounds and also assessed its potential anti-proliferative effect on pancreatic cancer cells. Our data showed that the LP extract was water-soluble and possessed a total phenolic content of 96 mg of gallic acid equivalents (GAE)/g, flavonoid levels of 52 mg catechin equivalents (CAE)/g, proanthocyanidin levels of 29 mg CAE/g. Several phenolic compounds such as gallic acid, chlorogenic acid, catechin and epicatechin were identified in the LP extract with levels of 0.39, 2.35, 0.47 and 2.9 mg/g, respectively. Results from six different antioxidant assays revealed that the LP extract pocessed potent antioxidant and free radical scavenging capacity. Although antioxidant capacity of the extract was lower than that of vitamin E, vitamin C and BHT, it could be significantly improved if the extract was to be further purified. We also showed that the LP extract (200 µg/mL) significantly reduced the viability of MiaPaCa-2 and ASPC-1 pancreatic cancer cells to levels comparable to that of the chemotherapeutic agent gemcitabine. For this reason lilly pilly should be further investigated for its health promoting and potential anti-cancer benefits, particularly for pancreatic cancer. © 2014 Elsevier GmbH.

Tea has been widely consumed around the world for thousands of years and drinking tea is a daily habit for people of all ages. Tea is a major source of flavanoids, which have become well known as antioxidants. Tea also contains caffeine and theanine, which have been found to associate with health benefits. Many animal and epidemiological studies have been conducted to investigate the link between tea consumption and human health. However, common questions that arise about tea consumption include: whether all teas are the same, why drinking tea is linked with health benefits, how do the different ways of tea preparation impact on availability of tea components, how much and how long a person should consume tea to obtain health benefits, and whether there is any negative health effect associated with drinking tea. To answer these questions, this paper outlines the tea components and their link to human health, discusses major factors affecting availability of tea components in a tea cup, and reviews the latest epidemiological evidence linking tea consumption to human health. © 2014 Copyright Taylor and Francis Group, LLC.

While amyloid-related diseases are at the center of intense research efforts, no feasible cure is currently available for these diseases. The experimental and computational techniques were used to study the ability of glyco-acridines to prevent lysozyme amyloid fibrillization in vitro. Fluorescence spectroscopy and atomic force microscopy have shown that glyco-acridines inhibit amyloid aggregation of lysozyme; the inhibition efficiency characterized by the half-maximal inhibition concentration IC 50 was affected by the structure and concentration of the derivative. We next investigated relationship between the binding affinity and the inhibitory activity of the compounds. The semiempirical quantum PM6-DH+ method provided a good correlation pointing to the importance of quantum effects on the binding of glyco-acridine derivatives to lysozyme. The contribution of linkers may be explained by the valence bond theory. Our data provide a basis for the development of new small molecule inhibitors effective in therapy of amyloid-related diseases. © 2013 American Chemical Society.

The aims of this study were to develop optimal conditions for decaffeination and spray drying procedures to produce decaffeinated and high caffeine powders from green tea (Camellia sinensis). Blanching the tea leaves with water at 100. °C for 4. min at a water-to-tea ratio of 20:1. mL/g removed 83% of the caffeine while retaining 94% of the catechins. The optimal spray drying conditions, which gave the highest yield of green tea powder and the highest concentrations of the naturally occurring epistructured catechins were found to be 180. °C for the inlet temperature and 115. °C for the outlet temperature. Using these optimal conditions, a decaffeinated green tea powder (7 mg/g caffeine) and a high caffeine powder (95. mg/g) were produced. These two green tea powders had excellent physical properties and could be used as instant teas by consumers or utilized in the food, cosmetic and nutraceutical industries. © 2012 Elsevier B.V.

The pH of the aqueous brewing solution was maintained at values ranging from 1 to 9 during the green tea extraction and the effects on the tea's extracted constituents were studied. The epistructured catechins were stable under acidic conditions but epimerized or degraded at pH. =. 6. The extractable solids contained more epistructured catechins at pHs 3-5 but more non-epistructured catechins at pHs 6-7. More tea cream was obtained at pH 1 but the concentration of catechins, caffeine and theanine was low in this fraction. Therefore, to maximize the extraction of the epistructured catechins and to minimize their epimerization and degradation and to maximize the extraction of caffeine and theanine, the results suggest that the pH should be maintained between 3 and 5.3 during the aqueous brewing process. © 2012 Elsevier Ltd.