Dr Quan Vuong

The Australian native plant, lemon-scented tea tree (LSTT) is rich in polyphenols with strong antioxidant activities. Encapsulation enhances the potential applications of plant extracts and additionally protects them from degradation. The encapsulating agent is one of the key elements in the encapsulation process. In this study, lemon pomace powder (LPP) was investigated as a new carrier agent for LSTT leaf phenolic extract, and its performance was compared with the commonly used polysaccharide (i.e., maltodextrin (MD)) and protein-based (i.e., soy protein isolate (SPI)) coating materials. The encapsulation efficiency, colour, polyphenol and antioxidant property retention, particle morphology, crystallinity, flow properties, and release behaviour in food simulants and gastrointestinal fluid were studied to compare the performance of the carrier agents individually and in combinations. The encapsulation efficiency of lemon pomace powder (LPP) was above 95 % and the order for the retention of polyphenol and antioxidant capacities were MD>LPP>SPI. LPP offers better flow properties and unique particle morphology, which was also amorphous in nature with some degree of crystallinity. The release profile in the food simulants showed a controlled and sustained release rate over the tested period, which was comparable with MD and SPI. In gastrointestinal fluids, the percent release followed the order of SPI>LPP>MD for the carrier agents. The incorporation of LPP with MD and SPI can improve several properties of the individual carrier agents. Thus, LPP can be used as a potential carrier agent for polyphenols in functional food formulation either on its own or in combination with other coating materials.

Herbal teas, which are a rich and diverse source of polyphenols, have been widely consumed due to their association with various health benefits. Preparation techniques can significantly affect the level of polyphenols in a cup of tea. Thus, this study investigated the impact of different preparation techniques, including brewing time in hot water, microwave-assisted extraction with cold and hot water (cold and hot MAE) for both radiation time and power, and laboratory testing condition on extractability of polyphenols in infusion from a teabag. The results showed that brewing time using hot water significantly affected the extractability of polyphenols and antioxidant activity. Cold and hot MAE conditions also significantly affected the extractability of polyphenols and antioxidant activity from a teabag infusion. Hot brewing at 7 min and cold MAE at full power with second boiled (1.93 min on and 1 min off radiation) are recommended for the preparation of herbal tea from a teabag, as these conditions had comparable extractability of polyphenols and antioxidant activity in comparison with other preparation techniques. There are over 20 major chromatogram peaks, of which 7 were identified as gallic acid, catechin, caffeic acid, ferulic acid, epicatechin gallate, quercetin, and kaempferol, revealing potential health benefits of this herbal tea.

The lemon-scented tea tree (LSTT) is an Australian native herb and is a rich source of essential oil and phenolics. The ETHOS X extraction system is known as a commercial microwave-assisted extraction (MAE) system for extracting bioactive compounds from plant materials. This study investigated the influence of soaking time, radiation time, microwave power, and sample to solvent ratio on the extraction efficiency of polyphenols and antioxidant properties from lemon-scented tea tree leaves and optimized the extraction conditions using response surface methodology (RSM). The effectiveness of ETHOS X was further compared with ultrasound-assisted extraction (UAE) and shaking water bath (SWB) techniques. The results revealed that soaking time did not significantly affect the recovery of phenolics from the leaves (p > 0.05). Thus, soaking is not required for the ETHOS X extraction of polyphenols from LSTT leaves. RSM was successfully applied to explore the impact of ETHOS X extraction conditions and optimize the extraction conditions. Radiation time significantly affects the recovery yield of phenolics (p < 0.05) positively, whereas irradiation power and sample to solvent ratio adversely influenced the extraction yields of phenolics. The optimal ETHOS X extraction conditions were: radiation time of 60 min, irradiation power of 600 W, and sample to solvent ratio of 2 g/100 mL. Under these conditions, 119.21 ± 7.09 mg of phenolic, 85.31 ± 4.55 mg of flavonoids, and 137.51 ± 12.52 mg of proanthocyanidins can be extracted from a gram of dried LSTT leaves. In comparison with UAE and SWB, ETHOS X is not more effective for the extraction of phenolics than UAE and SWB. However, this technique can save half of the solvent volume compared to UAE and SWB techniques.

Soy milk by-product (SMB), the insoluble fraction of the soybean cotyledon, is a rich source of phytochemicals such as isoflavones, soysaponins and other phenolic compounds. However, they are susceptible to degradation due to high moisture content in SMB. Therefore, drying is needed to remove moisture content in SMB for further applications and to prevent spoilage. This study aimed to determine the fate of phenolics, soysaponins, major isoflavones and antioxidant activity in SMB during two conventional drying processes, including fan forced oven (FFO) and vacuum oven (VO), and then compare with freeze drying to identify the most suitable drying conditions. Results showed that FFO did not significantly affect retention of phenolics, soysaponins and antioxidant capacity but had a significant impact on diadzin and genistin. FFO at 100 °C for 140 min was the most suitable condition for drying SMB. In contrast, VO did not significantly affect soysaponin, diadzin and genistin, but significantly influenced phenolic content and antioxidant capacity. VO at 60 °C for 330 min was the most suitable condition for drying SMB. In comparison with freeze drying, FFO at 100 °C for 140 min retained better soysaponin (55.96 mg ESE/g), diadzin (79.60 µg/g) and genistin (159.4 µg/g) and consumed less energy, thus this condition is recommended for dehydration of SMB for further applications.

Scaevola spinescens is endemic to Australia and traditionally used as a medicinal plant. While its bioactive compounds have been studied, their concentrations in different parts of the plant have not been reported. This study compared total phenolic content (TPC), flavonoids, saponins and antioxidant properties, as well as major individual phytochemical compounds in the whole root, root bark, root wood, whole stem, stem bark, stem wood, and leaf of S. spinescens. The results showed the leaf had significantly highest concentrations of TPC followed by the root bark and stem bark (47.34, 12.24 and 10.20 mg GAE/g, respectively). Flavonoids concentrations were also significantly higher in the leaf compared to the root bark and stem bark (20.95, 6.22 and 4.19 mg CE/g, respectively). For saponins, the root bark contained significantly highest concentrations (112.58 mg EE/g). Luteolin 7-glucoside was isolated and identified in the leaf of S. spinescens. Eight major compounds were identified with the leaf displaying the highest diversity of major compounds, and in higher concentrations, compared to the other plant constituents. As the leaf and root bark contained the highest concentrations of phytochemicals, these plant parts are recommended as starting material for future studies, to further isolate and identify the major compounds from S. spinescens and investigate their biological properties for use in pharmaceutical and food applications.

Gac (Momordica cochinchinensis) is commercially used for production of Gac oil. Gac pulp, which accounts for 40-50% of fruit weight, is major by-product. This study aimed to optimise extraction conditions including pH, temperature, time, ratio and ultrasonic power for recovery of pectin from Gac pulp, and compare its properties using ultrasound-assisted extraction (UAE) and acidic hot water extraction (AHWE) techniques, the typical advanced and conventional techniques for pectin extraction. Response surface methodology with Box-Behnken design was applied for both techniques. The results showed that pH was the most influential factor. Optimal AHWE conditions were identified at 90°C for 100 min with solvent to sample ratio of 50 mL/g and pH of 1.5, while optimal UAE conditions were 35 min, pH of 1.5, and ultrasonic power of 200 W. The recovery yield of pectin from UAE (53.80% ± 6.04) was significantly higher than that of AHWE (42.97%± 5.08). Pectin obtained from two techniques were low methoxyl pectin (DE < 50%) with good solubility, potent free radical scavenging capacity, and similar structure. As UAE has advantages of short extraction time, more efficient recovery of pectin with better properties, UAE is recommended for recovery of pectin from Gac pulp for further applications.

Scaevola spinescens is endemic to Australia and has traditionally been used by Aboriginal and Torres Strait Islander communities to treat a variety of conditions including colds, flu, fever, stomach pain, urinary disorders, sores, tinea, leprosy, and cancer. Extracts prepared from S. spinescens are non-toxic and have been linked with various medicinal properties including antiviral, antibacterial, anti-inflammatory, and anticancer activities. These studies support the ethnopharmacological use of S. spinescens by Indigenous peoples of Australia and highlight the need for further investigations on the plant for potential use in pharmaceutical and food applications. This review provides a comprehensive, up-to-date review of the literature on S. spinescens focusing on the traditional use, medicinal properties, phytochemicals, and factors that affect their composition during pre-treatment and extraction, as well as providing a framework for future studies of the plant.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.