Phytochemical retention and antioxidant capacity of xao tam phan (Paramignya trimera) root as prepared by different drying methods

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.     

Management of Surface Drying Temperature to Increase Antioxidant Capacity of Thyme Leaf Extracts (Thymus vulgaris L.)

Thyme leaves are an important source of essential oils with antioxidant activity; these compounds are located in trichomes on the leaf surface. The drying conditions affect not only the drying time but also the antioxidant activity. In the literature, a drying temperature of 70°C appears to be the best for drying thyme leaves according to their antioxidant capacity. Considering drying periods at different temperatures also could be beneficial. With these considerations, the goal of this work was to establish a drying strategy with which to manage a drying temperature on the leaf surface that will enable the drying time to be shortened and improve the antioxidant capacity (AC) of the extract of dried thyme leaves. The drying strategy consisted of two consecutive drying periods in order to manage the drying temperature on the leaf surface. The first drying period was carried out at 80°C (T _a1) until the sample surface reached a temperature of 70°C, and the temperature was then immediately set to 70, 60, 50, and 40°C (second drying period, T _a2) at different air velocities (v; 1 and 2 m s^?1). Compared to constant drying conditions, two consecutive drying periods were found to improve the drying kinetics: the AC increased from 10.5 to 27.4% while reducing the drying time by 14.5 to 39.2%. The use of this drying strategy was found to be an interesting means of intensifying the convective drying of thyme leaves and its application should be considered when drying similar materials with bioactive compounds on the surface.     

Development of green extraction process to produce antioxidant-rich extracts from purple coneflower

The present study was conducted to develop subcritical water extraction (SWE) of Echinacea purpurea flowers. The influence of temperature and extraction time on quality of extracts considering total phenols content, total flavonoids content, antioxidant capacity and extraction yield, was determined. Optimized extraction parameters for maximised investigated responses were as follows: 147.56 °C and 8.43 min. The experimental values agreed with the values predicted, thus indicating the adequacy of central composite experimental design for modelling the SWE of bioactive compounds from E. purpurea. Results of the study also highlighted the potential application of E. purpurea subcritical water extracts as a source of valuable bioactive compounds.     

Bioactive Compounds and Bioactivities of Centella asiatica (L.) Urban Prepared by Different Drying Methods and Conditions

Centella asiatica (L.) Urban has attracted significant research and commercial interest due to its many health-promoting bioactive compounds, especially phenolic compounds and triterpene saponins, which possess several functional capacities, including antioxidant activity and antimicrobial activity. Prior to its use, however, C. asiatica usually needs to be dried to extend its storage life and to prepare the material for subsequent pharmaceutical processing. The present study investigated the effects of selected drying methods and temperature on the drying characteristics, phenolic compounds, triterpene saponins, antioxidant activity, and antimicrobial activity of dried C. asiatica. Hot-air drying (HAD), combined infrared–hot air drying (IR-HAD), and low-pressure superheated steam drying (LPSSD) were carried out at various temperatures (50, 60, 70°C). The results showed that higher drying temperatures led to higher drying rates but to lower levels of total phenolic compounds, total triterpene saponins, antioxidant activity, and antimicrobial activity. At the same drying temperature, IR-HAD resulted in the highest drying rates; this was followed by LPSSD and HAD in a descending order. Nevertheless, LPSSD resulted in the highest levels of the tested bioactive compounds, antioxidant activity, as well as antimicrobial activity. LPSSD at 50°C yielded dried C. asiatica of the best overall quality.     

Composition Profiles and Functional Properties of Dietary Fiber Powder from Lime Residues: Effects of Pretreatment and Drying Methods

Lime residues after juice extraction have proven to be a potential raw material for producing dietary fiber (DF) powder due to their good functional properties. Compositions and antioxidant activity of DF powder from lime residues as affected by selected pretreatment (hot-water blanching and ethanolic soaking) and drying methods, viz. hot air drying, vacuum drying, and low-pressure superheated steam drying (LPSSD) at 60–80°C, were investigated. Fresh lime residues contained significant amounts of vitamin C, phenolic compounds, and flavonoids. Hesperidin was a major flavonoid and only one polymethoxyflavone (i.e., tangeretin) was detected in small amounts. A decrease in the amount of interested bioactive compounds and their antioxidant activity was noted at almost all steps of processing. Higher retention of bioactive compounds was noted when the residues were subject either to vacuum drying or LPSSD; the total antioxidant activities were 61–62% and 81–82% when being assessed by the β-carotene bleaching and DPPH assays, respectively. Vacuum drying at 80°C was the most suitable condition for preparing DF powder from lime residues due to its short required drying time and its ability to retain bioactive compounds. The in vitro analyses imply that DF powder prepared by vacuum drying at 80°C has the potential to reduce blood glucose and cholesterol levels by exhibiting high glucose retardation index (GRI) and bile acid retardation index (BRI).     

Comparison of two alternatives of combined drying to process blueberries (O'Neal): Evaluation of the final quality

In this work, we examined and compared two combined alternatives for the drying of blueberries (O’Neal). Pretreatments of osmotic dehydration (60°Brix sucrose solution at 40°C for 6 h) and hot air drying (HAD) (60°C, 2.5 m/s for 90 min) were performed to reach the same water content. Pretreated blueberries were then dried by microwave at different microwave output power values: 562.5, 622.5, and 750 W. The combined drying processes were also compared with HAD alone (control). The effects of the processes over blueberries were studied in terms of decrease in water content, drying rate (DR), mechanical properties (firmness and stiffness), optical properties (L*, a*, and hue angle (h)), antioxidant capacity, and rehydration capacity. The hot air–microwave drying decreased the process time and presented a high drying rate compared with the osmotic dehydration–microwave processes and the control drying. In terms of quality, the antioxidant and rehydration capacities were the most affected. The results showed that the best drying method to obtain the desired final product was the hot air–microwave drying (750 W).     

Effect of the condition of spray-drying on the properties of the polypeptide-rich powders from enzyme-assisted aqueous extraction processing

Abstract

Enzyme-assisted aqueous extraction processing (EAEP) is an environmentally friendly technology that simultaneously extracts both oil and protein. It has shown to be commercial feasibility for high oil recovery (～97%) and favorable protein functionality properties. The present study used soy skim, the liquid co-products obtained using EAEP to produce a polypeptide-rich spray-dried powder. The effects of inlet drying air temperature (140?°C, 160?°C, 180?°C and 200?°C), feed flow rate (3, 6, 9, and 12?mL/min), and solids concentration (25%, 30%, 35%, and 40%) on the properties of the polypeptide-rich powders were investigated. Water activity (a_w), color characteristics, bulk density, Carl Index (CI), Water Solubility Index (WSI), micro-morphology, peptide distribution, and antioxidant capacity were significantly affected by different spray-drying parameters. The results of antioxidant capacity test showed that the spray drying conditions significantly affected the antioxidant capacity of the polypeptide-rich powders. The polypeptide molecular weight size and distribution, the composition of the peptide chain, and the cross-linking with other substances could all affect its antioxidant capacity. Overall, good quality polypeptide-rich powders in terms of physicochemical characteristics, micro-morphology, and functional properties can be produced by spray-drying at an inlet temperature of 160?°C, a feed flow rate of 6?mL/min, and solids concentration of 35%.     

Effects of Drying and Extraction Methods on the Quality and Antioxidant Activity of Sea Buckthorn (Hippophae rhamnoides) Berries and Leaves

Sea buckthorn is a promising source of bioactive compounds. However, there is limited information on the effect of post harvest drying and extraction of sea buckthorn on its antioxidant capacity. The effect of freeze, air, and solar dryingon the extraction yield of sea buckthorn berries and leaves was evaluated with respect to their bioactive content. Sequential extraction with solvents of different polarity and solvent-free microwave-assisted extraction were applied. Freeze-drying has better performance in the berries’ extracts, while air-drying has better performance in the leaves’ extracts. All data were analyzed by Multi Factor Analysis of Variance (ANOVA) and Duncan's post-hoc tests at a level of α = .05. Although the extraction yield in the sequential extraction of sea buckthorn berries is significantly better, the leaves’ extracts exhibit superior radical scavenging ability. Accelerated solar drying appears to preserve sea buckthorn leaves without degrading their antioxidant content. The components responsible for the high antioxidant activity of leaves’ extracts were found to be several flavonoids and polyphenols. The extract obtained by the microwave extraction of fresh berries exhibits moderate antioxidant activity compared to the polar extracts of freeze-dried berries.     

Drying kinetics and effect of air-drying temperature on chemical composition of Phyllanthus amarus and Phyllanthus niruri

In this study, the drying kinetics of Phyllanthus amarus and Phyllanthus niruri were investigated experimentally in an air-drying oven as a function of drying temperature (50, 60, and 70°C). The effects of the air-drying temperature on the phenolic content and the LC–MS profile were also studied. Increases in air-drying temperature reduced the drying time and increased the effective moisture diffusivity. An Arrhenius relationship with activation energy values of 22.828 and 43.129?kJ/mol for P. niruri and P.amarus, respectively, expressed the effect of temperature on the diffusivity. Air drying at 70°C increased the availability of some phenolic compounds. However, the higher temperature negatively affected some sensitive components.     

Spray Drying and Process Optimization of Unclarified Pomegranate (Punica granatum) Juice

In this study, production of pomegranate juice powder using a spray dryer was investigated. To prevent stickiness, maltodextrin dextrose equivalent 6 (DE6) was used as a drying agent. While feed flow rate, feed temperature, and air flow rate were kept constant, air inlet temperature (110–140°C), percentage maltodextrin (MD; maltodextrin dry solids/100 g feed mixture dry solids; 39.08–64.12%), and feed mixture concentration (19.61–44.11 °Brix) were chosen as the independent variables. Product properties investigated included moisture content, hygroscopicity, anthocyanin content, color change, solubility, bulk density, total phenolics content, antioxidant capacity, and sensory properties. The products were produced with high yield (86%) and high antioxidant activity (77%). MD and drying temperature were found to be the most important variables in production of pomegranate juice powders. Because total color change (ΔE), bulk density, antioxidant capacity, and powder yield were affected strongly by the independent variables, these parameters were used in optimization of the process. The optimum temperature, feed mixture concentration, and percentage maltodextrin were 100°C, 30.8 °Brix, and 53.5% MD, respectively. This study revealed that by applying these optimal conditions, pomegranate juice powder with a 55% dry solids yield, 9.78 total color change, 0.35 g/mL bulk density, and 57.8% antioxidant capacity were produced.     

Effects of drying conditions on physicochemical and antioxidant properties of banana (Musa cavendish) peels

A significant amount of banana peels is generated as waste annually and shows great potential as a lead material for further utilization in the nutraceutical industry. However, potentiality of banana peel utilization largely depends on the favorable drying condition of the material before it can be used for further processing. Therefore, it is necessary to identify the suitable drying conditions for banana peel. This study investigated the effect of six different drying methods on the quality of banana peels. The results showed that different drying conditions significantly affected the physical, chemical, and antioxidant properties of dried peels. Microwave irradiation at the power level of 960?W for 6?min was the most suitable condition, as these dried peels had good physical properties, minimum loss of bioactive compounds, and antioxidant properties. This was followed by freeze-drying, vacuum oven at 60°C, hot air oven at 120°C, dehumidified air at 60°C, and sun drying. The peels dried by microwave possessed a total phenolic content of 25.26?mg of gallic acid equivalents/g of dry matter (DM) and potent antioxidant capacity [(1,1-diphenyl-2-picrylhydrazyl) of 37.70; 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid of 46.35; ferric reducing antioxidant power of 45.94; and cupric ion reducing antioxidant capacity of 64.55?mg of trolox equivalents/g of DM]. Therefore, the study recommends the use of microwave irradiation under the studied condition (power level of 960?W for 6?min) for further processing and utilization.     

Microencapsulation of Kaffir Lime Oil and Its Functional Properties

This paper describes the effects of spray drying temperature and wall materials on functional properties of kaffir lime oil microcapsules. The effects of spray drying were studied at inlet air temperatures at 160, 180, and 200°C. Two coating materials (konjac glucomannan and gum arabic) were employed in this study. The results indicate that kaffir lime oil had antibacterial activity against all tested pathogens and was able to inhibit Vibrio cholerae comparable to a standard antibiotic. The combination of konjac glucomannan and gum arabic (KGM+GA) can enhance the yield and retention of total oil in the microcapsules more than using konjac glucomannan alone as a wall material. Increasing inlet air temperature resulted in a decrease of antibacterial activity and amount of bioactive volatile compounds. Physical and chemical properties of the microcapsules did not differ significantly (p > 0.05) in terms of process yield, a _w , moisture content, efficiency in retention of total, surface and inner oil, water solubility index, and color except at inlet air temperature of 200°C. However, it was found that the kaffir lime oil microcapsules from KGM+GA produced at inlet temperature of 180°C had the best functional properties in terms of antibacterial activity and efficiency of retention of total encapsulated oil.     

Effect of Different Drying Methods on the Microwave Extraction of Phenolic Components and Antioxidant Activity of Highbush Blueberry Leaves

In the last few decades, researchers have found blueberry leaves to be an interesting source of different phenolic compounds, and drying is an important part of their postharvest and sample preparation processes. In the current study, blueberry leaves were dried using microwave-assisted hot air drying or hot air drying alone at 45, 60, and 75°C to 10–15% wet basis. Corresponding drying characteristics were determined by fitting the moisture ratio obtained in each case with eight theoretical and semitheoretical models for hot air and microwave drying stages. It was observed that best fitting drying models for blueberry leaves depended not only on the nature of the biomaterial but also on the method of drying and the temperature of drying. Phenolic content, monomeric anthocyanin content, and the corresponding antioxidant activity in terms of 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition activity and ferric reducing ability of plasma (FRAP) activity were evaluated for the leaf extract obtained following microwave extraction of the dried samples obtained using the above-mentioned drying methods and were compared to the corresponding bioactive compositional characteristics of freeze-dried blueberry leaves. It was observed that the freeze-dried sample had the highest content of total phenolics and total monomeric anthocyanins along with high antioxidant activity. Furthermore, extracts obtained from the microwave-dried leaf samples obtained with a drying temperature of 60°C had highest total phenolic content and highest total monomeric anthocyanin content among all other drying methods and the extract had an antioxidant activity similar to the freeze-dried blueberry leaf samples, implying that microwave drying at 60°C is a potential alternative to freeze drying for preservation of the phenolic components and antioxidant activity of dried blueberry leaves.     

Drying Kinetics and Color Retention of Dehydrated Rosehips

Abstract

Freshly harvested rosehips (Rosa canina L.) were dehydrated in a parallel flow type air dryer at six air temperatures (30, 40, 50, 60, and 70°C) at air velocities of 0.5, 1.0, and 1.5 m/s. Drying air temperature and velocity significantly influenced drying time and energy requirement. Minimum and maximum energy requirement for drying of rosehips were determined as 6.69 kWh/kg for 70°C at 0.5 m/s, and 42.46 kWh/kg for 50°C, 1.5 m/s. In order to reduce drying energy consumption, it is recommended that the drying air velocity must not be more than 0.5 m/s and drying air temperature should be 70°C. In addition, the influence of drying air temperature and air velocity on the color of dried rosehip has been studied. Hunter L, a, b values were used to evaluate changes in the total color difference (ΔE) on dried rosehips. 70°C drying air temperature and 1 m/s air velocity were found to yield better quality product.     

Drying of Orthosiphon aristatus leaves: Mathematical modeling,drying characteristics,and quality aspects

The stage of maturity for Orthosiphon aritatus (OA) leaves revealed that stage I (young leaves) provided the highest bioactive compounds. Vacuum blanching (VB) for 75?s gave the highest sinensetin (28.4% increment) and eupatorin (21.0% increment) compared with heated water blanching (HWB). The modified Henderson model was the most suitable desorption isotherm model for the OA leaves. The VB and unblanched OA leaves were dried by different drying methods, including convection tray drying (CTD, 40–60°C), heat pump dehumidify drying (HPD, 40–60°C), mixed mode solar drying (64.6°C), and freeze-drying. Three-parameter model (TP) was the best model to explain all drying curves. The drying constant, K in the TP and activation energy were fitted to the Arrhenius model. Effective moisture diffusivities were increased with the VB, drying temperatures, and HPD. The highest specific moisture extraction rate was obtained from the VB and dried in the HPD at 60°C. The quality aspects of sinensetin (10.2% retention), eupatorin (10.7% retention), total phenolics, and antioxidant activity revealed the best quality for the OA leaves pretreated by the VB and dried in the HPD at 60°C and could reduce drying time by 44.8% compared with the CTD. The VB of the OA leaves and dried using the HPD at 60°C were recommended.     

Study and comparison of different drying processes for dehydration of raspberries

The aim of the present study was to evaluate and compare different drying methods (microwave, hot air?+?microwave, and osmotic dehydration?+?microwave) in raspberries (cv. Heritage). A portion of raspberries was pretreated with osmotic dehydration (60°Brix sucrose solution at 20°C for 360?min) and another with hot air drying (HAD) (1.5?m/s air speed at 60°C for 300?min). Pretreated raspberries were then dried by microwave and at three different intensities (3.5, 7.5, and 11?W/g). Physicochemical properties (moisture content, water activity, and drying rate) and quality parameters (optical properties, mechanical properties, antioxidant capacity, and rehydration capacity) of dried raspberries were evaluated. Results showed that the microwave drying (MWD) at 7.5?W/g (50?min and final temperature of 79?±?5.1°C) allowed a high yield of dried raspberries. The combined processes were not efficient to accelerate the decrease of moisture content, due to the low drying rate of the pretreatments. In terms of quality, none of the drying processes allowed a high retention of the antioxidant capacity. However, they allowed an appropriate rehydration performance. The combination of HAD with MWD allowed obtaining a good appearance and desirable texture on the dried product. Thus, this last option seems to be the best among the drying methods tested, but additional studies are required to improve the efficiency of the process and the effect on the antioxidant capacity during drying.     

Effect of drying methods on bioactive compounds,nutritional, antioxidant,and antidiabetic potential of brown alga Durvillaea antarctica

Abstract

The effects of vacuum, solar, convective, infrared, and freeze drying (VD, SD, CD, IRD, FD) on Durvillaea antarctica were evaluated in terms of nutritional composition, color, bioactive components, and antioxidant and antidiabetic activities. Nutritional composition of the dried seaweeds scarcely varied, while a tendency to lose the reddish tone occurred. CD-seaweed had highest phytochemical and vitamin contents, while FD-samples showed best retention of pigments. Both samples also exhibited the strongest antioxidant and antidiabetic activities. The highest essential amino acids and polyunsaturated fatty acids contents were found in IRD- and SD-samples, respectively. In general, FD and CD were proved to be viable drying options for D. antarctica.     

Optimization of ultrasound-assisted extraction of bioactive compounds from B. forficata subsp. Pruinosa

Extracts containing bioactive compounds were obtained from Bauhinia forficata leaves by ultrasound-assisted extraction (UAE) with three different solvents (n-hexane, ethyl acetate, and ethanol) and were compared with those obtained by a conventional method (maceration). Box-Behnken experimental design was applied to examine and optimize the effect of the extraction temperature (40°C-60°C), power (20%-80%), and sample to solvent ratio (1:10 to 1:20 (w/v)) on the total phenolic content (TPC), total flavonoid content (TFC), and the ferric reducing antioxidant power (FRAP) of B. forficata leaf extracts. This experimental design generated second-order polynomial models, which accurately describe the experimental data, allowing the prediction of optimal conditions for the investigated responses. Optimal extraction was achieved under the following conditions: 80% power, temperature of 41°C, and a 1:20 sample to solvent ratio. Under these conditions, the experimental yield was 8.33 ± 0.32%, total phenolic content was 59.47 ± 0.71 mg GAE · g_extract⁻¹, total flavonoid content was 62.30 ± 3.38 mg QE · g_extract⁻¹, and the ferric reducing antioxidant power was 726.7 ± 15.7 μmol Fe(II)EQ · g_extract⁻¹, which were close to the predicted values, which validated the models. The major compounds found in B. forficata extracts were tocopherols, phytol, heneicosane, and β-Sitosterol.     

Effect of Fluidized Bed Drying Temperature on Various Quality Attributes of Paddy

Abstract

As reported by many researchers, it was found that fluidized bed paddy drying using high drying air temperatures of over 100°C affected the head rice yield and whiteness of dried rice. However, only a few studies on fluidized bed paddy drying with drying air temperatures below 100°C were so far reported. The main objective of this work was therefore to study the effect of fluidized bed drying air temperature on various quality parameters of Suphanburi 1 and Pathumthani 1 Indica rice. Paddy was dried from the initial moisture contents of 25.0, 28.8, and 32.5% dry basis to 22.5 ± 1.2% dry basis using inlet drying air temperatures between 40 and 150°C at 10°C/step. After fluidized bed drying, paddy was tempered and followed by ambient air aeration until its final moisture content was reduced to 16.3 ± 0.5% dry basis. The results showed that the head rice yield of Suphanburi 1 was significantly related to the inlet drying temperature and initial moisture content whilst there was no significant relationship between the head rice yield, drying temperature and initial moisture content for Pathumthani 1. The whiteness of the two rice varieties was slightly decreased with increase in drying air temperature and initial moisture content. It was also found that the hardness of both cooked rice varieties exhibited insignificant difference (p < 0.05) comparing to rewetted rice, which was gently dried by ambient air aeration in thin layer. The thermal analysis by DSC also showed that partial gelatinization occurred during drying at higher temperatures. Using inlet drying air temperatures in the range of 40–150°C therefore did not affected the quality of cooked rice and paddy. The milling quality of paddy was also well maintained.     

Microwave-assisted extraction as an advanced technique for optimization of saponin yield and antioxidant potential from Phyllanthus amarus

The objective of this study was to apply microwave-assisted extraction (MAE) as an advanced technique for optimization of saponin yield and antioxidant potential from Phyllanthus amarus. The findings indicated that the optimal MAE parameters consisted of 100% methanol, irradiation time 4 s/min, extraction time 50 min, and solvent to sample ratio 50 mL/g. Under these optimal parameters, saponin content (SC), saponin extraction efficiency (SEE), and total phenolic content (TPC) of P. amarus were 229.5 mg escin equivalents (EEs)/g dried sample, 82.8%, and 40.7 mg gallic acid equivalents (GAEs)/g dried sample, respectively. The antioxidant capacity of P. amarus in terms of 2,2ˊ-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical scavenging capacity (ARSC), 2,2-diphenyl-1-picryl-hydrazil radical scavenging capacity (DRSC), and ferric reducing antioxidant power (FRAP) were 487.3, 330.6, and 233.5 mg trolox equivalents (TEs)/g dried sample, respectively. These measured values were not significantly different from the predicted values by response surface methodology (227.9 mg EE/g dried sample, 82.1%, and 39.2 mg GAE/g dried sample for SC, SEE, and TPC and 484.8, 297.3, and 226.6 mg TE/g dried sample for ARSC, DRSC, and FRAP, respectively). Hence, the optimal MAE parameters are suggested for effective extraction of saponins from P. amarus for further investigations and applications.