Optimized Drying of Kaprow Leaves for Industrial Production of Holy Basil Spice Powder

The present study investigated the changes in color, volatile compounds, total phenolic content, total flavonoid content, and antioxidant activity of two holy basil leaves (kaprow in Thai) Ocimum sanctum L. cultivars, kaprow khao and kaprow daeng, after three drying treatments, namely hot air (HA), low relative humidity air drying (LRH), and far-infrared radiation (FIR). Overall, HA dried showed a greater decrease in L values than did LRH and FIR dried for both kaprow cultivars. A significant decrease in total phenolic content (TPC), total flavonoid content (TFC), and ferric reducing antioxidant power (FRAP) was found in hot-air (HA) dried compared to fresh leaves, while TPC, TFC, and FRAP in LRH and FIR dried kaprow were significantly increased. Kaprow daeng and kaprow khao attributes represented by such compounds as β-caryophyllene, methyl eugenol, and eugenol were found to increase during drying. We found that eugenol was a major volatile compound ranging from 18% in HA dried to 23% in FIR dried samples in kaprow khao, whereas methyl eugenol was the main volatile compound in kaprow daeng ranging from 35% in fresh to 49% in FIR dried samples. Our results have demonstrated that LRH and FIR should be considered as a suitable drying method for kaprow with respect to preserving its color, antioxidant property, phenolic compounds, and volatile compounds. The present study has provided useful information for industrial use of kaprow powder production.     

Improvement of quality and antioxidant properties of dried mulberry leaves with combined far-infrared radiation and air convection in Thai tea process

Combined far-infrared radiation with hot-air convection (FIR-HA) drying was used for improving colour and antioxidant properties of mulberry leaf tea. Antioxidant properties and phenolic compounds of FIR-HA dried mulberry tea were determined and compared with the commercial product and with fresh leaves. We found that a smaller decrease in L and b values of the FIR-HA dried tea than those of commercial tea was observed. FIR-HA tea was found to have similar colour to fresh leaf while the commercial tea had darker colour. A significant decrease in total phenolic acid content (TPC) and total flavonoid content (TFC) was found in hot-air (HA) dried commercial tea compared to fresh leaves, while TPC in FIR-HA dried tea was significantly increased. Similar results were found in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activities. However, the results were different for ferric reducing antioxidant power (FRAP). Both teas had lower FRAP values compared to fresh leaves. Eleven phenolic compounds were identified in fresh leaf and in mulberry tea, namely p-coumaric acid, benzoic acid, (+)-catechin, chlorogenic acid, vanillic acid, syringic acid, sinapic acid, protocatechuic acid, ferulic acid, gallic acid and caffeic acid. The total content of phenolic compounds (TPCC) increased in FIR-HA dried samples compared to those of HA dried tea, except for chlorogenic and syringic acids, which were found in greater amounts in HA dried commercial tea. Our results have demonstrated that FIR-HA should be considered as a suitable drying method for mulberry tea with respect to preserving its antioxidant properties and phenolic compounds.     

Proximate Composition and Antioxidant Potential of Leaves from Three Varieties of Mulberry (Morus sp.): A Comparative Study

In this study, leaves of three indigenous varieties of Mulberry namely, Morus alba L., Morus nigra L. and Morus rubra L. were investigated for their antioxidant potential and their proximate composition was determined. The yields of 80% methanolic extracts ranged between 8.28–13.89%. The contents of total phenolics (TPC), total flavonoids (TFC) and ascorbic acid (AA) ranged between 16.21–24.37 mg gallic acid equivalent (GAE)/g, 26.41–31.28 mg rutin equivalent (RE)/g and 0.97–1.49 mg/g, respectively. The antioxidant activity of leaf extracts was evaluated by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH^•) radical scavenging actity, 2,2′-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid (ABTS^•+) radical cation scavenging capacity and ferric ion reducing power and values ranged between 1.89–2.12, 6.12–9.89 and 0.56–0.97 mM Trolox equivalent/g of dried leaves, respectively. The investigated features reveal good nutritive and antioxidant attributes of all the varieties with mutually significant differences.     

Dehydration of red bell-pepper (Capsicum annuum L.): Change in drying behavior, colour and antioxidant content

The sun, oven (50 and 70 °C) and microwave oven (210 and 700 W) drying behaviors of red bell-pepper slices were investigated. Effects of these drying methods in terms of colour indices and antioxidant activity of pepper slices were also studied. “Midilli and Küçük” model exhibited high coefficient of determination (R²) values for all the drying methods used in the assay, ranging between 0.994-0.999, while “Page” and “Modified Page” models fit better for oven drying at 70 °C. The calculated effective diffusivity (D_eff) values (m²/s) of pepper slices for the drying processes ranged between 0.31 and 87.39 × 10⁻⁹. Sun dried and followed by microwave oven (700 W) dried samples revealed the highest L^*, a^* and b^* colour values than the other dried samples. Microwave oven dried (210 W) and oven dried (50 °C) samples exhibited the lowest TEAC and DPPH radical scavenging activities among the dried samples.     

Comparative study of drying methods on chemical constituents of Malaysian red seaweed

ABSTRACT

This study determined the proximate composition, phytochemical and antioxidant activity of the edible red seaweed, Kappaphycus alvarezii, under different drying conditions, namely, oven dried, sun dried, vacuum dried, and freeze dried. The proximate composition of K. alvarezii has shown no significant difference (p?>?0.05) in macronutrient components except fat content. Phytochemical studies conducted on total phenolic content and total flavonoid content showed that vacuum-dried extracts demonstrated the highest total phenolic content at 12.97?mg?PGE?g^?1 DE. In vitro antioxidant activities of seaweed extract by ferric-reducing antioxidant potential and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity proved that oven-dried extracts showed the highest ferric-reducing antioxidant power value, 272.95?µM TE mg^?1, and highest scavenging activity, EC₅₀ 9.55?mg?mL^?1. In general, sun-dried extracts showed lowest antioxidant among all treatments.     

The role of drying methods on enzymatic activity and phenolics content of impregnated dried apple

Infusion of antioxidants into vegetables is a new food strategy managed by matrix processing. Raw and blanched apple were air- or freeze-dried. In the case of freeze-dried samples, different freezing methods were previously applied: conventional (?28°C), blast freezing (?30°C), and liquid N₂ (?196°C). Afterwards, air- and freeze-dried samples at different conditions were impregnated with a concentrated (40°Brix) tea extract and finally, air-dried for their stabilization. Total phenolic content (TPC), antioxidant capacity (AC), enzymatic activity, and microstructure were analyzed. Regardless of pretreatments, the impregnation and the further drying improved the antioxidant potential. Samples with the most porous microstructure free of degradative enzymes provided high AC (78.5?±?0.9?mg Trolox/g dried matter) and TPC (16.7?±?0.2?mg GAE/g dried matter).     

Major Phenolic Compounds, Antioxidant Capacity and Antidiabetic Potential of Rice Bean (Vigna umbellata L.) in China

Interest in edible beans as nutraceuticals is increasing. In the present study, the individual phenolic acids, the total phenolic content (TPC), the total flavonoid content (TFC), and the antioxidant and antidiabetic potential of 13 varieties of rice beans from China were investigated. Eight phenolic compounds (catechin, epicatechin, p-coumaric acid, ferulic acid, vitexin, isovitexin, sinapic acid, quercetin) were analyzed on an ultra-performance liquid chromatography (UPLC) mass spectrometry (MS) system. The rice bean varieties had significant differences in total phenolic compounds (ranging from 123.09 ± 10.35 to 843.75 ± 30.15 μg/g), in TPC (ranging from 3.27 ± 0.04 to 6.43 ± 0.25 mg gallic acid equivalents (GAE)/g), in TFC (ranging from 55.95 ± 11.16 to 320.39 ± 31.77 mg catechin (CE)/g), in antioxidant activity (ranging from 39.87 ± 1.37 to 46.40 ± 2.18 μM·TE/g), in α-glucosidase inhibition activity (ranging from 44.32 ± 2.12 to 68.71 ± 2.19) and in advanced glycation end products formation inhibition activity (ranging from 34.11 ± 0.59 to 75.75 ± 0.33). This study is the first report on phytochemistry and biological activities in rice beans.     

Identification of phenolic compounds and antioxidant activity of guava dehydrated by different drying methods

Abstract

The influence of different drying techniques on guava was investigated, including phenolic components and antioxidant activities. Through drying processes, total phenolic content (TPC) increased and formation of small molecular phenolic acids (multi-methoxy benzoic acid and sinapic acid) was promoted. UPLC-ESI-QTOF-MS determination showed flavanol compounds, hydrolyzable tannins, ellagic acid conjugates and cinnamic acid derivatives were four predominant phenolics of guava. Drying treatments caused degradation of catechin and its derivatives. Contrarily, drying treatments contributed to higher contents of procyanidin trimers. Moreover, thermal drying treatments led to degradation of macromolecular tannins and formation of smaller molecular tannins and ellagic acid conjugates, while simultaneously reduced the stabilities of most intrinsic ellagic acid conjugates. Furthermore, drying processes increased the yield of cinnamic acid dihexose, probably generating from lignin or phenolics–carbohydrate complex. Freeze drying and hot air drying showed better performance on retention of TPC and enhancement of antioxidant activity (AA).     

马铃薯皮中多酚类物质的抗氧化性研究

通过体外抗氧化体系测定马铃薯皮多酚的抗氧化活性。除超氧阴离子的能力;马铃薯皮多酚清除羟基自由基的能力;马铃薯皮多酚清除DPPH自由基的能力;马铃薯皮多酚对油脂的抗氧化能力。马铃薯皮多酚对超氧阴离子的清除率最高达18.33%,且在低浓度清除能力明显高于同浓度抗坏血酸(Vc);马铃薯皮多酚对羟基自由基的清除率最高达92.26%。对DPPH自由基清除率最高达86.08%。油脂中添加马铃薯皮多酚提取液,可以明显降低油脂的过氧化值(POV)。马铃薯皮多酚对超氧阴离子,羟基自由基和DPPH自由基都有很好的清除效果,且在一定程度上降低油脂过氧化值随时间而延长的程度,是很好的天然抗氧化剂。     

Antioxidant Activity of Subcritical Water Extracts from Chaga Mushroom (Inonotus obliquus)

The subcritical water (SCW) extraction of Chaga mushroom (CM) was carried out at various temperatures (50, 100, 150, 200, 250, and 300°C) and times (10, 30, and 60 min), and then antioxidant activities of the SCW extracts were evaluated by determining 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, reducing power (RP), superoxide dismutase (SOD)-like activity, and total phenol content (TPC). The DPPH and ABTS radical scavenging activities, and the SOD-like activity of the extracts increased with elevated temperatures and times. For example, DPPH and ABTS radical scavenging activities, and SOD-like activity of the extracts at 250°C for 60 min were 72.5, 97.8, and 92.3%, respectively, while those at 50°C for 60 min were 63.2, 14.4, and 22.6%, respectively. However, the activities decreased at 300°C. The highest TPC and RP were found at 250°C for 30 min with values of 10.724 mg/mL and 1.063 optical density, respectively. These results indicate that SCW extraction was significantly effective on the increase of antioxidant activity of the CM.     

Effect of agronomic practices and drying techniques on nutritional and quality parameters of onions (Allium cepa L.)

The effects of four drying treatments (freeze-drying, hot air drying, oven drying, and vacuum oven drying) on the bioactive compounds (total phenolics, total flavonoids, and quercetins), color, and antioxidant capacity of organic and nonorganic onions of two varieties (Red Baron and Hyfort) subjected to two agronomic treatments (OSOP and CSCP) were investigated. The average final dry weight of the samples was 9.82?±?0.41%. After drying, there was a significant increase in total phenolics, total flavonoids, total quercetin, and antioxidant capacity in comparison with fresh onion samples, which suggested that drying can improve the extractability of phenols and accordingly the antioxidant activity of onions. Different drying techniques also resulted in different fractions of individual quercetins. Dried organic onions had higher levels of bioactive compounds and antioxidant capacity than dried nonorganic onions for a same variety. The highest antioxidant capacity displayed by freeze-dried and hot-air-dried organic Red Baron onion is in agreement with their higher phenolic and flavonoid contents compared to all other samples.     

Study on Optimum Extraction Conditions for Olive Leaf Extracts Rich in Polyphenol and Flavonoid

Ultrasound-assisted extraction (UAE) of polyphenols and flavonoids from olive leaves was investigated. The effects of temperature (27?37°C), solvent concentration (10?70% ethanol (EtOH), v/v) and time (30?60 min) were determined by both experimental and Response Surface Methodology (RSM) techniques. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. For total phenolic content (TPC), 43.8252 mg-GAE/g dried leaf was predicted at the optimum conditions (34.18°C, 43.61% (v/v) of EtOH, and 59.99 min). In case of total flavonoid content (TFC), 31.9920 mg-CE/g dried leaf was calculated at the optimum conditions (34.44°C, 70% (v/v) of EtOH, and 60 min).     

Red pepper (Capsicum annuum L.) drying: Effects of different drying methods on drying kinetics,physicochemical properties,antioxidant capacity,and microstructure

Results of an experimental study are presented and discussed for pulsed vacuum drying (PVD), infrared-assisted hot air-drying (IR-HAD), and hot air-drying (HAD) on drying kinetics, physicochemical properties (surface color, nonenzyme browning index, red pigments, rehydration ratio, water holding capacity, and ascorbic acid), antioxidant capacity (ferric reducing antioxidant power and 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity), and microstructure of red pepper. As expected, the drying time decreased with an increase in drying air temperature, IR-HAD needed the shortest drying time, followed by HAD and PVD. The effective moisture diffusivity (D_eff) of red pepper under PVD, HAD, and IR-HAD was computed to be in the range 1.33–5.83?×?10^?10, 1.38–6.87?×?10^?10, and 1.75–8.97?×?10^?10 m²/s, respectively. PVD provided superior physicochemical properties of dried red pepper compared to samples dried by HAD and IR-HAD. In detail, PVD yielded higher rehydration ratio, water holding capacity, red pigment and ascorbic acid content, brighter color, lower nonenzyme browning index, and comparable antioxidant capacity compared to samples dried by HAD and IR-HAD at the same drying temperature. Furthermore, PVD promoted the formation of a more porous structure, while HAD and IR-HAD yielded less porous structure. The current findings indicate that PVD drying has the potential to produce high-quality dried red pepper on commercial scale.     

Inhibition behavior of Tragia involucrata L. phenolic compounds against acidic medium corrosion in low carbon steel surface

The antioxidant and anticorrosive effect of Tragia involucrate L.(T. involucrate L.) was evaluated to aid in finding new compounds which can be used for various purposes. The total phenolic(TPC) and flavonoid content(TFC),antioxidant activity(DPPH, reducing potential and phosphomolybdenum), and electrochemical measurements,Fourier transform infrared(FT-IR), UV–visible(UV–vis) spectral analysis, scanning electron microscopy/energydispersive X-ray spectroscopy(SEM–EDX) and atomic force microscopy(AFM) were done to analyze the potency and also the inhibition efficiency of T. involucrate L. against 1 mol·L~(-1) HCl on low carbon steel. The TPC(145.21 mg GAE·g~(-1)), TFC(52.32 mg QCE·g~(-1)) and antioxidant activities were found to be significant. The electrochemical studies performed by AC impedance measurements showed significant changes in impedance spectra without causing any change in Nyquist plots. An increase in charge transfer resistance(Rct) values, a blockage in active sites exhibiting cathodic and anodic inhibition shows the action of inhibitor on low carbon steel. This was later confirmed by FT-IR and UV–vis which showed variation in absorption band at 270 nm and273 nm(before immersion) and 208 and 281 nm(after immersion). The same was tested again by SEM–EDX through altered strength of iron and oxygen bands and using AFM by analyzing the change in average roughness values of low carbon steel before(61.65 nm) and after(97.87 nm) exposure to blank acid without inhibitor, while it was shifted to 81.58 nm in acid with inhibitor. All these results showed strong evidence adding values to T. involucrate L. plant extract in inhibiting corrosion on low carbon steel and by promoting antioxidant importance of the extract which helps in scavenging free radicals.     

Fatty Acid Composition, Antioxidant Properties, and Antiproliferative Capacity of Selected Cold-Pressed Seed Flours

Cold-pressed seed flours from pumpkin, parsley, mullein, cardamom, and milk thistle were examined for total oil, fatty acid profile of the oil, total phenolic content (TPC), scavenging activities against peroxyl (ORAC), hydroxyl (HOSC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) (RDSC) radicals, and antiproliferative capacity against HT-29 human colon cancer cells. The cold-pressed parsley seed flour contained a very high concentration of total oil—17.6 g/100 g flour—with primarily C18:1 fatty acid at 86.2 g/100 g fatty acids. All other flour oils had relatively high levels of saturated fats, ranging from 39.0 to 62.9 g/100 g fatty acids. The tested seed flours demonstrated significant TPC and free radical scavenging activities. Milk thistle seed flour had the highest TPC value of 25.2 mg gallic acid equivalent per g flour (GAE mg/g) followed by that of parsley seed flour at 8.1 GAE mg/g. Milk thistle seed-flour extract also had significantly higher antioxidant activities than all other extracts against all tested radicals. The milk thistle seed-flour extract had an ORAC value of 1131 μmol trolox equivalents (TE) per g flour (TE μmol/g), a HOSC value of 893 TE μmol/g, and an RDSC value of 61 TE μmol/g. Also, ORAC, HOSC, and TPC values were significantly correlated (P < 0.01) under the experimental conditions. The cold-pressed milk thistle seed flour inhibited the proliferation of HT-29 cancer cells in a dose-dependent manner. Results from this study suggest that these cold-pressed seed flours may serve as natural sources of antioxidants and may be used to improve human health.     

Comparative analyses of three dehydration methods on drying characteristics and oil quality of in-shell walnuts

Developing an effective drying method for in-shell walnuts (Juglans regia L.) is a major postharvest processing concern in the nut industry. Three drying methods, including hot air drying (AD), vacuum drying (VD), and hot air-assisted radio frequency drying (ARFD), were experimentally compared and analyzed. The changes in lipid oxidation attributes, fatty acid composition, total antioxidant capacity (TAC), and total phenolic concentration (TPC) of walnuts were determined after dehydration and during storage. The results showed that the drying time required for in-shell walnuts using ARFD was the shortest (138?min), followed by VD (185?min) and AD required the longest time (300?min). Particularly, AD resulted in the highest lipid oxidation, followed by VD and ARFD. The walnuts treated by ARFD contained more unsaturated fatty acid than those treated by AD. Moreover, both the reduced power assay and free radical scavenging capacity tests showed that ARFD and VD had little effect on the TAC and TPC of walnuts during the drying process and storage. Overall, ARFD provides an effective and rapid drying method for in-shell walnuts.     

Effect of maltodextrin concentration and inlet temperature during spray drying on physicochemical and antioxidant properties of amla (Emblica officinalis) juice powder

The effects of inlet temperatures of 125, 150, 175 and 200 °C and maltodextrin levels at 3, 5, 7 and 9% on the physicochemical properties, total phenolic content (TPC) and 2,2-diphenyl picryl hydrazile (DPPH) scavenging activity of spray dried amla juice powder were studied. Moisture content and hygroscopicity of powder were significantly affected by inlet temperature and maltodextrin level. However, an increase in the level of maltodextrin did not significantly affect the bulk density and water solubility index (WSI). An increase in drying temperature and maltodextrin concentration decreased the free radical scavenging activity of the powder. Morphological study revealed that at higher inlet temperatures the spray dried powder had small sized particles that were densely packed. Spray dried amla juice powder made with 7% maltodextrin and processed at 175 °C inlet temperature had less hygroscopicity, acceptable color and potent free radical scavenging activity.     

Antioxidant Activities and Phenolic Compositions of Wheat Germ as Affected by the Roasting Process

Wheat germ is a good source for wheat germ oil, and it is a by‐product with highly concentrated nutrients from the wheat flour‐milling industries. In the present study, raw wheat germ was firstly heat‐treated at 180 °C for 20 min in a fluidized bed dryer, and further roasted at 180 °C for different periods of time. Roasting influence on total phenolic content (TPC), antioxidant activities, and phenolic compositions of wheat germ were evaluated. The roasting process significantly increased the TPC and antioxidant activities including free radical scavenging against DPPH and ABTS radicals, FRAP, and ORAC. In particular, the wheat germ roasted at 180 °C for 20 min showed higher antioxidant activity than those roasted at 180 °C for 5 and 10 min. Three major phenolic acids, namely, ferulic, chlorogenic, and caffeic acid, and four main flavonoids, namely, schaftoside and its isomers or adduct of sinapic acid were identified by HPLC. In general, the content of individual phenolic compounds decreased with prolongation of the roasting time except for ferulic acid. The results suggest that the antioxidant activities of wheat germ can be enhanced by roasting, and the enhancement effect might be partially attributed to the formation of Maillard reaction products (MRP).     

Antioxidant Activity of the Phenolic Leaf Extracts from <Emphasis Type="Italic">Monechma ciliatum</Emphasis> in Stabilization of Corn Oil

The total phenolic content and the antioxidant potential of methanolic extract (ME), ethyl acetate extract (EAE), and hexane extract (HE) from Monechma ciliatum leaves (MCL) were evaluated. The Folin-Ciocalteu, β-carotene bleaching, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and the accelerated oxidation methods were used for evaluation. Both the extraction yield and the antioxidant activity (AOA) were strongly dependent on the solvent. Among the extracts, ME exhibited highest total phenolic compounds (TPC) and IC₅₀ values for DPPH, followed by EAE and HE, respectively. Peroxide value (PV), anisidine value (AV) conjugated dienes (CD), and thiobarbituric acid reactive substances (TBARS) were taken as the parameters for evaluation of stabilization efficacy of MCL extracts and results revealed MCL to be a potent antioxidant for the stabilization of corn oil. As a general trend, increased AOA was observed for increased extract concentration. The predominant phenolic compounds identified by HPLC-DAD in MCL extracts were p-coumaric acid, vanillin and ferulic acid.     

Antioxidant potential of atmospheric freeze-dried apples as affected by ultrasound application and sample surface

ABSTRACT

Atmospheric freeze drying (AFD) yields products of a similar quality to the conventional vacuum freeze-drying technique, but reduces the operating cost. However, it involves very low drying rates. The sample surface/mass ratio is one of the process variables that can be taken into account to reduce drying time. Moreover, power ultrasound (US) can also be used to intensify this process because of its effects on external and internal mass transfer resistance. However, both factors may affect not only the drying time but also the final product quality. Therefore, the aim of this study was to address the influence of both ultrasound application and the sample surface/mass ratio on the drying process and the antioxidant potential of atmospheric freeze-dried apple. For that purpose, two sample geometries with different surface/mass ratio were considered: slabs (30?×?30?×?10?mm³) and cylinders (diameter: 9?mm and height: 30?mm). The samples were freeze dried (?10°C) with ultrasound application (21.7?kHz) at different power levels (0, 10.3, 20.5, and 30.8?kW/m³). The total phenolic content (TPC), antioxidant capacity (AC), and ascorbic acid content (AA) were measured in the dried apple. The drying time was significantly shorter for cylindrical samples than for slabs, probably due to their higher surface/mass ratio. The application of US increased the drying rate, this increase being greater for the slab than for the cylindrical particles used in this study. In general, AFD reduced the TPC, AC, and AA, the final content being significantly greater for slabs than for cylinders. This fact can also be related to the lower surface/mass ratio in the case of slabs. US application further reduced TPC, AC, and AA content, probably due to some cellular damage produced by the acoustic waves and to the oxygen transfer improvement. Nevertheless, the bigger particles (slabs) dried with ultrasound needed a 10% of drying time than the smaller ones (cylinders) dried without ultrasound. Moreover both kind of samples presented similar antioxidant potential.