Retention of phytochemical properties and antioxidant potential of Conyza canadensis (L.) under different drying methods

The aim of this study was to determine the effect of different drying methods on the nutritional content and antioxidant activity of purslane. Two different purslane samples have been dried using four different methods (sun, vacuum, hot air, and freeze drying). Dried and fresh samples were analyzed for their dry matter, β-carotene content, chlorophyll a and chlorophyll b contents, total flavonoid content, total flavonol content, total phenolic content, %DPPH radical scavenge activity, metal chelating activity, and color. The dry matter content of fresh purslane was 3.86%-5.28%. The β-carotene, chlorophyll a and b amounts varied from 61.31 to 67.08 mg/100 g, 103.11 to 138.11 mg/100 g and 56.14 to 62.06 mg/100 g, respectively on dry weight basis. The total flavonoid, total flavonol, and total phenolic contents were 9.61-28.20 mg RE (rutin equivalent)/g DW (dry weight), 3.48-17.27 mg RE/g, and 14.86-17.95 mg GAE (gallic acid equivalent)/g DW, respectively. DPPH scavenging activity ranged from 158.19 to 168.22 μg/mL, and metal chelating activity varied between 5.75% and 22.44%. Fresh purslane color values L*, a*, and b* ranged from 33.41 to 35.25, -6.70 to -7.28, and 13.51 to 14.60, respectively. Dry matter content, total phenolic content, antioxidant activity, β-carotene, flavonoid, flavonol, and color (L*, a*, and b*) values were significantly affected by drying method. Drying methods caused a significant decrease in β-carotene, total flavonoid, total flavonol, and total phenolic contents of purslane. On the other hand, an increase in dry matter, metal chelating, chlorophyll a and chlorophyll b have been observed as a result of drying. Considering the variations in the effects of drying methods on the examined parameters and the disadvantages of some drying methods; in addition to the reasonable results obtained by hot air drying. Hot-air drying process could be suggested as a recommendable drying process for purslane.

Aims: This study aimed to investigate the total phenolic and flavonoid content and DPPH free-radical scavenging activity of Vernonia amygdalina planted in Mekong Delta. The optimized conditions for maceration of pandan leaves included drying method, ratio of pandan leaf powder-to-solvent, and extraction time.
 Methodology: The fresh pandan leaves were divided into two equal portions, subjected to different drying methods: shade and oven drying. The dried leaf powder was macerated in ethanol at room temperature. The maceration was conducted with 3 different ratios of pandan leaf powder-to-solvent (w/v) (1:10, 1:15 and 1:20), and the extraction time was 1, 2 and 3 days. The total flavonoid content was determined using aluminum chloride method whereas the total phenolic content was assessed using Folin-Ciocalteu assay. Meanwhile, the antioxidant activity of the plant extracts was quantitatively evaluated using DPPH test.
 Results: The results indicated that the best conditions for maceration of pandan leaves were 1:10 shade-dried leaf powder-to-solvent ratio in 1-day extraction time. Accordingly, the total flavonoid and phenolic content was found to be the highest value of 130.02 ± 2.24 mg QE/g of dried extract and 100.67 ± 1.76 mg GAE/g of dried extract (p < 0.05), respectively. The lowest IC50 of DPPH free-radical scavenging activity of pandan leaf extract was found to be 0.90 ± 0.02 mg/mL (p < 0.05). In addition, the Pearson’s correlation coefficient between IC50 of DPPH free-radical scavenge activity and total flavonoid content was R2 = 0.74 compared to that of phenolic content with the value of R2 = 0.69, indicating that the IC50 of DPPH free-radical scavenge capacity of pandan leaves was influenced chiefly by flavonoid compounds.
 Conclusion: There was a significant difference in phenolic and flavonoid content and DPPH free-radical scavenging activity between shade-dried and oven-dried pandan leaf extracts.

Pereskia bleo, a widely cultivated plant known for its medicinal applications, contains abundant phytochemicals, including phenolics and flavonoids, predominantly in its leaves. The drying process, a standard practice for enhancing the shelf life, could affect the bioactive compounds within the leaves. Therefore, this study aims to evaluate the impact of various drying methods on the colour, total phenolic content, flavonoid content, and antioxidant activity of P. bleo leaves. The tested drying methods include shade, oven, microwave, and freeze-drying. The colour of fresh and dried leaves was assessed using a Minolta chromameter. The total phenolic content (TPC) and total flavonoid content (TFC) of the P. bleo leaves extracts were determined using the Folin-Ciocalteu’s and aluminium chloride colourimetric assay, respectively. Antioxidant capacities were analysed with DPPH radical scavenging and ferric-reducing antioxidant power assay (FRAP). The results showed that microwave drying has significantly less impact than the other drying methods on the colour attributes of the leaves (p<0.05). Notably, microwave-dried P. bleo leaves demonstrated significantly higher TPC (77.31 ± 0.70 mg GAE/g dry extract) and TFC (35.79 ± 1.34 mg QE/g dry extract) compared to leaves dried using the other tested methods (p<0.05). Additionally, microwave-dried P. bleo leaves displayed the highest DPPH inhibition (91.62%) and exhibited the most potent IC50 value (76.90 ± 1.06 µg/mL) compared to oven and shade-dried leaves (p<0.05). P. bleo leaves dried with a microwave also recorded a significantly higher FRAP value (62.66 ± 0.10 µg TE/g dry extract) than oven-dried leaves (p<0.05). In conclusion, microwave drying emerged to be an efficient drying method in preserving the colour and antioxidant properties of the P. bleo leaves, suggesting its potential as a favourable drying technique for retaining bioactive compounds in medicinal plant materials.

This study aims to evaluate the effects of different drying methods on the physical properties, total phenolic content, total flavonoid content, and antioxidant activity of extracts from Moringa oliefera L. (MO) leaf waste. The effects of two drying techniques, namely, sun drying (A1) and tray drying (A2), on the physical and antioxidant properties of the extracts obtained using three extracting solvents, i.e., water (b1), ethanol (b2), and ethyl acetate (b3), were investigated. These extracts were analyzed for their physicochemical and antioxidant properties. The antioxidant properties were determined with the Folin Ciocalteau, aluminum chloride, and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. Fourier transform infrared spectrophotometry (FTIR) was used to identify functional groups in the active compounds. It was found that the physical properties of the MO extract, including yield, pH, total solids, and color, showed significant differences for the two drying methods (p < 0.05). The b3 extract had the highest value for total phenolic contents, total flavonoid contents, and antioxidant activities, followed by b2 and b1, respectively, for both the sun drying and tray drying methods. There was a significant correlation between the total phenolic and flavonoid contents and antioxidant activity (IC50). This study reveals that waste material from MO leaves could be utilized as an antioxidant agent, which is expected to reduce environmental pollution from the MO processing industry.

The focus of the present study was to determine the association of the anti-oxidant activity of Costus speciosus (Koen Ex. Retz.) Sm. with the total phe-nolic content and the total flavonoid content. The antioxidant activity of the extracts was quantified by diphenylpicrylhydrazyl (DPPH) assay. The total phenolic content was determined by the Folin-Ciocalteau method and the total flavonoid content was determined by the aluminium chloride method. Among the four extracts of the plant, the ethanol extract exhibited the high-est antioxidant activity and also the highest total phenolic and flavonoid con-tents. A strong correlation was observed between the antioxidant activity and the total phenolic and flavonoid contents. A statistical model was de-rived to explain this dependence and a non-linear association was observed between the antioxidant activity and the total flavonoid content.

Moringa stenopetala is a socioeconomic valued tree that is widely available and cultivated in Southern part of Ethiopia. The leaves have been traditionally used as a food source with high nutritional and medicinal values. The present work was carried out to evaluate the effect of thermal treatment on the total phenolic content, total flavonoid content, antioxidant activities and α-amylase inhibition of aqueous leaf extracts obtained from M. stenopetala during maceration and different decoction time interval (5, 10 and 15 min). The total phenolic and flavonoid contents were determined by the Folin-ciocalteu and aluminum chloride methods, respectively whereas antioxidant activities were determined by 2,2-diphenyl-1-picryl-hydrazyl(DPPH) radical scavenging, reducing power, phosphomolybdenum and ferrous ion chelating assays and α-amylase inhibition potential was determined using 3,5-dinitrosalicylic acid method. Total phenolic and total flavonoid contents ranged from 34.35 ± 1.06 to 39.47 ± 1.33 mgGAE/g and 10.44 ± 0.61 to 20.36 ± 0.93 mgQRE/g, respectively. Decoction for 10 min extract showed ferrous ion chelating (92.52 ± 0.17 %), DPPH radical scavenging (91.52± 0.59 %), α-amylase inhibition (69.06 ± 0.14%), ferric reducing power (0.765 ± 0.14) and total antioxidant activity (0.329 ± 0.32), respectively. DPPH, reducing power, total antioxidant and α-amylase inhibition activities showed positive linear correlation (R2=0.853, R2= 0.857 , R2= 0.864 and R2=0.930), respectively with total phenolic content but ferrous ion chelating activity were found to be weakly correlated (R2=0.481). Based on present investigation, it could be concluded that major lose of total phenolic content, antioxidant and α-amylase inhibition activities of the crude leaf extracts of M. stenopetala leaves were observed at decoction time for 15 min. Therefore, to maintain the total phenolic content, antioxidant and α-amylase inhibition activities of leaves, cooking practice should be at the optimum decoction time (5-10 min). Key words: Moringa stenopetala, antioxidant, total phenolic content, α-amylase inhibition.

Caesalpinia sappan L (CS) heartwood is used as a natural red colorant in several Asian ethnic traditional drinks both as sole ingredient or mixed with other herbs. However, the pigment is unstable and easily degraded during storage which affects consumer acceptance. This research aimed to investigate the effect of different blanching and drying methods on the color stability, brazilin content, and antioxidant activity of CS heartwood drinks. Steam blanching, water blanching, sun drying and cabinet drying were examined in this study. The most common method applied in traditional production, without blanching and sun drying, was used as a control. The experimental design used was complete randomized design with triplicates. Data are presented as mean ± standard deviation and analyzed by SPSS statistics version 20. The results showed that blanching and drying methods affected the color intensity. For a pure CS heartwood herbal drink, the sample prepared with water blanching and cabinet drying (BCD) showed the highest red value, leading to a 48 % improvement compared to the control. This red value is in accordance with the brazilin content. Sample BCD showed the highest brazilin content, which was 376 % higher than that of the control. Similarly, the BCD sample had the highest antioxidant activity and total phenolic content, with IC50 values of 98.99 ppm and 213.12 mg GAE g–1, respectively. This result revealed that brazilin might act as an antioxidant. Similar to the pure CS drink, the highest quality of mixed herbal drink was obtained by BCD sample. The results suggest that the combination of water blanching and cabinet drying (BCD) was the best method to improves the quality of CS heartwood drink both in pure and mixed herbal drinks as a functional drink. HIGHLIGHTS Samples treated with blanching and drying had higher brazilin content of Sappan heartwood drink There is a correlation between brazilin content and color intensity as well as antioxidant activity Blanching and cabinet drying improved the color stability of Sappan heartwood drink Blanching and cabinet drying increased the total phenolic and flavonoid content of Sappan heartwood drink GRAPHICAL ABSTRACT

Drying methods effect on bioactive compounds, phenolic profile, and antioxidant capacity of mango powder

Introduction: Sargassum polycystum is one of marine algal which has a potent antioxidant anticancer activities. This research aims to investigate phytochemical composition, antioxidant activity, and in vitro cytotoxicity of marine algal Sargassum polycystum on cervical HeLa cancer. Methods: Sargassum polycystum collected from Dompu beach, Lombok, Nusa Tenggara Barat Province, Indonesia, were extracted into organic solvent of n-hexane, ethylacetate, chloroform and ethanol, respectively. Subsequently, Sargassum polycystum extracts were applied for Thin Layer Chromatography (TLC) analysis, phytochemistry test, total phenolic and total flavonoid contents, as well as for antioxidant activity test by DPPH (2,2-diphenyl-1-picrylhydrazyl) method, and in vitro cytotoxicity evaluation on HeLa cells by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5diphenyltetrazolium bromide) assay. Results: Phytochemical analysis of S. polycystum extracts are positive for metabolites of flavonoid, steroid, tannin and glycoside. TLC analysis revealed that S. polycystum extracts containing four phytochemical components. Ethylacetate extract of S. polycystum showed the highest total phenolic content, and exhibited greater antioxidant activity than ethanol extract. Total phenolic and total flavonoid content in ethylacetate extract are 548.61 g/mL and 40.06 g /mL, respectively. Ethylacetate extract of S. polycystum with IC 50 value of 298.3 g/mL is assigned to have a weak antioxidant activity against DPPH free radical. The results indicate that antioxidant activity of ethylacetate extracts of S. polycystum is directly correlated with its total phenolic and flavonoid content. Moreover, S. polycystum extracts demonstrated a strong anticancer activity on cervical HeLa cells with IC 50 ranging from 38.3 g/mL to 112.8 g/mL. Conclusion: This work confirmed that S.polycystum are promising natural antioxidant and anti-cervical cancer agents.

Wild guava (Psidium guajava L.) commonly grows in tropical forests, and its leaves have long been used by Asian ethnic minorities as herbal tea and traditional medicine. This study aimed to evaluate the effects of different drying methods (sun drying, hot air drying, microwave drying, vacuum drying, and freeze drying) on the retention of bioactive compounds, antioxidant, and antidiabetic activities of wild guava leaves collected in Vietnam. The results showed that drying methods significantly affected the retention of bioactive compounds, biological activities, and color of guava leaves. The freeze-dried leaves had the highest levels of total phenolic content (173.25 ± 0.68 mg gallic acid equivalent g−1 dw), total flavonoid content (24.46 ± 0.78 mg QE g−1 dw), antioxidant capacity, and in vitro antidiabetic activity compared with others, while sun-dried leaves showed the lowest values of those parameters. The principal component analysis (PCA) showed a strong correlation among biological activities and contents of bioactive compounds, including antioxidant activity, in vitro antidiabetic activity, total phenolic content, and total flavonoid content (r 2 = 0.999, p < 0.0001). Specifically, the biological activities strongly and positively correlated epicatechin, rutin, chlorogenic acid, catechin, and gallic acid. Freeze-dried guava leaves had the highest positive scores, followed by hot air-dried, microwave-dried, vacuum-dried, and sun-dried samples. FD treatment sample also exhibited better color and sensory properties than others. Consequently, freeze drying is recommended as the most suitable drying method for preserving the bioactive compounds and sensory characteristics of dried wild guava leaves.

Total phenolic, flavonoid content, and antioxidant activity of flour, noodles, and steamed bread made from different colored wheat grains by three milling methods

This work aimed to investigate the effect of five drying methods, namely hot-air drying (HD), microwave drying (MD), vacuum drying (VD), vacuum microwave drying (VMD), and vacuum freeze-drying (VFD), on the bioactive compounds, antioxidant activity, color, sensory attributes, and microstructure of purple cabbage. Different drying methods considerably affected the quality factors of the products. The highest remaining total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC) concentrations were observed in the VFD cabbage at 10.57 mg GAE/g, 7.01 mg RE/g, 6.54 C-3-G mg eqiv/g, respectively. This was followed by the VMD samples at a TPC at 9.06 GAE mg/g, TFC level of 5.84 mg RE/g, and TAC at 3.80 C 3 – G mg eqiv/g. Furthermore, the VFD samples displayed the best performance in antioxidant activity. The antioxidant activity of the VMD samples was lower than the VD and MD samples, but higher than the HD samples. In terms of color and flavor, the VMD samples displayed a low ∆E (P < .05) value, while the flavor resembled that of fresh purple cabbage, compared to the VFD sample. According to these chemical and physical indicators and drying time. VMD is better for drying treatment of purple cabbage.

Fresh peach blossoms of two varieties were dried by using different methods, which include shade drying, freeze drying, microwave drying and hot air drying (at 30, 60, 90, 120 °C). The effects of different drying methods on phenolic contents, antioxidant and tyrosinase inhibitory activity were evaluated. Among the seven drying treatments, microwave drying yielded the highest contents of total phenolics, flavonoids, anthocyanins, proanthocyanidins and individual phenolic compounds in dried peach blossoms, while hot air drying at 30 °C gave the lowest retention of total phenolics, flavonoids, anthocyanins. As compared with shade drying and freeze drying, hot air drying at 60, 90, 120 °C resulted in higher retention of phenolic content. The highest antioxidant activity in dried peach blossoms was obtained by microwave drying, while hot air drying at 30 °C gave the lowest. The effect of different drying methods on antioxidant activity of dried peach blossoms was consistent with that of phenolic content. The highest tyrosinase inhibitory activity was achieved by hot air drying at 120 °C for variety ‘yingchun’ and 90 °C for variety ‘huangjinmeili’, but there was no significant difference among hot air drying at 60, 90, 120 °C for both varieties. The tyrosinase inhibitory activities of peach blossoms by microwave drying and freeze drying were comparable and much lower than that of shade drying. The results indicated that microwave drying was a desirable method for the preservation of phenolic compounds and antioxidant activity in peach blossoms, while shade drying and hot air drying at high temperature were favorable for tyrosinase inhibitory activity.

Acanthopanax senticosus (Rupr. and Maxim.; AS) fruit, an underutilized byproduct, possesses significant bioactive potential, yet its quality is highly influenced by drying methods. This study systematically evaluated the effects of five drying techniques, including vacuum freeze-drying (VFD), vacuum drying (VD), microwave drying (MD), hot-air drying (HD), and natural drying (ND), on the color retention, bioactive composition, volatile profile, and antioxidant activity of AS fruit. VFD preserved the highest levels of total phenolic content (TPC) and total flavonoid content (TFC), particularly chlorogenic acid, rutin, and quercitrin, leading to superior antioxidant activity. Amino acid analysis indicated that VFD retained the highest concentrations of key essential amino acids, minimizing thermal degradation. Correlation analysis revealed a strong association between TPC, TFC, and antioxidant activity, emphasizing their functional significance. Through multivariate statistical analysis, 12 volatile compounds were identified as potential biomarkers to distinguish AS fruit samples processed using different drying methods, highlighting significant metabolic differences between drying techniques. Overall, VFD emerged as the optimal method for preserving AS fruit's bioactive integrity, offering valuable insights for post-harvest processing strategies in the nutraceutical industry.

Antioxidant and anti-diabetic activities in commercial and homemade pomegranate molasses in Lebanon