Ultrasonic-assisted enzymatic extraction and antioxidant activity of polysaccharides from Setaria viridis

Ultrasonic-assisted enzymatic extraction (UEAE) and response surface methodology (RSM) were used to isolate polysaccharides from Setaria viridis (SVP). Optimal extraction conditions in the enzymatic hydrolysis process were: extraction duration, 68 min; extraction temperature, 51°C; ratio of enzyme to raw material, 1.6%; and ratio of liquid to raw material, 20 mL/g. Then, following ultrasonic treatment (180 W, 60°C, 60 min), the experimental yield was 8.94 ± 0.38%. Crude SVP was purified by DEAE cellulose-52 chromatography and Sephadex G-100 chromatography, resulting in the isolation of three fractions (designated SVP-1, SVP-2 and SVP-3). These SVPs were mainly composed of glucose residue, and SVP-3 had a significantly higher uronic acid content than the other two fractions. Additionally, all fractions showed strong antioxidant activities in vitro.     

Evaluation of physical and chemical properties of carrots dried by Refractance Window drying

The Refractance Window? (RW) technique was used to dry carrot slices (3?cm diameter; 0.2 and 0.4 cm thickness) at 74 and 94°C. Moisture loss, texture, color, total polyphenol content (TPC), and antioxidant activity (AA) were evaluated as response variables and were compared with the values of a control (fresh carrot) and the slices dried via convective drying (C) at the same temperatures. The RW method produced a reduction of drying time of 26–51% (p < 0.05) when compared to convective drying. The color, TPC, and AA values for the RW treatment did not differ (p > 0.05) compared with the control. The texture values showed a difference with respect to the control for the two drying methods used. However, between the two drying methods there was no difference in the texture (p > 0.05). The results suggest that the RW technology can be used to develop products with better functional properties compared with those obtained via conventional air-drying methods.     

Effect of two drying methods on antioxidant activity and hypoglycemic action of polysaccharides in three cultivars of lychee pulp

Effect of air drying and freeze drying on polysaccharides of lychee with three cultivars was determined in terms of polysaccharides yield, antioxidant capacity and hypoglycemic action. The results show that Guiwei lychee pulp had the highest crude polysaccharide yield among three lychees. However, Feizixiao lychee had the lowest EC₅₀ concentration and the highest FRAP (Ferric reducing antioxidant power) value. Moreover, Guiwei lychees dried by air drying had the best effect for improving glucose tolerance of normal mice and diabetic mice. Three freeze dried lychees had no significant effect. The effect of air dried Guiwei samples on decreasing TG was the best and it was even better than dapagliflozin group. Only freeze-dried Guiwei lychee could significant decrease the TC content in blood among all lychee samples. In a word, Feizixiao lychees had the best antioxidant capacity and Guiwei lychees had the best hypoglycemic effect. Air drying was better drying method for lychee polysaccharides than freeze drying in this study.     

蔗渣酶法水解过程的酶吸附和活性

以纸浆甘蔗渣纤维素为底物,使用纤维素酶为催化剂,在50℃,pH为4.8的条件下研究了釜式及固定床反应流程,考察酶的吸附及活性.结果表明,固定床反应器的酶吸附比釜式多,而酶的活性变化在两种型式反应器中比较接近.     

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.     

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.     

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.     

Effect of different drying methods on morphological,thermal, and biofunctional properties of lulo (Solanum quitoense Lam.) fruit powders

Four different powders of dried lulo (Solanum quitoense Lam.) were obtained by hot air drying (HD), ultrasound-assisted hot air-drying (HDUS), freeze-drying (FD), and spray-drying (SD). The morphological (SEM) and thermal (TGA–DSC) characterization were made, and some biofunctional properties such as dietary fiber (DF) content and antioxidant capacity (ABTS and DPPH assays) were evaluated. The homogeneous morphology of SD particles was evident from SEM analysis, in contrast to the irregular morphology of the other dried powders. All of the dried lulo powders were thermally stable until 220°C. Although, the initial composition of the mixtures (fruit pulp/maltodextrin DE-20, 2:1, w/w) was the same, some differences on DF content and antioxidant activity were found, indicating that the drying method influenced significantly the chemical composition of powdered products. A higher insoluble dietary fiber (IDF) percentage was found in FD sample; in contrast, a higher in vitro antioxidant capacity values against ABTS and DPPH free radicals were found for HD and SD powders.     

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.     

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).     

Chemo‐enzymatic synthesis of lipophilic ferulates and their evaluation for antioxidant and antimicrobial activities

An efficient chemo‐enzymatic synthesis of ferulic acid‐based structured lipids mimicking triacylglycerol with a pendant phenolic moiety was carried out for the first time. Initially, ferulic acid was reduced to coniferyl alcohol, followed by its esterification with fatty acids. The key step in the synthesis was dihydroxylation of the olefinic side chain of coniferyl ester, which was eventually esterified with fatty acids to generate phenolic structured lipids. Two such compounds of varying fatty acid chain lengths were synthesized in good yield. Structural confirmation of both compounds is based on IR, ¹H and ¹³C NMR, and MS techniques. The synthesized compounds were tested for in vitro antioxidant and antimicrobial activities. Both compounds exhibited moderate to good antioxidant activity. The phenolic structured lipid with only shorter‐chain fatty acids showed antibacterial activity. Both compounds did not show any antifungal activity.     

Rapid FTIR determination of water,phenolics and antioxidant activity of olive oil

A rapid Fourier transformed infrared (FTIR) attenuated total reflectance (ATR) spectroscopic method was applied to the determination of water content (WC), total phenol amount (TP) and antioxidant activity (ABTS ^{. +}) of virgin olive oils (VOO) and olive oils. Calibration models were constructed using partial least squares regression. Oil samples with WC ranging from 289 to 1402 mg water/kg oil, with TP from 46 to 877 mg gallic acid/kg oil and with ABTS ^{. +} from 0 to 5.7 mmol Trolox/kg oil were considered for chemometric analysis. Better results were obtained when selecting suitable spectral ranges; in particular, from 2260 to 1008 cm^?1 for WC, from 3610 to 816 cm^?1 for TP and from 3707 to 1105 cm^?1 for ABTS ^{. +}. Satisfactory LOD values by the FTIR‐chemometric methods were achieved: 9.4 (mg/kg oil) for WC; 12.5 (mg gallic acid/kg oil) for TP, and 0.76 (mmol Trolox/kg oil) for ABTS ^{. +}. The evaluation of the applicability of these analytical approaches was tested by use of validation sample sets (n = 16 for WC, n = 11 for TP and n = 14 for ABTS) with nearly quantitative recovery rates (99–114%). The FTIR–ATR method provided results that were comparable to conventional procedures. Practical applications : The presented method is based on ATR–FTIR in combination with multivariate calibration methodologies and permits a simultaneous evaluation of important quality parameters of VOO (WC, TP and ABTS ^{. +}). This approach represents an easy and convenient means for monitoring olive oil quality with the advantage of ease of operation, speed, no sample pretreatment and no consumption of solvents. The data obtained with this method are comparable to those obtained using the official reference method. Therefore, the technique is highly plausible as an alternative to the standard procedure for routine analysis or control at‐line of production processes.     

The drying strategy of atmospheric freeze drying apple cubes based on glass transition

Freeze drying (FD) yields the best quality of dried apple cubes but at the cost of long drying time and also the overall cost. To achieve economical freeze drying along with a high quality product an atmospheric freeze drying (AFD) technique was developed to dry apple cubes. The effect of different air temperature loading scheme on product quality and drying process was studied during AFD. According to the glass transition temperature of apple, a step-up temperature loading strategy for AFD process was developed to reduce the drying time by almost half and provided a similar good product quality.     

Optimization of ultrasound-assisted extraction for the maximum quantity and quality of phenolics from Stachys lavandulifolia

The response surface methodology was used to evaluate the effects of extraction time, power of ultrasound, liquid to solid ratio, and solvent composition on the quantity and quality (from aspect of antioxidant activity) phenolics of Stachys lavandulifolia. The best extraction time, power of ultrasound, liquid to solid ratio, and solvent composition for both the quality and quantity of phenolics were 14 min, 300 W, 40 (v/w), and 57% methanol, respectively. Only the liquid to solid ratio was effective on the quality of phenolics. Also, the comparison between the ultrasound-assisted extraction and maceration methods showed the suitability of ultrasound-assisted extraction for extracting phenolics from this plant.     

Microbial and biochemical analysis of dried fish and comparative study using different drying methods

In the present study, certain quality parameters of raw and traditionally sun-dried (TSD) Bombay duck samples are compared with dried fish samples obtained from hot air dryer (HAD), freeze dryer, and a newly developed and patented solar conduction dryer (SCD). The parameters analyzed are total viable count, total fungal count, total volatile nitrogen, and trimethylamine (TMA) content and color. It is found that the experimentally dried fish have better microbial and biochemical quality as compared to TSD fish. This study addresses the issue of unhygienic open sun drying and handling of dried products and the need to adopt use of dryers based on the recently developed appropriate drying technology such as SCD which is expected to be transformed into sustainable technology.     

Effects of three conventional drying methods on the lipid oxidation,fatty acids composition,and antioxidant activities of walnut (Juglans regia L.)

Three walnut (Juglans regia L.) drying methods (sun drying, direct oven drying, and intermittent oven drying) were employed, and the consequent changes in lipid oxidation attributes, such as acid value (AV), peroxide value (POV), saponification value (SV), fatty acid composition, and antioxidant activity [including reducing power, superoxide anion scavenging activity, 1,1-diphenyl-2-picrylhydrazyl free radical scavenging activity (DPPH), lipoxygenase (LOX) activity, total phenols content (TPC), and total flavonoids content (TFC)] were investigated in this study. Sun drying resulted in the highest AV, POV, and SV, followed by direct oven drying and intermittent oven drying. Antioxidant activities and related compounds, TPC and TFC, were initially increased and then declined during drying, and a significant correlation was found between antioxidant activity and TPC and TFC. The LOX activities of all samples showed an increasing trend, although those of the sun-dried samples were the lowest. The walnuts dried with the intermittent oven drying method contained more linoleic acid than those dried by direct oven drying. Overall, intermittent oven drying appears to be a promising strategy for fresh walnut drying.