Retention Of Antioxidant Activity Research Articles

Influence of drying treatments on antioxidant capacity of forage legume leaves

This study was aimed to investigate the antioxidant capacities of four common forage legume leaves namely, Arachis pintoi (Pintoi), Calapogonium mucunoides (Calapo), Centrosema pubescens (Centro), and Stylosanthes guanensis (Stylo). Two different drying methods (oven-drying and freeze-drying) were employed and antioxidant activities were determined by DPPH, Ferric Reducing Antioxidant Power (FRAP) and β-carotene bleaching assays. Total phenolic content (TPC) was determined using Folin-Ciocalteu assay. Freeze-dried extract showed the highest antioxidant activities by DPPH (EC50 values 1.17-2.13mg/ml), FRAP (147.08-246.42μM of Fe(2+)/g), and β-carotene bleaching (57.11-78.60%) compared to oven drying. Hence, freeze drying treatment could be considered useful in retention of antioxidant activity and phenolic content.

Studies on retention of antioxidant activity, phenolics and flavonoids in high pressure processed black grape juice and their modelling

The effect of high pressure processing on total antioxidant activity, phenolic and flavonoid content of black grapes juice was studied. Response surface methodology (RSM) was used for designing the experiment keeping high pressure (400–600 MPa), temperature (40–60 °C) and processing time (2–4 min) as independent variables. The data obtained were analysed using multiple regression technique and quadratic models were found to fit well (R2, 85.61–96.65%) in describing the effect of high pressure, temperature and time on total antioxidant activity, phenolics and flavonoids. The optimum levels were found to be 550 MPa, 44 °C and 2 min for pressure, temperature and processing time, respectively (desirability, 95.00) for getting the maximum retention of total antioxidant activity, phenolics and flavonoids in the juice. The experimental and predicted valued of responses showed high correlation (R2, 99.26–99.90%) at the optimised levels of the variables.

Spray drying of Tinospora cordifolia leaf and stem extract and evaluation of antioxidant activity

Tinospora cordifolia (Guduchi) is widely used in folk medicine/ ayurvedic system of medicine, also in ayurvedic 'Rasayanas' to improve the immune system and used as general tonic, anti-periodic, anti-spasmodic, anti-inflammatory, anti-arthritic and anti-diabetic agent. Numerous studies have been reported on the health benefits of individual parts or whole Guduchi plant. However, most of the work has focused on the extracts of T. cordifolia. In this study, T. cordifolia leaf and stem extract powders were prepared using spray drying at 90°C outlet temperature of the spray dryer. The powder morphology has also been studied by scanning electron microscopy. The antioxidant activity was followed by DPPH method. The leaf extract powder showed higher retention of antioxidant activity than stem extract powder.

Retention of antioxidant activity in gamma irradiated argentinian sage and oregano

The effect of 30kGy of gamma radiation on the antioxidant activity of methanolic and aqueous extracts prepared from dry gamma irradiated sage and oregano were analysed. The antioxidant activity was characterised by DPPH radical test and by reducing power assay within an extract concentration range of 0–40mg/ml of methanol or water. In addition, the total phenolic content in the extracts was determined. From the EC50 estimated values, it was established that, by both methods, oregano extracts showed a higher antioxidant activity than sage extracts. Oregano extracts also showed a phenolic content significantly higher than sage extracts. A good correlation between the phenolic content and the antioxidant activity was also observed. The 30kGy dose applied to dry sage and oregano for sanitization did not significantly affect the capacity to inhibit the DPPH radical or the reducing power, nor did it affect the total phenolic content of the methanolic and aqueous extract.

Influence of blanching and low temperature preservation strategies on antioxidant activity and phytochemical content of carrots, green beans and broccoli

The objective of this study was to investigate the effect of blast freezing and blanching in combination followed by chilling, on the antioxidant activity (ARP), phenols, ascorbic acid and colour of broccoli, carrots and green beans. No significant changes ( p > 0.05) in ARP of blanched frozen (BLFR) broccoli, carrot and green beans were observed. In contrast, UBFR (unblanched frozen) treatments caused a significant decrease ( p < 0.05) in ARP and ascorbic acid content of vegetable samples. BLFR treated samples had better retention of antioxidant activity and ascorbic acid as compared to UBLR counterparts at chill storage (4 °C) for 7 days. However, no significant changes were observed in phenol content for all vegetables. Ascorbic acid decreased exponentially for both blanched and unblanched samples. The reaction rate constant ( k) increased from 1.06 × 10 −1 day −1 to 1.17 × 10 −1 day −1 for blanched and unblanched broccoli florets and from 4.6 × 10 −3 day −1 to 1.98 × 10 −1 day −1 for blanched and unblanched carrots during 7 days storage. Result presented here indicates greater stability of nutritional parameters for BLFR samples compared to UBFR samples during 7 days storage at 4 °C for all vegetables.

Quality assessment of dehydrated red bell pepper using tempering drying cycles

SummaryQuality assessment of red bell pepper dices preserved through batch dehydration introducing tempering cycles were performed in this work. The parameters considered were: the percentages of ascorbic acid and final antioxidant activity retention, as well as the influence of calcium chloride on diffusivity and colour values. Although, a similar final moisture content was reached through different red bell pepper dehydration processes, but the one with tempering cycles had better qualities than those without tempering. Ascorbic acid and final antioxidant activity retention showed higher values and so were colour intensities compared to control samples in all cases. In respect to the effective diffusivity coefficients, there was an increment as the calcium chloride concentration increased. As of the treatments with tempering cycles, the best scheme was 15 min drying time and 30 min tempering time at 60 °C.

Preservation of Cocoa Antioxidant Activity, Total Polyphenols, Flavan‐3‐ols, and Procyanidin Content in Foods Prepared with Cocoa Powder

Little is known about the effects of common cooking processes on cocoa flavanols. Antioxidant activity, total polyphenols (TP), flavanol monomers, and procyanidin oligomers were determined in chocolate frosting, a hot cocoa drink, chocolate cookies, and chocolate cake made with natural cocoa powder. Recoveries of antioxidant activity, TP, flavanol monomers, and procyanidins ranged from 86% to over 100% in the chocolate frosting, hot cocoa drink, and chocolate cookies. Losses were greatest in the chocolate cake with recoveries ranging from 5% for epicatechin to 54% for antioxidant activity. The causes of losses in baked chocolate cakes were investigated by exchanging baking soda with baking powder or combinations of the 2 leavening agents. Use of baking soda as a leavening agent was associated with increased pH and darkening color of cakes. Losses of antioxidant activity, TP, flavanol monomers, and procyanidins were associated with an increased extractable pH of the baked cakes. Chocolate cakes made with baking powder for leavening resulted in an average extractable pH of 6.2 with essentially complete retention of antioxidant activity and flavanol content, but with reduced cake heights and lighter cake color. Commercially available chocolate cake mixes had final pHs above 8.3 and contained no detectable monomeric flavanols after baking. These results suggest that baking soda causes an increase in pH and subsequent destruction of flavanol compounds and antioxidant activity. Use of an appropriate leavening agent to moderate the final cake pH to approximately 7.25 or less results in both good leavening and preservation of cocoa flavanols and procyanidins.

Influence of natural antioxidants and their carry‐through property in biscuit processing

AbstractBACKGROUND: The present study has explored the use of natural antioxidants from plant sources such as hexane (G‐1) and chloroform (G‐2) extracts of Garcinia, Peltophorum ferrugineum flower extract (FE), turmeric powder (C‐1) and curcumin (C‐2), in biscuit preparation in the place of synthetic ones, and their carry‐through properties were evaluated during processing and storage. Microstructure and electrophoretic characterization of biscuit dough were carried out to understand the influence of these natural antioxidants in the processing of biscuits.RESULTS: Biscuits prepared with C‐1, C‐2, G‐1, and G‐2 were well acceptable, and FE biscuits were least acceptable. Among the antioxidants used, C‐2 was found to retain only 11.23% activity whereas G‐2 had retained 51% activity after baking, which was comparable to synthetic antioxidant butylated hydroxyanisole (BHA) and better than tert‐butylhydroquinone (TBHQ). Microstructure studies of biscuit dough indicated that in the case of G‐1, G‐2, C‐1 and BHA the gluten network formation was intact when compared to FE and TBHQ. Supportive electrophoresis studies indicated that there was no change in the wheat protein subunits of different samples except for FE biscuit dough.CONCLUSION: Based on the result of retention of antioxidant activity during baking and storage, hexane and chloroform extracts of Garcinia (G‐1, G‐2) and turmeric powder (C‐1) were found to be suitable for use in biscuits as natural antioxidants and results were comparable with BHA. The present study also indicated that protein subunits of biscuit dough were not affected by antioxidants. However, antioxidants influenced the protein–starch–lipid network during biscuit dough formation. Copyright © 2008 Society of Chemical Industry

Delivering polyphenols for healthy ageing

AbstractThere is a growing demand for delivery of antioxidants through functional foods with the concomitant challenge of protecting their bioactivity during food processing and subsequent passage through the gastrointestinal tract. This study focuses on the retention of antioxidant activity of polyphenolic antioxidants after encapsulation/spray‐drying. The polyphenolic compounds present in grape‐seed extract (GSE), apple polyphenol extract (APE) and olive‐leaf extract (OLE) were analysed by chromatographic methods. Catechin, epicatechin and gallic acid were identified in GSE and APE. Oleorupein is the major compound found in OLE. Total polyphenol content was found to be the highest in APE followed by GSE and OLE. These extracts were encapsulated using protein‐lipid emulsions and subsequently spray‐dried. Optical microscopy and particle size distribution analysis indicated the sphericity and uniform size distribution pattern of the dry particles. Radical scavenging activity studies demonstrated significant retention of antioxidant activity after the encapsulation and spray‐drying process.

Chitosan microspheres for encapsulation of α-lipoic acid

Encapsulation of α-lipoic acid (LA) was carried out using chitosan as an encapsulant matrix. Placebo and LA-loaded chitosan microspheres were prepared by a spray-drying process. Scanning electron microscopy (SEM) studies confirmed the spherical particle geometry and the smooth surface morphology of LA-loaded particles. The particle size distribution (PSD) analysis of the placebo and LA-loaded microspheres has shown that 50% of the microspheres were less than 3.53 and 7.89 μm, respectively. The structural interactions of the chitosan matrix with the encapsulated LA were studied by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) which revealed structural interactions of lipoic acid with the encapsulant matrix. The antioxidant activity of encapsulated lipoic acid was studied using the free-radical scavenging assay. This study demonstrated significant retention of antioxidant activity of lipoic acid (75%) after encapsulation in the chitosan matrix. Encapsulation efficiency of lipoic acid obtained in this study was 55.2% when ethanol and acetic acid (1:1 v/v) was used as incubation/extraction medium.

The effect of sorghum type and processing on the antioxidant properties of African sorghum-based foods

This work determined the effect of sorghum type and different processing technologies of traditional African sorghum foods on total phenols, tannin content and antioxidant activity. The products were prepared by fermentation, conventional and extrusion cooking of whole and decorticated ground grain. The tannin sorghum types, had higher ABTS and DPPH antioxidant activities, compared to the types without tannins. Antioxidant activity was significantly correlated with total phenols and tannins ( r > 0.95). Decortication, reduced antioxidant activity of both tannin and non-tannin sorghum by 82–83% due to the removal of the pericarp and the testa, which decreased phenols. Processing, generally decreased antioxidant activity, however, conventionally cooked porridges had higher antioxidant activity than the extrusion cooked products. The retention of antioxidant activity, particularly in fermented and unfermented porridges, means that whole tannin sorghum can be processed into foods with potential health benefits.

Retention of Antioxidant Activity in Minimally Processed Mandarin and Satsuma Fruits

Changes in overall antioxidant activity of the water-soluble fraction of some mandarin derivatives were studied. In particular, fresh juices and segments packaged with two plastic films having different permeability were considered. The evolution of antioxidant properties as affected by processing and storage conditions were not entirely related to ascorbic acid changes. Mandarin juices showed good retention of the original antioxidant activity at the end of storage. The less permeable film resulted in a better retention of segment antioxidant power.

EFFECT OF HARVESTING METHOD AND DRYING TREATMENT ON THE ANTIOXIDANT ACTIVITY OF SAGE

Sage contains the antioxidant thujone, which can be used to preserve foods in place of synthetic antioxidants. This study was conducted to determine if different harvesting methods would affect greater retention of antioxidant activity (AOA) of sage. The harvesting methods evaluated included sickle harvest, hand harvest, and flail harvest. Harvested samples were air-dried (temperature range 15 to 49C) and oven-dried (continuous 49C). Leaf area analysis indicated that flail harvesting induced substantial chopping and size reduction of the harvested material. AOA of sample extracts was measured using a carotinoid bleaching process against a standard BHT solution. Our results show a definite difference in retention of AOA between the harvesting methods (sickle 65%, hand 55%, flail 50% of BHT). This difference between harvesting methods was the same over the two drying treatments, although oven drying resulted in a decrease in AOA for all harvesting methods. Supported by USDA grant 93-34150-8409 and the Oklahoma Agricultural Experiment Station.