Antioxidant Capacity Of Fruit Juices Research Articles

Evaluation of the Antioxidant Capacity of Fruit Juices by Two Original Analytical Methods.

Two analytical methods previously developed by our groups were employed to estimate the antioxidant capacity of commercial fruit juices. The electrochemical method, which measures the scavenging activity of antioxidants towards OH radicals generated by both hydrogen peroxide photolysis and Fenton's reaction, is based on the recovery of the cyclic voltametric response of the redox probe Ru(NH3)63+ at a Glassy Carbon electrode modified with a thin film of an insulating polyphenol, in the presence of compounds with antioxidant properties. The values of the antioxidant capacity of the fruit juices are expressed as vitamin C equivalents/L. The chromatographic method is based on the generation of OH radicals via Fenton's reaction in order to test the inhibition of their formation in the presence of antioxidant compounds by monitoring salicylate aromatic hydroxylation derivatives as markers of •OH production, by means of HPLC coupled to coulometric detection. The results are expressed as the percentage of inhibition of •OH production in the presence of the tested juice compared to the control sample. When OH radicals are produced by Fenton's reaction, the antioxidant capacity of the juices, estimated by both methods, displays an analogous trend, confirming that they can be considered an alternative for measuring the ability of antioxidants to block OH radical formation.

Phenolic, Headspace and Sensory Profile, and Antioxidant Capacity of Fruit Juice Enriched with Salvia officinalis L. and Thymus serpyllum L. Extract: A Potential for a Novel Herbal-Based Functional Beverages.

Since certain constituents are not naturally present in pure fruit juices, incorporating herbal extracts can provide specific sensory properties to the beverages and improve their biopotential. In our previous research, it was found that sage (Salvia officinalis L.), wild thyme (Thymus serpyllum L.), and combinations of their extracts had the highest total phenolic content and a unique composition of volatile compounds, which can contribute to the aromatic and antioxidant qualities of functional products. Therefore, this research aimed to investigate the potential of sage and wild thyme extracts, as well as their mixture (wild thyme:sage at 3:1, v/v), to enrich fruit juices (apple, pineapple, and orange). Obtained beverages were evaluated for sensory properties as well as phenolic and headspace composition (UPLC-MS/MS and HS-SPME/GC-MS analysis) and antioxidant capacity (ORAC assay). The incorporation of wild thyme extract in pineapple juice provided the most harmonious flavor and the highest content of volatile compounds (on PDMS/DVB fiber). The orange juice formulations were the most enriched with phenolic and volatile compounds (on DVB/CAR/PDMS fibers). The highest antioxidant capacity was observed in the formulation with orange juice and sage extract (22,925.39 ± 358.43 µM TE). This study demonstrated that enriching fruit juices with sage and wild thyme extracts could create functional beverages with improved sensory and health-promoting properties, providing valuable insights for the food and beverage industry to meet the growing demand of health-conscious consumers for natural and functional products.

Stability of the phenolic compounds and antioxidant capacity of five fruit (apple, orange, grape, pomelo and kiwi) juices during in vitro‐simulated gastrointestinal digestion

SummaryThe in vitro digestive stability of phenolic compounds and the antioxidant capacity of five kinds of commonly consumed fruit juices in the daily diet, including apple juice (AJ), orange juice (OJ), grape juice (GJ), pomelo juice (PJ) and kiwifruit juice (KJ), were studied. Following in vitro digestion, the total phenolic (TP) content of fruit juices decreased to different extents by 35%, 25.3%, 23.5%, 22.2% and 7.8% for KJ, OJ, PJ, GJ and AJ, respectively. The individual phenolic content showed similar changes to the TP content, showing reductions of naringenin‐trisaccharide in OJ and PJ, epicatechin in GJ, and chlorogenic acid in AJ by 43.74%, 27.59%, 47.11% and 33.28%, respectively. Conversely, the antioxidant capacity of fruit juices during digestion measured by ABTS assay increased from 4.79% to 35.53%, except in KJ, which decreased by 19.34%. These results show the health benefits of fruit juices after processing and contribute towards establishing suitable dietary recommendations.

Food and ascorbic scavengers of hydrogen peroxide

Common spectrometric methods to determine hydrogen peroxide scavenging activity require time-consuming extraction protocols and become poorly reliable because of the sample turbidity or the presence of UV-absorbing compounds. The present work suggests the use of reaction calorimetry to determine the antioxidant capacity of fruit juices, fruit puree, tea, coffee and alcoholic beverages, like wines. This experimental approach that does not imply the above drawbacks and does not require any extraction protocol allows the direct monitoring of the reaction between food beverages and H2O2. The overall exothermic effect reflects the extent of the scavenging activity of the samples versus hydrogen peroxide. The reliability of the approach is assessed through the study of the reaction between hydrogen peroxide and ascorbic acid at different concentration and pH at room temperature.

Comparison of the effects of blending and juicing on the phytochemicals contents and antioxidant capacity of typical korean kernel fruit juices.

Four Korean kernel fruit (apple, pear, persimmon, and mandarin orange) juices were obtained by household processing techniques (i.e., blending, juicing). Whole and flesh fractions of each fruit were extracted by a blender or a juicer and then examined for phytochemical content (i.e., organic acids, polyphenol compounds). The antioxidant capacity of each juice was determined by ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. Results revealed that juices that had been prepared by blending whole fruits had stronger antioxidant activities and contained larger amounts of phenolic compounds than juices that had been prepared by juicing the flesh fraction of the fruit. However, the concentration of ascorbic acid in apple, pear, and mandarin orange juices was significantly (P<0.05) higher in juice that had been processed by juicing, rather than blending. The juices with the highest ascorbic acid (233.9 mg/serving), total polyphenols (862.3 mg gallic acid equivalents/serving), and flavonoids (295.1 mg quercetin equivalents/serving) concentrations were blended persimmon juice, blended mandarin orange juice, and juiced apple juice, respectively. These results indicate that juice extraction techniques significantly (P<0.05) influences the phytochemical levels and antioxidant capacity of fruit juices.

Bioactive Properties of Fruit Juice of Pomegranate (&lt;i&gt;Punica granatum&lt;/i&gt;) Grown in Dry Regions of Sri Lanka

Pomegranate (<em>Punica granatum</em>) is a popular fruit in Sri Lanka, rich with medicinal properties and extensively used in traditional Ayurvedic medicines. Total phenolic content, vitamin C and antioxidant activity of the fruit (aril) juice were determined in fruits harvested from three locations in the southern dry zone (DL 1a). The total phenolic content and vitamin C, as determined by the Folin-Ciocalteau method, were 22.2±6.5 and 8.7±2.3 g/L, respectively, but significantly lower than that of pomegranate collected from Chilaw, a popular pomegranate growing area in the north-west (DL 3). However, the antioxidant capacity of the fruit juice of pomegranate from DL 1a was comparable with the same of DL 3. Antioxidant capacity of pomegranate fruit juice was positively correlated with total phenol content and vitamin C content. The results revealed the bioactive properties of fruit juice extracted from local pomegranate trees grown in home gardens of the southern dry region of Sri Lanka, emphasizing potential exploitations of these properties of pomegranate in the fruit juice industry. Tropical Agricultural Research Vol. 23 (4): 370-375 (2012) DOI:<strong> </strong><a href="http://dx.doi.org/10.4038/tar.v23i4.4873">http://dx.doi.org/10.4038/tar.v23i4.4873</a>

A Comparative Study of the Analysis of Antioxidant Activities of Liquid Foods Employing Spectrophotometric, Fluorometric, and Chemiluminescent Methods

The antioxidant profile of liquid foods is complex and includes different lipid and water-soluble compounds. These should be considered when assessing total antioxidant capacity (TAC) of these beverages, since it may act synergistically rather than individually. This study describes and compares the use of spectrophotometric methods (Trolox equivalent antioxidant capacity, TEAC and 2,2-diphenyl-1-picrylhydrazyl, DPPH), fluorometric (oxygen radical antioxidant capacity, ORAC), and photochemiluminescence (PCL) for the measurement of the TAC of different liquid foods (fruit juice mixed with milk and vegetables beverage). An evaluation was also made for the influence of certain compounds (ascorbic acid, phenolic compounds, total carotenoids, and tocopherols) with antioxidant capacity that was present in the samples studied. The different methods studied allow the determination of the TAC of the analyzed foods in a precise and accurate way. The TAC values in the studied samples differ from the applied method. An overall antioxidant potency composite index was calculated by assigning each test's equal weight. When an index score was applied, ORAC method had the higher antioxidant capacity values in the analyzed liquid foods in comparison with the other methods. The correlations among the different methods used for the determination of the antioxidant capacity depend on food, that is, mainly due to compounds (lipid and water soluble) of the different food matrix. In addition, ascorbic acid was the main contributor to antioxidant capacity of fruit juice mixed with milk beverages measured with the different methods. However, in vegetables beverages, phenolic compounds were found to correlate more significantly with antioxidant capacity values.

A rapid antioxidant assay based on acidic potassium permanganate chemiluminescence

Abstract The total antioxidant capacity of fruit juices and teas was established using flow-injection analysis with acidic potassium permanganate chemiluminescence detection, and the results were compared to those of two conventional assays. The chemiluminescence procedure was rapid (over 100 samples could be run per hour) and precise (relative standard deviation assays was observed for 20 tea samples (r = 0.955). In general, green teas gave larger responses than black teas with both procedures, but there was considerable variation between brands. Moreover, when coupled with chromatographic separation, this chemiluminescence assay can be used to examine the contribution of individual antioxidants and monitor specific changes in foods and beverages during production and storage. Epigallocatechin and epigallocatechin gallate were found to contribute over 65% of the total chemiluminescence signal (integrated peak area) for a green tea sample. In the chromatogram for a black tea, these peaks were present but less prominent, and a small cluster of peaks representing theaflavins was observed.