Determination of phenolic compounds and their antioxidant activity in fruits and cereals (original) (raw)
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Total Phenolics and Antioxidant Capacity Assays of Selected Fruits
Th e biologically active compounds, especially fruit phenolics, are responsible for reduced risk of developing chronic diseases (cardiovascular disease, cancer, diabetes, etc.), due to their antioxidant activities. Th is study summarized some chemical principles of antioxidant capacity assays and the antioxidant capacity of selected fruit varieties (strawberry, sour cherry, cornelian cherry, blackthorn). We determined the contents of total phenolics (TPC), total fl avonoids (TF), total non-fl avonoids (TNF) and total anthocyanins (TA) in selected fruits. Th e content of TPC, TF and TNF in fruits was analyzed by Folin-Ciocalteu colorimetric method, while the TA content of extracts was determined by bisulphite bleaching method. Total antioxidant capacity (TAC) of selected fruits were analyzed using 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation (ABTS), 2,2-diphenil-1-picrylhydrazyl radical scavenging capacity (DPPH), ferric ion reducing antioxidant power (FRAP) and oxygen radical absorbance capacity (ORAC). Cornelian cherry had the highest content of TPC, while sour cherry cv. Marasca had the highest content of TA. TAC was the highest in cornelian cherry fruits and decreased in other fruits as follow: sour cherry, blackthorn and strawberry. Th e fruit extracts had diff erent TAC in relation to the method applied, and the diff erent TAC of fruits can be ascribed to their TPC, TF, TNF or TA content. Th ere was a direct correlation between the TAC determined using DPPH and ORAC methods and the TA content of fruit extracts. Using FRAP method correlation was weaker, but using ABTS method correlation was not observed. Th e ripping correlation between TF or TNF and TAC was observed using ABTS and ORAC methods.
Antioxidant Activity and Total Phenolic Content in Some Cereals and Legumes
International Journal of Food Properties
The antioxidant activities and total phenolic content of 4 cereals (buckwheat, wheat germ, barley, and rye) and 4 legume seeds (lentils, mungo bean, red kidney bean, and soy bean) were determined. The total phenolic content (TPC), determined according to the Folin-Ciocalteu method, for cereal samples varied from 13.2 to 50.7 mg Gallic acid equivalent/g of dried extract, while for legume samples varied from 17.0 to 21.9 mg Gallic acid equivalent/g of dried extract. Antioxidant activities were comparatively assessed by 2,2-diphenyl-1- picrylhydrazyl (DPPH) scavenging capacity, ferric ion-reducing antioxidant power (FRAP) and the thiobarbituric acid (TBA) method. The tested plant extracts showed promising antioxidant and free radical scavenging activity, thus justifying their traditional use. Among examined cereals all the applied methods, except TBA method, have shown that buckwheat have the highest antioxidant activity, while among examined legumes results varied depending on the met...
Journal of Agricultural and Food Chemistry, 2006
The measurement of antioxidant capacity in fruits differs from that of other biological samples due to their low pH and very low lipophilic antioxidant capacity. In this report, we present a modified 2,2azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) method for fruits and compare its performance with the other commonly used antioxidant methods of 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). The antioxidant capacity and reaction kinetics of four phenolic compounds, two antioxidant standards, and five fruits were also investigated. The modified ABTS method prepared at a pH of 4.5 with sodium acetate buffer is highly stable and easily applied to fruit samples as compared to the standard (pH 7.4) version. The measured antioxidant capacity of samples varied with the assay method used, pH, and time of reaction. Traditional antioxidant standards (trolox, ascorbic acid) displayed stable, simple reaction kinetics, which allowed end point analysis with all of assays. Of the phenolic compounds examined, chlorogenic and caffeic acids exhibited the most complex reaction kinetics and reaction rates that precluded end point analysis while gallic acid and quercetin reached stable end points. All fruit extracts exhibited complex and varied kinetics and required long reaction times to approach an end point. Because the antioxidant capacity of fruit extracts is a function of the array of individual antioxidants present, accurate comparisons among fruit samples require that reaction times be standardized and of sufficient length to reach steady state conditions and that more than one assay be used to describe the total antioxidant activity of fruit samples.
Food Research International, 2011
Agri-food waste (AFW) and by-products represent sources of phytochemicals, such as phenols and antioxidant compounds that can be used as functional ingredients in animal feed. In this study, a selection of AFW and by-products were collected and analysed for their nutrient composition. After chemical (with methanol) and physiological (in vitro digestion) extraction, total phenolic content and antioxidant capacity (AOC) were determined in AFW and by-product samples using Folin-Ciocalteu and 2,2 0-azinobis(3-ethylbenzothiazoline 6-sulfonic acid)-ABTS methods, respectively. Sample digestibility was also assessed using a multi-step enzymatic technique. After chemical extraction, grape marc showed the highest total phenolic content (4480.5 ± 886.58 mg TAE/100g; p < .05). Fruit and vegetable waste (FVW), orange peel, strawberry, citrus pulp and Camelina sativa cake showed a total phenolic content ranging from 238.0 ± 4.24 to 1583.0 ± 154.35 mg TAE/100g. Grape marc also showed the highest AOC (15440.7 ± 2671.85 mg TE/100g). In all other samples, AOC ranged from 43.3 ± 3.17 to 1703.9 ± 391.07 mg TE/100g. After physiological extraction, total phenolic content values higher than 3000 mg TAE/100g were observed in FVW, grape marc and orange peel. Grape marc, C. sativa cake and orange peel had AOC values of over 5000 mg TE/100g. The digestibility of AFW and by-products ranged from 44.20 to 97.16%. The lowest digestibility value was observed in grape marc (44.2 ± 2.31%). In conclusion, the results obtained in this study indicate that AFW and by-products could be a source of bioaccessible phenols and antioxidant molecules as ingredients for monogastric compound feeds. HIGHLIGHTS Agri-food waste and by-products can be reused in feed industry. Agri-food waste and by-products are a source of valuable compounds as phenols and antioxidant molecules.
Antioxidant activity of small grain cereals caused by phenolics and lipid soluble antioxidants
Journal of Cereal Science, 2011
In this study, the content of soluble, free forms of phenolic compounds (total phenolics, flavonoids, PVPP (polyvinylpolypyrrolidone) bound phenolics, proanthocyanidins and phenolic acids), as well as the content of carotenoids and tocopherols, were determined in whole grains of bread and durum wheat, rye, hull-less barley and hull-less oat, each represented with four genotypes. Antioxidant activity was evaluated as radical scavenging activity with DPPH (2,2-diphenyl-1-picrylhydrazyl) reagent, as well as by hydrogen transfer reaction (reduction power) based on the reduction of Fe 3þ . Generally, a considerable variation in antioxidant activities and phytochemical contents was observed between the cereals. Remarkably higher DPPH radical scavenging ability and reducing power were detected in hull-less barley, followed by rye and hull-less oat and durum and bread wheat, indicating that small grain species have different major antioxidants with different properties. Hull-less barley had the highest content of total free phenols, flavonoids, PVPP bound phenolics and contained flavan-3-ols, not found in other species. Hull-less oat had the highest content of tocopherols, very high content of yellow pigments and PVPP bound phenolics. Ferulic acid was the major free phenolic acid in small grain cereals tested. The relationship between the content of soluble phenols, as well as reducing power and DPPH scavenging activity are also considered.
Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries. From evaluation of data presented at the First International Congress on Antioxidant Methods in 2004 and in the literature, as well as consideration of potential end uses of antioxidants, it is proposed that procedures and applications for three assays be considered for standardization: the oxygen radical absorbance capacity (ORAC) assay, the Folin-Ciocalteu method, and possibly the Trolox equivalent antioxidant capacity (TEAC) assay. ORAC represent a hydrogen atom transfer (HAT) reaction mechanism, which is most relevant to human biology. The Folin-Ciocalteu method is an electron transfer (ET) based assay and gives reducing capacity, which has normally been expressed as phenolic contents. The TEAC assay represents a second ET-based method. Other assays may need to be considered in the future as more is learned about some of the other radical sources and their importance to human biology. Mention of a trade name, proprietary product, or specific equipment does not constitute a guarantee by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may be suitable.
Plant foods for human nutrition (Dordrecht, Netherlands), 2018
The aim of this study was to investigate the free individual phenolics and the in vitro antioxidant capacity of blackberry, acerola, yellow guava, guabiju, jambolan and jabuticaba fruits in two edible stages. Of the thirty-three phenolics investigated by liquid chromatography - tandem mass spectrometry (LC-MS/MS), twenty-five were quantified and the major ones were catechin, isoquercitrin, epicatechin and gallic acid. The highest values for the total phenolic content (in dry matter) were observed for acerola (83.6 to 97.7 mg gallic acid equivalents g DM) and blackberry (18.9 to 28.3 mg gallic acid equivalents g DM); however, acerola, jabuticaba, and blackberry showed the highest antioxidant capacities (134.6 to 1120.4 mg Trolox equivalents g for 2,2-diphenyl-1-picrylhydrazyl and 43.6 to 501.8 μmol Trolox equivalents g for ferric reducing antioxidant power). For most fruits, the antioxidant capacity decreased during the ripening, possibly due to a decrease in the concentration of mos...
Phenolic Acid Profiles and Antioxidant Activity of Major Cereal Crops
Antioxidants, 2020
Phenolic acids (PAs) are a dominant group of phenolic compounds in cereals, existing mostly bound to compounds of cell wall. In this study, a total of 25 cereal grain samples, including wheat, winter and spring barley, corn, and popcorn, were evaluated for bound PAs and antioxidant activity in a two-year field trial. The PA contents, determined by HPLC, were significantly affected by cereal type. The mean total PA content was highest in popcorn and corn (3298 and 2213 μg/gdm, respectively), followed by winter and spring barley (991 and 908 μg/gdm, respectively) and wheat (604 μg/gdm). Ferulic acid was the most abundant, accounting from 62% to 83% of total PAs (in popcorn and winter and spring barley, respectively). Across cereals, p-coumaric (35–259 μg/gdm) and p-hidroxybenzoic (45–79 μg/gdm) were also dominant, while in corn and popcorn o-coumaric (71 and 89 μg/gdm, respectively) also occurred in higher content. The mean total phenol content ranged from 853 μg GAE/gdm (wheat) to 14...