Antioxidant Activity Of Grains Research Articles

The effect of malting on phenolic compounds and radical scavenging activity in grains and breakfast cereals.

Breakfast cereals are popular grain foods and sources of polyphenols. Malting alters polyphenol content and activity; however, effects are varied. The total polyphenol content (TPC), radical scavenging activity (RSA), and polyphenol profile were analyzed in unmalted and malted grains (wheat, barley, and sorghum) and breakfast cereals (wheat, barley) by Folin Ciocalteu Reagent (FCR), % inhibition of the free radical 2,2-diphenyl-1-picryl-hydrazyl, and high performance liquid chromatography. Higher TPC was observed in all malted grains and breakfast cereals compared with unmalted samples (p<0.05). Higher RSA was also observed in all malted samples compared to unmalted samples (p<0.05) except for wheat grain to malted wheat grain. In this study, malting induced additional polyphenols and antioxidant activity in grains and cereal products. Malted grain breakfast cereals may be practical sources of polyphenol antioxidants. PRACTICAL APPLICATION: This study utilized malting in a unique way to investigate potential health benefits of polyphenols and antioxidant activity in grains (wheat, barley, and sorghum) and ready-to-eat breakfast cereals (wheat and barley). This study found that grains and breakfast cereals are important sources of antioxidant polyphenols, and these were significantly increased in malted varieties. Understanding this is important as grains and breakfast cereals are widely consumed staple foods. Consuming healthier grain products may be a practical strategy in reducing the risk of noncommunicable diseases such as colorectal cancer and type-2 diabetes, where wholegrain consumption may be important in prevention.

Effect of cooking on the bioactive compounds and antioxidant activity in grains cowpea cultivars

The present study evaluated the effect of cooking on the levels of bioactives compounds and antioxidant activity in grains cowpea cultivars. The analysis were performed on the raw samples and after cooking in pressure cooker. Regarding the bioactive compounds present, the grain cultivar BRS Arace exhibited the highest levels of total phenolic compounds (mg/100 g) both before and after cooking, 205.10 ± 2.89 and 150.62 ± 2.64, respectively. Spermine and spermidine were identified in the cultivars (mg/kg) BRS Milenio in the amount of 120.5 in crude and 50.4 in cooked grain, in the BRS Tumucumaque in the amount of 116.2 in crude and 47.9 in cooked grain, exhibited significant losses of these compounds after cooking. It was not detected the presence of anthocyanins and flavonoids in the grain cultivars. For the antioxidant activity were observed different behaviors for each grain cultivar in the two methods evaluated. The grain cultivar BRS Arace presented the highest antioxidant activity before cooking according to both methods tested (μmol TEAC/100 g), 614.7 ± 5.43 (DPPH) and 660.1 ± 7.98 (ABTS). The grain cultivar BRS Xiquexique 419.8 ± 6.80 exhibited the highest antioxidant activity and the grain cultivar BRS Milenio 552.1 ± 4.78 after cooking. A strong correlation between the antioxidant activity and phenolic content and total flavonoid was found. It is concluded that the grains cultivars maintained important nutritional and functional characteristics following processing, recommending that the cowpea consumption with broth cooking for retaining compounds with antioxidant properties.

Antioxidant Activities of Selective Gluten Free Ancient Grains

Ancient grains were known for special nutritional values along with gluten free qualities. Amaranth, quinoa, teff, and buckwheat flours were evaluated for pasting properties, water holding capacities, phenolic contents, and antioxidant activities (free and bound). They all had higher water holding capacities than wheat flour. Amaranth, quinoa, and teff showed higher pasting viscosities than wheat flour. Buckwheat flour had the highest free, bound and total phenolic contents among the flours in all aqueous extracts. The bound phenolic contents were higher than the free phenolic contents regardless of the solvents with the exception of water extraction of quinoa and buckwheat. The free phenolic compounds for all four flours were highest in water extract, and least in 100% ethanol. Bound antioxidant activities were much higher than the free antioxidant activities regardless of solvents for all products. The free antioxidant activities from water and 50% ethanol were higher than 100% ethanol. In contrast, more bound phenolics were extracted with 100% ethanol than water and 50% ethanol. Our study suggested that the total phenolic contents and antioxidant activities of grains could be underestimated in the literature without considering the bound phenolic compounds. These ancient grains have nutrition, antioxidants, and textural qualities suitable for functional foods.

Effect of processing on the antioxidant activity of millet grains

Millets are generally dehulled and subjected to a hydrothermal treatment before consumption, thus the hulls can be used as a potential source of antioxidants. Several millet grains, namely kodo, finger (Ravi), finger (local), proso, foxtail, little and pearl millet were studied. Antioxidant activities of phenolic extracts obtained from whole grains, as well as their corresponding dehulled and cooked grains and hulls were studied for their total phenolic content (TPC), radical scavenging capacity, and antioxidant activity in a β-carotene/linoleate emulsion. The phenolics present in whole grains were identified and quantified using HPLC and HPLC/MS and results were expressed as total for each of the phenolic groups. The TPC ranged from 2 to 112μmol ferulic acid equivalents/g defatted meal. All varieties exhibited effective inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, peroxyl and superoxide radicals. Dehulling and cooking affected the TPC and radical scavenging and antioxidant activities of the grains, depending on the variety. In general, the antioxidant activity of phenolic extracts was in the order of hull>whole grain>dehulled grain>cooked dehulled grain With the exception of the two finger millet varieties, hulls of other millet grains had high TPC, thus demonstrating their superior antioxidant activity. Hydroxybenzoic acids, hydroxycinnamic acids and flavonoids in whole grains were identified as contributors to the observed effects. Therefore, dehulling of grain and hydrothermal treatments affect the phenolic content and antioxidant potential of millet grains.

Antioxidant Activity in Barley (Hordeum Vulgare L.) Grains Roasted in a Microwave Oven under Conditions Optimized Using Response Surface Methodology

Microwave processing and cooking of foods is a recent development that is gaining momentum in household as well as large-scale food applications. Barley contains phenol compounds which possess antioxidant activity. In this study the microwave oven roasting condition was optimized to obtain grains with high antioxidant activity measured as the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical. Antioxidant activity of grains roasted under optimum conditions was assessed based on DPPH radical scavenging activity, reducing power and inhibition of oxidation in linoleic acid system. The optimum condition for obtaining roasted barley with high antioxidant activity (90.5% DPPH inhibition) was found to be at 600 W microwave power, 8.5 min roasting time, and 61.5 g or 2 layers of grains. The roasting condition influenced antioxidant activity both individually and interactively. Statistical analysis showed that the model was significant (P < 0.0001). The acetone extract had significantly high inhibition of lipid peroxidation and DPPH radical scavenging activity compared to the aqueous extract and alpha-tocopherol. The reducing power of acetone extracts was not significantly different from alpha-tocopherol. The acetone extract had twice the amount of phenol content compared to the aqueous extract indicating its high extraction efficiency. GC-MS analysis revealed the presence of phenol acids, amino phenols, and quinones. The aqueous extract did not contain 3,4-dihydroxybenzaldehyde and 4-hydroxycinnamic acid which are phenol compounds reported to contribute to antioxidant activity in barley grain.