The total polyphenols and the antioxidant potentials of some selected cereals and pseudocereals

The objective of the present study was to investigate the effect of phenolic substances and proteins on the antioxidant potentials in some cereals and pseudocereals and to compare their bioability. The polyphenol dry matter extracts (PDME) from the investigated seeds of buckwheat, rice, soybean, amaranth and quinoa with 1.2 M HCl in 50% methanol/water (PDME50%Met/HCl) exhibited higher inhibition of lipid peroxidation than the ones extracted with 50% methanol/water (PDME50%Met) and were comparable to the antioxidant activity of butylated hydroxyanisole at concentration of 0.2 mg mL⁻¹. The antioxidant activities of these seed extracts determined by 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate)-ABTS^●+/K₂S₂O₈, β-carotene bleaching (β-carotene), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods showed high correlation coefficients (R ²) such as 0.9515, 0.9058 and 0.8723, respectively, with the presence of total polyphenols estimated by Folin-Ciocalteu assay. These results indicate that the major antioxidant components in these extracts mostly derived from the polyphenols, and proteins showed only minimal values of bioactivity. Based on high contents of polyphenols, anthocyanins, flavonoids and their antioxidant activities pseudocereals such as buckwheat, quinoa and amaranth can be a substitute for cereals for common and atherosclerotic diets and sometimes in the allergic cases.     

Effect of fermentation on antioxidant properties of some cereals and pseudo cereals

The influence of fermentation by two types of microorganisms (lactic acid bacteria Lactobacillus rhamnosus, and yeast Saccharomyces cerevisiae) on antioxidant activities and total phenolics of 4 cereals, namely buckwheat, wheat germ, barley and rye, was determined and compared with those of their unfermented counterparts. The total phenolic content (TPC), determined by the Folin–Ciocalteu method, increased upon fermentation. Antioxidant activities (AOA) were assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging capacity, ferric ion-reducing antioxidant power (FRAP) and thiobarbituric acid (TBA) methods. The presence of those microorganisms was more or less important for enhanced levels of antioxidant activity. Thus fermentation offers a tool to further increase the bioactive potential of cereal products.     

Proanthocyanidins in cereals and pseudocereals

Proanthocyanidins (PAs) are a class of oligomeric flavonoids found in a variety of plant foods. Intake of PAs in human diet has been associated with a reduced occurrence of various chronic disorders. Cereal and pseudocereal grains are staple food items. Grain genotypes containing PAs can be developed as functional foods to efficiently improve human health. This review summarises the occurrence of PAs in diverse grains, including rice, wheat, barley, sorghum, millets, buckwheat, and some forage grasses. Great diversity in PA structure and composition has been recorded. The biological activities of the grain PAs, such as antioxidant, antiinflammatory, anticancer, and antidiabetic capacities, are also reviewed. The bioavailability and metabolism of grain PAs in human digestive tract are discussed. Future research directions are suggested on how to improve our understandings of the chemistry of PAs in cereals and pseudocereals and of the biological properties for human health applications.     

杂粮多酚功能活性研究进展

杂粮中多酚物质含量丰富,加大对杂粮多酚功能活性的深入研究对我国杂粮产业及国民健康具有十分深远的意义。本文综述了国内外杂粮多酚的抗氧化、抗癌、抗心脑血管疾病、降血糖、抗菌等功能活性的研究进展,为杂粮多酚的进一步研究和开发奠定理论基础。      

Comparison of total antioxidant capacity and phenolic composition of some apple juices with combined HPLC–CUPRAC assay

It was aimed in this study to identify and quantify various constituents (particularly phenolics) of apple juice and to quantitatively compare the total antioxidant capacities of juices obtained from apple varieties grown in Turkey.     

In vitro gastrointestinal digestion of mango by-product snacks: Potential absorption of polyphenols and antioxidant capacity

Mango by-products are considered cheap sources of valuable foods and nutraceutical ingredients. In this work, antioxidant capacity (AOX), and potential absorption ability (PAA) of extractable polyphenols (EP) from mango by-product snacks (MB-S) were evaluated at different stages of in vitro gastrointestinal digestion. A wheat and oat-based control snack and three MB-S formulations (F1, F2 and F3) were prepared. Mango by-products were added at the expense of wheat in MB-S (paste-peel-seed): F1 (70-30-0), F2 (70-15-15), F3 (70-7.5-22.5). The highest release of polyphenols was observed after the gastric digestion. In the intestinal stage, MB-SF1 was the snack with the highest EP content (23.39 mg GAE/g db), two times greater than the control. Gallic acid and mangiferin were the main polyphenols identified in MB-S. The incorporation of mango seed in the MB-S reduced the polyphenols PAA by 10.29%. However, compared with the control snack, consumption of 30 g MB-SF1 provided additional 45 mg polyphenols.     

Tocopherols composition of Portuguese wild mushrooms with antioxidant capacity

The antioxidant composition and properties of 18 Portuguese wild mushrooms (Clitocybe alexandri, Cortinarius glaucopus, Fistulina hepatica, Hydnum repandum, Hygrophoropsis aurantiaca, Hypholoma capnoides, Laccaria amethystina, Laccaria laccata, Lactarius aurantiacus, Lactarius salmonicolor, Lepista inversa, Lepista sordida, Mycena rosea, Russula delica, Russula vesca, Suillus collinitus, Suillus mediterraneensis, Tricholoma sulphureum) were evaluated, in order to contribute to the overall characterisation of these products. Their radical-scavenging capacity, reducing power and inhibition of lipid peroxidation measured in liposome solutions was fully studied. Furthermore, the tocopherols composition was determined by HPLC-fluorescence. The analysed mushrooms contain powerful antioxidants such as phenols (0.51–7.90 mg/g) and tocopherols (0.02–8.04 μg/g). β-Tocopherol was the vitamer detected in higher amounts, while δ-tocopherol was not detected in the majority of the samples. All the species proved to have antioxidant activity being more significant for H. aurantiaca (EC₅₀ values lower than 1.35 mg/ml) due to the contribution of antioxidants such as phenols (7.90 mg/g) and tocopherols (0.02–1.94 μg/g). The ongoing research states the nutraceutical potential of all these unique species, making the information available for a better management and conservation of mushrooms and related habitats.     

Comparison of antioxidant capacity and phenolic composition of peel and flesh of some apple varieties

BACKGROUND: Apples contain a large concentration of phenolic compounds, dependent on factors such as cultivar, harvest, storage conditions, and processing. This study aims to identify the essential phenolic compounds present in various apple varieties, to measure their total antioxidant capacity (TAC) with the CUPRAC (cupric ion reducing antioxidant capacity) and ABTS (2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonate)) methods, and to correlate their TAC values with HPLC findings. RESULTS: The order of TAC (mmol Trolox g^?1 fresh weight) of apple peels determined with the CUPRAC method was: Granny Smith > Amasya > Sky Spur > Ervin Spur > King Luscious ≥ Arap Kizi ≥ Lutz Golden. The theoretically calculated TAC values of HPLC‐quantified compounds, with the aid of the combined HPLC‐CUPRAC method, accounted for 18.4–33.5% of the experimentally observed CUPRAC capacity of peel extracts and 19.5–56.3% of flesh extracts, depending on apple variety. CONCLUSION: In synthetic samples of apple antioxidants, the CUPRAC‐TAC values of constituents, identified and analyzed by HPLC, proved to be additive, enabling measurement of the cooperative action of antioxidants using the proposed methodology. Apple peel showed higher contents of phenolics and therefore higher TAC than apple flesh, confirming the health benefit of the consumption of apples together with peel. © 2012 Society of Chemical Industry     

Properties of extruded whole grain cereals and pseudocereals flours

Common cereals such as wheat are widely used worldwide in extruded products. Nevertheless, other locally available grains would be beneficial for local consumers regarding taste preference, nutritional needs and sustainability. Locally available cereals, that is millet, teff, sorghum and pseudocereals, that is quinoa and amaranth flours were extruded at the same processing conditions, and the resulting properties were compared to those of extruded refined wheat flour. Amaranth flour contained the highest protein content (16%). Sorghum was the highest in calories because of its high lipid content (10%). The extrusion process greatly increased a water solubility index (WSI) of amaranth from 11% to 61%, while the WSI level of quinoa was almost not affected (WSI of 4%). The expansion properties varied differently among grain types. These grains had a sectional expansion index (SEI) ranging between 11 and 13, which could not achieve the performance of the refined wheat (SEI of 22). The lowest expansion was observed for amaranth flour which contained the lowest starch content. Sorghum extrudates, interestingly, provided comparable stress at rupture value to that of wheat. For the mechanical properties, none of these local grains could fully replace refined wheat at the employed extrusion conditions.     

Effects of genotype, location and baking on the phenolic content and some antioxidant properties of cereal species

In order to assess the effect of genotype, location and their interaction on total phenolic content (TPC) of chemical extracts, the whole grains of durum and soft wheat, oat, barley and triticale were evaluated. Data showed differences in phenolic content of chemical extracts among cereal species and the analysis of variance confirmed the key role of location. Besides TPC and trolox equivalent antioxidant capacity (TEAC) values assessed by chemical extraction were compared with those obtained with an in vitro digestive enzymatic extraction. Differences were found between methanolic and enzymatic extracts, and data confirmed that enzymatic technique enhanced extraction of antioxidants but pointed out lesser differences among cereal types. The breads obtained by flours enriched with different levels of bran were also evaluated. Chemical extracts highlighted the increasing levels of antioxidants according to bran enrichments, without pointing out changes caused by baking. The enzymatic extraction instead did not show differences regarding to bran enrichments, but documented a loss in antioxidant properties of breads in respect to corresponding flours. On the other hand the scarce differences between flours and corresponding breads did not allow asserting that baking modified the TPC and TEAC, independently of the extraction methods used. Indeed, during baking process, also the observed phenolic acids profile variations did not vary the antioxidant properties of breads.     

Comparative study on composition and antioxidant properties of mint and black tea extract

The antioxidant properties of plants could be correlated with oxidative stress defence in different human diseases. The present study was undertaken to evaluate and compare the antioxidant potential and the phytochemical composition in the aqueous extracts of mint leaves, black tea and black tea enriched with mint extract. All the three preparations exhibited free radical‐scavenging potential for nitric oxide (NO) radical, superoxide anion radical and hydroxyl radical, and the values were lesser than those of the antioxidants which acted as standards. In comparison, the mint extract exhibited higher free radical and NO scavenging effect. Hydroxyl radical and superoxide scavenging effects were more pronounced in tea with the mint extract, while the reducing power was exhibited more significantly by the black tea extract. The phytochemical compounds were identified and the total phenols and flavonoids were quantified and compared between these extracts.     

Studies on deep-fat fried snacks from some cereals and legumes

Deep-fat fried products, prepared from cereals, legumes and their blends, are universally popular due to their desirable organoleptic profile. Grain types differ in their chemical make-up and physicochemical properties, which may account for the differences in the oil content of the snacks. In addition, the frying medium also plays an important role in the oil pick-up during deep-fat frying. This work attempts to correlate these parameters with the oil content in a traditional Indian extruded and deep-fat fried product, sev, using flours from rice, wheat, amaranth, chickpea, cowpea, black gram and green gram. No correlation between the proximate constituents (water-holding capacity and oil-holding capacity) and the oil content of the fried sev was seen. Oil content in sev was minimum when fried in cottonseed oil. © 1998 SCI.     

Characterisation of pseudocereal and cereal proteins by protein and amino acid analyses

Maize, wheat, amaranth, rice and soybean were screened for protein content. Alcohol‐soluble (A1 and A2) and glutelin (G1 and G2) fractions were isolated and compared in terms of their amino acid and protein compositions. The average proportions of nitrogen content between total alcohol‐soluble proteins (TASP) and total glutelins (TGlu) in the pseudocereals amaranth and soybean were about 1.8:26.9 and 14.9:12.3 respectively. In the cereals maize and wheat these proportions were 47.8:33.2 and 44.7:31.2 respectively. The sum of essential amino acids was 47.6 and 60.3 g per 100 g protein in amaranth and soybean respectively. The highest contents of methionine, lysine and arginine were found in the pseudocereals. The relatively high content of essential amino acids shows that pseudocereals could be used as a nutrient substitute for cereals. © 2002 Society of Chemical Industry     

UHPLC-ESI-QTOF-MS phenolic profiling and antioxidant capacity of bee pollen from different botanical origin

In this work, bee pollen samples from different botanical origin were investigated for antioxidant capacity. Thereafter, a phenolic profiling was produced through a mass spectrometric untargeted metabolomic approach. Marked differences were identified in TPC, ranging from 4.2 (Magnolia) to 29.6 mg g⁻¹ GAE (Lamium). Wide differences were also recorded in antioxidant capacity (ORAC, ABTS and DPPH assays). Untargeted profiling allowed annotating 467 compounds with flavonoids being the most frequent class of phenolics followed by phenolic acids, tyrosols, lignans and other. OPLS-DA clearly discriminated the most represented floral families (Umbelliferae, Rosaceae and Fabaceae), suggesting, thus, that botanical origin leaves a characteristic phenolic signature in pollen. Overall, 35 phenolics accounted for most of the discrimination, with flavonoids being the most represented class. Despite the fact that further research is needed, the phenolic profile of bee pollen is a promising tool to investigate the botanical origin.     

Browning of white wines: correlation with antioxidant characteristics, total polyphenolic composition and flavanol content

Browning is a serious problem in relation to white wine quality, which mostly affects the sensory attributes. It is well known to be associated with polyphenol oxidation, and therefore it may be accompanied by changes in the antioxidant capacity. On the basis of this consideration, thirteen experimental white wines, vinified and stored under identical conditions, were subjected to accelerated browning, and efforts were made to distinguish compositional parameters that might be related to the extent of browning development. Further, the relation of browning with the reducing power and the antiradical activity were assessed. Regression analysis at 95% significance level indicated that the antiradical activity is likely to be exerted principally by the flavanol fraction (r² = 0.92) and to a lesser extent by total phenols (r² = 0.85), as opposed to reducing power, which is mainly affected by total phenols (r² = 0.78), suggesting that synergistic phenomena account for the overall antioxidant status of white wines. In addition, the total phenolic and flavanol concentration correlated significantly with the browning rate constants and provided strong evidence that browning development might be predominately associated with flavanol (r² = 0.84) and to a lesser extent with total phenolic (r² = 0.79) oxidation.     

三种食醋中酚类物质及抗氧化能力的比较研究

通过光谱和高效液相色谱技术对苹果醋、山西老陈醋及恒顺香醋中酚类物质以及抗氧化能力进行分析研究,评价三种醋的营养价值。结果表明:三种醋都具有较高的总酚,且粮食醋大于苹果醋。同时总酚与抗氧化能力呈显著正相关。在色谱条件下,以没食子酸等十六种单体酚作为标准品,苹果醋中能被定量的单体酚有8种,其中绿原酸(6.56mg/L)、咖啡酸(3.03mg/L)和根皮苷(1.76mg/L)含量最为丰富,是苹果醋相对粮食醋的特征单体酚;粮食醋(山西老陈醋和镇江香醋)中能被定量的单体酚有5种,其中没食子酸含量最高(在山西老陈醋中含量为60.56mg/L,恒顺香醋中为241.96mg/L),山西老陈醋和恒顺香醋中多酚物质结构比例差距较大。