Phytochemical profiles and antioxidant capacity of pigmented and non-pigmented genotypes of rice (Oryza sativa L.)

Pigmented rice (Oryza sativa L.) genotypes become increasingly important in the agroindustry due to their bioavailable compounds that have the ability to inhibit the formation and/or to reduce the effective concentration of reactive cell-damaging free radicals. This study aimed at determining the concentrations of free, and bound phytochemicals and their antioxidant potential (DPPH and ABTS assays) as well as the vitamin E and carotenoids contents of non-pigmented and pigmented rice genotypes. The results confirmed that the content of total phenolics and flavonoids contents, as well as the antioxidant capacity (DPPH and ABTS assays) of pigmented rice was several-fold greater than non-pigmented ones (4, 4, 3 and 5 times, respectively). Compounds in the free fraction of pigmented rice had higher antioxidant capacity relative to those in the bound form, whereas the non-pigmented rice cultivars exhibited the opposite trend. Ferulic acid was the main phenolic acid of all rice genotypes, whereas black rice contained protocatechuic and vanillic acids in higher contents than red rice and non-pigmented rice genotypes. For vitamin E (tocopherols and tocotrienols) and carotenoids (lutein, zeaxanthin and β-carotene) contents, no obvious concentration differences were observed between non-pigmented and pigmented rice, with the black rice exhibiting the highest carotenoid content. Overall, pigmented rice genotypes contain a remarkable amount of bioactive compounds with high antioxidant capacity; therefore, they have great potential as a source of bioactives for developing functional food products with improved health benefits

Primary amino acid composition and its use in discrimination of Greek red wines with regard to variety and cultivation region

The primary amino acid content of 54 Greek red wines from several regions and grape varieties was determined by reversed-phase high performance liquid chromatography (HPLC) using precolumn derivatization with OPA (o-phthalaldehyde) and fluorescence detection. For each wine sample, 21 amino acids have been determined. Wine samples from the 4 most common Greek red grape cultivars, which are part of the Greek VQPRD (Vins de Qualité Produits dans des Regions Délimitees) wines, and from 4 foreign red grape varieties, were used. Wines from cv. Kotsifali had the highest amino acid content among the samples from indigenous varieties, followed by those originating from cvs Agiorgitiko, Mandilaria and Xinomavro. In contrast to wines from cv. Grenache rouge, which contained high amounts of amino acids, those from Cabernet Sauvignon, Syrah and Merlot had lower amounts. A classification of samples on the basis of variety and region was achieved by application of the discriminant analysis of the amino acid composition data. 22 % of the wine samples, originating from grapes cultivated in 'organic vineyards', had a low arginine content.

Impact of acidification and protein fortification on thermal properties of rice, potato and tapioca starches and rheological behaviour of their gels

Producción CientíficaThe impact of acidification and non-gluten protein fortification (egg-albumin and soy-protein isolate) on thermal transitions of rice, potato and tapioca starches as well as the viscoelastic properties of their gels prepared at two casting temperatures, 90ºC and 120ºC, was investigated. The thermal and rheological behaviour of starches depended on their botanical origin and were significantly influenced by the presence and type of protein added as well as by the pH of the aqueous dispersion. Acidification to pH 4.5 increased the gelatinization temperature of rice starch in the presence of albumin or soy proteins, while reduced it in the case of tapioca starch, regardless of the presence of proteins. Acidification of rice starch dispersions decreased significantly the apparent gelatinization enthalpy; this effect was even greater in the presence of proteins. The addition of proteins brought about a structuring effect on tapioca gels leading to higher viscoelastic moduli and lower tan δ values. In general, acidification led to weaker gel structures, with more pronounced effect for potato starch, most likely related to its higher phosphate content (charge screening). Much weaker gels were obtained at 120ºC compared to those processed at lower temperatures; however, protein incorporation reinforced gel structure, an effect that was not observed in gels formed at 90º, as also revealed by microstructure analysis using confocal scanning laser microscopy. In conclusion, protein addition and pH adjustments of aqueous starch dispersions can provide an effective means to modulate the functional and textural properties of gel-like starch-based gluten-free formulations.Ministerio de Economía, Industria y Competitividad - FEDER (Projects AGL2012-35088 and AGL2015-63849-C2-2-R)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA072P17

Inactivation of Endogenous Rice Flour β-Glucanase by Microwave Radiation and Impact on Physico-chemical Properties of the Treated Flour

Producción CientíficaThe apparent reduction of β-glucan (BG) molecular weight in rice based gluten-free (GF) breads fortified with cereal BG concentrates reveals the presence of β-glucanase activity in rice flour. Inactivation of endogenous β-glucanase in rice flour thus seems to be necessary step when developing GF breads enriched with BG of high molecular-weight. The aim of this work was to study the thermal inactivation of endogenous β-glucanase in rice flour by means of microwave (MW) processing; rice flours preconditioned at four different moisture levels (13%, 16%, 19%, 25%) were treated by MW radiation at 900 W and five MW treatment times (ranging from 40s to 8 min, applied stepwise at 20s intervals). The effects of microwaves on starch crystallinity, pasting and thermal properties of MW-treated rice flours were also explored. The β-glucanase activity in rice flours was assessed by the rate of decrease in specific viscosity of a dilute solution of a purified β-glucan preparation, upon addition of flour extracts. MW proved to be a useful alternative for thermal inactivation of endogenous β-glucanase in rice flours when applied to moistened samples. The inactivation process followed a first order kinetic response and the apparent rate constant of thermal inactivation increased exponentially with the moisture content of the flour, M, according to the equation 0.0146·exp (0.212·M) (R2 = 0.97). The MW time required for complete β-glucanase inactivation was only 4 min when the initial flour moisture increased to 25%. Following MW treatment, the starch crystallinity was unaffected (p>0.05) and the side effects of the treatment on flour pasting and thermal properties were rather negligible.Ministerio de Economía, Industria y Competitividad - FEDER (Projects AGL2012-35088 and AGL2015-63849-C2-2-R

Sodium ion interaction with psyllium husk (Plantago sp.)

The nature of and factors effecting sodium interactions with psyllium were investigated in vitro. In a batch extraction system, psyllium mucilage gel retained at least 50% of sodium across a range of concentrations (5–300 mg sodium per g psyllium) and pH (2–10) environments. FTIR and Na NMR analyses of psyllium gels indicated that binding was complex with non-specific multi-site interactions. The potential use of psyllium husk as a binding agent for the reduction of bioavailable sodium was therefore evaluated. The binding of sodium at physiologically relevant conditions (pH 1.2 (stomach) and 6.8 (intestine)) was studied in a gastrointestinal tract (GIT) pH simulated model. Results show consistently high sodium retention (∼50%) across the GIT model and less than 20% loss of bound sodium under the simulated intestinal pH conditions after repeated washings

Mashes to Mashes, Crust to Crust. Presenting a novel microstructural marker for malting in the archaeological record

The detection of direct archaeological remains of alcoholic beverages and their production is still a challenge to archaeological science, as most of the markers known up to now are either not durable or diagnostic enough to be used as secure proof. The current study addresses this question by experimental work reproducing the malting processes and subsequent charring of the resulting products under laboratory conditions in order to simulate their preservation (by charring) in archaeological contexts and to explore the preservation of microstructural alterations of the cereal grains. The experimentally germinated and charred grains showed clearly degraded (thinned) aleurone cell walls. The histological alterations of the cereal grains were observed and quantified using reflected light and scanning electron microscopy and supported using morphometric and statistical analyses. In order to verify the experimental observations of histological alterations, amorphous charred objects (ACO) containing cereal remains originating from five archaeological sites dating to the 4th millennium BCE were considered: two sites were archaeologically recognisable brewing installations from Predynastic Egypt, while the three broadly contemporary central European lakeshore settlements lack specific contexts for their cereal-based food remains. The aleurone cell wall thinning known from food technological research and observed in our own experimental material was indeed also recorded in the archaeological finds. The Egyptian materials derive from beer production with certainty, supported by ample contextual and artefactual data. The Neolithic lakeshore settlement finds currently represent the oldest traces of malting in central Europe, while a bowl-shaped bread-like object from Hornstaad– Ho¨ rnle possibly even points towards early beer production in central Europe. One major further implication of our study is that the cell wall breakdown in the grain’s aleurone layer can be used as a general marker for malting processes with relevance to a wide range of charred archaeological finds of cereal products

Structural heterogeneities in starch hydrogels

Hydrogels have a complex, heterogeneous structure and organisation, making them promising candidates for advanced structural and cosmetics applications. Starch is an attractive material for producing hydrogels due to its low cost and biocompatibility, but the structural dynamics of polymer chains within starch hydrogels are not well understood, limiting their development and utilisation. We employed a range of NMR methodologies (CPSP/MAS, HR-MAS, HPDEC and WPT-CP) to probe the molecular mobility and water dynamics within starch hydrogels featuring a wide range of physical properties. The insights from these methods were related to bulk rheological, thermal (DSC) and crystalline (PXRD) properties. We have reported for the first time the presence of highly dynamic starch chains, behaving as solvated moieties existing in the liquid component of hydrogel systems. We have correlated the chains’ degree of structural mobility with macroscopic properties of the bulk systems, providing new insights into the structure-function relationships governing hydrogel assemblies