Ivan Kreft

Composition and technological properties of the flour and bran from common and tartary buckwheat

Abstract Common buckwheat and tartary buckwheat were milled in a stone mill. The contents of protein, lipid, starch, dietary fibre and vitamins B1, B2 and B6 were analysed in the flour and bran. There was a prevalence of unsaturated fatty acids—C18:1, C18:2, C18:3 and C20:1. In both species most lipid substances are concentrated in the bran. In common buckwheat bran, protein content was 21.6%, and in tartary buckwheat, 25.3%. There were relatively small differences in the contents of vitamins B1 and B2 between the two main utilisable milling fractions, but more substantial differences in the contents of vitamins B6 (up to 0.61 mg/100 g in the tartary buckwheat bran fraction). Total B vitamin content was higher in tartary buckwheat than in common buckwheat. On the basis of these analyses, it can be concluded that tartary buckwheat bran is an excellent food material with a potential for preventative nutrition.

Characteristics of spelt wheat products and nutritional value of spelt wheat-based bread.

Spelt wheat cultivars (cv.) Hercule, Rouquin and Ostro, grown in the Alpine region of Italy, were compared to the common wheat cv. Manital and durum wheat Grazia for protein, ash and dietary fibre contents. The spelt wheat cultivars studied had higher contents of soluble dietary fibre and protein than the standard wheat or the durum wheat. In the bread of spelt wheat (cv. Hercule), there was more rapidly digested starch (RDS) and a higher starch digestion index (SDI) in comparison to wheat bread. The bread made of whole spelt wheat flour (cv. Hercule) had less total starch, more resistant starch and less rapidly digested proteins in comparison to bread made of white spelt wheat flour and white wheat flour (cv. Manital). In pasta and extruded products of whole spelt flours, more protein, ash and dietary fibre was found in comparison to the same products made of white spelt wheat flour.

Trace elements in flour and bran from common and tartary buckwheat

The contents of Se, Cr, Rb, Zn, Fe, Co, Sb, Ba, Ni, Ag, Hg and Sn were analysed in the flour and bran of common and tartary buckwheat, obtained by milling in a stone mill. In both species most trace elements are concentrated mainly in the bran. However, there are relatively small differences in the contents of iron, antimony, and chromium between flour (extraction rate 55%) and bran fractions. In tartary buckwheat fine flour (extraction rate 42%) there is a lower trace element content than in normal flour. The potential use of buckwheat bran as a dietary source of Zn, and Se, is indicated.

Degradation of Rutin and Polyphenols during the Preparation of Tartary Buckwheat Bread

The impact of bread making and baking procedure on rutin, quercetin and polyphenol concentration and antioxidant activity of tartary buckwheat (Fagopyrum tataricum) bread and breads made of mixtures of tartary buckwheat and wheat flour was studied. A decrease in polyphenol concentration through baking was observed in all samples. The high DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging capacity in mixed breads (32-56%) and in tartary buckwheat bread (85-90%) decreased slightly through the bread making process, while an increase of antioxidant activity in bread made of 100% wheat flour during bread making was observed. With the addition of water to mixtures containing tartary buckwheat during the preparation of the dough, rutin concentration decreased, while quercetin concentration increased. The rutin concentration continued to decrease during the bread baking process, while the concentration of quercetin remained stable. After baking, rutin (0.47 mg/g) was present only in bread made of 100% tartary buckwheat flour along with quercetin (4.83 mg/g).

Chemical composition and protein quality of buckwheat (Fagopyrum esculentum Moench)

The chemical composition and protein quality of two varieties of buckwheat were measured and compared with the values of wheat. The protein quality was based on amino acid composition and true protein digestibility, biological value, net protein utilization, and utilizable protein obtained in N-balance experiments with rats. The protein content in buckwheat was approximately 12% and thus very much the same as in wheat. The fat content in buckwheat was close to 3% whereas the crude fiber concentration was very high (12.7 and 17.8%, respectively, for two varieties). The high fiber content caused a low concentration of soluble carbohydrates with the lowest value of 48.7%. Both buckwheat varieties had a high tannin content (1.76 and 1.54%, respectively). The protein quality was very high, with biological values above 90%. This can be explained by a high concentration of most essential amino acids, especially lysine, threonine, tryptophan, and the sulphur-containing amino acids. However, due to the high contents of crude fiber and tannin, the true protein digestibility was slightly below 80%.

Nutrient Content in Buckwheat Milling Fractions

ABSTRACT Buckwheat seeds (Fagopyrum esculentum Moench) were milled into 23 fractions: seven fine flours, three coarse flours, four small semolina, two big semolina, six bran, and one husk fraction. A considerable variation in gross chemical composition was found among the milling fractions. The protein content varied from 4.4 to 11.9% (db) in flours and from 19.2 to 31.3% in bran fractions; starch varied from 91.7 to 70.4% in flours and from 42.6 to 20.3 in bran. The percentage of soluble dietary fiber contained in total dietary fiber was higher in flours than in semolina and bran fractions. Ash, Fe, P, tannin, phytate content, and color were also investigated. A unique distribution of phytate was found in starch. Correlation is significantly positive in husk, bran, and semolina fractions, while correlation is significantly negative in flour fractions. Depending on technological or nutritional demands, appropriate fractions may be chosen to achieve the desired end-use product.

New insights into globoids of protein storage vacuoles in wheat aleurone using synchrotron soft X-ray microscopy

Mature developed seeds are physiologically and biochemically committed to store nutrients, principally as starch, protein, oils, and minerals. The composition and distribution of elements inside the aleurone cell layer reflect their biogenesis, structural characteristics, and physiological functions. It is therefore of primary importance to understand the mechanisms underlying metal ion accumulation, distribution, storage, and bioavailability in aleurone subcellular organelles for seed fortification purposes. Synchrotron radiation soft X-ray full-field imaging mode (FFIM) and low-energy X-ray fluorescence (LEXRF) spectromicroscopy were applied to characterize major structural features and the subcellular distribution of physiologically important elements (Zn, Fe, Na, Mg, Al, Si, and P). These direct imaging methods reveal the accumulation patterns between the apoplast and symplast, and highlight the importance of globoids with phytic acid mineral salts and walls as preferential storage structures. C, N, and O chemical topographies are directly linked to the structural backbone of plant substructures. Zn, Fe, Na, Mg, Al, and P were linked to globoid structures within protein storage vacuoles with variable levels of co-localization. Si distribution was atypical, being contained in the aleurone apoplast and symplast, supporting a physiological role for Si in addition to its structural function. These results reveal that the immobilization of metals within the observed endomembrane structures presents a structural and functional barrier and affects bioavailability. The combination of high spatial and chemical X-ray microscopy techniques highlights how in situ analysis can yield new insights into the complexity of the wheat aleurone layer, whose precise biochemical composition, morphology, and structural characteristics are still not unequivocally resolved.

Low-energy X-ray fluorescence microscopy opening new opportunities for bio-related research

Biological systems are unique matter with very complex morphology and highly heterogeneous chemical composition dominated by light elements. Discriminating qualitatively at the sub-micrometer level the lateral distribution of constituent elements, and correlating it to the sub-cellular biological structure, continues to be a challenge. The low-energy X-ray fluorescence microspectroscopy, recently implemented in TwinMic scanning transmission mode, has opened up new opportunities for mapping the distribution of the light elements, complemented by morphology information provided by simultaneous acquisition of absorption and phase contrast images. The important new information that can be obtained in bio-related research domains is demonstrated by two pilot experiments with specimens of interest for marine biology and food science. They demonstrate the potential to yield important insights into the structural and compositional enrichment, distribution and correlation of essential trace elements in the lorica of Tintinnopsis radix, and the lateral distribution of trace nutrients in the seeds of wheat Triticum aestivum.

Development of gluten-free bread using tartary buckwheat and chia flour rich in flavonoids and omega-3 fatty acids as ingredients

In this study, chia seed flour, which is rich in omega-3 alpha-linolenic acid, and common and tartary buckwheat flour, which has a high antioxidant activity, were integrated into different types of bread with the aim of improving their nutritional value and healthy features. Our results indicate that bread made with chia and tartary buckwheat flour was more acceptable in many nutritional aspects compared to the control (common wheat bread); it contained a higher amount of protein (20%), insoluble dietary fibres (74%), ash (51%), and alpha-linolenic acid (67.4%). Moreover, this bread possessed lower energy (14%) and carbohydrate contents (24%) compared to the control. Tartary buckwheat also improved the total antioxidant capacity of the bread (about 75%) and provided a considerable amount of flavonoids, which are healthy non-nutritional compounds. Overall, chia and tartary buckwheat represent excellent raw materials for the formulation of gluten-free bread with high nutritional value.

Selenium Species in Selenium-Enriched and Drought-Exposed Potatoes

The aim of this work was to study selenium (Se) speciation in the potato ( Solanum tuberosum L.) cultivar Desiree, enriched in Se by foliar spraying with a water solution containing 10 mg of Se/L in the form of sodium selenate. Four combinations of treatments were used: well-watered plants with and without Se foliar spraying and drought-exposed plants with and without Se foliar spraying. Water-soluble Se compounds were extracted from potato tubers by water or enzymatic hydrolysis with the enzyme protease XIV, amylase, or a combination of protease XIV and amylase. Extraction was performed using incubation at a constant temperature and stirring (37 degrees C at 200 rpm) or by ultrasound-assisted extraction (300 W), using different extraction times. Separation of soluble Se species (SeCys2, SeMet, SeMeSeCys, selenite, and selenate) was achieved by ion-exchange chromatography, and detection was performed by inductively coupled plasma-mass spectrometry (ICP-MS). Results showed that the concentration of selenate extracted was independent of the enzymatic extraction technique (approximately 98 ng/g for drought-exposed and 308 ng/g for well-watered potato tubers), whereas the extraction yield of SeMet changed with the protocol used (10-36%). Selenate and SeMet were the main soluble Se species (representing 51-68% of total Se) in potato tubers, regardless of the growth conditions.