Fermentation-induced changes in the nutritional value of native or germinated rye

Processing is important both for the sensory and nutritional quality of grains. In the case of whole grains, it especially may influence the levels and bioavailability of the bioactive compounds. Yeast, lactic acid and mixed fermentation were shown to vary in their effects on native and germinated wholemeal rye flour. The presence of Saccharomyces cerevisiae was important for enhanced levels of the analysed compounds. The levels of folates, free phenolic acids, total phenolic compounds, lignans and alkylresorcinols were increased especially by fermentation of germinated rye, which also resulted in lower pH when compared with native rye flour, the level of folate was increased up to seven-fold and that of free phenolic acids by up to ten-fold after germination and fermentation. Tailored fermentation thus offers a tool to further increase the bioactive potential of wholemeal rye.     

Phytosterols in wheat genotypes in the HEALTHGRAIN Diversity Screen

The phytosterol contents of 130 winter wheat, 20 spring wheat, 10 durum wheat, 5 spelt, 5 einkorn, and 5 emmer wheat genotypes, grown at the same location in the same year, were analyzed with gas chromatography. Considerable variation was observed in total phytosterol contents in all wheat types. The total sterol contents ranged from 670 to 959 microg/g of dm in winter wheat and from 797 to 949 microg/g of dm in spring wheat. The highest sterol contents were found in spelt, durum wheat, and einkorn wheat. The proportions of the main phytosterols also varied substantially among the different genotypes. The most abundant phytosterol in all wheat genotypes was sitosterol (40-61% of total sterols), whereas the highest variation was seen in total stanols (7-31% of total sterols). The comprehensive data set produced in this study constitutes a valuable basis for plant breeding and selection of phytosterol-rich genotypes.     

Phytochemicals and dietary fiber components in rye varieties in the HEALTHGRAIN Diversity Screen

Ten rye varieties grown in one location were analyzed for their contents of dietary fiber (arabinoxylan and beta-glucan) and phytochemicals (folate, tocols, phenolic acids, alkylresorcinols, and sterols). The varieties included old and modern varieties from five European countries. Significant differences were observed in the contents of all phytochemicals in whole grains and in the fiber contents in the flour and bran. The old French varieties Haute Loire and Queyras had high contents of most phytochemicals, whereas the Polish varieties Dankowskie-Zlote and Warko were relatively poor in phytochemicals. The varieties with a high content of folate tended to have low alkylresorcinol contents and vice versa. Furthermore, high contents of arabinoxylans were associated with high contents in tocols and sterols. The 10 selected rye samples comprising old populations and old and modern varieties from different ecological regions of Europe demonstrate high natural variation in their composition and show that landraces and old populations are useful genetic resources for plant breeding. The contents of single phytochemicals can likely be affected by breeding, and they may be adjusted by the right selection of genotype.     

Antioxidant activity of steryl ferulate extracts from rye and wheat bran

Antioxidant activity of steryl ferulates from other sources than rice have not yet been studied much, despite the fact that rice steryl ferulates (gamma-oryzanol) have been shown to possess good antioxidant activity. In this study, steryl ferulate extracts from wheat or rye bran were studied for their capability to inhibit hydroperoxide formation in bulk methyl linoleate and methyl linoleate emulsion. Further, their activity to scavenge DPPH radicals was analyzed. The activities were compared to synthetic steryl ferulates, rice steryl ferulates, ferulic acid, and alpha-tocopherol. Nonrice cereal extracts of steryl ferulates exhibited good antioxidant activity, especially in the bulk lipid system. The radical scavenging activity was similar to that of nonesterified ferulic acid, indicating that the ferulic acid moiety is responsible for the antioxidant properties. This study illustrates a new aspect to the health-promoting properties of rye and wheat.     

Foaming of Differently Processed Oats: Role of Nonpolar Lipids and Tryptophanin Proteins

The baking properties of oats are poor, mainly due to the lack of gluten matrix and hence the surface properties of the aqueous phase are crucial for the gas retention in oat dough. Our aim was to study the composition and foaming properties of the water‐soluble fraction from differently processed oats. A water extract from kilned oats contained nonpolar triglycerides and had poor foaming properties, whereas removing lipids with hexane extraction improved the foaming capacity and foam stability. A water extract from supercritical carbon dioxide extracted oats (CO₂‐oats) was free from nonpolar lipids and had good foam stability and excellent foaming capacity. Moreover, oat lipid‐binding proteins, tryptophanins, were highly concentrated in the CO₂‐oats‐derived foam and apparently played an important role in the foam structure. Supplementing CO₂‐oats extract with small quantities (<0.05%) of nonpolar lipids of oats destructed its foaming properties. In a preliminary baking trial, the addition of the nonpolar lipids to CO₂‐oats and wheat‐starch‐based baking recipes resulted in baked goods with reduced volume. The study showed that nonpolar triglycerides were present in the aqueous phase of oat in a quantity that impaired foaming. Moreover, this was the first study showing that tryptophanins, lipid‐binding proteins of oats, were highly concentrated in foams prepared of oats free of water‐extractable nonpolar lipids. In conclusion, tryptophanins can be considered as the foam‐active proteins of oats that prevent the lipid‐induced destabilization of foam structures which could improve the baking properties of oats.     

Potential of dry fractionation of wheat bran for the development of food ingredients,part I: Influence of ultra-fine grinding

Wheat bran is an undervalued by-product of white flour and has great nutritional potential due to its high content in fibres and bioactive compounds. Micronized bran could be used as a food ingredient to improve the nutritional potential of cereal products, or be used as a starting material for other processes (bioactive compound extraction or bran fractionation). The aim of this work was to find a way to efficiently decrease the particle size of bran. The influence of the grinding temperature (ambient or cryogenic grinding) on the granulometric distribution of particles, their composition, and their microstructure was studied, at lab-scale and pilot-scale. It showed that the intrinsic characteristics of bran (glass transition within intermediate layers at −46 °C) had more influence on its grinding behaviour than the type of grinding device used: the particles size distributions obtained after grinding at lab-scale and pilot-scale were very similar. At both scales, the granulometric curves were narrow for cryogenic grinding, while for ambient grinding they were spread over the whole particle size range. Ultrafine particles were obtained in both ambient and cryogenic conditions. Negative temperatures, by increasing the material’s brittleness, favoured a fast fragmentation of bran: one step of cryogenic grinding allowed a median particle size of nearly 50 μm to be reached, whereas three successive steps of ambient grinding were needed for the same result. On the other hand, ambient temperature favoured the dissociation of the different constituent layers of wheat bran, and produced less composite particles than cryogenic grinding.     

The HEALTHGRAIN Cereal Diversity Screen: concept, results, and prospects

One hundred and fifty bread wheat lines and 50 other lines of small-grain cereals (spelt, durum wheat, Triticum monococcum, Triticum dicoccum, oats, rye, and barley) were selected for diversity in their geographical origin, age, and characteristics. They were grown on a single site in Hungary in 2004-2005, harvested, milled, and analyzed for a range of phytochemicals (tocols, sterols, phenolic acids, folates, alkylresorcinols) and fiber components that are considered to have health benefits. Detailed analyses of these components in the different species are reported in a series of accompanying papers. The present paper discusses the comparative levels of the bioactive components in the different species, showing differences in both ranges and mean amounts. Furthermore, detailed comparisons of the bread wheat lines show that it is possible to identify lines in which high levels of phytochemicals and dietary fiber components are combined with good yield and processing quality. This means that commercially competitive lines with high levels of bioactive components are a realistic goal for plant breeders.     

Effect of parent genotype on somatic embryogenesis in Scots pine (Pinus sylvestris)

Controlled crosses of seven Scots pine (Pinus sylvestris L.) trees produced 49 families that included both reciprocals and selfings. Embryogenic cultures were initiated from immature megagametophytes and after 6 months in maintenance culture, mature somatic embryos were produced from the surviving 166 lines. The effect of parent genotypes on the cultures was evaluated at initiation of the tissue culture period, after 6 months in maintenance culture and at embryo maturation. The effect of the maternal parent was most pronounced at culture initiation. After 6 months in tissue culture, the maternal effect had decreased and the effects of both parents were significant. By the somatic embryo maturation stage, the maternal effect was still considerable but the paternal effect was no longer detectable. There was little correlation between the ranking of mothers and fathers, indicating that the maternal effect was caused by factors other than the paternal effect. No mother x father interaction was found, indicating that mothers successful at initiation and after 6 months in tissue culture, pollinated by any of the successful fathers, produced somatic lines and mature somatic embryos.