Susanna Kariluoto

Process-induced changes on bioactive compounds in whole grain rye.

Manufacturing of healthy wholegrain foods demands knowledge of process-induced changes in macro-, micro- and non-nutrients. The high content of dietary fibre is a challenge in relation to good product texture and sensory quality. The stability and bioavailability of bioactive compounds have a marked influence on the health effects of cereal foods. It was confirmed that sterols, folates, tocopherols and tocotrienols, alkylresorcinols, lignans, phenolic acids and total phenolics are concentrated in the bran layers of the rye grain, and are only present at low levels in the flour endosperm. The levels of folate and easily-extractable phenolic compounds increase in germination and sourdough baking, but there are negligible changes in the levels of sterols, lignans and alk(en)ylresorcinols. The levels of tocopherols and tocotrienols are reduced during the sourdough fermentation. In conclusion, many of the bioactive compounds in wholegrain rye are stable during food processing, and their levels can even be increased with suitable processing.

The HEALTHGRAIN Wheat Diversity Screen: Effects of Genotype and Environment on Phytochemicals and Dietary Fiber Components

Analysis of the contents of bioactive components (tocols, sterols, alkylresorcinols, folates, phenolic acids, and fiber components) in 26 wheat cultivars grown in six site x year combinations showed that the extent of variation due to variety and environment differed significantly between components. The total contents of tocols, sterols, and arabinoxylan fiber were highly heritable and hence an appropriate target for plant breeding. However, significant correlations between the contents of bioactive components and environmental factors (precipitation and temperature) during grain development also occurred, with even highly heritable components differing in amount between grain samples grown in different years on different sites.

Effect of baking method and fermentation on folate content of rye and wheat breads

ABSTRACT The effect of baking method on folates of rye and wheat breads, as well as the effect of sourdough fermentation of rye, were examined. Sourdough fermentations were performed both with and without added yeast, and samples were taken throughout the baking process. Samples were analyzed microbiologically for their total folate content after trienzyme extraction. Individual folate vitamers were determined by HPLC after affinity chromatographic purification. The lowest folate contents for both rye and wheat breads were found from breads baked without added yeast. Total folate content increased considerably during sourdough fermentation due to increased amounts of 10-HCO-H2folate, 5-CH3-H4folate, and 5-HCO-H4folate. Bakers yeast contributed markedly to the final folate content of bread by synthesizing folates during fermentation. Proofing did not influence total folate content but changes in vitamer distribution were observed. Folate losses in baking were ≈25%. The variety of sourdoughs and baking pro...

Folate in Wheat Genotypes in the HEALTHGRAIN Diversity Screen

As part of the diversity screen of the HEALTHGRAIN project, the total folate contents of bread wheat (130 winter and 20 spring wheat genotypes), durum wheat (10 genotypes), earlier cultivated diploid einkorn and tetraploid emmer wheat (5 genotypes of each), and spelt (5 genotypes), grown in the same location in a controlled manner, were determined by a microbiological assay. The total folate contents ranged from 364 to 774 ng/g of dm in winter wheat and from 323 to 741 ng/g of dm in spring wheat, thus showing a marked variation. The highest mean for total folate content was measured in the durum wheat genotypes, whereas the earlier cultivated diploid and tetraploid wheat genotypes and spelt were shown to possess comparable or even higher folate contents than bread wheat. HPLC analysis of selected genotypes showed that 5-formyltetrahydrofolate was the major vitamer. The data provide a basis for breeding wheat genotypes with improved folate content.

Fermented Wheat Bran as a Functional Ingredient in Baking

ABSTRACT The aim of the current study was to identify factors influencing the technological functionality of fermented bran. The influences of fermentation type and type of wheat bran on the microbial community, bioactivity, arabinoxylans (AX), and activity of xylanases were studied in the bran ferments. Furthermore, technological quality of ferments was established by using them to replace wheat in baking with a 20% substitution level. Solubilization of AX and endogenous xylanase activity of bran were influenced by the type of bran, fermentation type, and conditions. Peeled bran had a clearly reduced microbial load and different microbial community in comparison to native bran. Bran from peeled kernels contained 10-fold lower activities of endogenous xylanases in comparison to native bran. Yeast fermentation of bran from peeled kernels increased the level of folates (+40%), free phenolic acids (+500%), and soluble AX (+60%). Bread containing yeast-fermented peeled bran had improved volume (+10–15%) and c...

Effects of Genotype and Environment on the Content and Composition of Phytochemicals and Dietary Fiber Components in Rye in the HEALTHGRAIN Diversity Screen

The effects of genotype and environment on the content of bioactive components in rye were determined with four varieties being grown on one site for three years and on three additional sites in the third year and a fourth variety being included in all trials except year 1. Clear differences were observed in the extent to which the contents of dietary fiber components (arabinoxylan, beta-glucan, total dietary fiber) and phytochemicals (folates, alkylresorcinols, sterols, tocols, phenolic acids) varied between varieties and between the same varieties grown in different sites (United Kingdom, France, Hungary, Poland) and years (2005-2007 in Hungary), with sterols being the most stable and phenolic acids the least. However, no single variety could be selected as having the highest overall level of bioactive components or as being more stable in comparison across environments.

Effect of soybean processing on content and bioaccessibility of folate, vitamin B12 and isoflavones in tofu and tempe.

PURPOSE To compare the content of bioaccessible folate, vitamin B12, and isoflavones in tofu and tempe, as influenced by soybean variety and food processing, particularly fermentation. PRINCIPAL RESULTS Raw soybeans contained 2207-2671 μg/kg (dry matter) folate, cooked tempe 1493-4143, and cooked tofu 968-1273 μg/kg, the difference was attributed to the fermentation in tempe. Vitamin B12 was detected only in tempe (0.16-0.72 μg/kg). Isoflavone aglycones were formed during soaking of soybeans, with only minor differences between the contents in cooked tempe (average 1922-2968 μg/kg) or tofu (1667-2782 μg/kg) but strongly depending on bean variety. CONCLUSIONS Folate and vitamin B12 contents were mainly influenced by microbial activity during fermentation, whereas isoflavone aglycone content was determined by bean variety. Tofu had lower folate and vitamin B12, but equal isoflavone contents as tempe. Bioaccessibility of folate (80-100%) and isoflavone aglycones (100%) were high.

Effects of Environment and Genotype on Folate Contents in Wheat in the HEALTHGRAIN Diversity Screen

This study examined the environmental and genetic variation in folate contents and compositions of wheat genotypes. The selected genotypes, 24 from winter wheat and 2 from spring wheat, were grown in Martonvasar, Hungary, for three consecutive years as well as at four locations (Hungary, France, United Kingdom, and Poland) in one year. Total folate contents were determined by microbiological assay, and folate vitamers were determined for selected genotypes by high-performance liquid chromatography. Statistically significant differences in folate content arose among both harvesting years and growing locations. Grains grown in Hungary had the highest average folate content and those from Poland the lowest. Altogether, a 2.8-fold difference in total folate content appeared, ranging from 323 ng/g of dm (Chinese Spring, grown in Hungary in 2005) to 889 ng/g of dm (Riband, grown in Hungary in 2007). In general, the total folate content varied more greatly among the four growing locations than among the three harvesting years. Environmental factors affected folate content more strongly than genetic factors. In addition, small grains with high bran yield and low thousand kernel weight had high folate contents. The dominant vitamer in wheat genotypes was 5-HCO-H4folate. Other formylated folates and 5,10-CH+-H4folate also existed in significant amounts. Variation in the proportions of 5-HCO-H4folate and 5-CH3-H4folate were mainly responsible for the variation in total folate content: samples with high total folate content had a high proportion of 5-CH3-H4folate and a low proportion of 5-HCO-H4folate. Genotypes with both low and high folate contents, as well as with narrow or broad range, were identified. Thus, the study produced important data for plant breeding to select lines with stable folate contents.

Isolation and characterization of folate-producing bacteria from oat bran and rye flakes.

The aim of this research was to identify endogenous bacteria in commercial oat bran and rye flake products in order to study their folate production capability while maintaining the soluble dietary fibre components in physiologically active, unhydrolyzed form. Fourty-two bacteria were isolated from three different oat bran products and 26 bacteria from one rye flake consumer product. The bacteria were tentatively identified by sequence analysis of the 16S rRNA genes. The identification results revealed up to 18 distinct bacterial species belonging to 13 genera in oat bran, and 11 species belonging to 10 genera in rye flakes. The most common bacterial genus in oat bran was Pantoea, followed by Acinetobacter, Bacillus, and Staphylococcus. Pantoea species dominated also in rye flakes. The extracellular enzymatic activities of the isolates were studied by substrate hydrolysis plate assays. Nearly 80% of the isolates hydrolyzed carboxymethylcellulose, whereas starch-degrading activities were surprisingly rare (10%). Beta-glucan was hydrolyzed by 19% of the isolates. Protease, lipase or xylanase activity was expressed by 24%, 29%, and 16%, respectively, of the isolates. Representatives of the genera Bacillus, Curtobacterium, Pedobacter, and Sanguibacter showed the highest diversity of enzymatic activities, whereas members of Janthinobacterium and Staphylococcus possessed no hydrolytic activities for the substrates studied. Production capability for total folates was analyzed from aerobic cell cultures at the stationary growth phase. The amount of folates was determined separately for the cell mass and the supernatant by microbiological assay. For comparison, folate production was also examined in a number of common lactic acid bacteria. The best producers in oat bran belonged to the genera Bacillus, Janthinobacterium, Pantoea, and Pseudomonas, and those in rye flakes to Chryseobacterium, Erwinia, Plantibacter, and Pseudomonas. Supernatant folate contents were high for Bacillus, Erwinia, Janthinobacterium, Pseudomonas, and Sanguibacter. Compared to the endogenous bacteria, lactic acid bacteria were poor folate producers. The results of this work provide the first insight into the potential role of endogenous microflora in modulating the nutrient levels of oat and rye based cereal products, and pave way to future innovations of nutritionally improved cereal foods.

In situ enrichment of folate by microorganisms in beta-glucan rich oat and barley matrices.

The objective was to study folate production of yeast strains, bacteria isolated from oat bran, and selected lactic acid bacteria as well as one propionibacterium in oat and barley based models. Simultaneously, we aimed at sustaining the stability of viscosity, representing the physicochemical state of beta-glucan. Total folate contents were determined microbiologically and vitamers for selected samples by UHPLC. Folate in yeast cells comprised mainly 5-methyltetrahydrofolate and tetrahydrofolate. Folate production by microbes in YPD medium was different to that in cereal fermentations where vitamers included 5-methyltetrahydrofolate, 5,10-methenyltetrahydrofolate and formylated derivatives. Microbes producing significant amounts of folate without affecting viscosity were Saccharomyces cerevisiae ALKO743 and Candida milleri ABM4949 among yeasts and Pseudomonas sp. ON8 and Janthinobacterium sp. RB4 among bacteria. Net folate production was up to 120 ng/g after 24 h fermentation and could increase during 2-week storage. Glucose addition increased the proportion of 5-methyltetrahydrofolate. Streptococcus thermophilus ABM5097, Lactobacillus reuteri, and Propionibacterium sp. ABM5378 produced folate but in lower concentrations. Both endogenous and added microbes contribute to folate enhancement. Selection of microbes with folate producing capability and limited hydrolytic activity will enable the development of products rich in folate and beta-glucan.