Epidemiological studies have clearly shown that whole-grain cereals can protect against obesity, diabetes, CVD and cancers. The specific effects of food structure (increased satiety, reduced transit time and glycaemic response), fibre (improved faecal bulking and satiety, viscosity and SCFA production, and/or reduced glycaemic response) and Mg (better glycaemic homeostasis through increased insulin secretion), together with the antioxidant and anti-carcinogenic properties of numerous bioactive compounds, especially those in the bran and germ (minerals, trace elements, vitamins, carotenoids, polyphenols and alkylresorcinols), are today well-recognised mechanisms in this protection. Recent findings, the exhaustive listing of bioactive compounds found in whole-grain wheat, their content in whole-grain, bran and germ fractions and their estimated bioavailability, have led to new hypotheses. The involvement of polyphenols in cell signalling and gene regulation, and of sulfur compounds, lignin and phytic acid should be considered in antioxidant protection. Whole-grain wheat is also a rich source of methyl donors and lipotropes (methionine, betaine, choline, inositol and folates) that may be involved in cardiovascular and/or hepatic protection, lipid metabolism and DNA methylation. Potential protective effects of bound phenolic acids within the colon, of the B-complex vitamins on the nervous system and mental health, of oligosaccharides as prebiotics, of compounds associated with skeleton health, and of other compounds such as alpha-linolenic acid, policosanol, melatonin, phytosterols and para-aminobenzoic acid also deserve to be studied in more depth. Finally, benefits of nutrigenomics to study complex physiological effects of the 'whole-grain package', and the most promising ways for improving the nutritional quality of cereal products are discussed.

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New hypotheses for the health-protective mechanisms of whole-grain cereals: what is beyond fibre?

Impact of sourdough on the texture of bread.

The production of sourdough bread can be traced back to ancient times. Sourdough is a mixture of flour and water that is fermented with lactic acid bacteria (LAB). Sourdough is an intermediate product and contains metabolically active yeast and LAB strains. The LAB that develop in the dough may originate from selected natural contaminants in the flour or from a starter culture containing one or more known species of LAB. Sourdough can be produced in bakeries or obtained from commercial suppliers. The microbial ecology of the sourdough fermentation is determined by ecological factors. Microbiological studies have revealed that more than 50 species of LAB, mostly species of the genus Lactobacillus, and more than 20 species of yeasts, especially species of the genera Saccharomyces and Candida, occur in this ecological niche. The sourdough microflora is composed of stable associations of lactobacilli and yeasts, in particular due to metabolic interactions. As shown for certain industrial sourdough processes, such microbial associations may endure for years, although the fermentation process runs under non-aseptic conditions. A reproducible and controlled composition and activity of the sourdough microflora is indispensable to achieve a constant quality of sourdough bread.

The sourdough microflora: biodiversity and metabolic interactions

Culturalable and non-culturable microorganisms naturally ferment majority of global fermented foods and beverages. Traditional food fermentation represents an extremely valuable cultural heritage in most regions, and harbors a huge genetic potential of valuable but hitherto undiscovered strains. Holistic approaches for identification and complete profiling of both culturalable and non-culturable microorganisms in global fermented foods are of interest to food microbiologists. The application of culture-independent technique has thrown new light on the diversity of a number of hitherto unknown and non-cultural microorganisms in naturally fermented foods. Functional bacterial groups ("phylotypes") may be reflected by their mRNA expression in a particular substrate and not by mere DNA-level detection. An attempt has been made to review the microbiology of some fermented foods and alcoholic beverages of the world.

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Review: Diversity of Microorganisms in Global Fermented Foods and Beverages

Lactobacilli in sourdough fermentation

Cereals are globally number one as food crops as well as substrates for fermentation Well known products are beer, sake, spirits, malt vinegar, and baked goods made from doughs leavened by yeasts or sourdough Fermentation processes are enabled by technological measures that act on the metabolically resting grains and direct ecological factors controlling the activity of lactic acid bacteria and yeasts Fermentable substrates originate from endogenous or added hydrolytic enzyme activities Examples of their management are malting, koji technology, addition of enzymes from external sources and sourdough, which stands on the origin of all fermentation When sourdough is continuously propagated under the conditions applied in bakery practice, a stable association of only few species of lactic acid bacteria (LAB) and yeasts achieve dominance and ensure a controlled process The variation of the ecological parameters acting on the microbial association such as the nature of cereal, temperature, size of inoculum, and length of propagation intervals leads in each case to a characteristic species association, thus explaining that altogether 46 LAB species and 13 yeast species have been identified as sourdough specific

Microbial ecology of cereal fermentations

Adaptability of lactic acid bacteria and yeasts to sourdoughs prepared from cereals, pseudocereals and cassava and use of competitive strains as starters.

Impact of ecological factors on the stability of microbial associations in sourdough fermentation

Concentration and purification of orotic acid directly from whey with an expanded bed adsorption system

A novel anamorphic yeast, strain LTH 6662T, was isolated from cassava sourdough. The isolate supposedly originated from cassava flour or was a contaminant thereof. Sequencing of the D1/D2 domain of the 26S rRNA gene indicated that strain LTH 6662T represents a novel species. Its closest relatives were members of the Cryptococcus humicola complex. The novel strain had several physiological characteristics that differed from those of related species: the ability to assimilate raffinose and cadaverine; the inability to assimilate soluble starch, xylitol, galactitol, butane-2,3-diol, sodium nitrite and lysine; the ability to grow without vitamins and at 42 °C; and the inability to produce starch-like substances. Its major ubiquinone was Q-10. In addition, buds were formed on small neck-like structures. In liquid medium, green or blue fluorescent substances were produced. The name Cryptococcus thermophilus sp. nov. is proposed, with LTH 6662T ( = DSM 19443T = CBS 10687T) as the type strain.

Stephanie A. Vogelmann

Papers

Microbial ecology of cereal fermentations

Adaptability of lactic acid bacteria and yeasts to sourdoughs prepared from cereals, pseudocereals and cassava and use of competitive strains as starters.

Impact of ecological factors on the stability of microbial associations in sourdough fermentation

Concentration and purification of orotic acid directly from whey with an expanded bed adsorption system

Cryptococcus thermophilus sp. nov., isolated from cassava sourdough