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11 Articles

Surdough fermentation (I part)

by luciano

The study highlights the action of sourdough both in hydrolyzing (breaking) the proteins rich in proline (gliadin) involved in activating the human immune system both in the hydrolyser gluten (favoring digestibility) and ,above all, the high glutenins molecular weight.

Sourdough and its potential for degradation of gluten

Sourdough is produced using a culture of lactobacillus, frequently in combination with yeast. Sourdough is the oldest method for leavening bread and is still used for some applications. For example, in making bread from rye, perhaps because the dough made from rye flour needs a low pH to be appropriate for baking (Arendt et al., 2007). In comparison with yeast-treated doughs for wheat- or rye-based breads, sourdough produces a distinctively tangy or sour taste, mainly as a result of lactic acid produced by the lactobacilli. Moreover, during sourdough fermentation, proteolysis provides compounds that are precursors for the aroma volatiles and amino acids which are converted by microbes to compounds which are precursors of flavours (Gänzle et al., 2008). Traditionally sourdough is added as an ingredient to unmodified flour of wheat or rye for breadmaking. However, some authors (Rizzello et al., 2007) have proposed sourdough as the major ingredient and the only source of proteins for making gluten-free bread.

Ancient wheat species and human health: Biochemical and clinical implications

by luciano

An important study that highlights the interesting characteristics of ancient varieties of wheat in relation, above all, to some widespread gastrointestinal diseases (“This manuscript reviews the nutritional value and health benefits of ancient wheats varieties, providing a summary of all in vitro, ex vivo, animal and human studies that have thus far been published.”)

Ancient wheat species “Although there is no precise definition, it is generally accepted that ancient wheat has remained unchanged over the last hundred years. In contrast, modern species have been extensively modified and subject to cross-breeding in what is commonly referred to as the “Green Revolution”. This term was developed to refer to a set of research and technological transfer initiatives that occurred between the 1930s and the late 1960s. The Green Revolution was initiated by Strampelli, who was among the first, in Europe and in the World, to systematically apply Mendel’s laws to traits such as rust resistance, early flowering and maturity and short straw. As a consequence, Italian wheat production doubled, an achievement that during the fascist regime was referred to as the “Wheat Battle” (1925–1940) [10]. After the Second Word War, some of Strampelli’s wheat varieties were used as parents in breeding programmes in many countries in a phase of the Green Revolution, defined as Norman Borlaug’s Green Revolution. This phase was instrumental in the development of the high-yielding varieties [10]. Thereafter, during the 1960s, research was concentrated on improving the storage protein quality, thereby increasing the technological properties. Agronomists bred cultivars of maize, wheat, and rice that were generally referred to as “high-yielding varieties” based on a higher capacity for nitrogen-absorption than other varieties. High levels of nitrogen in the soils causes the lodging of wheat before harvest. Therefore, semi-dwarfing genes were bred to improve to reduce both lodging and the maturation cycle. The principle results of this revolution were the development of modern varieties characterized by higher yield, a reduced susceptibility to diseases and insects, an increased tolerance to environ- mental stresses, a homogeneous maturation (to optimize harvest) and a higher gluten content (to improve bread and pasta quality). Whilst these intensive breeding programs helped to increase production and techno- logical quality, a concomitant decrease in genetic variability as well as a gradual impoverishment of the nutritional and nutraceutical properties of the wheat occurred, mainly determined by the complete replacement of ancient local breeds with modern varieties.”

Some passages of the study help to focus the most significant evidences that, although referring to a limited number of researches, open interesting perspectives for a greater use of ancient grains in order to reduce the disorders deriving from the ingestion of gluten:
About monococcum wheat: “Compared with soft wheat, einkorn showed a lower content of both total and resistant starch (mean value: 655 vs 685 g/kg dry matter (DM) and 25.6 vs 30–88 g/kg DM respectively) [7]. However, the amount of amylose molecules, that are digested more slowly, was higher than the amount of amylopectin molecules, thereby lowering both glucose and insulin levels in the blood after meals [14] and maintaining satiety for longer periods [15]. By evaluating the average protein content, einkorn protein values were 59% higher than those of modern wheat [16], but the bread-manufacturing quality of storage proteins were poor, making it better suited to the preparation of cookies or pasta [17]. The comparative analysis of lipids and fatty acid composition in einkorn and soft wheat germ revealed a higher content of lipids (+50%) in einkorn, with a greater proportion of monounsat- urated fatty acids (+53%), and lower polyunsaturated (−8%) and saturated fatty acids (−21%) [16]. With respect to phytochemicals, einkorn showed the highest concentration of phytosterols and tocols (1054 and 57 μg/g DM respectively), but this difference was mostly marked in the HEALTHGRAIN dataset [12]. In addition, einkorn, khorasan wheat and emmer wheat cultivars showed the highest content of total carotenoids (2.26, 6.65 and 8.23 μg/g DM respectively) and lutein (7.28, 4.9 and 2.7 μg/g DM), the major carotenoid with respect to all the other species [18,19]. Of interest, several lines of einkorn showed lutein values from three to eight-fold higher than soft wheat and two-fold greater than those for durum wheat. Some authors suggested that the higher carotenoid content in einkorn-made products could be a result of lower processing losses, linked to lower lipoxygenase activity [7]. “

Although there is insufficient evidence to suggest that ancient wheat varieties prevent gluten-related disorders, several studies have shown that a diet based on less-immunoreactive wheat products, with fewer amounts and types of reactive prolamins and fructans, may help in the improvement of gastrointestinal and/or systemic symptoms of some auto-immune or chronic diseases (eg, irritable bowel syndrome, etc.) [34]. These less-immunoreactive varieties, like einkorn, may be good targets for slowing the development of disease in populations genetically predis- posed to celiac disease and other wheat sensitivities [42].

On the other hand, a subsequent paper investigating how in vitro gastro-intestinal digestion affects the immune toxic properties of gliadin from einkorn (compared to modern wheat), demonstrated that gliadin proteins of einkorn are sufficiently different from those of modern wheat, thereby determin- ing a lower immune toxicity following in vitro simulation of human digestion [40].

Although concrete functional benefits are difficult to ascertain from random individual human trials, since they are subject to differences and/or limitations in experimental design, participant number and participant characteristics in the case of parallel arm studies, results unanimously suggest that the consump- tion of products made with ancient wheat varieties ameliorate not only pro-inflammatory/anti-oxidant parameters (where investigated) but also glycaemic and lipid status. Ancient wheat species and human health: Biochemical and clinical implications. Stefano Benedettelli et altri. September 2017. (Available online at www.sciencedirect.com)

Lodging is the bending over of the stems near ground level of grain crops, which makes them very difficult to harvest, and can dramatically reduce yield.


Ancient wheat species and human health

Gluten and “toxic” fractions (part I)

by luciano

– the structure of the gliadin and the toxicity of some fraction –
Gluten which is a protein compound formed by the prolamine, known as gliadin in wheat and responsible for the main phenomena of adverse reactions, and glutenin present mainly in the endosperm of cereal caryopsis such as wheat, spelled, rye and barley. Gluten is formed when water, flour and yeast are mixed: gliadin and glutenin combine to form a mixture characterized by viscosity, elasticity and cohesion. Therefore the quantity and integrity of the proteins that make up the gluten present in a flour are an important index to evaluate the quality and aptitude for baking.
Gliadin and glutenin, therefore, have been the subject of numerous research both in relation to the properties concerning the rheological characteristics of the doughs and to the adverse reactions that activate the immune system. Studies have been carried out on celiac disease that have discovered who and how this pathology is caused: they are some peptides (a set of amino acids) present, especially in the gliadin that contain sequences that are toxic, ie they activate the adverse reaction in genetically predisposed subjects of the immune system. The gliadin, in turn, is composed of several sub-units and these contain the “toxic” fractions in different quantities and qualities. Not only has William Hekkins’ research highlighted how the shape and location of gliadin molecules also influence not only chemical and physical properties but also toxicity.
“The gliadin proteins are heterogenous in different regions of the molecule and consequently differ in phisical and chemical properties. About 35% of the gliadin molecule is the alfa helix form, whereas 35% are beta turns(5). The latter are concentrated in the N terminal and C terminal more apolar parts of the gliadin. The remaining part has a random structure. These form have conseguences for the immunogenecity of the different regions in the molecule. Especially beta-turns are immunogenic.” The Toxicity of wheat prolamins William TH. J. M. Hekkens Annales Nestlé 1995 n. 51.
The study also analyzed the mechanism underlying the toxicity by detecting how “the passage of undigested gliadin fragments (fragments longer than 8 amino acids) or a lower tolerance to gliadin causes the immune system to react”. It is not enough, therefore, to know how much gliadin is present in a grain, but it is necessary to have the complete screening of its sub-units (quality, quantity, and, according to the study mentioned also form and position). The study on the “structure of gliadin” could partly explain why some ancient grains (for example, the monococcus), despite having a quantity of gliadin (and in particular alpha gliadin) not inferior to modern grains, have almost zero toxic levels.
The Toxicity of wheat prolamins