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Grain varieties with low toxic fraction content: an opportunity for products dedicated to children

by luciano

LC/MS ANALYSIS OF GLUTEN PEPTIDES DERIVED FROM SIMULATED GASTROINTESTINAL DIGESTION OF DIFFERENT WHEAT VARIETIES: QUALITY AND SAFETY IMPLICATIONS. Sforza, Stefano & Prandi, Barbara & Bencivenni, Mariangela & Tedeschi, Tullia & Dossena, Arnaldo & Marchelli, Rosangela & Galaverna, Gianni. (2011):

Abstract:

“Gluten content of wheat is highly variable, depending on the plant genetics and the growing conditions. Beside short peptides, gastrointestinal digestion of gluten also produces longer ones, since the high proline content of gliadins (16-26%) and glutenins (11-13%) makes them very resistant to the degradation by digestive proteases. In the present work, a method for the extraction of the prolamine fraction was applied to different wheat varieties, followed by a simulated gastrointestinal digestion of the gliadin extracted. The peptide mixtures generated were characterized by LC/MS, and most abundant peptides were identified by low- and high-resolution multiple stage MS techniques and through synthesis of authentic standards. These peptides were also semiquantified in the different samples against a suitable internal standard. The peptide mixtures were found to be highly variable, according to the different content and type of gliadins present in wheat varieties, with strong differences among the varieties tested, both qualitatively (the sequences of the peptides generated) and quantitatively (their amount). The greatest difference was found between common and durum wheat varieties. Peptides present only in the former varieties were identified, and used as molecular markers for identifying and quantifying the presence of common wheat when added to durum wheat samples. Most of the peptides identified were also already known to be pathogenic for people affected by celiac disease, an autoimmune enteropathy triggered by gluten proteins, which develops in some genetically susceptible subjects after gluten consumption. Some samples belonging to defined varieties showed a lower amount of celiac-related pathogenic peptides upon digestion, due to a lower gliadin content. Albeit not safe for celiac patients, the use of these varieties in the formulations of baby food could be of great help for lowering the spread of the disease, since the prevalence of celiac disease seems to be promoted by an early exposure to a large amount of gluten peptides”.

Ancient and modern grains, gluten intolerance and pesticides: Enzo Spisni answers readers’ questions

by luciano

Grani antichi e moderni, intolleranza al glutine e pesticidi: Enzo Spisni risponde alle domande dei lettori
(DA: Redazione Il Fatto Alimentare 11 Agosto 2017)

La questione dei grani antichi e della sensibilità al glutine fa molto discutere. Non sorprende quindi, che l’articolo “Pasta con grano antico o moderno: il problema dell’intolleranza al glutine è lo stesso? Spisni risponde a Bressanini” abbia scatenato un acceso dibattito. Ecco le risposte di Enzo Spisni, docente di Fisiologia della Nutrizione all’Università di Bologna, ai tanti commenti dei lettori del Fatto Alimentare.
Prima l’incipit. Ho sottolineato che tutti possono fare divulgazione scientifica, ma solo tre figure hanno le competenze e possono (per la legge italiana) modificare il modo di alimentarsi e la dieta delle persone. In un paese in cui troppi parlano di diete senza avere competenze e in cui famosi farmacisti vanno in televisione a suggerire diete e dichiarano di avere migliaia di “pazienti”, mi sembra quantomeno un appunto doveroso.
Veniamo alle definizioni. Si definiscono antichi o tradizionali le cultivar presenti prima della cosiddetta “Rivoluzione Verde”. Le differenze sostanziali tra i grani pre-rivoluzione e quelli post-rivoluzione possiamo riassumerle in quattro punti:
1. La forza del glutine. Si parte da grani che hanno un valore W di forza del glutine di 10-50 e si arriva ai moderni che hanno una forza intorno ai 300-400. È evidente che la struttura del glutine cambia per venire incontro alle necessità dell’industrializzazione degli alimenti.
2. La taglia. I grani pre-rivoluzione sono a taglia alta (diciamo oltre il metro e trenta), mentre i post sono a taglia bassa (molto al di sotto del metro).
3. La produttività per ettaro, che aumenta molto nei moderni a fronte però dell’aumento dell’input di azoto attraverso la concimazione. Lascio il discorso su quanto azoto per ettaro agli agronomi, ma chi in campo è passato dal coltivare moderni in convenzionale a grani antichi in biologico si è reso ben conto del risparmio in denaro generato dalla minore concimazione e dal minore uso di chimica.
4. La minore variabilità genetica, nel senso che le cultivar antiche erano un insieme di genotipi con una biodiversità complessivamente elevata, mentre post-rivoluzione si è andati verso la selezione di grani “in purezza”, fatta di piante tutte geneticamente identiche, con una perdità netta di biodiversità non trascurabile. In altre parole è cambiato il concetto di adttamento: mentre una variabilità genetica ampia è in grado di adattarsi ai mutamenti ambientali, una variabilità genetica ridotta richiede un maggior intervento dell’uomo nel tentativo di meglio adattare il campo al tipo di grano coltivato. E l’intervento dell’uomo molto spesso si traduce in utilizzo di prodotti chimici.

Surdough fermentation (II part)

by luciano

Surdough and phytates
“Increasing fiber content in flour may result in a lower assimilation of minerals complexed by phytates. An optimisation of the fermentation step with surdough allowed to improve both the bioavailability of minerals as well as the sensory attributes of the resulted bread. (16mo. IFOAM Organic World Congress, Modena, Italy, June 16-20, 2008 Archived at ttp://orgprints.org/view/projects/conference.html)”.

Note: Phytic acid is traditionally considered an anti-nutritional factor, ie a substance that can limit the absorption or use of nutrients. In the specific case, by binding to them to form insoluble salts (phytates and phytin), phytic acid hinders the absorption of some minerals (calcium, iron, magnesium and zinc).

Sourdough fermentation and basic baking properties
“Unfortunately, there is often a trade- off between degradation of reactive gluten and retention of gluten for basic baking properties. Large amounts of time and heat may be needed for microbial enzymes to break down problematic pep- tides. To fully degrade the 33-mer α-gliadin peptide in wheat required 24 h at 30 °C (Gallo and others 2005), while durum required 72 h of fermentation at 37 °C to meet gluten-free la- beling standards (De Angelis and others, 2010). HMW glutenins, which are important for baking and pasta integrity, are degraded prior to and more extensively than reactive prolamins during sour- dough fermentation (Ga ̈nzle and others 2008; Wieser and others 2008). Extensively fermented dough has a high ratio of gliadins to glutenins, which is very undesirable for bakers. The disulfide bonds holding together the gluten macropolymer (GMP), an in- tegral component of baking quality, begin to degrade long before glutens. Only 5 h of fermentation with Lactobacilli or acidic chem- icals degraded GMP by up to 46% (Wieser and others 2008). Pentosans, an important component for baking rye bread, were also hydrolyzed in germinated sourdough (Loponen and others 2009). Consequently, the long and hot sourdough fermentation to hydrolyze prolamins compromises functional baking properties of the dough. (A Grounded Guide to Gluten: How Modern Genotypes and Processing Impact Wheat Sensitivity – Chapter Fermentation and microbial enzymes – Lisa Kissing Kucek, Lynn D. Veenstra, Plaimein Amnuaycheewa, and Mark E. Sorrells. Comprehensive Reviews in Food Science and Food Safety Vol. 14, 2015.)”.

Microbiology of sourdough
“It is well known that the type of bacterial flora developed in each fermented food depends on water activity, pH (acidity), minerals concentration, gas concentration, incubation temperature and composition of food matrix (Font de Valdez et. al. 2010). The microflora of raw cereals is composed of bacteria, yeast and fungi (104 – 107 CFU/g), while flour usually contains 2 x 104 – 6 x 106 CFU/g (Stolz, 1999). In sourdough fermentation major role play heterofermentative species of LAB (Salovaara, 1998; Corsetti & Settani, 2007), especially when sourdoughs are prepared in a traditional manner (Corsetti et. al., 2003). Lactobacillus sanfranciscensis, Lactobacillus brevis and Lactobacillus plantarum are the most frequently lactobacilli isolated from sourdough (Gobbetti, 1998; Corsetti et. al. 2001; Valmorri et. al., 2006; Corsetti & Settanni, 2007). The following yeasts have been detected in cereals (9 x 104 CFU/g) and flour (2 x 103 CFU/g): Candida, Cryptococcus, Pichia, Rodothorula, Torulaspora, Trychoporon, Saccharomyces and Sporobolomyces. Saccharomyces cerevisiae is not found in the raw materials. Its occurance in sourdough has been explained by the application of baker’s yeast in most daily bakery practice (Corsetti et. al., 2001). The importance of antagonistic and synergistic interactions between lactobacilli and yeasts are based on the metabolism of carbon hydrates and amino acids and the production of carbon dioxide (Gobetti & Corsetti 1997). Lactic and acetic acid are predominant products of sourdough fermentation). Influence of Acidification on Dough Rheological Properties Daliborka Koceva Komlenić, Vedran Slačanac and Marko Jukić Faculty of Food Technology, Josip Juraj Strossmayer University of Osijek, Croatia 2012- www.intchopen)”.

 

Gluten and intestine

by luciano

Digestion of Gluten Peptides in the Large Intestine

It has been shown that removing gluten from the diet affects the composition of the bacterial community in the large bowel, where the undigested food in the small intestine and could be hydrolyzed by microbial metabolism, generating beneficial compounds for the host.

“Alimentary protein digestion followed by amino acid and peptide absorption in the small intestinal epithelium is considered an efficient process. Nevertheless, unabsorbed dietary proteins enter the human large intestine as a complex mixture of protein and peptides.53,63 The incomplete assimilation of some dietary proteins in the small intestine has been previously demonstrated, even with proteins that are known to be easily digested (e.g., egg protein).64,65 The high proline content of wheat gluten and related proteins renders these proteins resistant to complete digestion in the small intestine. As a result, many high molecular weight gluten oligopeptides arrive in the lower gastrointestinal tract.66 While gluten peptides pass through the large intestine, proteolytic bacteria could participate in the hydrolysis of these peptides. A recent study from our group has shown that some of the gluten ingested in the diet is not completely digested while passing through the gastrointestinal tract, and is consequently eliminated in feces.

Moreover, it has been shown that the amount of gluten peptides present in feces is proportional to the amount of gluten consumed in the diet. Therefore, several gluten peptides are resistant to both human and bacterial proteases in the gastrointestinal tract.66,67

The large intestine is the natural habitat for a large and dynamic bacterial community. Although the small intestine contains a significant density of living bacteria, the density in the large intestine is much higher. The large intestine has as many as 1011–1012 cells per gram of luminal content that belong to thousands of bacterial taxa. Furthermore, the large intestinal microbiota is extremely complex and performs specific tasks that are beneficial to the host.68–71 Among the important functions that the intestinal microbiota performs for the host are several metabolic functions.72 In contrast to the rapid passage of dietetic components through the small intestine, the transit of the luminal material through the large intestine is considerably slower. The longer transit time in the large intestine has been associated with important bacterial metabolic activity.53 Therefore, undigested food in the upper gut could be hydrolyzed by microbial metabolism in the large intestine, generating beneficial compounds for the host.

The resistance of gluten peptides to pancreatic and brush border enzymes allows large amounts of high molecular weight peptides to enter the lower gastrointestinal tract. Therefore, gluten peptides are available for microbial metabolism in the large intestine and could be important to the composition of the intestinal microbiota. It has been shown that removing gluten from the diet affects the composition of the bacterial community in the large bowel.78,79 De Palma et al.78 observed that healthy subjects who followed a gluten-free diet for 1 month had reduced fecal populations of Lactobacillus and Bifidobacterium, but the population of Enterobacteriae such as E. coli appeared to increase. Similar results were obtained in studies with CD patients. Treated CD patients also showed a reduction in the diversity of Lactobacillus and Bifidobacterium species.80,81Gluten Metabolism in Humans. Alberto Caminero, … Javier Casqueiro, in Wheat and Rice in Disease Prevention and Health, 2014”