ABSTRACT
The aim of this study was to analyze the effects of microbial transglutaminase (mTG) on the immunoreactivity of wheat and gluten-free cereals flours to the sera of patients with celiac disease (CD) and non-celiac gluten sensitivity (NCGS). Both doughs and sourdoughs, the latter prepared by a two-step fermentation with Lactobacillus sanfranciscensis and Candida milleri, were studied. In order to evaluate the IgG-binding capacity toward the proteins of the studied flours, total protein as well as protein fractions enriched in albumins/globulins, prolamins and glutelins, were analyzed by SDS-PAGE and enzyme-linked immunosorbent assay (ELISA). Results showed that while mTG modified both gluten and gluten-free flour by increasing the amount of cross-linked proteins, it did not affect the serum's immune-recognition. In fact, no significant differences were observed in the immunoreactivity of sera from CD and NCGS patients toward wheat and gluten-free protein extracts after enzyme treatment, nor did this biotechnological treatment affect the immunoreactivity of control samples or the sera of healthy patients. These results suggest that mTG may be used as a tool to create innovative gluten and gluten-free products with improved structural properties, without increasing the immune-reactivity toward proteins present either in doughs or in sourdoughs.
ABSTRACT
The aim of this work was to evaluate the effects of microbial transglutaminase (mTG) and sourdough on gluten-free (GF) flours. Besides deamidation and incorporation of amines, mTG catalyses protein cross-links, modifying dough structure. Sourdough from lactic acid bacteria (LAB) and yeast modifies dough protein composition, determining proteolysis, which induce the formation of aroma precursor metabolites. The chemical-physical interactions of volatile molecules with various constituents of the matrix affect the retention of aroma compounds. Here, the effect on volatile molecule profiles and on protein networks formation after mTG treatment in sourdoughs obtained with four GF flours belonging to cereals, pseudo-cereals and legumes (rice, corn, amaranth and lentil) was investigated. Sourdough was prepared with a two-step fermentation using Lactobacillus sanfrancisciensis (LSCE1) and Candida milleri (PFL44), then mTG was added after 21 h of fermentation at increasing levels. The results showed that mTG had the capacity to modify GF flour proteins and improve protein networks formation, involving mainly the prolamin protein fraction. This is particularly relevant for the production of GF backed goods generally lacking of technological, structural and sensorial features compared with products obtained with wheat flour sourdough fermentation. Interestingly, mTG treatment of sourdough affected also the volatile composition and indeed possibly the final organoleptic properties of the products.
