Wheat storage proteins and products of their hydrolysis may cause coeliac sprue in genetically predisposed individuals with high expression of main histocompatibility complex HLA-DQ2 or DQ8, since by consuming wheat, they become exposed to proline- (P) and glutamine (Q)-rich gluten. In bread-making, the hydrolysis of gliadins and coeliac-toxic peptides occurs with varied efficiency depending on the fermentation pH and temperature. Degradation of gliadins catalysed by Lactobacillus acidophilus 5e2 peptidases and a commercial prolyl endopeptidase synthesised by A. niger, carried out at pH 4.0 and 37 °C, reduces the gliadin concentration over 110-fold and decreases the relative immunoreactivity of the hydrolysate to 0.9% of its initial value. Hydrolysis of coeliac-toxic peptides: LGQQQPFPPQQPY (P1) and PQPQLPYPQPQLP (P2) under the same conditions occurs with the highest efficiency, reaching 99.8 ± 0.0% and 97.5 ± 0.1%, respectively. The relative immunoreactivity of peptides P1 and P2 was 0.8 ± 0.0% and 3.2 ± 0.0%, respectively. A mixture of peptidases from L. acidophilus 5e2 and A. niger may be used in wheat sourdough fermentation to reduce the time needed for degradation of proteins and products of their hydrolysis.

The aim of this study was to determine the suitability of HP-treated caprine milk for yoghurt production and to evaluate the effect of HP treatment on yoghurt properties. Reconstituted caprine milk was subjected to HP treatment (350 MPa/10 min/20 °C); a lactic acid starter culture (YC-X16, Chr. Hansen) was added. Milk was fermented at a temperature of 43 °C until pH 4.60. Bacterial counts, pH, color, rheological characteristics, texture, microstructure, and the sensory attributes of the yoghurt were determined after production and after seven days of storage at a temperature of 4 °C. HP treatment increased color saturation and whiteness index and induced a minor increase in milk pH. Minor differences in the acidification curve were noted. During storage, Streptococcus thermophilus counts were significantly higher in yoghurt from HP-treated than from untreated milk, whereas Lactobacillus delbruecki ssp. bulgaricus counts remained stable. A color analysis did not reveal differences between the experimental and control yoghurts. After storage, yoghurt made from HP-treated milk was characterized by thicker consistency and lower rheological stability than the control yoghurt. The micrographs of the yoghurts confirmed the differences in rheological parameters. Yoghurt produced from HP-treated caprine milk and stored for seven days received the highest scores in the sensory evaluation.