Quality evaluation by physical tests of a traditional Italian flat bread Piadina during storage and shelf-life improvement with sourdough and enzymes

The aim of this work was to study the possibility to improve the shelf life of a traditional Italian flat bread named Piadina, typically cooked in the Romagna region, by using sourdough fermentation and enzymes. To evaluate Piadina quality during storage, chemical parameters, subjective and objective mechanical tests were used. Moreover, NIR spectroscopy, coupled with principal component analysis (PCA) and partial least square regression (PLS), was used to discriminate the samples as a function of formulation and to predict storage time, respectively. The results show that the samples containing yeasts and lactic acid bacteria have higher values in water content. This result is also confirmed by the fact that the average water activity of the control sample is significantly lower compared with that of the samples containing enzymes, yeasts, lactic acid bacteria. For all formulations, rollability is significantly affected by storage time with decreased scores observed during storage. The synergistic action between enzymes, yeasts and lactic acid bacteria increases the shelf life, in terms of rollability. The evaluated texture parameters did not significantly correlate with subjective rollability. The PCA applied to spectroscopic data shows a clear separation between samples with different sourdough percentage, while the results of PLS regression, conducted to estimate the storage time, report determination coefficient spanning from 0.959 to 0.969.