VALORIZATION OF PRICKLY PEAR PEELS & SEED PRESS-CAKE IN TRADITIONAL SOURDOUGHS AND EVALUATION OF THEIR BREAD-MAKING CAPACITIES

Abstract

The prickly pear fruit's peel (PPP) and seed press-cake (SPC) are discarded during the pulp and the seed-oil processing. This study incorporated these two by-products in the preparation of sourdoughs and evaluated their bread-making capacities. The seed press-cake was recovered during the mechanical extraction of the seed oil, ground and used to produce S1 sourdough. The peels were milled and their puree was utilized to produce firm and liquid sourdoughs S2 and S3, respectively. The prepared sourdoughs had an average pH of 3.24 and a total titratable acidity (TTA) between 13.4 and 27.4 mL NaOH 0.1M/10g. The doughs fermented with these sourdoughs had different rising capacities (167 to 259%) and specific volumes (1.53 to 2.26 cm³/g). The sourdough-fermented doughs produced equivalent amounts of CO₂. The doughs fermented with the peels sourdoughs produced more ethanol than that with press-cake sourdough. Fermented doughs had a final TTA between 7.8 and 11.5 mL NaOH 0.1M/10g and a final mean pH of 3.47. The control dough fermented with baker's yeast alone had a low final TTA of 4.5 mL NaOH 0.1M/10g and a comparable pH to that of the sourdough-fermented doughs. Our results suggest the incorporation of prickly pear by-products in sourdoughs formulation and use to inoculate bread dough to decrease food waste and improve the quality of baked products.