Development of type II sourdoughs using Lactiplantibacillus plantarum CIDCA 8327 in gluten-free matrices

Sourdough fermentation is a well-established biotechnological strategy for improving the technological and nutritional properties of bakery products. The use of selected lactic-acid bacteria (LAB) as starter cultures in type II sourdoughs represents a tool for gluten-free product development. This study aimed to characterize type II sourdoughs using Lactiplantibacillus plantarum CIDCA8327 as a starter culture in two gluten-free matrices: chia expeller (CE) and a blend of chia expeller with buckwheat flour (1:1, CE:BF), with dough yields of 400 and 300, respectively. Bacterial suspensions were prepared from MRS cultures (37 °C, 24 h), centrifuged, and resuspended to achieve an inoculum of 7 log CFU/g. Fermentation was conducted at 30 °C for 24 h. Sourdoughs were characterized for LAB counts (MRS agar), yeast and mold counts (Sabourade agar), pH, titratable acidity (% lactic acid), free amino acid content (ninhydrin method), and antioxidant activity (DPPH radical inhibition assay). After fermentation, LAB counts increased significantly, reaching 9.60±0.06 log CFU/g in CE and 9.01±0.02 log CFU/g in CE:BF, while mold and yeast found were <4 log CFU/g in both samples. The pH decreased from 6.1 to 4.40 in CE and from 6.2 to 3.66 in CE:BF, while titratable acidity increased to 1.04 and 1.84% lactic acid in CE and CE:BF, respectively. Free amino acid content increased significantly in CE (from 21.8 to 42.4 mg glycine/100g), indicating active proteolytic activity, while the CE:BF matrix showed high baseline amino acid levels (47.5 mg/100g) with no significant further increase post-fermentation. Antioxidant activity improved markedly in both matrices, with DPPH inhibition increasing from 12.4 to 37.4% and from 26.3 to 56.5% in CE and CE:BF, respectively. These results demonstrate that L. plantarum CIDCA8327 effectively ferments gluten-free substrates based on chia and buckwheat, producing type II sourdoughs with enhanced proteolysis, and improved antioxidant capacity, supporting its potential for their use in functional breadmaking.