Hydrolysate from a mixture of legume flours with antifungal activity as an ingredient for prolonging the shelf-life of wheat bread.

Aiming at identifying antifungal compounds from plant matrices to be used as ingredients in the bakery industry, a water/salt-soluble extract (WSE) was produced from a legume enzyme hydrolysate, consisting of a mixture of pea, lentil, and faba bean flours, and assayed towards Penicillium roqueforti DPPMAF1. Agar diffusion assays allowed the selection of the optimal processing conditions for hydrolysis. As shown by hyphal radial growth rate, the inhibition was observed towards several fungi, including Aspergillus parasiticus CBS971.97, Penicillium carneum CBS 112297, Penicillium paneum CBS 101032, Penicillium polonicum 112490. A multi-step purification was carried out to identify the active compounds. The antifungal activity was attributed to native proteins (nsLTP, ubiquitin, lectin alpha-1 chain, wound-induced basic protein, defensin-1, defensin-2) and a mixture of peptides, which were released during hydrolysis. Nine peptides were purified and identified as sequences encrypted in legume vicilins, lectins and chitinases. WSE was used as ingredient for making bread under pilot plant conditions. Chemical, structural and sensory characterization of bread showed the lack of significant changes compared to control. The bread made with the legume hydrolysate had a longer shelf-life than that of the control.

Long-Term Fungal Inhibition by Pisum sativum Flour Hydrolysate during Storage of Wheat Flour Bread.

In order to identify antifungal compounds from natural sources to be used as ingredients in the bakery industry, water/salt-soluble extracts (WSE) from different legume flour hydrolysates obtained by the use of a fungal protease were assayed against Penicillium roqueforti DPPMAF1. The agar diffusion assays allowed the selection of the pea (Pisum sativum) hydrolysate as the most active. As shown by the hyphal radial growth rate, the WSE had inhibitory activity towards several fungi isolated from bakeries. The MIC of the WSE was 9.0 mg/ml. Fungal inhibition was slightly affected by heating and variations in pH. The antifungal activity was attributed to three native proteins (pea defensins 1 and 2 and a nonspecific lipid transfer protein [nsLTP]) and a mixture of peptides released during hydrolysis. The three proteins have been reported previously as components of the defense system of the plant. Five peptides were purified from WSE and were identified as sequences encrypted in leginsulin A, vicilin, provicilin, and the nsLTP. To confirm antifungal activity, the peptides were chemically synthesized and tested. Freeze-dried WSE were used as ingredients in leavened baked goods. In particular, breads made by the addition of 1.6% (wt/wt) of the extract and fermented by baker's yeast or sourdough were characterized for their main chemical, structural, and sensory features, packed in polyethylene bags, stored at room temperature, and compared to controls prepared without pea hydrolysate. Artificially inoculated slices of a bread containing the WSE did not show contamination by fungi until at least 21 days of storage and behaved like the bread prepared with calcium propionate (0.3%, wt/wt).