The present study investigated the effect of solid-state fermentation (SSF) of cold-pressed (CP) and hexane-extracted (HE) canola meals with Aspergillus niger NRRL 334 and A. oryzae NRRL 5590 on the functionalities of protein products extracted from them. After SSF, proteins were recovered using alkaline extraction-isoelectric precipitation (AE-IP) or salt extraction-dialysis (SE). SSF of the two meal types reduced the protein content of the extracts produced by AE-IP. There were varied effects to solubility, foaming, and emulsifying properties as a result of SSF under the combined influence of functionality pH, strain, meal type, and protein extraction method. The protein isolate produced from CP meal using SE had increased solubility at pH 7 (from 51.8 to 90.7%) when the meal was fermented with A. oryzae. Both strains resulted in an over 2-fold increase in the emulsifying activity index (at pH 7) of AE-IP products from CP meal. For both protein extraction methods, the protein products from A. niger fermented HE meal had better foaming capacity (FC) at pH 7 than the controls (non-fermented), but reduced FC at pH 3. Overall, regardless of meal fermentation, the SE products were richer in protein and had higher oil holding capacity (OHC), whereas the water holding capacity (WHC) was higher for AE-IP isolates. SSF of the meals generally improved the O/WHC of the extracted proteins. The findings suggest that canola protein functionality could be effectively modulated by SSF with different microbial strains under various processing conditions to enhance their applicability in the food industry.

In this study, the effects of solid-state fermentation (SSF), including strain (Aspergillus niger NRRL 334 and A. oryzae NRRL 5590) and fermentation time (24, 48, and 72 h) on the nutritional value of cold-pressed (CP) and hexane-extracted (HE) canola meals were examined. SSF increased the protein content of both types of meals (from ~36 to ~40%) while reducing the oil content of CP meals (from ~12 to 9%). There was a significant reduction (~80%) in the phytic acid content of both types of meals after fermentation using either fungi. Overall, fermented samples showed a decrease in the total phenolic content from 2.7-3.1 to ~1.0 mg gallic acid equivalents (GAE)/g DM (a ~65% reduction), of which specifically the HE meal fermented with A. niger sample had the greatest decrease from 3.1 to 0.6 mg GAE/g DM (~81% reduction). Seventy-two hours of fermentation decreased the in vitro protein digestibility (IVPD) of the meals. In contrast, a shorter fermentation time (24 h) increased the IVPD as compared to the controls (from ~73% to 77-81%), with the exception of the CP meal fermented with A. niger which had decreased IVPD at all fermentation times. Overall, the changes indicate that SSF using A. niger or A. oryzae can be useful to positively modify the composition of different canola meals and improve their nutritional value by significantly increasing the protein content, decreasing the levels of antinutrients, while only slightly reducing IVPD.