Abstract
The present study investigated the effect of solid-state fermentation
(SSF) of cold-pressed (CP) and hexane-extracted (HE) canola meals withAspergillus 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.