EXPLORING BIOPROCESSING TECHNOLOGIES FOR DIVERSE INDUSTRIAL APPLICATION OF CANOLA

Abstract

Globally, canola is the second largest oilseed crop after soybean, which is processed for the commercial production of high value oil. The industrial processing steps for canola oil extraction include preprocessing (cleaning, pressing, flaking, and cooking), mechanical pressing, and/or organic solvents. This process results in large quantities of protein-rich (~ 40% dry basis) meal as a co-product. The meal is used partially in animal diet (<30% inclusion) due to high levels of antinutritional factors (ANFs) such as high fibers, phytic acid, and glucosinolates, and low metabolizable energy. Thus, this research was designed to examine various bioprocessing technologies (i.e., traditional sprouting, solid state fermentation, submerged state fermentation, co-culture fermentation, mild pretreatments, and their combinations) for possible advancement in canola use. Canola seed sprouting for 6-day period led to an increase in protein content and a reduction in ANFs and oil content of sprouts compared to ungerminated seed. Subsequent submerged state fermentation of 6- day old sprouts using three different strains (Aureobasidium pullulans, Trichoderma reesei and Neurospora crassa) further increased protein content and lowered ANFs. Solid-state fermentation of 144 h old sprouts using A. pullulans, N. crassa and T. reesei enhanced the protein content and reduced ANFs of sprouts. Sprouting canola seed for three days helped in hull removal, leading to high protein meal accompanied by low fiber and phytic acid level. Three-day seed sprouting had no effect on oil yield, but free fatty acid content was higher compared to seed oil. Co-culture fermentation of HECM under solid state process showed maximum reduction in fiber content with co-culture of A. pullulans and N. crassa while a combination of A. pullulans and T. reesei promoted the highest GLS and phytic acid reductions compared to other combinations, which indicated the advantage of coculture inoculation over monoculture in terms of ANFs reduction. Mild pretreatment of HECM using deionized water resulted in washed HECM (WHECM) with lower soluble sugars and GLS compared to untreated HECM, whereas protein and amino acid were concentrated due to the removal of soluble components. WHECM compared to HECM showed higher protein digestibility when fed to rainbow trout. Subsequent mono- and coculture fermentation of HECM and WHECM under submerged process resulted in higher protein and amino acid content and lower ANFs levels compared to uninoculated controls. The results of cellulase, endoglucanase and β-glucosidase activity indicated the crucial role of used substrates, fungi, fermentation modes (solid state/submerged stated) and inoculation methods (mono-/co-culture) on enzyme activities.