Abstract
The aims were to assess how particle size reduction and
carbohydrate-hydrolyzing enzyme treatment influence
protein recovery from rapeseed cold-pressed cake and to
determine the effect of these pretreatments in protein
extraction procedures varying in ionic strength, pH, and
total solid content. Defatted press cake (median particle
size 600 µm) was milled to 21-164 µm and 7 µm median
particle sizes by pin disc milling and air-flow milling,
respectively. The milled press cake samples were treated
with a carbohydrate-hydrolyzing enzyme preparation, after
which proteins were extracted in saline (pH 6) or
alkaline (pH 12) buffer at 5 % solid content, or in water
at 20 % solid content. Particle size reduction of the
press cake did not influence enzyme action or protein
yield, suggesting that protein release from the press
cake is not physically limited by cell walls or internal
cell structures. As an exception, protein release from
the aleuronic cells appeared to be hindered by intact
cell walls. Enzyme treatment improved protein recovery,
more substantially when the extraction was carried out in
water at 20 % solid content than in saline or alkaline
conditions at 5 % solid content. The enzyme mediated its
positive effect most probably by reducing the water
holding capacity of the press cake, thereby facilitating
solid-liquid separation, and releasing anionic compounds
which improved protein solubility through electrostatic
stabilization. The results suggest that
carbohydrate-hydrolyzing enzymes are beneficial for
rapeseed protein extraction at reduced water content or
when no salt or alkali is added to increase protein
solubility.
Original language | English |
---|---|
Pages (from-to) | 2392-2399 |
Number of pages | 8 |
Journal | Food and Bioprocess Technology |
Volume | 8 |
Issue number | 12 |
DOIs | |
Publication status | Published - Sept 2015 |
MoE publication type | A1 Journal article-refereed |
Keywords
- Milling
- Pectinase
- Microscopy
- Differential scanning calorimetry