RESULT: Protein hydrolysis by protease followed by extraction of non-starch lipids with WSB increased yield to 1.9 ± 0.3% from 1.0 ± 0.1% with no protease treatment. The lipid profile showed a significant increase in phospholipid compounds extracted with protease hydrolysis (5.9 ± 0.8 nmol·g-1 ) versus without enzymatic treatment (2.4 ± 1.3 nmol g-1 ).
CONCLUSION: Improved lipid extraction yield and phospholipid compounds following protease-assisted extraction method provided additional insight towards the understanding of protein-lipid interaction in wheat flour. The new protease-assisted extraction method may be applied to analyzing non-starch lipids in other types of wheat flours and other cereal flours. © 2021 Society of Chemical Industry.
METHODS: 5'-phosphodiesterase (5'-PDE) enzyme was characterized from adzuki beans, in which the optimum pH and temperature were determined. In addition, the stability of 5'-PDE was assessed at different pH and temperature. The effects of cations and EDTA were evaluated to characterize the 5'-PDE enzymes further.
RESULTS: The alkaline 5'-phosphodiesterase has an optimum pH of 8.5. This enzyme is also thermostable, with an optimum temperature of 80°C. The stability in terms of temperature and pH was also determined, and was found to be stable in the pH range of 7.0-8.5. This enzyme was found to retain more than 80% of its activity for 4 days at 60 and 65°C. In addition, the effects of 14 different metal ions, 4 types of detergents and ethylenediaminetetraacetic acid (EDTA) on 5'-PDE were studied. Ca2+, K+, Mg2+ and Li+ activated 5'-PDE while Na+, Zn2+, Ni+, Hg+, Cu2+, Pb2+, Fe2+, Al3+, Ba2+ and Co2+ were inhibitory. EDTA, Triton X-100 and sodium dodecyl sulfate (SDS) were strong inhibitors of 5'-PDE, while Tween 80 and Tween 20 were slightly inhibitory. The effects of cations and EDTA suggest that 5'-PDE from adzuki beans is a metalloenzyme.
CONCLUSIONS: Although 5'-PDE from adzuki beans has a high temperature optimum of 80°C, the enzyme is more stable at 60°C, and different cations affected the activity of the enzyme differently.