3.2. Degradation of the main components in peanut cell wall
Viscozyme® L, as a complex plant hydrolase, decomposes
the cell wall structure. During the process of aqueous enzymatic
extraction, the main components in the wall, cellulose, hemicellulose
and pectin, are progressively degraded, meanwhile protein and oil bodies
are gradually released. To elucidate the degradation of the cell wall in
the aqueous enzymatic extraction process in more detail, we analyzed the
changes in the main cell wall components (Table 1).
The maximum degradation rate of CDTA-soluble pectin (67.4%),
Na2CO3-soluble pectin (87.0%),
hemicellulose (39.1%), and cellulose (57.1%) was reached at
solid-liquid ratios of 1:3, 1:4, 1:5, and 1:3, respectively (Table 1). A
high protein yield (86.64%) and the maximum yield of oil bodies
(42.18%) were recorded at solid-liquid ratios of 1:3 and 1:4, at which
the
degradation rates of CDTA-soluble pectin,
Na2CO3-soluble pectin, and cellulose
were the highest (Fig. 1, Table 1). The highest degradation rate of
CDTA-soluble pectin (81.1%),
Na2CO3-soluble pectin (76.0%),
hemicellulose (62.7%), and cellulose (55.1%) were obtained at enzyme
concentrations of 1.00, 1.25, 0.75, and 1.00%, respectively. The
highest protein yield (77.86%) and the maximum yield of oil bodies
(35.76%) was attained at enzyme concentration of 1.25%, at which
Na2CO3-soluble pectin had the best
degradation rate (Fig. 1, Table 1). Enzyme hydrolysis parameters had a
significant effect on the content of the main cell wall components
(Table 1). The maximum degradation rate of CDTA-soluble pectin (75.5%),
Na2CO3-soluble pectin (70.0%),
hemicellulose (43.0%), and cellulose (44.8%) were reached at enzyme
hydrolysis temperatures of 50, 45, 40, and 45 °C, respectively. The
highest protein yield (78.54%) and the maximum yield of oil bodies
(37.88%) was obtained at 55 °C and 50 °C, respectively, at which
CDTA-soluble pectin had the best degradation rate. The degradation rates
of CDTA-soluble pectin, Na2CO3-soluble
pectin, hemicellulose, and cellulose were 62.2% at 80 min enzyme
hydrolysis time, 51.3% at 60 min, 55.3% at 60 min, and 62.6% at 100
min, respectively. The maximum protein yield (80%) and the maximum
yield of oil bodies (37.92%) was recorded when CDTA-soluble pectin had
the most optimal degradation rate and the enzyme hydrolysis time of 80
min (Fig. 1).