(583bb) Multifunctional Reactor Engineering for Galacturonic Acid (GA) Production: Enzymatic De-Polymerization of Pectin-Rich Biomass With Simultaneous Adsorption of GA Onto Anion Exchange Resins

Multifunctional Reactor Engineering
for Galacturonic Acid (GA) Production: Enzymatic De-polymerization of
pectin-rich biomass with simultaneous adsorption of GA onto Anion Exchange
Resins  

Galacturonic
acid (GA) is one of the main compounds produced after the enzymatic hydrolysis
of pectin-rich biomass generated as waste from the processing of citrus fruits,
apples, and sugar beet.  Production statistics for the last five years indicate
that several million (MM) tons of these wastes annually accumulate in USA at an
approximate range of 3.0 to 3.5 MM tons for citrus processing waste (CPW), 2.0
to 2.5 MM tons (dry weight) for sugar beet processing waste (SBPW), and
0.20-0.25 MM of dry apple processing waste (APW) (NASS, 2011 and 2013).GA has
the potential to be considered as a renewable platform for the synthesis of
relevant products or it may be used in direct applications as is shown in
Figure 1. A novel process in a multifunctional reaction system has been developed
to produce GA from the enzymatic hydrolysis of citrus pectin with its
simultaneous separation from the reaction media by adsorption onto weakly basic
anion exchange resins (WBAER). This study is based on the following
experimental steps at laboratory scale: 1) adsorption of pure GA onto WBAER in
a batch reactor to determine the adsorption kinetic parameters; 2) determination
of the kinetic parameters for the de-polymerization of citrus pectin by enzymatic
hydrolysis to produce GA in a self-buffered reaction media by the formation of
sodium galacturonate (NaGA); 3) development and evaluation of a multifunctional
reaction system for the enzymatic hydrolysis of citrus pectin to produce GA
with its simultaneous adsorption onto WBAER. Some preliminary results are shown
in Figures 2, 3, 4, and 5 for the kinetics of GA adsorption, self-buffered
enzymatic hydrolysis of pectin, and the integrated process for the enzymatic
hydrolysis of pectin with simultaneous adsorption of GA respectively in a multifunctional
batch reactor.  All the data generated in these experimental steps are being
utilized to calculate the engineering parameters needed for process design and
scale-up for the conversion of grapefruit processing waste (GPW) into sugars,
GA, and other value-added products (flavonoids).

Figure 1.  Potential utility of Galacturonic acid as a
platform feedstock for green specialty chemicals

Figure 2.  The
graph shows the graphical determination of kinetics order for the adsorption of
GA onto two commercial WBAER. The graph shows that the adsorption process
follows second-order kinetics; such behavior means that there is more than one
parameter that affects the kinetics of the adsorption process.

Figure 3. 
Linearization of Michaelis-Menten kinetic model for the enzymatic hydrolysis of
citrus pectin in a self-buffered reaction media at an enzyme loading of 50 μL/100 mL of a 0.5 wt% pectin solution. Based on this
graph a values for K_m= 14.27 mmol/L  and V_m = 0.0822 were
calculated using 50 μL of  Pectinex Ultra SPL combined
with 20 μL of Accellerase XY. The substrate
concentration [S] was defined and calculated as the monomer concentration of
homogalacturonan.

Figure 4.
Graph of galacturonic acid concentration (here described as [HGA]) leaved in the
reaction media during the enzymatic hydrolysis of pectin and simultaneous
adsorption onto WBAER (Amberlite IRA-67) at various resin loadings (0, 0.4g,
0.45g, 0.5g, and 0.55g).  The concentrations were calculated applying the
equation of Henderson-Hasselbalch for the determination of dissociated
carboxylic acids in a buffer solution, and based on the monitoring of the
changes in pH during the reaction time.

Figure 5.
Graph of galacturonic acid concentration (here described as [HGA]) adsorbed
onto WBAER (Amberlite IRA-67) during the enzymatic hydrolysis of pectin and
simultaneous adsorption at various resin loadings ( 0.4g, 0.45g, 0.5g, and
0.55g). The concentrations were calculated applying the equation of
Henderson-Hasselbalch for the determination of dissociated carboxylic acids in
a buffer solution, and based on the monitoring of the changes in pH during the reaction
time.

Bibliographic 
References

National
Agricultural Statistics Service (NASS) (eds.) (2011). Citrus Fruit 2011
Summary. United States Dept. of Agriculture (USDA).On http://usda01.library.cornell.edu/usda/
current/CitrFrui/CitrFrui-09-22-2011.pdf. Last date accessed on 02.15.2013.

National
Agricultural Statistics Service (NASS) (eds.) (2013). Noncitrus Fruits and Nuts
2012 Preliminary Summary, January 2013. United States Dept. of Agriculture
(USDA). On http://usda01.library.cornell.edu/ usda/current/
NoncFruiNu/NoncFruiNu-01-25-2013.pdf. Last date accessed on 02.26.2013.