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. 2022 Jun 17;11(12):1793.
doi: 10.3390/foods11121793.

Optimization of a Simultaneous Enzymatic Hydrolysis to Obtain a High-Glucose Slurry from Bread Waste

Teresa Sigüenza-Andrés  1 , Valentín Pando  2 , Manuel Gómez  1 , José M Rodríguez-Nogales  1
Affiliations

Optimization of a Simultaneous Enzymatic Hydrolysis to Obtain a High-Glucose Slurry from Bread Waste

Teresa Sigüenza-Andrés et al. Foods. .

Abstract

Bread and bakery products are among the most discarded food products in the world. This work aims to investigate the potential use of wasted bread to obtain a high-glucose slurry. Simultaneous hydrolysis of wasted bread using α-amylase and glucoamylase was carried out performing liquefaction and saccharification at the same time. This process was compared with a traditional sequential hydrolysis. Temperature and pH conditions were optimized using a response surface design determining viscosity, reducing sugars and glucose concentration during the enzymatic processes. The optimal conditions of pH and temperature in the saccharification stage and the simultaneous hydrolysis were pretty similar. Results show that the slurry produced with simultaneous process had a similar glucose yield at 2 h, and at 4 h a yield higher than that obtained by the sequential method of 4 h and could reduce time and energy.

Keywords: discarded bread; glucoamylase; glucose; liquefaction; saccharification reducing sugars; α-amylase.

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Conflict of interest statement

The authors declare no conflict of interest with respect to the work described in this manuscript.

Figures

Figure 1
Figure 1
(a) Evolution of experimental and theoretical reducing sugar concentration (RSE and RST, respectively) and viscosity curve (VE and VT) during liquefaction of trial No. 16. (b) Evolution of experimental and theoretical glucose concentration (GLE and GLT) during saccharification of trial No. 16. (c) Evolution of RSE, RST, GLE, GLT and VT and VE during simultaneous hydrolysis of the trial No. 16.
Figure 1
Figure 1
(a) Evolution of experimental and theoretical reducing sugar concentration (RSE and RST, respectively) and viscosity curve (VE and VT) during liquefaction of trial No. 16. (b) Evolution of experimental and theoretical glucose concentration (GLE and GLT) during saccharification of trial No. 16. (c) Evolution of RSE, RST, GLE, GLT and VT and VE during simultaneous hydrolysis of the trial No. 16.
Figure 2
Figure 2
Response surface plots for the sequential hydrolysis. LIQ and SAC phases as function of temperature and pH for (a) slope of the viscosity curve (Vmi), (b) theoretical reducing sugar concentration at 120 min (RST120) and (c) theoretical glucose concentration at 120 min (GLT120).
Figure 3
Figure 3
Response surface plots for simultaneous hydrolysis phase as function of temperature and pH for (a) slope of viscosity curve (Vmi), (b) theoretical RS concentration at 120 min (RST120), (c) theoretical glucose concentration at 120 min (GLT120) and (d) theoretical glucose concentration at 240 min (GLT240).
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