Samane Torabi; S. R. Hasanbeigi; Behzad Sattari; Barat Ghobadian
Abstract
Bread waste is the common part of food biomass in the world. The aim of this study was to investigate the effects of saccharification time and also substrate concentration on the amount of glucose as well as bioethanol obtained from bread wastes folowing hydrolysis processing. The bread wastes were crushed ...
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Bread waste is the common part of food biomass in the world. The aim of this study was to investigate the effects of saccharification time and also substrate concentration on the amount of glucose as well as bioethanol obtained from bread wastes folowing hydrolysis processing. The bread wastes were crushed to small parts and then mixed with water at ratio of 10-15 (w/v%). Alpha-amylase and glucoamylase enzymes were used for liquefaction and saccharification, respectively. The effects of saccharification time and substrate loading parameters on the amount of glucose were investigated by using response surface methodology (central composite design) with Design Expert software. The glucose-derived from hydrolysis processing was measured by glucose kit. Aflatoxin contents of the bread wastes (as control sample) and optimum sample obtained from the hydrolysis processing (sample with the maximum glucose) were measured. Fermentation processing was carried out by using Saccharomyces cerevisiae yeast. The results showed that the highest amount of glucose (100.21 g/l) in enzymatic hydrolysis was obtained at the saccharification time of 48 h and substrate loading of 150 g/l. The hydrolysis processing at the higher concentrations and longer duration, due to high viscosity and adhesion, reduced the concentration of glucose, so high concentration did not have any favorable effect on the hydrolysis processing. The hydrolysis processing reduced Aflatoxin B1 and B2 at a ratio of 76% and 16%, respectively. The greatest amount of bio-ethanol in the fermentation phase (45.35 g/l) was obtained at 36 hours with efficiency of 88.7%. It could be related to the consumption of glucose produced in the hydrolysis phase due to proper growth of the cell mass during fermentation phase in this duration. The recommended time for the fermentation processing is 36 hours.
