Table 3 Comparison with previous reports of bread to ethanol process including SSF and SHF
Bread type | Treatment/fermentation conditions | Bread concentration % w/w | **Ethanol yield per kg of bread @ 48 h | Enzymes used | References |
|---|---|---|---|---|---|
Waste wheat-rye bread | SSF (slurried with enzymes at 35 °C prior to fermentation) | 15 | 333.31 (*354.36) | α-Amylase and glucoamylase, plus protease | [45] |
Waste wheat-rye bread | SSF (slurried at 45 °C for 20 min prior to fermentation) | 15 | 373.15 (*398.4) | α-Amylase, β-glucanase, pentosanase, cellulase, plus protease | [45] |
Waste wheat-rye bread | SSF of liquefied WB | 30 | 416–425 | α-Amylase, amyloglucosidase plus protease | [46] |
Waste wheat-rye bread | SSF post microwave pretreatment | 15 | 375.5 (*384.6) | α-Amylase and glucoamylase, plus protease | [45] |
Waste wheat-rye bread | SSF post Ultrasonic pretreatment | 15 | 365.1 (*366.8) | α-Amylase and glucoamylase, plus protease | [45] |
Waste wheat-rye bread | Separate hydrolysis and fermentation (SHF) standard process | 15 | 378.7 (*386.0) | STARGEN 002 (α-amylase and glucoamylase) plus protease | [45] |
mixture of wheat and buckwheat flours | SHF standard process | 16 | 303.2–408.1 (67 h) | α-Amylase plus a glucoamylase | [1] |
Sandwich WB | Yeast SSF of gelatinized and/liquefied WB | 3 | 456–478.4 (*466–474.3) | α-Amylase plus a glucoamylase | This work |
Sandwich WB | Yeast SSF of untreated WB | 3 | 448.9 (*459.9) | α-Amylase plus a glucoamylase | This work |
Sandwich WB | Thermophilic bacteria SSF of untreated WB | 3 | 437.1 (*446.8) | P. thermoglucosidasius TM333 crude α-amylase only | This work |