Table 4 The comparison of various pretreatment methods for JAS

Alkali

2% (w/v) NaOH, 121 °C, 1 h, washing to neutral pH

>240

0.23

A large amount of water for neutralization

[29]

Acid/alkali

0.5 % (v/v) H₂SO₄, 121 °C, 1 h/4% (w/v) NaOH, 121 °C, 1 h, washing to neutral pH

>260

0.33

A large amount of water for neutralization, high sugars yield, high energy cost

[30]

Acid

1% (v/v) H₂SO₄, 130 °C, 1.5 h

–

–

Low sugars yield, water saving

[31]

Acid

0.5% (v/v) H₂SO₄, 121 °C, 1 h

–

0.18

Low sugars yield, water saving

[32]

Alkali

4% (w/v) NaOH, 121 °C, 1 h washing to neutral pH

>260

0.26

A large amount of water for neutralization, high sugars yield

[32]

Alkali/peroxide

2% (w/v) NaOH–6% (v/v) H₂O₂, 121 °C, 1 h, washing to pH 8.8

45

0.27

Water saving, high sugars yield

This work