![The influence of different catalysts and concentrations on LG, LGO, total carbon yield. (1) Experimental conditions: 1 g of IIR residues, 190 °C, 2 h, 40 μL of 15 mM catalyst (TsOH, MSA, H2SO4), and 100 mL Diox. (2) Experimental conditions: 1 g of IIR residues, 190 °C, 2 h, 40 μL of H2SO4 concentrations (10 mM, 15 mM, 25 mM, 30 mM), and 100 mL Diox. Note: YieldTotalcarbon%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\left[\mathrm{Yield}\right]}_{\mathrm{Total carbon}} \left(\mathrm{\%}\right)$$\end{document}=YieldHMF%+YieldFF%+YieldLG%+YieldLGO%\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\left[\mathrm{Yield}\right]}_{\mathrm{HMF}} \left(\mathrm{\%}\right)+{\left[\mathrm{ Yield}\right]}_{\mathrm{FF}} \left(\mathrm{\%}\right)+{\left[\mathrm{ Yield}\right]}_{\mathrm{LG}} \left(\mathrm{\%}\right)+{\left[\mathrm{ Yield}\right]}_{\mathrm{LGO}} \left(\mathrm{\%}\right)$$\end{document}, and these yields were the highest yield](https://www.researchgate.net/publication/368362854/figure/fig4/AS:11431281119725123@1676175472739/The-influence-of-different-catalysts-and-concentrations-on-LG-LGO-total-carbon-yield_Q320.jpg)
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Biomass Conversion and Biorefinery
https://doi.org/10.1007/s13399-023-03892-9
ORIGINAL ARTICLE
Characterization ofisolated starch fromIsatis indigotica Fort. root
andanhydro‑sugars preparation using its decoction residues
TingtingXu1· XinGao1· YuanzhangLi1· ChangquLin1· PeipeiMa1· ZhongzhongBai1· JunZhou1· HongliWu1·
FeiCao1 · PingWei1
Received: 10 October 2022 / Revised: 29 January 2023 / Accepted: 31 January 2023
© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2023
Abstract
Isatis indigotica Fort. root (Ban-lan-gen, IIR), a traditional Chinese medicine (TCM), has an ancient and well-documented
history for its medicinal properties. Aside from epigoitrin, indole alkaloids, and their corresponding derivatives as medicinal
ingredients, it also contains lots of biomass such as starch. Herein, a new starch was isolated from IIR and the physicochemical
properties such as amylose content, moisture content, ash content, morphology, thermal properties, and crystallography were
characterized systematically. The amylose content of IIR starch was 19.84 ± 0.85%, and the size and shape of starch granules
is ellipsoidal shape with sizes from 2 to 10μm. IIR starch exhibited a C-type pattern and had 25.92% crystallinity (higher
than that of corn starch). The gelatinization temperature of IIR starch was 58.68–75.41°C, and its gelatinization enthalpy was
ΔHgel = 4.33J/g. After decocting, the IIR’s residues can be used to prepare anhydro-sugars in a polar aprotic solvent. The total
carbon yield of levoglucosan (LG), levoglucosenone (LGO), 5-hydroxymethylfurfural (HMF), and furfural (FF) could reach
69.81% from IIR’s decoction residues in 1,4-dioxane with 15mM H2SO4 as the catalyst. Further, the residues after dehydration
were prepared into biochar by thermochemical conversion and the BET surface area of biochar was 1749.46 m2/g which has
good application prospect in soil improvement and alleviates obstacles of IIR continuous cropping.
Keywords Isatis indigotica Fort. root· Starch· Decoction residues· Anhydro-sugars· Biochar
1 Introduction
Isatis indigotica Fort., a member of the Cruciferous family,
is native to China, and its dried roots are named Ban-lan-gen
[1]. Numerous pharmacological studies have reported that the
extracts or isolated compounds of I. indigotica Fort. root (IIR)
have anti-inflammatory and antiviral activities and can be
further processed into Ban-lan-gen granule which is used in
China for the treatment of eruptive epidemic diseases such as
hepatitis B [2], pneumonia [3], influenza [4, 5], and so on. IIR
is one of the drugs recommended by the Chinese government
for the prevention and control of severe acute respiratory
syndrome (SARS) in 2003 [6]. During the COVID-19
pandemic, the screening of antiviral Chinese medicines
showed that IIR had an obvious inhibitory effect on the new
coronavirus [7]. To this date, I. indigotica is widely cultivated
in China, and the output of IIR reached 50,000 tons in 2020.
According to the standard of China National Medical Products
Administration (YBZ-PFKL-2021008), the extraction rate of
Ban-lan-gen granules from IIR is only 25 ~ 38%; thus, lots of
extracted residues are discarded as waste.
As the storage organ of I. indigotica Fort., IIR contains
lots of nutrients such as starch or protein except medicinal
ingredients. There were reports in some literature about the
lignocellulose contents of IIR, but these data are very different
from each other. For example, Li etal. [8] reported that the
starch content of IIR was 26.88–43.89%, and Jia etal. [9] found
that the contents of starch, reducing sugar, and crude fiber in
IIR were 2.36%, 1.30%, and 25.72%, respectively. Although
the main reason for this confusion was the inconsistency of
determination methods, it showed that IIR and its decoction
residues contain a large amount of starch components.
* Hongli Wu
hlwu@njtech.edu.cn
* Fei Cao
csaofeiw@njtech.edu.cn
1 College ofBiotechnology andPharmaceutical Engineering,
Nanjing Tech University, 30 South Puzhu Road,
Nanjing211816, People’sRepublicofChina
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