Steam Pretreatment Research Articles

Pretreatment of Oil Palm Empty Fruit Bunch (OPEFB) at Bench-Scale High Temperature-Pressure Steam Reactor for Enhancement of Enzymatic Saccharification

Up scaling of biomass pretreatment from laboratory scale to a bench-scale reactor is one of important steps in the application of the pretreatment for pilot or commercial scale. This study reports the optimization of pretreatment conditions, namely reaction temperature and time, by one factor at a time (OFAT) method for the enhancement of enzymatic saccharification of oil palm empty fruit bunch (OPEFB). OPEFB was pretreated using high temperature-pressure steam reactor with different reaction temperatures (160, 170, 180, 190, 200 °C) and times (10, 20, 30, 40, 50 min). The effectiveness of the pretreatment was determined based on chemical compositions of untreated and pretreated OPEFB and sugar production from enzymatic saccharification of the pretreated OPEFB. Solubilized components in the water that generates the steam were also determined. Pretreatment at 180°C for 20 min provides the highest sugar yields (97.30% of glucose yield per initial cellulose and 88.86% of xylose yield per initial hemicellulose). At the optimum condition 34.9% of lignin and 30.75% of hemicellulose were successfully removed from the OPEFB and resulted in 3.43 delignification selectivity. The relationship between severity factor and by-products generated and the sugars obtained after enzymatic saccharification were discussed. The pretreated OPEFB at the optimum condition was also characterized for its morphological characteristic by scanning electron microscopy (SEM) and crystallinity by X-ray diffractometry (XRD) and then compared it with untreated one. The steam pretreatment caused some fiber disruptions with more defined and opened structures and increased of the crystallinity index (CrI) by 2.9% compared to the untreated OPEFB

Characterization of wet microalgal cells pretreated with steam for lipid extraction

• Steam pretreatment employed to disrupt microalgal cells for lipids extraction. • Maximum curvature of cell increased from 1.88 × 10 −6 to 1.43 × 10 −7 m −1 after treatment. • Fractal dimension of microalgal cells increased from 1.25 to 1.47 after treatment. • Lipid recovery from wet microalgal cells increased 2.1-fold after treatment. Steam pretreatment was employed to disrupt microalgal cells for lipids extraction. Effects of steam pretreatment on microstructure of microalgal cells were investigated through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Effect of treatment on lipid extraction was also studied. Microalgal cell walls were distorted after steam pretreatment due to the hydrolysis of organic macromolecules contained in cell wall. Maximum curvature was increased from 1.88 × 10 −6 m −1 to 1.43 × 10 −7 m −1 after treatment with the steam at 130 °C. The fractal dimension of microalgal cells increased from 1.25 to 1.30 after pretreatment for 15 min, and further increased to 1.47 when the pretreatment time was increased to 60 min. Increased steam pretreatment temperature and time enhanced the hydrolysis of organic macromolecules, and finally destroyed microalgal cell walls at pretreatment temperature of 130 °C and pretreatment time of 60 min. Lipid extracted from wet microalgal was significantly increased (2.1-fold) after pretreatment.

Multi-scale characterization of the thermal – mechanically isolated bamboo fiber bundles and its potential application on engineered composites

Bamboo fiber bundles (BFB) were firstly isolated by using the method of high-temperature saturated steam pretreatment following with mechanically rub-twisting. The microstructure, chemical composition, cell-wall mechanics, water absorption and tensile properties of BFB were then characterized and the interrelationships among the investigated properties were analyzed. Results indicated that thermal - mechanical isolation method can effectively extract the fiber bundles from bamboo culms with little damage on the microstructure of bamboo fibers. Both thehygroscopicity and cell-wall mechanics of BFB have been improved due to the degradation of hemicelluloses and increased crystallization degree induced by the saturated steam at the temperature of 180 °C for 30–40 min. BFB presented an obvious advantage in tensile properties as compared to other fibrous materials and were invulnerable to the thermal–mechanical isolation, which opens up the potential applications to reinforce the polymer matrix composites instead of synthetic fibers. Furthermore, the bending strength and modulus of laminated veneer lumber increased significantly with the addition of BFB, indicating that the isolated BFB also has the potential to be applied on engineered composites.

Impact of steaming pretreatment process on characteristics and antioxidant activities of black garlic (Allium sativum L.).

Impact of steaming pretreatment processes on physical properties, bioactive compounds and antioxidant activities, of black garlics (Allium sativum L.) was studied. Steaming pretreatment at different times (0, 4 and 6min) was conducted before incubating in 60°C-incubator at different incubation times (0, 9 and 18days). Different steaming pretreatment processes affected the color and hardness of black garlic differently, while total polyphenol content (TPC) and total flavonoid content (TFC) were also determined by the steaming pretreatment time used. TPC and TFC increased with increasing of incubating time, where the highest those bioactive compounds was observed from 18-day incubation, especially with 4min of steaming pretreatment (p ≤ 0.05). Increase of those bioactive compounds was in accordance with increasing of DPPH radical scavenging activity (DPPH) and ferric reducing antioxidant power (FRAP) of black garlic during incubation. In addition, black garlic obtained from 18-day incubation with steaming pretreated for 4min revealed the optimum condition providing the black garlic with high in both DPPH and FRAP, compared with others (p ≤ 0.05). Therefore, steaming pretreatment could effectively improve the efficiency of black garlic production process by increase the generation rate of bioactive compounds as well as induce antioxidant properties of black garlic with shorten process time.

Lignocellulosic pretreatment-mediated phenolic by-products generation and their effect on the inhibition of an endo-1,4-β-xylanase from Thermomyces lanuginosus VAPS-24

The inhibitory effect of eight model lignin derivatives (ferulic acid, guaiacol, kraft lignin (alkali, low sulfonate content), p-coumaric acid, gallic acid, syringic acid, vanillin and vanillic acid) on XynA activity was evaluated. The model lignin derivatives viz. gallic acid, vanillic acid and vanillin were inhibitory to XynA activity, with an over 50% reduction in activity at concentrations as low as 0.5mg/ml. However, enzyme deactivation studies in the absence of substrate showed that these pretreatment by-products do not interact with the enzyme except when in the presence of its substrate. The effect of the main structural properties of the pretreatment-derived phenolics, for example their hydroxyl and carbonyl group types, on XynA enzyme inhibition was investigated. The presence of carbonyl groups in phenolics appeared to confer stronger inhibitory effects than hydroxyl groups on XynA activity. The hydrolytic potential of XynA was not inhibited by a mixture of phenolics derived after steam pretreatment of woody biomass (Douglas fir and Black wattle). It appears as if the liquors from steam-pretreated woody biomass did not possess high enough phenolic content to confer XynA inhibition. The xylanase (XynA from Thermomyces lanuginosus) is, therefore, a striking choice for application in biofuel and fine chemical industries for the xylan degradation in steam-pretreated biomass.

Potentiality of Saccharomyces Boulardii in Fermentation of Bio-Ethanol Derived from Fruit Wastes

An astronomical increase in vehicular usage has led to the depletion of existing fossil fuels and forced researchers to find alternative sources of fuels. Extensive studies are utilizing Saccharomyces cerevisiae for bioethanol production. Therefore, in the present study, the potential application of Saccharomyces boulardii derived bioethanol from fruit wastes was explored. The orange, sweet lime, and banana peels were subjected to various pre-treatment procedures and used as substrates for yeast mediated fermentation. The cellulosic de-linearization of fruit peels induced by alkaline and steam pre-treatments was analysed using Fourier Transform Infrared Spectroscopic analysis. The chemical nature of fruit waste-derived bioethanol was compared with commercial ethanol using gas chromatographic analysis. Bioethanol used in ratios 0%, 4%, 8%, 12% by volume as part of fuel blends were subjected to performance testing. This testing process was carried out on a single-cylinder, four-stroke spark-ignition engine and the effect of bioethanol content (by volume) on the operational parameters like total fuel consumption, brake specific fuel consumption, brake thermal efficiency, volumetric efficiency, and equivalence ratios were assessed. FTIR spectra showed significant changes in the chemical structure of fruit peels due to pretreatments. The bioethanol yields increased up to 24 h of fermentation after which there was a steady decline. These results were confirmed by an increase in pH of the biomass after 24 h up to 72 h. Enzymatic hydrolysis of fruit peels resulted in higher bioethanol yield as compared to acid treatment. The fruit derived bioethanol showed ideal physicochemical characteristics for use as automobile fuel. The same showed decent performance when tested on a four-stroke, spark ignition engine

Effects of steam pretreatment on fouled membrane in chemical cleaning for flux recovery in drinking water treatment.

This paper shows the possibility of using steam pretreatment to improve the efficiency of membrane recovery chemical cleaning. Before applying chemicals to clean a fouled membrane, steam pretreatment was employed to loosen the structure of the foulant layer and weaken the attachment of those foulants on the membrane. Although longer steam contact times would lead to even better cleaning efficiency, the steam pretreatment duration was limited to less than 2min to maintain membrane integrity. When cleaning fouled membranes with 1mol/L HCl, the cleaning efficiency without steam pretreatment went from 83.3 to 90.2% as cleaning time increased from 30 to 180min. As for 90-s steam pretreatment, the cleaning efficiency showed high values of more than 93% regardless of cleaning time. When the concentration of HCl was decreased to 0.2mol/L, the cleaning efficiencies with a 90-s steam pretreatment was 78.6% and 92.6% for relatively short cleaning times of 30 and 60min, respectively; this is much higher than the 62.2% and 76.7% achieved when cleaning without steam pretreatment. In addition, when using alkaline solution as the cleaning chemical, similar results were obtained. This implies that the application of steam before chemical cleaning is effective in improving cleaning efficiency, and so, this technique has the potential to reduce the amount of cleaning chemical required for membrane recovery cleaning.

A comparison of different pre-extraction methods followed by steam pretreatment of bamboo to improve the enzymatic digestibility and ethanol production

In this work, investigation of pre-extraction of bamboo under three different conditions (alkaline, neutral, and acidic) prior to acid catalyzed (AC) steam pretreatment on the conversion of polysaccharides into fermentable sugars and ethanol was reported. Pre-extraction process was demonstrated to significantly improve the enzymatic digestibility of bamboo and reduce the formation of inhibitory compounds for fermentation. Comparing to the pre-extraction of bamboo under neutral and acidic conditions, alkaline pre-extraction of bamboo yielded the highest monomeric sugar yields following enzymatic hydrolysis, which were approximately 86% of glucose and 82% of xylose (based on the initial sugar composition). The fermentation of sugars released during enzymatic hydrolysis with pentose-hexose fermenting Saccharomyces cerevisiae Lg8-1 strain achieved the final ethanol concentrations of 50.1, 46.3, and 49.0 g/L, corresponding to the ethanol yields of 70.5%, 68.9%, and 65.1% (based on theoretical ethanol yield of the initial bamboo) for the prep-extraction of bamboo under alkaline, neutral, and acidic conditions, respectively. The results indicate that the pre-extraction of extractives and ash followed by AC steam pretreatment is a promising approach to improve the bioconversion of bamboo biomass to biofuels.

The Production of Lipids Using 5-Hydorxymethy Furfural Tolerant Rhodotorula graminis Grown on the Hydrolyzates of Steam Pretreated Softwoods

Acid catalyzed (SO2) steam pretreated softwoods inevitably contain furans such as 5-hydorxymethy furfural (HMF) and furfural, which are derived from the respective degradation of component hexoses and pentoses. As these materials are known to be inhibitory to fermentation, six oleaginous yeasts were grown on corn steep liquor (CSL) medium containing HMF (0.2%) and furfural (0.1%) to assess their resistance to possible inhibition and its possible influence on lipid production. R. graminis showed the highest tolerance to HMF (0.2%) and furfural (0.1%) when they were added individually to the CSL medium. However, when both HMF (0.2%) and furfural (0.1%) were added together, this inhibited the growth of R. graminis. Subsequent evaporation of the CSL medium successfully removed furfural from the CSL medium and increased the sugar concentration. However, the residual concentration of HMF (0.4%) still inhibited R. graminis growth. To try to improve HMF tolerance, R. graminis was slowly acclimatized in medium containing HMF (0.4%) and was eventually able to produce 1.8 g/L of lipids after four days of growth in the HMF containing medium. This was close to the same amount of lipid produced as when R. graminis was grown in the CSL medium without HMF and furfural. This indicated that an acclimatization strategy is a promising way to enhance lipids production when R. graminis is grown on the hydrolyzates of SO2-catalyzed steam pretreated lignocellulosic substrates.

Effect of Dilute Acid and Alkaline Pretreatments on Enzymatic Saccharfication of Palm Tree Trunk Waste for Bioethanol Production

The sugar palm tree (Arenga pinnata) was abundant in Indonesia and has high cellulose contents for bioethanol production. However, the lignin content was the major drawback which could inhibit saccharification enzymes and therefore removing the lignin from the biomass is important. This paper evaluated the effects of pretreatments using nitric acid (HNO3) and ammonium hydroxide (NH4OH) at 2 to 10% (v/v) on reducing sugar and ethanol contents and compared with the effects of steam pre-treatment. The pretreated samples were hydrolyzed using cellulase enzymes at pH 5.0 with a substrate concentration of 10% (w/v) for 24 to 72 h at 50 °C. Subsequent assessments of enzymatic saccharification following pre-treatment with 10% (v/v) HNO3 showed maximum reducing and total sugar contents in palm tree trunk waste of 5.320% and 5.834%, respectively, after 72 h of saccharification. Following pretreatment with 10% (v/v) of NH4OH, the maximum reducing and total sugar contents of palm tree trunk waste were 2.892% and 3.556%, respectively, after 72 h of saccharification. In comparison, steam pretreatments gave maximum reducing sugar and total sugar contents of 1.140% and 1.315% under the same conditions. Simultaneous saccharification and fermentation (SSF) was conducted at 37 °C (pH 4.8) and 100 rpm for 120 h using 10% (v/v) Saccharomyces cerevisiae and cellulase enzyme with a substrate concentration of 10% (w/v). The result showed the highest ethanol content of 2.648% was achieved by using 10% (v/v) HNO3. The use of 10% (v/v) NH4OH gained a yield of 0.869% ethanol while the steam pretreatment could obtained 0.102% ethanol.

Comparison of alkaline and acid-catalyzed steam pretreatments for ethanol production from tobacco stalk

In this study, tobacco stalk (TS), the solid residue from tobacco industry, was utilized as the raw material for the production of bioethanol through combining processes of alkaline pretreatment or acid-catalyzed (AC) steam pretreatment followed by enzymatic hydrolysis and fermentation. The results indicate that both the two pretreatment strategies could efficiently improve the enzymatic digestibility of TS. Compared to alkaline pretreatment, AC steam pretreatment solubilized more xylan into the liquid phase while preserving more lignin in the pretreated solid substrate. Following enzymatic saccharification of whole pretreated materials from two pretreatment methods at a modest enzyme loading of 15 mg protein/g glucan, the slurry from alkaline pretreatment achieved a slightly higher total monomeric sugar yields than that of AC steam pretreatment. The sugars in the obtained enzymatic hydrolysates from both the two pretreatment technologies showed good sugar-to-ethanol conversion during fermentation with Saccharomyces cerevisiae Lg8-1 strain. The overall mass balances showed that yields of ethanol were 2.75 and 2.69 kg per 10 kg of untreated TS for alkaline and AC steam pretreatments, respectively.

Effect of Mechanical Pretreatment for Enzymatic Hydrolysis of Woody Residues, Corn Stover and Alfalfa

This work aimed to investigate the effects of biomass species on fermentable sugar production, with respect to both energy consumption and sugar yield, using the modified traditional mechanical system from Pulp & Paper Mills as a potential biorefinery step. The study explored four lignocellulosic biomass species including corn stover, alfalfa, white birch and black spruce during the pretreatment process with and without the addition of NaOH. This was followed by a disk refining pretreatment under various operating conditions of gap size and consistency through a pilot scaled disk refining system. The study characterized and analyzed the chemical components and sugar streams obtained from the biomasses using the thermochemical and refining pretreatment and also analyzed the energy consumption of the disk refining system. The results show that for all the biomasses, the thermochemical process mainly removed lignin and hemicelluloses through a steaming pretreatment. From low to high, the lignin contents of the four biomasses are shown as follows: corn stover, alfalfa, white birch and black spruce. With respect to the refining pretreatment, when the gap size remains constant, black spruce has the longest fibers while corn stover has the shortest. Moreover, using enzymatic hydrolysis to evaluate the sugar yield revealed that the thermochemical pretreatment increased the sugar yield in accordance with how much lignin was removed from each biomass as well as their final lignin content. However, the additional refining treatment had a greater effect on corn stover and alfalfa than on white birch and black spruce due to the reduction in fiber length. Therefore, with respect to existing mechanical refining equipment, the modified thermochemical disk refining pretreatment (TCDRP) has a greater effect on agricultural biomass and hardwood (white birch). Specifically, the sugar yield of the TCDRP corn stover was the highest (97.3%) when compared to the other biomasses, while its energy consumption was 196 kWh/ton.

Improving enzymatic saccharification of hardwood through lignin modification by carbocation scavengers and the underlying mechanisms

In this work, the beneficial effect of carbocation scavenger additives on hardwood pretreatment was revealed by significantly improved biomass saccharification: cellulose hydrolysis yield was increased by over 15% after steam pretreatment of poplar, while that was enhanced by more than 48% after dilute acid pretreatment. Besides, the relative contributions of lignin towards enzyme binding and physical barrier effect for proposed mechanisms were quantified. Results indicated that the addition of carbocation scavenger, 2-naphthol-7-sulfonate, resulted in acid groups incorporation of 62.36 mmol/kg to lignin, which mitigated enzyme non-productive binding. Moreover, enlarged biomass porosity and reduced surface lignin coverage were detected through BET and XPS analysis, respectively, which mostly related to the diminished physical barrier effect of lignin. As a result, the lignin inhibitions were significantly suppressed through the addition of carbocation scavenger, giving rise to significantly improved enzymatic hydrolysis of hardwood.

Chemical-free thermomechanical pulping of empty fruit bunch and sugarcane bagasse

The biomass resources oil palm empty fruit bunch (EFB) and sugarcane bagasse, which are residues from the palm oil and sugar industries, continue to be investigated for more applications. With increasing concern for the environment, cleaner production has been a worldwide aim of researchers. In this study, thermomechanical pulp (TMP) from EFB and sugarcane bagasse was prepared with disc refining after steam pretreatment of the raw materials. Afterwards, refining and handsheet properties of TMP using various percentages of unbleached soda bagasse pulp (USBP) were studied. Fiber characterizations and handsheet properties showed that pulp of acceptable quality was obtained via thermomechanical pulping. Moreover, energy consumption during PFI refining of EFB TMP was higher than that of bagasse TMP. Physical properties were further enhanced through introduction of USBP. The results firmly support the feasibility of cleaner thermomechanical pulping of EFB and sugarcane bagasse.

Introducing low-quality feedstocks in bioethanol production: efficient conversion of the lignocellulose fraction of animal bedding through steam pretreatment

BackgroundAnimal bedding remains an underutilized source of raw material for bioethanol production, despite the economic and environmental benefits of its use. Further research concerning the optimization of the production process is needed, as previously tested pretreatment methods have not increased the conversion efficiency to the levels necessary for commercialization of the process.ResultsWe propose steam pretreatment of animal bedding, consisting of a mixture of straw and cow manure, to deliver higher ethanol yields. The temperature, residence time and pH were optimized through response-surface modeling, where pretreatment was evaluated based on the ethanol yield obtained through simultaneous saccharification and fermentation of the whole pretreated slurry. The results show that the best conditions for steam pretreatment are 200 °C, for 5 min at pH 2, at which an ethanol yield of about 70% was obtained. Moreover, the model also showed that the pH had the greatest influence on the ethanol yield, followed by the temperature and then the residence time.ConclusionsBased on these results, it appears that steam pretreatment could unlock the potential of animal bedding, as the same conversion efficiencies were achieved as for higher-quality feedstocks such as wheat straw.

The influence of lignin migration and relocation during steam pretreatment on the enzymatic hydrolysis of softwood and corn stover biomass substrates.

To be effective, steam pretreatment is typically carried out at temperatures/pressures above the glass transition point (Tg) of biomass lignin so that it can partly fluidize and relocate. The relocation of Douglas-fir and corn stover derived lignin was compared with the expectation that, with the corn stover lignin's lower hydrophobicity and molecular weight, it would be more readily fluidized. It was apparent that the Tg of lignin decreased as the moisture increased, with the easier access of steam to the corn stover lignin promoting its plasticization. Although the softwood lignin was more recalcitrant, when it was incorporated onto filter paper, it too could be plasticized, with its relocation enhancing enzymatic hydrolysis. When lignin recondensation was minimized, the increased hydrophobicity suppressed lignin relocation. It was apparent that differences in the accessibility of the lignin present in Douglas-fir and corn stover to steam significantly impacted lignin fluidization, relocation, and subsequent cellulose hydrolysis.

Fungal transformation and reduction of phytotoxicity of grape pomace waste

Grape pomace (GP) from Vitis labrusca, the main byproduct from “American table wine” production, is recalcitrant to degradation, and its accumulation is a serious problem with negative environmental impacts. In this work, transformation of grape pomace using a steam pretreatment followed by incubation of GP during a 90-day period with six different fungi were evaluated. Several fungi tested reduced the phytotoxicity of water-soluble fraction (WSFd) from steam-pretreated GP after 90 days’ incubation to lettuce and tomato seeds. U. botrytis caused the largest effective phytotoxicity reduction of WSFd (used in the concentration range of 10–1.25% p/v) and was the only fungus causing the removal of monoaromatic compounds. Therefore, this procedure with U. botrytis effectively reduces the availability of phytotoxic monoaromatic compounds in GP, which opens a way for the development of guidelines for the management of these wastes and their potential use as organic amendments in agricultural soil.

Saccharification of the pretreated husks of corn, peanut and coffee cherry by the lignocellulolytic enzymes secreted by Sphingobacterium sp. ksn for the production of bioethanol

The present work emphasizes to develop a cost-effective process for the saccharification of lignocellulosic agro-wastes viz., husks of corn, peanut and coffee cherry, utilizing the consortium of crude lignocellulolytic enzymes produced by the newly isolated Sphingobacterium sp. ksn followed by fermentation process with yeast strains. The agro-residues were subjected for steam pretreatment before enzymatic hydrolysis and compared with NaOH or H2SO4 pretreatments. Corn husk was found to be the best substrate for enzymatic hydrolysis for the production of fermentable sugars. The Saccharomyces cerevisiae and Candida tropicalis were employed individually or as co-culture for fermentation of the hydrolysate obtained after enzymatic breakdown of steam treated agro-residues. The maximum ethanol produced by utilizing enzymatic hydrolysate of the steam treated husk of corn as substrate by separate hydrolysis and fermentation were 20.61, 5.81 and 18.21 g L−1 respectively, whereas 20.66 and 5.85 g L−1 were acquired from the corresponding immobilized yeast cells after 72h of fermentation.

Production of bioethanol from sweet lime peel via a statistically optimized simultaneous saccharification and fermentation process using isolated enzymes

ABSTRACT The present study is to explore sweet lime peel and to investigate the possibility of isolation of enzymes for bioethanol production. Acid assisted steam pretreatment was employed for sweet lime peel as a pretreatment process in order to release more cellulose for hydrolysis. Cellulose content was increased from 25.4% to 34.8% by steam pretreatment. Cellulase and pectinase enzymes required for the hydrolysis of sweet lime peel were isolated from Aspergillus niger by solid-state fermentation. The activity of the in vitro produced cellulase and pectinase were 1.712 FPU/ml and 3.195 IU/ml, respectively. Simultaneous saccharification and fermentation of pretreated sweet lime peel was carried out using isolated cellulase and pectinase enzymes and Saccharomyces cerevisiae respectively. The optimization of process variables, time, pH and temperature on fermentation efficiency was also investigated using response surface methodology. The maximum fermentation efficiency of 71.73% was attained at pH 5°C and 37°C after 72 h of saccharification and fermentation.

Historical and pharmacological studies on rehmannia root processing– Trends in usage and comparison of the immunostimulatory effects of its products with or without steam processing and pretreatment with liquor

Ethnopharmacological relevanceThe dried root of Rehmannia glutinosa (RR) is a crude drug used in traditional Japanese Kampo medicine and traditional Chinese medicine (TCM). Sometimes, the crude drug is subjected to additional processing before use. Aim of the studyTo determine the effects of steam processing and pretreatment with liquor of RR through historical investigation, analytical chemistry, and pharmacological experiments. Materials and methodsWe inspected TCM literature from the Later Han Dynasty to the present day. Dried RR steamed for 3, 6, 9, or 12 h (steamed RRs, SRRs), dried RR soaked in yellow rice wine (liquor) (liquor-RR), and dried RR steamed for 6 h pretreated with liquor (liquor-SRR) were prepared. These samples were extracted using boiling water, and the inducible effects of the extracts on granulocyte colony-stimulating factor (G-CSF) secretion in cultured enterocytes and the content of their marker compounds were evaluated by using HPLC. ResultsThe effect of processing using both steaming and the pretreatment using liquor described in TCM literature over different eras was to enhance the warming effect and tonifying qi (energy) of RR. We found that SRR, processed by pretreatment with liquor, became mainstream since the Qing Dynasty. In SRR, stachyose content was decreased and fructose and manninotriose contents were increased with steaming time. However, the content of these compounds was not altered by pretreatment with liquor. RR extract induced G-CSF secretion in cultured enterocytes; moreover, the SRR extract steamed for more than 6 h had significantly stronger effects than that RR. Pretreatment with liquor did not cause any significant differences in the effects of RR or SRR. ConclusionsThe aim of processing for RR by both steaming and pretreatment with liquor in TCM literature over different eras was to enhance the tonifying effect on qi and its immunostimulatory effect. Although the effect of RR on the induction of G-CSF secretion in intestinal epithelial cells was enhanced by steaming, this enhancement was not enhanced by the pretreatment with liquor. These results provide scientific support for steaming, but could not elucidate a reason for pretreatment with liquor in TCM theory.