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Dielectric constant-based optimization for sustainable extraction of centellosides from Centella asiatica using bio-based solvents
(2026-08-01)
Pakaweerachat, Pattarabhorn
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Chysirichote, Teerin
This study systematically examined the influence of solvent polarity and extraction temperature on the recovery of four major centellosides: madecassoside (MAD), asiaticoside (ASI), madecassic acid (MDA), and asiatic acid (ASA) from Centella asiatica. Extractions were performed using ethanol-water, acetone-water, ethanol-ethyl acetate, and hexane-ethyl acetate mixtures at 30–70 °C, covering dielectric constants (ε = 2–70) that correspond to the polarity range of the selected solvent systems. Extraction yields (mg g⁻¹) are expressed on a dry-weight basis. Ethanol–water mixtures demonstrated the highest efficiency for polar glycosides, yielding 19.6 ± 0.3 mg g⁻¹ dry matter (mg g⁻¹ DM) for MAD and 17.2 ± 0.3 mg g⁻¹ DM for ASI at 70 °C, with temperature effects mainly attributed to enhanced mass transfer and no significant thermal degradation observed. In contrast, aglycones (MDA and ASA) achieved optimal yields (3.3–6.5 mg g⁻¹) in solvents with lower dielectric constants, where solvent composition predominated over temperature effects. Solvent polarity, expressed in terms of dielectric constant, provided a quantitative indicator linking solvent selection to centelloside recovery and solvent-temperature interactions. Ethanol-water systems are recommended for food and nutraceutical applications, while ethyl acetate-ethanol mixtures are suited for cosmetic formulations. This work establishes a polarity-temperature framework for enhancing extraction using bio-based solvents, contributing to more sustainable production of bioactive-rich extracts from C. asiatica for use in food, cosmetic, and pharmaceutical industries.
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Comparative Evaluation of Culture Media and pH Conditions for Xylanase Production in Aspergillus niger
(2025-09-01)
Pakaweerachat, Pattarabhorn
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Chysirichote, Teerin
Xylanase plays a crucial role in the degradation of hemicellulose and holds significant promise across a variety of biotechnological industries. This study investigates the effects of culture medium composition and initial pH on xylanase production by Aspergillus niger. Five different media; Mandels’, Vogel’s, Marciel’s, Okafor’s, and a modified Czapek-Dox, were evaluated for their ability to support enzyme synthesis. Additionally, initial pH levels ranging from 4.0 to 8.0 were tested to identify optimal production conditions. Among the tested media, Mandels’ medium supported the highest xylanase activity, while the optimal pH range for enzyme production was between 6.0 and 7.0. These findings provide valuable insights for optimizing large-scale xylanase production using A. niger, contributing to the development of more efficient and cost-effective bioprocesses. Notably, this study incorporates biomass-specific productivity metrics (IU/g biomass), allowing for a more accurate evaluation of the strain’s enzymatic efficiency. This quantitative approach may help inform future efforts to develop cost-effective and scalable bioprocesses, particularly when applied to low-cost agro-industrial substrates.
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Effects of Broth pH and Chilling Storage on the Changes in Volatile Profiles of Boiled Chicken Flesh
(2024-09-01)
Pakaweerachat, Pattarabhorn
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Chysirichote, Teerin
This study investigated the changes in volatile compounds in chicken flesh after boiling at various pHs (6.0–9.0) and after chilling storage (4.0±1.0℃) for 7 d. The volatile compounds were assessed qualitatively and quantitatively by using a headspace gas chromatography-mass spectrometry analysis. Twenty-one volatile compounds were discovered and categorized as amine, aldehyde, alcohol, ketone, acid, and furan. One type of amine, (2-aziridinylethyl) amine, was the most prevalent volatile component, followed by aldehyde, ketone, aldehyde, acid, ester, and furan. The results showed that the quantity and quality of the volatile compounds were influenced by a pH of the boiling medium. Additionally, the types and volatile profiles of the chicken were altered during chilling. In particular, in the chicken that was boiled at a pH of 8.0, the hexanal (an aldehyde) content increased the most after 7 d of chilling. Moreover, various alcohols formed after the 7 d of chilling of the chicken that was boiled at pHs of 8.0 and 9.0. Because of the oxidation and degradation of fat and proteins, the most altering volatile compounds were the reducing amines and the increasing aldehydes.
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Valorization of tannin rich triphala waste for simultaneous tannase and gallic acid production under solid state fermentation by Aspergillus niger
(2023-01-01)
Pakaweerachat, Pattarabhorn
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Chysirichote, Teerin
This research aimed to study gallic acid production by the activity of tannase secreted by Aspergillus niger ATCC 16888 under solid-state fermentation using Triphala waste. Gallic acid is commonly extracted from Triphala using hot water. The residue contains a high number of hydrolyzable tannins. The parameters for the SSF were studied which included a nitrogen supplementary with an aeration supply. Results indicated that Triphala waste (TW) was a good substrate for valorization with tannase and gallic acid production by A. niger. When the fermentation was supplemented with 0.75% sodium nitrate that combination provided the highest biomass, tannase and gallic acid concentrations of 254.2± 15.4 mg g−1<inf>DS,</inf> 49.4 ± 2.0 U g−1<inf>DS</inf> and 13.3 mg g−1<inf>DS</inf>, respectively, while the aeration at 0.3 vvm (0.75% sodium nitrate supplementary) provided the highest biomass tannase and gallic productions of 445.0 ± 43.0 mg g−1<inf>DS</inf>, 53.3 ± 5.3 U g−1<inf>DS</inf> and 168.5 ± 5.0 mg g−1<inf>DS</inf>, respectively. The results indicated that the number of nitrogen atoms and the rate of aeration had significant parameters for tannase production. The carbon/nitrogen (C/N) ratio of the substrate correlated with tannase production of A. niger. The optimum C/N ratio of the substrate for tannase production was approximately 20.
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Simultaneous isoquercitin and gallic acid production of Aspergillus niger on Triphala byproduct under solid state fermentation in packed-bed bioreactor
(2023-01-01)
Pakaweerachat, Pattarabhorn
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Klinthong, Worasaung
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Ohtaguchi, Kazuhisa
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Chysirichote, Teerin
Triphala byproduct from hot-water extraction (TPB), which was a traditional process, was valorized by solid state fermentation in this research. Since the leftovers from the extraction contain high rutin and tannin contents, they were hydrolysable to isoquercitin and gallic acid, which were their monomers, respectively. Aspergillus niger, a producer of α-L-rhamnosidase and β-glucosidase, was cultured on the TPB to produce both isoquercitin and gallic acid, which were powerful antioxidants used in medical applications. The solid-state fermentation (SSF) was conducted in the three-layered packed-bed bioreactor aerated with humid air at different rates (0.1, 0.2 and 0.3 L/L/min or vvm). The highest isoquercitin and gallic acid production rates were found in the SSF, with 0.1 vvm at 1.14/h and 0.3 vvm at 3.12/h, respectively. The interaction of aeration rate and fermentation time significantly affected the fungal growth and the production of gallic acid, while the isoquercitin production was affected only by the fermentation time. Moreover, the differences of their production yields in different positions of bed along the height of bioreactor found to be useful to design the harvesting period of the fermentation products including isoquercitin or gallic acid or simultaneous isoquercitin and gallic acid. The results clearly showed that aeration, harvesting time, and position of the bioreactor were crucial in designing the process for isoquercitin, gallic acid, or both.

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