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Impact of temperature on gluconic acid production during acetification by Acetobacter aceti
(2023-06-01)
Sriphochanart, Wiramsri
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Krusong, Warawut
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Mekkerdchoo, Orachon
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Suwapanich, Rachit
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Sriprom, Pongsert
The current approach to gluconic acid production is acetification at 30°C, a temperature that can be difficult to maintain in tropical countries. This study investigated the production of gluconic acid during acetification by Acetobacter aceti WK at high temperatures. An acid-tolerant and thermotolerant species, A. aceti WK, was used for acetification at three different temperatures, namely, 30°C (normal temperature), 37°C, and 40°C (high temperature). Acetification was performed in a 100 L bioreactor with 0.15% CaCl<inf>2</inf> for protection of the cells against high temperatures. The production of the organic acids, that is, acetic acid, gluconic acid, 2-keto gluconic acid, glucuronic acid, citric acid, succinic acid, lactic acid, and formic acid, was analyzed. Under acetification in the target total concentration of 80 g/L, the highest acetic acid content (39.3 g/L) was obtained at 37°C with an acetification rate of 0.3013 g/L/h, while the acetic acid content and acetification rate achieved at 30°C were 31 g/L and 0.3089 g/L/h, respectively. Additionally, gluconic acid presented at the highest concentration of 2.17 g/L. The rate of production of gluconic acid was 0.0169 g/L/h at 37°C. This acetification process at 37°C will be valuable as an alternative source for gluconic acid production for commercial applications.
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Application of baby corn husk as a biological sustainable feedstock for the production of cellulase and xylanase by Lentinus squarrosulus Mont.
(2023-02-01)
Vichitraka, Asanee
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Somboon, Pichayada
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Tantratian, Sumate
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Onmankhong, Jiraporn
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Sirisomboon, Panmanas
In an effort to use baby corn husk (BCH) as a sustainable feedstock for cellulase and xylanase production by the Lentinus squarrosulus Mont. isolate LS-YA (LSM-LS-YA), a suitable pretreatment method and fermentation strategies were developed. BCH pretreated with 1 M sodium hydroxide for 90 min, an alkaline pretreatment, exemplified an appropriate pretreatment method. In a 10-L external Venturi injector bioreactor, the highest cellulase and xylanase production was 4.12 ± 0.36 unit/mL and 6.15 ± 0.36 unit/mL, respectively, when 1 g/L diammonium hydrogen phosphate was used as the nitrogen source and the aeration rate was controlled at 0.2 vvm. This study provides an informative perspective on the production of cellulase and xylanase from agricultural lignocellulosic materials, which could reduce agricultural waste while supporting a zero-waste circular economy, and this fermentation process would be applicable to larger-scale production.
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Combination of Syzygium cumini (L) Skeels seed extract with acetic acid to control Escherichia coli on mint (Mentha cordifolia opiz.) leaves
(2022-07-15)
Tantratian, Sumate
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Krusong, Warawut
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Siriwetwut, Orawan
Four extraction methods were applied to extract phenolic compounds from Syzygium cumini seeds (SCS) with 50% ethanol solution. The microwave-assisted extraction provided the extract with highest yield and highest total phenolic and total flavonoid concentration which followed by ultrasonic-assisted extraction. The high-temperature and ambient extractions with a shaker provided no difference (p ≥ 0.05) in phenolic and flavonoid content. The HPLC analysis of SCS extracts illustrated gallic acid as the main component. The extract demonstrated a bactericidal effect against Escherichia coli at 6.25 mg ml−1. Mint leaves were found to carry high number of total viable count (TVC) and E. coli. The leaves soaked in acetic acid (AA) demonstrated a reduction of microbial number, but dark spot defect was found. Soaking in the mixture of 4.68 mg ml−1 SCS extract and 0.39 mg ml−1 AA caused the number of TVC and E. coli to reduce by 1.8 and 1.3 log<inf>10</inf> CFUg−1, respectively, while black spot was not detected. Nine day storage leaves showed satisfactory level of microbial quality and fresh-liked appearance. This demonstrated the potential application of SCS extract with AA as a synthetic substitute for microbial control on fresh leaf vegetables.
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Determination of antifungal volatile organic compounds of upland rice vinegar and their inhibition effects on Aspergillus flavus in dried chili pepper
(2022-04-01)
Pothimon, Ruttipron
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Krusong, Warawut
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Daetae, Pawinee
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Tantratian, Sumate
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Gullo, Maria
Determination of volatile organic components (VOC) produced in high acid upland rice vinegar was conducted using GC-MS. Acetic acid and ethyl acetate at 9.11% and 2.69% (v/v), respectively, were major VOC found in the vinegar while the others were isobutyl acetate, isobutyl alcohol, isoamyl acetate, isoamyl alcohol, phenethyl acetate and phenethyl alcohol. Subsequently, vinegar and VOC were tested, in vitro, for their inhibition on conidia germination of 103 conidia/mL of Aspergillus flavus. The exposure with 10% (v/v) of vapor-phase vinegar and pure acetic acid completely inhibited the germination of conidia with 30 min exposure, while VOC mixture of 9.11% (v/v) acetic acid, 0.08% (v/v) isoamyl alcohol, 0.45% (v/v) phenethyl alcohol and 0.01% (v/v) isobutyl alcohol with 45 min exposure could achieve the same target. Then, vinegar vapor was tested on the inhibition of conidia germination and aflatoxin production of A. flavus during 90 d subsequent storage of dried chili pepper. Complete inhibition of conidia germination and aflatoxin production were achieved with the 40 min exposure of 1.04 ± 0.03 mmol/L of vaporized vinegar. Our results showed that fumigation of upland rice vinegar containing antifungal VOC is a simple and an economical method for commercial preservation of dried chili pepper. Upland rice vinegar is a novel bio-fumigant for prevention of mycotoxin production in dried food and feed products during storage.
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Phenolic enrichment of Ma-Kieng seed extract using absorbent and this enriched extract application for safety control of fresh-cut cantaloupe
(2019-06-01)
Tantratian, Sumate
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Balmuang, Nunthanics
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Krusong, Warawut
The study aimed to investigate the antimicrobial effects of the Ma-kieng seed extract after treatments with different absorbents and the application on inhibition of microbial contaminants on fresh-cut cantaloupe. The phenolic compounds of MKSE were absorbed and desorbed with Diaion® HP-2MG, polyvinyl-polypyrrolidone and powdered activated carbon. The HPLC analysis of treated products showed the increase in flavonoid content except the treatment with powdered activated carbon, increased in phenolic content. All phenolic enriched extract showed increasing in antimicrobial activity efficacy. The phenolic compounds enriched extract with Diaion® and powdered activated carbon demonstrated the improvement in antimicrobial efficacy up to 4 times. Soaking in the 1 MBC equivalent of enriched extract solution for 2 min was able to reduce 1 log CFUg−1 of the spiked bacteria from the surface of fresh-cut cantaloupe and to control the number of tested bacteria during cold storage.
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Prediction of influence of stepwise increment of initial acetic acid concentration in charging medium on acetification rate of semi-continuous process by artificial neural network
(2014-01-01)
Krusong, Warawut
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Pornpukdeewatana, Soisuda
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Kerdpiboon, Soraya
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Tantratian, Sumate
Based on industrial vinegar production, ethanol concentration in charging medium is normally considered as a strong variable influencing the acetification for a given initial acetic acid concentration. Moreover, high initial acetic acid concentration is considered when higher than 100 g L-1 of acetic acid as finished product is obtained. This study assessed the effect of a stepwise increment of initial acetic acid concentration in fermentation medium of 45, 55, and 65 g L-1 after charging at constant ethanol concentration of 35 g L-1 on acetification rate (ETA) by high acid-tolerant strain of Acetobacter aceti WK. Average ETA was 8.144 + 0.09 g L-1 d-1 at 45 g L-1 and 8.655 + 0.09 g L-1 d-1 at 55 g L-1, and significant decreased to 6.819 + 0.23 g L-1 d-1 at 65 g L-1. An artificial neural network (ANN) model was applied to predict the ETA in semi-continuous acetification under the conditions of the study. The optimized ANN structure was revealed to contain two hidden layers and seven neurons per layer. The experimental acetification correlated to the predicted data with R2 of training and testing data set of 0.858 and validation data set of 0.831, respectively. Results indicated that the inputs as acetic acid and ethanol concentrations successfully predicted the ETA of semi-continuous acetification process. © 2013 Elsevier Ltd.

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