Warapa Mahakarnchanakul

Kasetsart University, Krung Thep, Bangkok, Thailand

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Publications (8)8.09 Total impact

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    ABSTRACT: Fusarium spp. are plant pathogens producing fumonisins and trichothecenes that both affect human and animal health. In the present study, 40 fungal strains were isolated and species identified from 35 shrimp feed samples and from 61 agricultural raw materials. F. verticillioides was the predominant species (85 %) mostly found in corn and soybean meal, while no Fusarium contamination was detected in shrimp feed. Levels of 10 % of F. oxysporum were isolated from peanut and 5 % of F. equiseti contamination in corn and peanut. To determine the ability of toxin production, enzyme-linked immunosorbent assay, polymerase chain reaction, and ultra-pressure liquid chromatography-tandem mass spectrometry were performed. All but four of the fumonisin-producing strains contained the FUM1 gene. No Fusarium synthesized T-2 toxin nor contained the Tri5 gene. This survey brings more data on mycotoxin contamination in the food chain of animal feed production, and leads to the awareness of the use of contaminated raw materials in shrimp farming.
    No preview · Article · Nov 2013 · Mycotoxin Research
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    Nampeung Anukul · Kanithaporn Vangnai · Warapa Mahakarnchanakul
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    ABSTRACT: Mycotoxins are the secondary metabolites produced from toxigenic fungi recognized as major food and feed contaminants. They are a source of grave concern in food contamination, resulting in mycotoxicosis in humans and animals. To date, many regulations on the allowable levels of each mycotoxin have been established in several countries. Consumers and food producers expect that toxin contamination in food and feed, based on government regulations and guideline levels, should have no adverse consequences on human and animal health. This review is an extension of the discussions during the international seminar entitled Risk Assessment and Risk Management of Mycotoxins for Food Safety in Asia, which was jointly organized by Kasetsart University (Thailand) and the Food and Fertilizer Technology Center for the Asian and Pacific Region (Taiwan) and held in Chonburi, Thailand, in September 2011. In this review, we discuss the recent findings on mycotoxins in food and feed, with emphasis on aflatoxins, fumonisins, ochratoxins, and zearalenone, as well as the national management programs that will supply a wider knowledge base for establishing appropriate control measures for mycotoxins in Asian countries. However, we believe that continuing support from national governments and regional communities is essential to encourage and fund activities that contribute to a reliable exposure risk assessment and risk management of mycotoxins in the region, and also to improve our understanding and practices in order to protect consumers from the health threat posed by mycotoxin contamination. Copyright
    Preview · Article · Sep 2013 · Journal of Food and Drug Analysis
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    ABSTRACT: Retarding browning and softening of fresh-cut mangosteen during storage under modified atmosphere packaging (MAP) by pretreatment with preservative dips was investigated. Mangosteens at stage 1 of maturity were peeled and immersed for 30 min in different mixed solutions including 2% sodium erythorbate + 0.2% calcium chloride (CaCl2), 1% aluminium sulfate + 1% sodium chloride (NaCl), 1% ascorbic acid (AA) + 1% NaCl + 1% CaCl2 and 1% citric acid + 1% NaCl + 1% CaCl2 prior to active MAP (5% O2 + 9% CO2) using low-density polyethylene bag. Quality changes of the fresh-cut mangosteens were monitored during storage at 4C for up to 12 days. The fruit treated with 1% AA + 1% NaCl + 1% CaCl2 exhibited the best quality of appearance and texture in terms of lightness, firmness, weight loss, exudation and sensory score during the storage. However, in-package atmospheric compositions of all treatments were similarly developed throughout the storage. Consumption of fresh-cut mangosteen has been increasing rapidly due to its unique lusciousness. However, discoloration and firmness loss of the product are crucial limiting factors to acceptability by consumers. Chemical treatment with the mixed solution of 1% ascorbic acid + 1% sodium chloride + 1% calcium chloride has high potential for practical applications due to its effectiveness in maintaining appearance and texture of the product. Furthermore, the use of inexpensive preservative results in reducing production cost.
    No preview · Article · Dec 2012 · Journal of Food Processing and Preservation
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    ABSTRACT: Pathogenic Vibrio parahaemolyticus in prawn has been a major cause of saefood-borne infection outbreaks. An understanding of its behavior in prawn helps ensure safety of the seafood consumption. The objective of this investigation was to understand the pathogenic V. parahaemolyticus behavior in non-sterile prawn in a laboratory and frozen food factory as responding to temperature. The behavior was observed in a laboratory. It was found that in the laboratory this pathogen grew in a temperature range of 15–44 °C but died in −20 to 10 °C. The primary Baranyi and modified Gompertz models excellently explained the pathogenic growth and death characteristics, respectively. The effects of temperature on the primary-model parameters were well described by the Kohler, Ratkowsky, asymptotic and non-linear Arrhenius models. The behavior of the pathogen was also observed in a freezing process line. The pathogen responded to temperature in a similar manner to that in the laboratory results although the actual line process involved more influencing factors. Therefore, the laboratory results of temperature effect on the pathogen behavior can provide a good guideline of safety for process design and control of the seafood. The response similarity was beneficial in the information usage of pathogen behavior in prawn which was satisfactorily interchangeable between these two environments.
    No preview · Article · Aug 2012 · Food Control
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    ABSTRACT: The ginger, galangal, turmeric, and fingerroot extracts were determined for their antimicrobial activities against foodborne pathogenic bacteria, spoilage bacteria and fungi by using agar dilution assay. Salmonella enterica serotype Typhimurium and Eschericia coli O157:H7 were resistant to ginger, galangal, turmeric, and fingerroot extracts. Minimal inhibitory concentrations (MICs) of ginger, galangal, turmeric and fingerroot extracts against those gram-negative bacteria were 8–10% (v/v). Fingerroot extract showed stronger inhibitory activity against Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus than ginger, turmeric, and galangal extracts. MICs of fingerroot extract was 0.2–0.4% (v/v). For the spoilage bacteria Lactobacillus plantarum and L. cellobiosus, galangal extract gave the most efficiency of with MIC at 4% (v/v). The results showed that fingerroot and ginger extracts had antifungal activity ranging from 8 to 10 and 10% (v/v) against Aspergillus flavus, A. niger, A. parasiticus and Fusarium oxysporum, respectively. Moreover, inhibition over time of E. coli O157:H7 was studied in TSB added with spice extracts at concentrations ranging from 8 to 10% (v/v). The 8% galangal and 10% fingerroot extracts showed bactericidal effect at 36 hours and 9 hours, respectively. While 8% turmeric extract showed bacteriostatic effect. In conclusion, rhizomatous spice extracts had antimicrobial effect against some spoilage and pathogenic microorganisms, thus it has potential to be used as natural preservative agents.
    Full-text · Article · Jan 2006
  • Chitsiri Thongson · P Michael Davidson · Warapa Mahakarnchanakul · Preeya Vibulsresth
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    ABSTRACT: The objective of this study was to determine the potential antimicrobial activity of extracts and essential oils of spices from Thailand against foodborne pathogenic bacteria. The antimicrobial efficacy of ginger (Zingiber officinale), fingerroot (Boesenbergia pandurata), and turmeric (Curcuma longa) was evaluated against five strains of Listeria monocytogenes and four strains of Salmonella enterica ssp. enterica serovar Typhimurium DT104. Antimicrobial activity was investigated in microbiological media by using an agar dilution assay and enumeration over time and a model food system, apple juice, by monitoring growth over time. In the agar dilution assay, water extracts of the three spices had no effect on L. monocytogenes. Similarly, 50% ethanol extracts of ginger or turmeric had no effect. In contrast, ethanolic fingerroot extracts at 5 to 10% (vol/ vol) inhibited most L. monocytogenes strains for 24 h in the agar dilution assay. Commercial essential oils (EO) of ginger or turmeric inhibited all L. monocytogenes at < or = 0.6 or < or = 10%, respectively. Fingerroot EO inhibited all strains at < or = 0.4%. In the enumeration-over-time assay, a 5% fingerroot ethanol extract reduced ca. 4 log CFU/ml Listeria by around 2 log in 24 h while 10% inactivated the microorganism in 9 h. Fingerroot EO at 0.2% inactivated 4 log CFU/ml L. monocytogenes in 6 to 9 h. Neither extracts nor commercial EO had any effect on Salmonella Typhimurium DT 104 with the exception of fingerroot EO, which inhibited all strains at < or = 0.7%. Addition of 0.2% fingerroot EO to apple juice reduced 4 log of L. monocytogenes Scott A and both strains of Salmonella Typhimurium to an undetectable level within 1 to 2 days. It was concluded that fingerroot EO and extract have potential for inhibiting pathogens in food systems.
    No preview · Article · Nov 2005 · Journal of food protection
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    C. Thongson · P.M. Davidson · W. Mahakarnchanakul · J. Weiss
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    ABSTRACT: Aims: The objective of this research was to determine the antimicrobial activity of conventional and high-intensity ultrasound-assisted (HI-US) solvent-extracted Thai spices, including ginger (Zingiber officinale Rose), fingerroot (Bosenbergia pandurata Holtt) and turmeric (Curouma longa Linn). Methods and Results: Extracts were obtained using hexane, isopropanol and a 7 : 3 isopropanol : hexane mixture as solvents with and without HI-US. The antimicrobial activity of the extracts was assayed against four strains each of Listeria monocytogenes and Salmonella Typhimurium DT 104 using an agar dilution assay. Application of HI-US did not alter antibacterial activity against S. Typhimurium, but antilisterial activity of some HI-US spice extracts decreased. Solvent type affected antimicrobial efficacy of extracts with hexane producing the least antimicrobial activity. Fingerroot extracted with isopropanol–hexane and without HI-US had the best antilisterial effect while HI-US–isopropanol fingerroot extract had the greatest antimicrobial efficacy against S. Typhimurium. Conclusions: Application of HI-US reduced time of extraction to 5 min, compared with the 24 h required for conventional extraction and maintained antimicrobial activity against Salmonella but slightly reduced activity against Listeria. Significance and Impact of the Study: HI-US in combination with proper solvent selection may offer a new tool to optimize extraction of spice essential oil for use as antimicrobial agents, and reduce processing time and costs.
    Full-text · Article · Sep 2004 · Letters in Applied Microbiology
  • E. Pattaratanawadee · C. Thongson · W. Mahakarnchanakul · P. Wanchaitanawong

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