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Kittipongpittaya K.,University of Massachusetts Amherst | Panya A.,Food Biotechnology Research Unit | McClements D.J.,University of Massachusetts Amherst | Decker E.A.,University of Massachusetts Amherst
JAOCS, Journal of the American Oil Chemists' Society | Year: 2014

Association colloids such as phospholipid reverse micelles could increase the rate of lipid oxidation in bulk oils. In addition to phospholipids, other surface active minor components in commercial oils such as free fatty acids may impact lipid oxidation rates and the physical properties of reverse micelles. In this study, the effects of free fatty acids on changes in the critical micelle concentration (CMC) of 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) in stripped corn oil (SCO) were determined by using the 7,7,8,8- tetracyanoquinodimethane solubilization technique. Different free fatty acids including myristoleic, oleic, elaidic, linoleic and eicosenoic were added at 0.5 % by wt along with the DOPC into the bulk oils. There was no significant effect of free fatty acids with different chain length, configuration and number of double bonds on the CMC value for DOPC in bulk oil. However, increasing concentrations of oleic acid (0.5 to 5 % by wt) caused the CMC value for DOPC in bulk oils to increase from 400 to 1,000 μmol/kg oil. Physical properties of DOPC reverse micelles in the presence of free fatty acids in bulk oils were also investigated by the small angle X-ray scattering technique. Results showed that free fatty acids could impact on the reverse micelle structure of DOPC in bulk oils. Moreover, free fatty acid decreased pH inside reverse micelle as confirmed by the NMR studies. The oxidation studies done by monitoring the lipid hydroperoxide and hexanal formation revealed that free fatty acids exhibited pro-oxidative activity in the presence and absence of DOPC. Different types of free fatty acids had similar pro-oxidative activity in bulk oil. © 2013 AOCS.

Theinsathid P.,Chulalongkorn University | Visessanguan W.,Food Biotechnology Research Unit | Kruenate J.,Metal and Materials Technology Center | Kingcha Y.,Chulalongkorn University | Keeratipibul S.,Chulalongkorn University
Journal of Food Science | Year: 2012

A novel type of environmentally friendly packaging with antibacterial activity was developed from lauric arginate (LAE)-coating of polylactic acid (PLA) films after surface activation using a corona discharge. Scanning electron microscopy (SEM)-based analysis of the LAE/PLA films confirmed the successful coating of LAE on the PLA surface. The mechanical properties of the LAE/PLA films with different levels of LAE-coating (0% to 2.6%[w/w]) were essentially the same as those of the neat PLA film. The antibacterial activity of the LAE/PLA films against Listeria monocytogenes and Salmonella enterica Serovar Typhimurium (S. Typhimurium) was confirmed by a qualitative modified agar diffusion assay and quantitative JIS Z 2801:2000 method. Using the LAE/PLA film as a food-contact antimicrobial packaging for cooked cured ham, as a model system, suggested a potential application to inhibit L. monocytogenes and S. Typhimurium on ham with a 0.07% (w/w) LAE coating on the PLA when high transparency is required, as evidenced from the 2 to 3 log CFU/tested film lower pathogen growth after 7 d storage but even greater antibacterial activity is obtained with a LAE coating level of 2.6% (w/w) but at the cost of a reduced transparency of the finished product. This article shows how we can simply develop functional green packaging of PLA for food with effective and efficient antimicrobial activity by use of LAE coating on the surface via corona discharge. © 2012 Institute of Food Technologists ®.

Namwong S.,Suan Sunandha Rajabhat University | Tanasupawat S.,Chulalongkorn University | Benjakul S.,Prince of Songkla University | Kudo T.,RIKEN | And 2 more authors.
Malaysian Journal of Microbiology | Year: 2014

The research was carried out to study the isolation, identification of protease-producing halophilic strains and investigation of hydrolysis of various anchovy muscle proteins by a halophilic protease from strain SR5-3. Methodology and results: Seven protease-producing halophilic strains were isolated from Thai fermented food. On the basis of phenotypic and chemotaxonomic characteristics including high DNA-DNA relatedness (70.0-77.3%), six strains were identified as Virgibacillus halodenitrificans and a halophilic bacterium, the highest protease producer, SR5- 3, was named as Halobacillus. The hydrolysis of different fish proteins by a halophilic protease from strain SR5-3 was determined. The halophilic protease completely digested fish collagen and myosin heavy chain (MHC), but partially hydrolysed actin. In order to study the effect of NaCl on proteolytic activity, the degree of hydrolysis of purified protease and commercial proteases towards anchovy protein powder was compared. The halophilic protease showed a greater degree of hydrolysis towards anchovy substrate than that from commercial proteases in the presence of 25% NaCl. Conclusion, significance and impact study: This study revealed that six V. halodenitrificans strains and a Halobacillus strain SR5-3 secreted halophilic proteases. Upon digestion of fish protein, a halophilic protease showed higher protease activity and stability in heavily NaCl concentration, suggesting its potential application in acceleration of fish sauce production.

Panya A.,Food Biotechnology Research Unit | Temthawee W.,Food Biotechnology Research Unit | Temthawee W.,Mahidol University | Phonsatta N.,Mahidol University | And 5 more authors.
Journal of Agricultural and Food Chemistry | Year: 2015

Development of an antioxidant assay explaining antioxidant behaviors in complex food systems has been a challenging topic for food scientists. This research aimed to investigate antioxidant capacities and interactions of selected synthetic antioxidants and commercial natural antioxidant extracts using the CAT assay and a newly developed ApoCAT assay, which used water- and lipid-soluble azo radical initiators, respectively. Results suggested that the higher the hydrophobicity of an antioxidant, the higher the antioxidant capacity of an antioxidant observed in the ApoCAT assay. The relationship between the two different assays was explained by the ratio between the ApoCAT and the CAT values. Interestingly, all lipophilic derivatives of the antioxidants exhibited higher ApoCAT/CAT ratios than their hydrophilic derivatives. In the case of the commercial food-grade antioxidants, green tea extract and mixed tocopherols showed a higher antioxidant capacity in the ApoCAT assay than in the CAT assay, while grape seed and rosemary extracts did not show significantly different changes in behaviors in both assays. The study on antioxidant interactions revealed that additive, synergistic, and antagonistic effects between hydrophilic antioxidants and natural extracts, and mixed tocopherols could be observed in both the CAT and the ApoCAT assays, depending on the combined ratios. In most cases, at a particular ratio, the synergistic effect reached the maximum level before suddenly dropping to additive and antagonistic effects in both assays. © 2015 American Chemical Society.

Sitdhipol J.,Chulalongkorn University | Tanasupawat S.,Chulalongkorn University | Tepkasikul P.,Food Biotechnology Research Unit | Yukphan P.,National Center for Genetic Engineering and Biotechnology | And 4 more authors.
Annals of Microbiology | Year: 2013

Forty-one tetrad-forming halophilic lactic acid bacteria were isolated from 7 kinds of fermented foods in Thailand. All the isolates were identified as the genus Tetragenococcus by their phenotypic characteristics. On the basis of 16S rRNA gene restriction analysis using MboI and AluI and 16S rRNA gene sequence analyses, 41 isolates could be divided into two groups (groups A and B). All 22 isolates in Group A were identified as T. halophilus. 16S rRNA gene sequences of the representative isolates, SP37-2 and KS87-1 exhibited 99.4-99.5 % similarity to that of T. halophilus ATCC 33315T. Nineteen isolates in Group B were identified as T. muriaticus. 16S rRNA gene sequences of the representative isolates, KM1-5 and KS87-14, showed 99.0-99.6 % similarity to that of T. muriaticus JCM 10006T. Histamine formation was determined by using HPLC and the histidine decarboxylase (hdc) gene of the newly isolated histamine-producing strain was partially sequenced. The strain KS87-14 prolifically formed histamine 10 times higher than the reported T. muriaticus JCM 10006T. The positive detection of KS87-14 was achieved by using hdcA gene-specific primers JV16HC and JV17HC. © 2012 Springer-Verlag and the University of Milan.

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