Suwimon Keeratipibul

Antimicrobial Activity of Lauric Arginate‐Coated Polylactic Acid Films against Listeria monocytogenes and Salmonella Typhimurium on Cooked Sliced Ham

UNLABELLED 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. PRACTICAL APPLICATION The effectiveness of an innovative antimicrobial LAE-coated PLA film against foodborne pathogens was demonstrated. Importantly, the application of the LAE to form the LAE-coated PLA film can be customized within current film manufacturing lines.

Microbiological evaluation of water during the 2011 flood crisis in Thailand

In 2011, a severe flood occurred in Thailand, covering nearly half the country in water for several months. The contamination of floodwater and subsequent contamination of water for human consumption could have potentially led to a widespread health crisis. However, to date, no study has been conducted to determine the safety of the waters used for human consumption in Thailand during the severe flood. Therefore, we conducted microbiological analysis of 4 kinds of water (floodwater, river water, tap water, and filtered tap water) collected from industrial and residential areas that were damaged due to flooding. Higher net levels of bacteria were found in water with a higher turbidity. No clear trend was observed in the pH value of all 4 water samples. The level of total bacterial contamination in the water samples was estimated by real-time quantitative polymerase chain reaction (PCR). Eleven of the 12 tap water samples and all of the filtered tap water samples had a total bacterial load that exceeded the Thai water quality standards. One of the tap water samples and one of the filtered tap water samples were found to be positive for Shigella sp., although none of the floodwater samples showed detectable levels of this pathogen as determined by PCR analysis. One of the samples of floodwater was also found to be positive for Leptospira sp., but none of the tap water or filtered tap water samples were positive. Most of the tap water samples and all filtered tap water samples were found to be contaminated with Vibrio cholerae. Bacterial contamination in water samples was also analyzed by denaturing gradient gel electrophoresis (DGGE) analysis. These results revealed that several microorganisms were transferred via floodwater to different areas in the central part of Thailand and cross-contaminated between floodwater and water for human consumption.

Factors influencing food safety management system adoption in Thai food‐manufacturing firms: Model development and testing

Purpose – The purpose of this paper is to investigate factors affecting the adoption of food‐safety management systems by Thai food‐manufacturing firms.Design/methodology/approach – The study employs a survey questionnaire using a sample of Thai food‐manufacturing firms. The three‐part questionnaire was mailed to managers performing food‐safety management activities in 480 firms. A total of 217 questionnaires were returned, with a response rate of 45.2 percent.Findings – The results of hypothesis testing indicated that the adoption of a food safety management system can be significantly predicted by: expected gain of social legitimacy; expected gain of economic competitiveness; perceived importance of external stakeholders (government, community, food safety organizations, and media); top management commitment to food safety; firm size and amount of export sales. It can also be predicted by the extent to which firms exchange food safety knowledge with other stakeholders.Practical implications – The result...

Enhancing gamma-aminobutyric acid content in germinated brown rice by repeated treatment of soaking and incubation

Gamma-aminobutyric acid (GABA), commonly produced by germination of brown rice grain, is a free amino acid which could help relieving or preventing non-communicable diseases in human. Several research works have been conducted on GABA production from germinated brown rice. However, the yielded GABA (10.1–69.2 mg/100 g germinated brown rice) was comparatively low; thus the amount was insufficient to be used as active ingredients in functional foods. The objective of this study was to explore alternative methods in order to gain higher yield of GABA. A new process of repeated soaking (in tap water at 35 °C, 3 h) and incubation (at 37 °C, 21 h) during germination was developed. The amount of GABA produced was highest at 116.88 ± 9.24 mg/100 g germinated brown rice (dry basis). However, an unpleasant odour was generated by some microorganisms during long germination. Lactic acid was applied at soaking step to overcome this problem; whereby 0.5% lactic acid solution (vol./vol.) could effectively control the microorganisms without impairing GABA producing ability and sensory qualities.

Application of the Chinese Steamed Bun Starter Dough (CSB‐SD) in Breadmaking

The application of Chinese steamed bun starter dough (CSB-SD) in breadmaking was investigated. The activation of CSB-SD to activate the growth of lactic acid bacteria (LAB) and to increase the number of yeast, prior to making bread, was conducted by mixing CSB-SD with wheat flour and water and then incubating for 24 h. Wheat flour was then substituted by this activated CSB-SD (aCSB-SD) at 10%, 30%, and 50% (w/w) to make bread. Dough and bread properties were studied comparing to the control (without aCSB-SD). From the farinograph results, a high aCSB-SD substitution level resulted in a less stability in dough with a higher degree of softening. Extensigraph results suggested that after aging, all the substituted dough yielded a greater resistance to extension with lower extensibility values than the control. Substitutions with 30% and 50% (w/w) aCSB-SD significantly increased the total CO(2) gas generation. Scanning electron microscopy SEM images of the 30% and 50% (w/w) substituted dough showed a well-developed gluten matrix. The 50% (w/w) substituted breads obtained a greater risen volume, finer crumb grain, and retained more softness after 5-d storage than the control. In addition, both the 30% and 50% (w/w) substituted breads showed a slightly increased mold stability, as compared to the 0% and 10% (w/w) substituted breads.

Establishment of a simple and rapid identification method for Listeria spp. by using high-resolution melting analysis, and its application in food industry.

Listeria monocytogenes is the causative bacteria of listeriosis, which has a higher mortality rate than that of other causes of food poisoning. Listeria spp., of which L. monocytogenes is a member, have been isolated from food and manufacturing environments. Several methods have been published for identifying Listeria spp.; however, many of the methods cannot identify newly categorized Listeria spp. Additionally, they are often not suitable for the food industry, owing to their complexity, cost, or time consumption. Recently, high-resolution melting analysis (HRMA), which exploits DNA-sequence differences, has received attention as a simple and quick genomic typing method. In the present study, a new method for the simple, rapid, and low-cost identification of Listeria spp. has been presented using the genes rarA and ldh as targets for HRMA. DNA sequences of 9 Listeria species were first compared, and polymorphisms were identified for each species for primer design. Species specificity of each HRM curve pattern was estimated using type strains of all the species. Among the 9 species, 7 were identified by HRMA using rarA gene, including 3 new species. The remaining 2 species were identified by HRMA of ldh gene. The newly developed HRMA method was then used to assess Listeria isolates from the food industry, and the method efficiency was compared to that of identification by 16S rDNA sequence analysis. The 2 methods were in coherence for 92.6% of the samples, demonstrating the high accuracy of HRMA. The time required for identifying Listeria spp. was substantially low, and the process was considerably simplified, providing a useful and precise method for processing multiple samples per day. Our newly developed method for identifying Listeria spp. is highly valuable; its use is not limited to the food industry, and it can be used for the isolates from the natural environment.

Managing Bioplastics Business Innovation in Start Up Phase

Fostering innovation in a mature company can often seem like a swim upstream—the needs of the existing business often overwhelm attempts to create something new. Mature companies understand that to compete today they need to innovate. But finding sources of innovation while still paying attention to the current business can be a struggle. Open innovation has played an important role to drive the new business in 21th century. Academic research commercialization may be challenged by the faculty members’ academic routines, institutional priorities, and faculty retention. In order to undertake applied research, university scientists must spend a certain amount of time each period to keep up with the latest scientific developments and absorb new ideas. Because almost all faculty members have teaching responsibilities, many of them fear that participation in the protection and commercialization of Intellectual Property Rights is time consuming. There are lots of basic researches focuses on polylactic acid (PLA), the most promising bioplastics, however that is still far behind the commercialization step. The close innovation system may take longer time to achieve excellence in its technology under fierce competition environment. This study illuminates the complexities and challenges involved in managing innovation toward specific results. These challenges seem to result, in part, from the multidisciplinary nature of R&D work, it associated with r isks, uncertainty and non-linear processes. One of the finding in this study is that many of the factors that drive innovative bioplastic industry are derived in collaboration with technology push and demand pull. The study’s findings contribute to our understanding of consumer attitudes towards ‘Green’ products such as bioplastics. Most critical in this respect is whether such products make economic sense for a company. This study may provide some guidelines to support development of a concrete direction for PLA under open innovation atmosphere.

Development of new multilocus variable number of tandem repeat analysis (MLVA) for Listeria innocua and its application in a food processing plant.

Listeria innocua is an important hygiene indicator bacterium in food industries because it behaves similar to Listeria monocytogenes, which is pathogenic to humans. PFGE is often used to characterize bacterial strains and to track contamination source. However, because PFGE is an expensive, complicated, time-consuming protocol, and poses difficulty in data sharing, development of a new typing method is necessary. MLVA is a technique that identifies bacterial strains on the basis of the number of tandem repeats present in the genome varies depending on the strains. MLVA has gained attention due to its high reproducibility and ease of data sharing. In this study, we developed a MLVA protocol to assess L. innocua and evaluated it by tracking the contamination source of L. innocua in an actual food manufacturing factory by typing the bacterial strains isolated from the factory. Three VNTR regions of the L. innocua genome were chosen for use in the MLVA. The number of repeat units in each VNTR region was calculated based on the results of PCR product analysis using capillary electrophoresis (CE). The calculated number of repetitions was compared with the results of the gene sequence analysis to demonstrate the accuracy of the CE repeat number analysis. The developed technique was evaluated using 60 L. innocua strains isolated from a food factory. These 60 strains were classified into 11 patterns using MLVA. Many of the strains were classified into ST-6, revealing that this MLVA strain type can contaminate each manufacturing process in the factory. The MLVA protocol developed in this study for L. innocua allowed rapid and easy analysis through the use of CE. This technique was found to be very useful in hygiene control in factories because it allowed us to track contamination sources and provided information regarding whether the bacteria were present in the factories.

Characterization and lipolytic activity of lactic acid bacteria isolated from Thai fermented meat

Twenty six strains of lactic acid bacteria (LAB) were isolated from Thai fermented meat products, including 7 samples of Nham (fermented pork), 7 Sai-krog-prieo (fermented sausage) and one Mum (fermented beef). The isolates were identified as Lactobacillus pentosus (5 isolates), Lactobacillus sp. (11 isolates), Pediococcus pentosaceus (5 isolates) and each isolate of Pediococcus lolii, Leuconostoc fallax, Weissella thailandensis, W. cibaria, and W. paramesenteroides based on their phenotypic characteristics and 16S rRNA gene sequence similarities (99.8-100 %). The isolates were primary screened for their lipolytic activity on agar plates. The rod-shaped isolates showed 0.031±0.030-0.938±0.127 U/ml of lipase activity in broth supplemented with Tween 20, Tween 40, Tween 60 or Tween 80. The isolate SS50-1 identified as Lactobacillus pentosus showed the highest activity in Tween 80 (0.938±0.127 U/ml). The coccal isolates showed lipase activity ranged from 0.029±0.006-1.090±0.033 U/ml when Tween 20, Tween 40, Tween 60 or Tween 80 was used as a substrate. The isolate SS48-4 identified as Pediococcus lolii showed the highest activity in Tween 80 (1.090±0.033 U/ml).

Development of Multiple-Locus Variable-Number Tandem-Repeat Analysis for Molecular Subtyping of Campylobacter jejuni by Using Capillary Electrophoresis

ABSTRACT Campylobacter jejuni is a common cause of the frequently reported food-borne diseases in developed and developing nations. This study describes the development of multiple-locus variable-number tandem-repeat (VNTR) analysis (MLVA) using capillary electrophoresis as a novel typing method for microbial source tracking and epidemiological investigation of C. jejuni. Among 36 tandem repeat loci detected by the Tandem Repeat Finder program, 7 VNTR loci were selected and used for characterizing 60 isolates recovered from chicken meat samples from retail shops, samples from chicken meat processing factory, and stool samples. The discrimination ability of MLVA was compared with that of multilocus sequence typing (MLST). MLVA (diversity index of 0.97 with 31 MLVA types) provided slightly higher discrimination than MLST (diversity index of 0.95 with 25 MLST types). The overall concordance between MLVA and MLST was estimated at 63% by adjusted Rand coefficient. MLVA predicted MLST type better than MLST predicted MLVA type, as reflected by Wallace coefficient (Wallace coefficient for MLVA to MLST versus MLST to MLVA, 86% versus 51%). MLVA is a useful tool and can be used for effective monitoring of C. jejuni and investigation of epidemics caused by C. jejuni.