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During koji fermentation, macerating enzymes from koji molds (Aspergillus oryzae and A. sojae) soften cell wall of soybean and facilitate proteolytic enzymes to access their substrates, and hence high amount of proteinous materials are released from their matrix. In this study, wheat bran and soybean were used as substrate for seed koji cultivation and koji fermentation respectively. Enzyme activities in seed koji were far lower than that of koji. This was due to limited growth of koji molds in seed koji. However, correlation between these proteases and soluble protein release in koji was found. Moreover, pectinase also showed correlation with soluble protein release in koji. The results indicated that protease and pectinase activities were crucial for protein digestion. Lack of one of these enzymes led to low protein digestion ability of koji mold. Selection of koji starter culture would be more precise if pectinase as macerating enzyme was considered during the koji fermentation. Activities of these target enzymes in seed koji could be extrapolated to that of the koji, and were useful for screening and selection of koji starter culture.

The use of starter cultures ( Tetragenococcus halophilus TS71, Zygosaccharomyces rouxii A22, and Meyerozyma (Pichia) guilliermondii EM1Y52) in reduced-salt moromi fermentation was investigated. Reduced-salt moromi fermentation (12%NaCl) with starter cultures was monitored for changes of microbiological and biochemical properties including volatile flavor compounds (VFCs) and biogenic amines (BAs) during three months. The inoculation was done after one-month fermentation with two combinations: TS71 and A22 (L2); and TS71, A22 and EM1Y52 (L3). Controls were 12% salt (CL) and 18% salt traditional (CT) without inoculation. Total bacteria counts significantly increased (P

The correlation of physical and physicochemical characteristics of five different chitosan on their fat-binding capacities was studied using in vitro model of gastrointestinal conditions. Increasing molecular weight (Mw) and tap density of chitosan could significantly increase their fat-binding ability. Higher Mw chitosan (2100 and 890 kDa) show significantly higher fat binding capacity than 30 kDa. When tested at chitosan to fat 1:40, the ratio often used as dietary supplement, higher tap density chitosan showed an improved fat-binding capacity at around 2-fold increase. Interestingly, 2100 kDa high density (HD1P) could maintain the highest oil entrapment, ranging between 0.77 and 27.50 g oil/g chitosan depending on the interaction ratios. In addition, HD1P already maximized its fat-binding capacity since 30 min under in vitro gastric condition. In vitro cholesterol- and bile acids-binding experiments were also performed with HD1P and found to bind cholesterol at 820.9 ± 21.43 mg/g chitosan, deoxycholic acid at 17.50 ± 0.18 mg/g chitosan, and cholic acid at 5.28 ± 0.57 mg/g chitosan. Therefore, this study shows that the ability of HD1P for binding high amount of fat at short dissolution time might be due to the combination characteristics of having high Mw and being in a high density form.

Crude extracts of fresh Dendrobium Sonia ‘Earsakul’ orchid flowers (DSE) were prepared using microwave assisted extraction (MAE; using household microwave oven) and hot water extraction (HWE; at constant 80 °C). The obtained DSEs were measured their absorbance at λmax of 543 and 583 nm and determined their total monomeric anthocyanin contents (TAC). Mathematical models of MAE of Dendrobium Sonia ‘Earsakul’ orchid flower were constructed using response surface methodology - Box-Behnken design. Studied parameters included flower to water ratio, microwave power, and extraction time, with absorbance at λmax as response. The data generated were 1) visible spectrum (400–700 nm) of DSE; 2) absorbance values at λmax and 3) TAC of DSEs obtained from various extraction conditions of MAE and HWE; 4) linear equations describing correlations between TAC and absorbance at λmax of DSEs; and 5) mathematical models of MAE of Dendrobium Sonia ‘Earsakul’ orchid.

In this study, 34 yeast isolates were obtained from koji and moromi samples of Thai soy sauce fermentation. However, the most interesting yeast strain was isolated from the enriched 2 month-old (M2) moromi sample and identified as Meyerozyma (Pichia) guilliermondii EM2Y61. This strain is a salt-tolerant yeast that could tolerate up to 20% (w/v) NaCl and produce extracellular and cell-bound glutaminases. Interestingly, its glutaminases were more active in 18% (w/v) NaCl which is a salt concentration in moromi. The extracellular glutaminase's activity was found to be much higher than that of cell-bound glutaminase. The highest specific activity and stability of the extracellular glutaminase were found in 18% (w/v) NaCl at pH4.5 and 37°C. A challenge test by adding partially-purified extracellular glutaminase from M. guilliermondii EM2Y61 into 1 month-old (M1) moromi sample showed an increased conversion of L-glutamine to L-glutamic acid. This is the first report of glutaminase producing M. guilliermondii isolated from the moromi of Thai soy sauce fermentation. The results suggested the potential application of M. guilliermondii EM2Y61 as starter yeast culture to increase l-glutamic acid during soy sauce fermentation.

Recently more research attention has been given to glyoxal (GO) and methylglyoxal (MG) in relevant to their role in biological and food systems. In this study, pre-column derivatization using 5,6-diamino-2,4-hydroxypyrimidine sulfate (DDP) for fluorescence detection on HPLC was optimized for fish sauce matrix. DDP–GO and DDP–MG derivatives detected had fluorimetric wavelengths coincided with the spectral characteristics reported. Standard addition experiment showed that the detection method was free from interference and matrix effect with good recovery (90–115 %) and precision (less than 8 % RSD at 88–242 ng/mL). Limit of detection for GO and MG were 11.7 and 10.9 ng/mL respectively. Prolonged storage of the fish sauce sample under 4, 25, 40, and 60 °C showed that GO increased at 40 and 60 °C while MG increased at 25, 40, and 60 °C. The results also suggested possible role of molecular oxygen in these formations. Together with GO and MO, browning development and Strecker aldehydes were also monitored.

Sensory descriptive analysis was performed on 52 Thai fish sauce samples by 15 trained panelists, with an intention to explore the aroma profiles and to correlate with their total nitrogen (TN) contents, which is conventionally used as a general standard for commercial product grading. Thai fish sauce aroma characteristics could be exemplified through eight descriptive attributes. Sweet, meaty and cheesy odors presented overall characteristics of Thai fish sauce, while salty and anchovy-like odors were noticeably perceived due to their high intensity in fish sauce. Aroma intensity of three attributes including sour, shrimp paste-like and fishy odors could categorize Thai fish sauce samples into two groups, i.e., high-TN and low-TN groups. This categorization was also observed when rating scores of the intensity of these eight odor attributes were applied on principal component analysis (PCA). Moreover, total volatile basic-nitrogen and pH of the samples were applied on PCA to better explain the contribution of aroma attributes to fish sauce products. Practical Applications Thailand is a major producer of fish sauce; hence, varieties of product qualities are available in the market. Generally, the products are graded in accordance to its total nitrogen (TN) content. However, manufacturers could distinguish the product quality based on its aroma profile. On the other hand, prices of products are based on TN and their characteristic aroma that consumers can perceive. The finding in this study would be applicable to fish sauce quality standardization based on aroma profiles that are correlated to conventional TN grading, as well as conservation of product authenticity.

Fifteen Thai herbal teas in comparison with teas of Camellia sinensis, were studied for their antioxidants and anti-glycation properties in correlation with their total phenolics, flavonoids, and non-flavonoids contents. Significant differences were observed among the tea infusions. Only stevia and sappan herbal teas had primary antioxidants and anti-glycation capacities comparable to C. sinensis. However, purple velvet, mulberry and false mallow herbal teas were exceptionally stronger in metal chelating capacity than the C. sinensis teas. Principal component analysis showed that total phenolics, particularly flavonoids highly correlated with primary antioxidants and anti-glycation. Cluster analysis showed that the properties of stevia and sappan herbal teas were similar to green, black and oolong teas. Some common, but rarely mentioned, Thai herbal teas could be choices of interest for healthy beverages and could be new dietary sources for bioactive compounds.

Glycation of the thermostable α-amylase, KLE, from Bacillus subtilis occurred during incubation with maltodextrin at 95C. This was revealed by the release of 5-hydroxymethyl-2-furfuraldehyde from the acid hydrolysis of glycated KLE (gKLE), the differences in the protein band patterns on SDS and Native-PAGE, and the shifting of the pI value from the range of 5.6–6.5 to that of 5.2–6.5. After glycation, the activity of gKLE was still retained. Furthermore, gKLE was more resistant to heat and pH compared with the nonglycated enzyme. The Km, reaction rate and efficiency to convert gelatinized cornstarch into maltodextrin of KLE were remained unchanged after glycation. This was different from the result obtained for BAN, another thermostable α-amylase produced by B. amyloliquefaciens. Glycation in BAN decreased the activity in converting gelatinized cornstarch into maltodextrin. Moreover, the stability and kinetic parameters of BAN were found to be negatively affected by glycation. PRACTICAL APPLICATIONS One of the major applications of starch is for the production of glucose, either in a form of crystalline or syrup which can be further processed into high-fructose syrup. This is done by starch hydrolysis which is composed of two major enzymatic steps, i.e., liquefaction and saccharification. Liquefaction, converting gelatinized starch to maltodextrin, is carried out by the action of thermostable α-amylase, while saccharification is by glucoamylase. During the process under the conditions of high concentration of reducing sugar and high temperature, thermostable α-amylase can be glycated. This non-enzymatic process occurs when reducing sugar and free amino groups are coexisted in the system. However, the glycated enzyme was found to be more stable than the native form. Hence, industrial thermostable α-amylase with a suitable degree of glycation, can be more efficient in hydrolytic process.

BACKGROUND: Aroma of fragrant rice greatly affects palatability as well as consumer acceptability. Loss of desirable volatile compounds such as 2-acetyl-1-pyrroline (2-AP) and increase in volatile lipid oxidation products in aged rice have been reported. The aim of this study was to monitor the changes in key volatile compounds of organic red fragrant rice cv. Hom Daeng during storage. Effects of packaging material, storage temperature and time were evaluated using solid phase microextraction/gas chromatography/mass spectrometry. RESULTS: Thirteen key volatile compounds including ten lipid oxidation products were monitored. For samples vacuum packed in Nylon/LLDPE pouches at ambient temperature, significant increases in hexanal, 2-pentylfuran, 1-octanol and 4-vinyl guaiacol and significant decreases in 2-AP and geranyl acetone were found after the second month (P⩽0.05). Vacuum packing in OPP/Al/LLDPE pouches or storage at 15 °C better retarded the formation of volatile lipid oxidation products and greater retained desirable odorants, including 2-AP. However, accumulation of lipid oxidation products and 4-vinyl guaiacol was apparent after the sixth month under these storage conditions. CONCLUSION: A greater extent and higher rate of undesirable changes in volatile compounds were found in samples stored under Nylon/LLDPE/ambient temperature condition. Nevertheless, this condition is acceptable for the retail trade of organic rice in Thailand. Storage conditions using reduced temperature or better packaging materials may be more appropriate for exported rice or superior-grade fragrant rice to better maintain the desirable rice aroma. Copyright © 2010 Society of Chemical Industry

Organoleptic and chemical properties of fish sauce made experimentally from the four cold water fish species–Arctic capelin, Atlantic herring, Atlantic cod and blue whiting–were compared with three first grade commercial fish sauces made from tropical anchovies. Although the flavor of the fish sauces made from cold water species were judged as inferior to the flavor of the tropical fish sauces, the blue whiting and Atlantic herring sauces obtained fair ranking. Chemical analyses revealed that sugar had been added in all the three commercial sauces. Although sugar is added during blending just before bottling, flavor enhancing chemical reactions, between amino groups and reducing sugars, probably occur during storage of the final product. Accordingly, this procedure should be adapted also in preparation of fish sauce from cold water species.

Fish protein hydrolysate (FPH) was produced from fish soluble concentrate (FSC), a by-product from canned fish industry, by using Flavourzyme™ and Kojizyme™. Hydrolysis conditions were optimized by using a response surface methodology (RSM). The model equations were proposed with regard to the effects of temperature ( T ), time ( t ), and enzyme concentration ( E ) on the degree of hydrolysis (DH). The optimum values for Flavourzyme™ concentration, substrate concentration, temperature, and hydrolysis time were found to be 50 LAPU/g protein, 20% (w/w), 45 °C, and 6 h, respectively (LAPU; Leucine Aminopeptidase Unit). While those values for Kojizyme™ were 40 LAPU/g protein, 20% (w/w), 50 °C, and 6 h, respectively. Kojizyme™ enhanced the formation of some bitter-taste amino acids such as tryptophan during hydrolysis process whereas Flavourzyme™ did not. The spray-dried FPH produced with Flavourzyme™ contained high protein content (66%). The bitterness of FPH was less than that of 1 ppm caffeine solution.

The effect of glycation on properties of thermostable glucoamylase was studied by incubating purified glucoamylase with maltodextrin at 60 °C. Glycation occurred during the incubation and was assessed by 5-(hydroxymethyl)-2-furfuraldehyde (HMF) released from acid hydrolysis of the glycated protein. Stability and kinetic parameters of the glycated glucoamylase and the intact enzyme were compared. The glycated enzyme was more resistant to the heat but glycation did not strongly affect pH stability and pI value significantly. In the presence of maltose as substrate, the Km value of the glucoamylase glycated by maltodextrin was lower than that of the intact enzyme. This indicated a greater affinity of the glycated enzyme for maltose. In the presence of maltodextrin as substrate, glycation led to increases in the rate of hydrolytic reaction. Moreover, glycation resulted in a higher efficiency of glucoamylase to convert the substrate into glucose. This might be due to a greater conformational flexibility of the glycated glucoamylase.

Cyclodextrin (CD) is synthesized by bacterial cyclodextrin glycosyltransferase (CGTase) and is widely used in food, pharmaceutical, cosmetic, and agricultural industries. In this study, Bacillus circulans CGTase was partially purified by ammonium sulfate precipitation at 50-70% saturation. The optimum pH and temperature for CD production from sago starch were found to be in the ranges of 4.5-5.0 and 55-60 degrees C, respectively. beta-CD was the predominant product, constituting 65% of all CD products. The beta-CD produced using partially purified and crude CGTase were compared and found to have no significant difference in yield and productivity. The appropriate proportion of CGTase to sago starch for beta-CD production was determined by response surface methodology. The most appropriate enzyme:substrate ratio was 50 U g sago starch(-1) CGTase and 60 g l(-1) sago starch.

Dynamic headspace (DHS) sampling, direct solvent extraction (DSE) and vacuum simultaneous steam distillation–solvent extraction (V–SDE) were used for sample preparation in volatile compound analysis in Thai soy sauce. The extracts obtained from two brands were then analyzed by gas chromatography-mass spectrometry (GC–MS). A comparative study of volatile compounds obtained from these preparation techniques was performed. Some similarities were observed among different characteristic volatile profiles obtained from each preparation technique. Highly volatile compounds were detected only by DHS whereas DSE and V–SDE gave a wide spectrum of chemical classes of compounds detected. Moreover, differences of volatile compounds detected from both soy sauces were noted. This might be due to the differences of production process employed and strains of microorganism used.

Enzymatic browning reaction in food systems is due to oxidation of phenolic compounds by oxido-reductase enzymes, e.g. polyphenol oxidase or ortho -diphenol oxidase (EC 1.10.3.1), tyrosinase (EC 1.14.18.1), laccase or para -diphenol oxidase (EC 1.10.3.2), as well as peroxidase (EC 1.11.1.7). Since tyrosinase and laccase are prevalent among fungi, these enzymes might be responsible for enzymatic browning occurring in soy sauce and soybean paste. Diphenolic compounds, i.e. resorcinol, catechol, hydroquinone, guaiacol, and tyrosine, induced browning in soybean paste moromi. This browning was related to enzymatic browning, since heating at 100 °C for 10 min destroyed the activity due to these substrates. Moreover, enzymatic browning inhibitors, i.e. ascorbic acid, KI, NaCl, or Na 2 SO 3 , suppressed this browning. Since resorcinol, which is an inhibitor of ortho- diphenol oxidase, also gave high browning activity, this indicated that the enzyme involved might be a laccase-like enzyme ( para -diphenol oxidase) with a wide range of substrates. Moreover, such enzymatic activity was also detected in the culture of the mould used in the starter culture, i.e. Aspergillus oryzae MUTK. This activity also showed similar substrate specificity, as seen in the moromi. Supplementation of the soybean extract enhanced the enzyme activity in the cultured broth.

Moromi samples of traditional Thai soy sauce from two conventional manufacturers A and B were used to investigate the browning and chemical changes related to the Maillard reaction (i. e. reactive amino compound, soluble protein, 5% trichloroacetic acid precipitated protein, reducing sugar, and 5-hydroxymethyl-2-furaldehyde). The samples were collected at specific intervals during the 60-day process of moromi fermentation. The browning (OD 420 nm; y) was expressed as powered regression with fermentation time-course (day; x), y=0.5191 * x 0.2367 , r 2 =0.978 and y=0.6188 * x 0.1596 , r 2 =0.821 for moromi A and B, respectively. The browning rate was high at the first 3 days and declined in the later stage, while the accumulation of 5-hydroxy-2-furaldehyde, which is the Maillard reaction intermediate, increased linearly. The size of proteins and peptides observed on sodium dodecyl sulphate-polyacrylamide gel electrophoresis and the measurement of the ratio of 5 % trichloroacetic acid precipitated protein to total soluble protein (PP/SP). This PP/SP ratio showed the linear correlation to browning rate with r 2 =0.921 and 0.965 for moromi A and B, respectively. The results suggested that the rate of browning of the moromi fermentation did not entirely depend upon the Maillard reaction rate. It appeared that the browning is enhanced with the proper size of proteins and peptides.

The amino-carbonyl reaction (Maillard reaction), also known as glycation, of egg-yolk phosphatidylethanolamine (PE) was induced by incubating PE (50 mg/ml) with D-glucose (222 mM) in a methanol medium containing 2,6-ditert-butyl-p-cresol as an antioxidant at 37 degrees C for 4 days. The resultant product, glycated PE (gPE), was then isolated from the reaction mixture by two-step normal and reversed-phase high-performance liquid chromatography with UV diode array detection and was characterized as having a 1:1:1 elemental ratio of phosphorus:nitrogen:sugar. The Fourier transform-nuclear magnetic resonance spectrum and infrared absorbance spectrum indicate the isolated gPE to have been deoxy-D-fructosyl PE, which is an Amadori product of PE. The fast atom bombardmentmass spectrometric data for the glycation product of authentic dioleoyl PE (1,2-di-9-octadecenoyl-sn-glycero-3-phosphoethanolamine) show that the molecular weight of gPE corresponds to that of glucose-conjugated PE in the form of an Amadori product. This Amadori product formation was also confirmed in PE/phosphate buffer dispersions and in phosphatidylcholine-PE liposome/phosphate buffer suspensions in the presence of D-glucose at 37 degrees C. gPE was degraded by phospholipase A2, C and D. Freshly spiked blood plasma and red blood cells (RBC) from nomal human volunteers contained substantial levels of gPE, the concentration corresponding to at least 9 mol% of PE. Remarkable formation of gPE, up to 15-45 mol% of PE in human blood plasma and RBC, was further confirmed by prolonged incubation with 5-45 mM D-glucose. The gPE formation in RBC was found to be proportional to the glycated hemoglobin formation.

Forty-five mutant male ODS rats, unable to synthesize ascorbic acid, were fed nine diets containing 5, 50 or 250 mg of vitamin E/kg diet and 150, 300 or 900 mg of vitamin C/kg diet for 21 days. The concentrations of vitamins C and E increased in liver and plasma in relation to the level of these vitamins in the diet. Vitamin C dietary supplementation increased the plasma vitamin E content at low levels of vitamin E intake, supporting the concept of an in vivo synergism between both antioxidant vitamins. Vitamin C, at the dietary levels studied, did not affect the lipid peroxidation. Vitamin E decreased liver and plasma endogenous levels of thiobarbituric acid-reactive substances and liver sensitivity to non-enzymatic lipid peroxidation. This was confirmed by a highly specific assay of lipid hydroperoxides using high performance liquid chromatography with chemiluminescence detection. The hepatic concentration of both phosphatidylcholine and phosphatidylethanolamine hydroperoxides decreased as the vitamin E content of the diet increased. The results show for the first time the capacity of vitamin E to protest against peroxidation of major phospholipids in vivo under basal unstressed conditions.

Hydroperoxide formation during Maillard reaction (amino-carbonyl reaction) was investigated using luminol-chemiluminescence-high performance liquid chromatography (CL-HPLC). From the equimolar reaction mixture of 1 M beta-alanine/D-glucose in phosphate buffer (pH 8.0) at 95 degrees C, two hydroperoxides and H2O2 were detected as chemiluminescent products in CL-HPLC, and the yields were proportional to the browning development. One of these hydroperoxides was isolated and identified as 3-hydroxy-5-hydroperoxy-2-methyl-5,6-dihydropyran-4-one (HMDP, pyrone hydroperoxide) by fast atom bombardment mass spectrometry. The HMDP formation was also confirmed in L-lysine/D-glucose and in bovine serum albumin/D-glucose with the physiological incubation at 37 degrees C for 4 days and 3 wk, respectively. Incubation at 37 degrees C of human plasma containing 5.5-25.0 mM of D-glucose for 60 h showed the glucose concentration-dependent formation of HMDP (10-35 microM of H2O2 equivalence). The HMDP was negative to thiobarbituric acid reaction and was degraded by peroxidases such as horseradish peroxidase, Athromyces ramosus peroxidase, heated cytochrome c, and microperoxidase. The results strongly suggested the formation of such hydroperoxide even in biological Maillard reaction termed as glycation, and implied its contribution in pathogenesis and oxidative lesions associated with hyperglycemia.

The optimum conditions of high-performance liquid chromatography combined with luminol chemiluminescence detection were established for the determination of hydrogen peroxide at picomole levels using a cation-exchange gel column. The gel column with distilled water as the mobile phase allowed a good separation of H 2 O 2 without causing any irreversible binding of H 2 O 2 to the column surface. The detection limit and the quantification limit of H 2 O 2 were 4 and 6–600 pmol, respectively. The suitability of the present method was verified by the determination of H 2 O 2 present in coffee drinks.

Acrylamide in Thai curry cooked in coconut milk was investigated using ion trap LC-ESI-MS/MS. The transitions of m/z 72 > 55 and 86 > 58 were monitored in multiple reaction monitoring mode for identification and quantification. A linear response was found for the acrylamide standard in the range of 400–30,000 pg, with correlation coefficients (r) greater than 0.99. The limit of detection (s/n = 3) and limit of quantification (s/n = 9) were 400 and 1200 pg, respectively. Sample preparation was performed by means of solvent extraction, giving recovery of 92–108% with relative standard deviation less than 10%. Thirty Thai curry samples were analyzed and found acrylamide at concentration in the range of less than 60–606 ng/g dry weight. Acrylamide was formed in solely heated coconut milk at 121 °C. Changes in 5-(hydroxymethyl)-2-furfuraldehyde, fructose, glucose and glutamic acid contents in coconut milk during heat treatment were observed as progress parameters for the Maillard reaction. Moreover, acrylamide was determined in equimolar model system of glutamic acid with glucose or fructose (1 mM), and yielded acrylamide, approximately 0.1% and 0.06% (w/w), respectively.

The catalase gene katA of Lactobacillus sakei SR911 was cloned and expressed in Escherichia coli UM2 and Lactobacillus plantarum TISTR850 under strong lactococcal promoter P59 in E. coli-lactococcus expression vector pIL1020. The L. plantarum TISTR850 is a catalase-deficient strain isolated from local fermented meat product. The recombinant L. plantarum TISTR850 was shown to decompose hydrogen peroxide, and catalase activity approximately three times higher that of natural catalase-producing strain L. sakei SR911. The recombinant protein was also detected by in situ activity staining of the catalase enzyme. The recombinant L. plantarum TISTR850 did not accumulate hydrogen peroxide under glucose-limited aerobic conditions and remained viable after 60 h of incubation. The recombinant and host strain L. plantarum TISTR850 were used as starter cultures in the fermented meat product, and lipid oxidation was monitored over a 7-day storage at 20 degrees C determined as thiobarbituric acid-reactive substances (TBARS) value. The lipid oxidation level in the fermented meat product seeded with the catalase genetically modified starter culture L. plantarum TISTR850 was significantly lower than that of the natural catalase-deficient strain.

Numerous investigations on aroma characteristics of fish sauce in particular samples have been conducted extensively; however, the relation of those volatile aroma profiles and aroma characteristics to quality and categorization of the product have never been reported. This study explored the contribution of volatile aroma components on product quality categorization of 52 Thai fish sauce samples. First, odour-active compounds were investigated by dynamic headspace gas chromatography–olfactometry (GC-O) from eight selected samples with four different qualities, including mature–unblended samples, premium-grade samples, first-grade samples and second-grade samples. Eleven odour-active compounds, i.e. acetic acid, propanoic acid, 2-methylpropanoic acid, butanoic acid, 3-methylbutanoic acid, dimethyl trisulfide, 3-(methylthio)propanal, 1-octen-3-ol, 2-butanol, trimethylamine and n-propanol, contributed to the aroma characteristics of Thai fish sauce. A combination score was assigned to express the integration of flavour dilution on dynamic headspace dilution analysis and intensity of odour perceived on GC-O. The combination scores were analysed with principal component analysis to categorize these eight selected samples. Furthermore, these odour-active compounds detected as released volatile compounds from 52 fish sauce samples were applied for categorization of 52 samples. As a result, both combination scores and relative concentrations of these odour-active compounds could discriminate the fish sauce products according to their conventional grading which is based on total nitrogen of the sample. Copyright © 2011 John Wiley & Sons, Ltd.

This study describes the occurrence of 3-hydroxy-5-hydroperoxy-2-methyl-5,6-dihydropyran-4-one (HMDP) in plasma obtained from normal subjects and patients with type 2 diabetes. We have shown previously that HMDP is a novel hydrophilic hydroperoxide formed in the in vitro Maillard reaction that could be analyzed using ultrasensitive chemiluminescence detection-high-performance liquid chromatography (CL-HPLC). The HMDP concentration was 273+/-227 nmol/l in normal subjects and 656+/-535 nmol/l in patients with diabetes. The HMDP concentration was proportional to the plasma glucose concentration level (r=0.640; P

Solid-state fermented Thai rice wines (Ou) were analysed to determine their chemical components. Determined parameters were pH (4.5-5.5), protein (0.45-0.99 g/100g), ash (0.10-0.30 g/100g), total solid (1.72-14.34 g/100g), glucose (4.07-7.91 mg/ml) contents and volatile compounds. The ethanol concentration was in the range of 12.15 to 104.60 mg/ml. Profiles of volatile compounds were analysed by dynamic headspace coupled with gas chromatography mass spectrometry and gas chromatography olfactometry. The potent odours were alcoholic and solvent-like, sweet, fruity, buttery, and pungent aromas. The concentration in Ou of n-propanol, iso-butyl alcohol, iso-amyl alcohol, furfuryl alcohol, benzene ethanol, acetol, 2,3-butanediol, glycerol, ethyl lactate, acetoin, furfural, 5-methyl furfural, 5-hydroxymethyl-2-furfural, and acetic acid were also determined by a direct injection technique. From principal component analysis, Ou samples could be categorized into two groups based on the concentration of ethanol and their profiles of volatile compounds.

Background The carambola fruit fly, Bactrocera carambolae Drew & Hancock is a high profile key pest that is widely distributed in the southwestern ASEAN region. In addition, it has trans-continentally invaded Suriname, where it has been expanding east and southward since 1975. This fruit fly belongs to Bactrocera dorsalis species complex. The development and application of a genetic sexing strain (Salaya1) of B. dorsalis sensu stricto (s.s.) (Hendel) for the sterile insect technique (SIT) has improved the fruit fly control. However, matings between B. dorsalis s.s. and B. carambolae are incompatible, which hinder the application of the Salaya1 strain to control the carambola fruit fly. To solve this problem, we introduced genetic sexing components from the Salaya1 strain into the B. carambolae genome by interspecific hybridization. Results Morphological characteristics, mating competitiveness, male pheromone profiles, and genetic relationships revealed consistencies that helped to distinguish Salaya1 and B. carambolae strains. A Y-autosome translocation linking the dominant wild-type allele of white pupae gene and a free autosome carrying a recessive white pupae homologue from the Salaya1 strain were introgressed into the gene pool of B. carambolae. A panel of Y-pseudo-linked microsatellite loci of the Salaya1 strain served as markers for the introgression experiments. This resulted in a newly derived genetic sexing strain called Salaya5, with morphological characteristics corresponding to B. carambolae. The rectal gland pheromone profile of Salaya5 males also contained a distinctive component of B. carambolae. Microsatellite DNA analyses confirmed the close genetic relationships between the Salaya5 strain and wild B. carambolae populations. Further experiments showed that the sterile males of Salaya5 can compete with wild males for mating with wild females in field cage conditions. Conclusions Introgression of sex sorting components from the Salaya1 strain to a closely related B. carambolae strain generated a new genetic sexing strain, Salaya5. Morphology-based taxonomic characteristics, distinctive pheromone components, microsatellite DNA markers, genetic relationships, and mating competitiveness provided parental baseline data and validation tools for the new strain. The Salaya5 strain shows a close similarity with those features in the wild B. carambolae strain. In addition, mating competitiveness tests suggested that Salaya5 has a potential to be used in B. carambolae SIT programs based on male-only releases.