Production and Characterization of Heme Iron Polypeptide from the Blood of Skipjack Tuna (Katsuwonus pelamis) Using Enzymatic Hydrolysis for Food Supplement Application.

Organic heme iron in the form of heme iron polypeptide (HIP) is a bioavailable form of iron that can be used for dietary supplements. However, one practical challenge with HIP is that the quality of HIP prepared with different batches of raw material could lead to HIP products with inconsistent characteristics. In this study, skipjack tuna blood, a by-product in canned tuna industry, was converted to HIP at different degrees of enzymatic hydrolysis. The variation in HIP physical-chemical characteristics from different batches was evaluated, including composition, solubility, and molecular weight distribution. It was found that the batch variation had no effect on HIP composition and solubility; however, the degree of hydrolysis (DH) and the size of peptides that interact with heme greatly influenced HIP solubility at pH 2. Tuna-HIP with a low DH (DH, 8%) had 1.76-fold greater solubility than tuna-HIP with a high DH (DH, 32%). High-performance liquid chromatography (HPLC) revealed that tuna-HIP with a low DH had a molecular weight ranging from 1 kDa to 5 kDa. In summary, HIP-derived tuna blood was found to contain 70.54 ± 3.22 mg/100 g of iron and exhibit good solubility at 58.0 ± 2.16% at pH 2. Thus, tuna-HIP with a low DH might be a suitable functional ingredient for iron fortification of food.

Data of microwave assisted extraction and conventional hot water extraction of Dendrobium Sonia 'Earsakul' orchid flower.

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.

Glutaminase-producing Meyerozyma (Pichia) guilliermondii isolated from Thai soy sauce fermentation.

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.

Development of a genetic sexing strain in Bactrocera carambolae (Diptera: Tephritidae) by introgression of sex sorting components from B. dorsalis, Salaya1 strain.

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.

Co-culturing of Pichia guilliermondii enhanced volatile flavor compound formation by Zygosaccharomyces rouxii in the model system of Thai soy sauce fermentation.

The roles of salt-tolerant yeasts such as Zygosaccharomyces rouxii, Candida versatilis, and Candida etchellsii in the production of volatile flavor compounds (VFCs) in soy sauce fermentation have been well documented. However, the knowledge of VFC production by other salt-tolerant yeasts is still limited. In this work, the roles of Z. rouxii and Pichia guilliermondii strains in VFC production were investigated in moromi medium as a model system for soy sauce fermentation. Inoculation of a single culture of either Z. rouxii or P. guilliermondii as well as co-cultures of these two yeasts into moromi medium showed increased numbers of viable yeast at around 0.7 to 1.9 log CFU/mL after 7days of cultivation at 30°C. During cultivation, both single and co-cultures displayed survival over a 7-day time period, compared with the controls (no culture added). Overall, yeast inoculation enhanced the production of VFCs in the moromi media with higher amounts of ethanol, alcohols, furanones, esters, aldehyde, acid, pyrone and phenols, known as important characteristic flavor compounds in soy sauce. Moreover, the co-culture produced more alcohols, furanones, esters, maltol and benzoic acid than the single culture of Z. rouxii.

Changes in volatile aroma compounds of organic fragrant rice during storage under different conditions.

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< or =0.05). Vacuum packing in OPP/Al/LLDPE pouches or storage at 15 degrees 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.

Investigation of acrylamide in curries made from coconut milk.

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 degrees 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 (1mM), and yielded acrylamide, approximately 0.1% and 0.06% (w/w), respectively.

Optimization of cyclodextrin production from sago starch.

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.

The occurrence of a novel hydrophilic hydroperoxide, 3-hydroxy-5-hydroperoxy-2-methyl-5,6-dihydropyran-4-one, as a reactive glycation product in human plasma.

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<0.01) but not with the glycated hemoglobin level. To investigate the in vivo effects of HMDP, a range of concentrations of the compound was incubated for different time periods with human serum albumin and lipoproteins. HMDP was found to induce denaturation of these macromolecules by modifying lysine residues and causing cross-linking and polymerization of proteins. In the presence of metal ions such as iron and copper, HMDP induced peroxidative degradation of lipoprotein lipids as measured by an elevation in thiobarbituric acid reactive substances (TBARS) concentration. These results suggested that HMDP is produced as a consequence of both hyperglycemia and increased oxidative stress, and may have the potential to contribute to the pathogenesis of arterial complications in diabetes mellitus.