Histamine is the main causative agent of scombroid fish poisoning (SFP). To prevent SFP outbreaks, methods for controlling histamine accumulation have been studied. Histamine accumulation in raw fish, including frozen and semi-dried fish products, can be prevented by employing Hazard Analysis and Critical Control Point (HACCP) and Good Agricultural Practices (GAP). However, there is little information about histamine producers and the methods for preventing histamine accumulation in fermented fishery products in Japan. In 2011, CODEX adopted a limit of 400 ppm for histamine content in fish sauce, indicating that many manufacturers of fermented fish products are required to implement appropriate countermeasures. Presented here is recent information about histamine-producing bacteria in fermented fish products.
Sensory properties, i.e., firmness, sugar contents, and color, were evaluated for Fuji apples and Niitaka pears irradiated with gamma rays, electrons, or X-rays. The sugar contents in Fuji apples and Niitaka pears were not changed by the three types of radiation. The change in the Hunter's value for radiation doses between 200 and 1,000 Gy was similar for all sources. Although the firmness of the samples decreased remarkably by the phytosanitary irradiation process at doses above 600 Gy, there were no significant differences in this response among the radiation sources. This study identified the applicability of X-ray irradiation as a phytosanitary treatment based on comparisons with gamma-ray and electron-beam irradiation. The effect of X-ray irradiation was similar to that of gamma-ray and electron-beam irradiation with respect to the quality of Fuji apples and Niitaka pears.
The objective of this study was to extract the oil from Camellia oleifera seeds by aqueous enzymatic oil extraction (AEOE). A novel process for extraction of oil using industrial enzymes from microwave puffing-pretreated Camellia oleifera seed powder was described. The results indicated that the free oil extraction efficiency obtained with microwave-assisted extraction was very high, which the recovery yield was up to 55% (dry weight of Camellia oleifera seed). Besides, microwave pretreatment of Camellia oleifera seed increased the tocopherols (by 22.2% – 39.4%), squalene(by 6.3% – 29.2%) and phytosterols (by 6.7% – 14.8%) of the oils extracted by AEOE. Moreover, a very low acid value and peroxide value of oil superior to those of oils obtained by previous works was obtained. From the obtained results, this novel process may prove to be an environment-friendly alternative to solvent extraction.
The extraction, purification, preliminary characterization and antioxidant activity of glycoproteins from Sepia pharaonis muscle (SPMG) were investigated. The optimal extraction conditions were obtained using a Box-Behnken design. The crude SPMG was purified by DEAE-Cellulose 52 ion-exchange and Sephadex G-100 gel chromatography and two fractions (SPMG-I and SPMG-II) were obtained. SPMG-I and SPMG-II were rich in Glu, Asp, Leu, Arg and Lys with the molecular weight of 42.5 and 36.3 kDa, respectively. The glucose was the predominant monosaccharide composition of SPMG-I and SPMG-II. The existence of O-glycosidic linkage in SPMG-I and SPMG-II was demonstrated by a β-elimination reaction. SPMG-I and SPMG-II were characterized by FT-IR. SPMG, SPMG-I and SPMG-II showed excellent antioxidant activities and SPMG-I exhibited the highest antioxidant ability. These may provide theoretical basis for further system research and rational development and utilization of SPMG resource.
A rapid pretreatment-free immunochromatographic assay (ICA) was developed for the screen of Escherichia coli O157:H7 (E. coli O157:H7) in bovine milk. Anti-E. coli O157:H7 immunoglobins of yolk (IgY) was conjugated with a core/shell-structured super-paramagnetic Fe3O4/Au composite nanoparticle (GoldMag) and showed a high coupling ratio of 8 µg IgY mL−1 nanoparticles at pH 8.0. The conditions of ICA strips using this IgY conjugate were optimized and could be used to measure spiked E. coli O157:H7 samples with a detection limit of 103 CFU mL−1 obtained by visual detection. Additionally, the magnetic signal intensities of the assay can quantitatively measure E. coli O157:H7 concentration in the range of 102 – 105 CFU mL−1 both in phosphate buffer solution (pH 7.4) and pretreatment-free milk samples with a detection limit of 102 CFU mL−1.
Here, we investigated the effect of irradiation by a low-intensity red light-emitting diode (LED) (photon flux 12 µmol•m−2•s−1) on rind color development in Satsuma mandarins after harvesting at two different periods. In the early harvest fruit, the a* value for Satsuma mandarin peel treated by red LED irradiation was 2.7 and 2.4 times higher than that for the dark treatment fruit at 4 and 8 days irradiation, respectively. In the commercial harvest fruit, the a* value of the peel treated by red LED irradiation was 1.2 and 1.4 times higher than for dark treatment at 4 and 8 days irradiation, respectively. Additionally, we examined the influence of red LED irradiation on the internal fruit quality of Satsuma mandarins from the two harvest periods. Low-intensity red LED irradiation did not affect fruit quality. We elucidated the effect of intermittent red LED irradiation on the change in a* value of mandarin fruits. These results indicated that treatment with low-intensity red LED irradiation is sufficient to develop a degree of rind color in mandarins without affecting the internal fruit quality.
A comparative metabolite profiling procedure was applied to differentiate four different Thai colored indica rice (Oryza sativa L.), including Hom Daeng (red), Rice Berry (purple), Hom Nin (black) and Hom Mali 105 (non-colored) over the course of germination. The samples taken during germination at 28 – 30°C with 90 – 95% relative humidity for a total of 48 h were subjected to an extraction and fractionation procedure, covering a wide spectrum of lipophilic and hydrophilic low molecular weight constituents. A clear differentiation by principal component analysis indicated that all samples represented similar pattern direction along PC1 according to metabolic changes during the germination process. A differentiation at every stage of germination was observed along PC2 for each of the varieties of colored rice. Relative quantifications of selected metabolites exhibited dynamic changes in the metabolites at different germination stages. Thai black and purple rice contained higher levels of metabolites than the red and colorless samples.
This study was performed to clarify the relationship between internal temperature and quality of steamed shrimps. Shrimps were steamed to different internal endpoint temperature (75°C, 80°C, 85°C, 90°C, 95°C) and evaluated in terms of cooking loss, color, texture and taste active compounds. Results showed that the texture and taste active compounds of steamed shrimps were largely affected by steaming cooking. Cooking loss increased with increasing of internal temperature. Steaming caused lighter muscle and yellow shell of shrimp compared with raw shrimps, and no significant differences in color were observed amongst shrimps with different internal temperature. The hardness and shear force of cooked shrimps increased with increasing temperature in initial stage, followed by a sight reduction when the internal temperature exceeding 85°C. The amount of umami amino acids, sweet amino acids and total free amino acids decreasing with increasing temperature. In addition, it was smaller in the amount of total nucleotides in meat of cooked shrimps than that of raw shrimps, but the amounts of both AMP (5′-adenosine monophosphate) and IMP (inosine monophosphate) in meat of cooked shrimps were almost same, irrespective of internal temperature.
Droplet size has an important effect on the stability and sensory quality of emulsions. This study aimed to analyze the effect of different treatments, including treatment under different temperatures and shearing, on the properties of coconut milk emulsions. Various coconut oil droplet sizes of coconut milk emulsion droplets after different treatments were investigated by observing the droplet sizes and micrographs. The stability of these samples was investigated by the creaming index of the emulsions. Result showed that heating increased the average droplet size of coconut milk. Freezing decreased the average droplet size of the emulsion to a minimum of 7.67 µm. High-speed shearing increased the average droplet size of the emulsion to a maximum of 10.29 µm. The creaming index of the emulsion squeezed from coconut meat that underwent freezing treatment was 35.10%, which was the minimum value. Thus, freezing treatment on coconut meat could induce the size of the emulsion droplets and improve the stability of the emulsions.
Endo-1,4-β-glucanase (EG) is involved in the metabolism of plant cell wall, and plays important roles in the growth and development of plants. EG is closely associated with cell elongation, fruit ripening, and tissue abscission. Here, two EG genes were cloned from Pyrus bretschneideri Rehd. cv. Chili, and their expression patterns were analyzed in fruit of Pyrus bretschneideri Rehd. cv. Chili and fruit of Pyrus pyrifolia Rehd. cv. Whangkeumbae. The two pear varieties showed different softening behaviors, ‘Chili’ maintained a stable firmness during the storage time, while the firmness of ‘Whangkeumbae’ decreased during the storage. The functions of two EG genes were discussed in the ripening and softening processes. During the 0°C storage period of ‘Chili’ pears, PbEG3 and PbEG4 expression levels both showed a downward trend. The expression levels of both the genes were high during the early harvest period (0 days), and declined rapidly thereafter. Treatment with 1-methylcyclopropene (1-MCP) inhibited PbEG3 expression, but had no significant effect on PbEG4. During the 0°C storage period of ‘Whangkeumbae’ pears, the expression of PbEG3 first increased, peaked at the 60 th day of storage, declining gradually thereafter until 120 d of storage. In contrast, PbEG4 gene expression displayed decreasing trend at first and increased thereafter. The different expression patterns of the PbEG3 and PbEG4 genes in ‘Chili’ pears and ‘Whangkeumbae’ pears showed that PbEG3 might be involved in ripening and softening, and the expression of the two genes are different in different cultivars.
The objective of this study was to investigate the effects of superfine grinding on the physicochemical and antioxidant properties of oat bran polysaccharides (OBP). The solubility of OBP increased from 8.1 to 11.3 mg/mL. The average molecular weights of raw OBP (rOBP) and superfine ground OBP (sOBP) were 655.6 and 489.6 kDa, respectively. The intrinsic viscosity of sOBP (4.58 mL/mg) was extremely lower than that of rOBP (94.75 mL/mg). The endothermic enthaphy change (ΔH) values of OBP with different water contents (0%, 50%, and 75%) changed from −328.79 J/g, −942.41 J/g, and −1.94 kJ/g to −197.01 J/g, −703.29 J/g, and −1.50 kJ/g, respectively. After being superfine grinding treated, sOBP exhibited higher antioxidant activities than rOBP based on FRAP, DPPH radical scavenging, and ABTS radical scavenging activities. The results suggested that superfine grinding treatment enhanced OBP's antioxidant activities. Physicochemical properties, including molecular weight, monosaccharide composition and solubility were key factors in OBP's antioxidant activities.
Sake samples having characteristics of 4-vinylguaiacol (4-VG)-like odor were analyzed by GC-MS and organoleptic methods. The quantified levels of 4-VG, 4-vinylphenol, 4-ethylguaiacol, and 4-ethylphenol of 15 sake samples, including 7 samples presenting 4-VG-like odor characteristics by multiple assessors, did not show a clear relation with the perception rate of 4-VG-like odor characteristics. Hence, we screened for other compound(s) responsible for the 4-VG-like odor characteristics, and found that odorous sake samples contain 2-methoxy phenol (guaiacol), 2,6-dimethoxyphenol (syringol), and 3-methyphenol at higher levels than the odor-less sample. The quantified level of guaiacol well matched the perception rate of 4-VG-like odor characteristics. The recognition threshold value of guaiacol in the sake and of 4-VG in the model sake solution was estimated as 14.6 µg/L and 141 µg/L, respectively. The concentration of guaiacol in the most odorous sake samples was higher than the estimated recognition threshold.
This study investigated how different combinations of xanthan gum and rice affect blood sugar levels after rice consumption. The addition of ≥1.0% xanthan gum during rice cooking (XGP-added groups) suppressed blood sugar levels 15 and 30 min after rice consumption. The glycemic index (GI) was significantly lower in all XGP-added groups than in the standard rice group. In all groups where xanthan gum sol was mixed with the cooked rice (XGS-mixed groups), blood sugar levels at 15 – 60 min were significantly lower and GI was lower than those in the standard rice group. Suppression of blood sugar levels by xanthan gum sol was more effective when consumed concurrently with rice than when consumed before or after consumption. The above findings revealed that blood sugar levels after rice consumption are suppressed most effectively when the rice is coated in xanthan gum sol.
The present study aimed to clarify the transport mechanism of sulforaphane (SFN), a potent phytochemical of broccoli, in Caco-2 cells. Transport study with an Ussing chamber system revealed the apparent permeability (Papp) of SFN in the apical-to-basolateral direction was much higher (31.2 ± 2.5 × 10−6 cm/sec) than that of (−)-epigallocatechin-3-O-gallate (0.54 ± 0.12 × 10−6 cm/sec). An efflux ratio analysis and several inhibition studies suggested SFN was passively transported across Caco-2 cell monolayers. Small amounts of glutathione conjugates of SFN in the basolateral side suggested that the transcellular pathway was, in part, involved in the transport of SFN. However, results showing that SFN transport was attenuated by sodium butyrate, a tight junction (TJ) closer, and competed with fluorescein, a selective marker of paracellular transport, clearly indicated that SFN was mainly transported through the TJ-controlled paracellular pathway.
We have reported that ingestion of the volatile fraction of winter savory (WSV) increased core body temperature (CBT), inhibited the decrease in body surface temperatures (BSTs) of the wrist, finger and ankle, and increased BSTs of the forehead and neck in humans who experience cold sensitivity. We also showed that carvacrol, a main component of WSV, contributed to the CBT-increase, but not to the inhibition of BSTs-decreases. Therefore, to elucidate the components in WSV affecting BST, we studied the effects of thymol, the second major component of WSV, on body temperature. Thymol ingestion inhibited BSTs-decreases of the wrist and finger. Moreover, changes in BST and CBT by a mixture of thymol and carvacrol were similar to those by WSV. These results suggest that thymol might facilitate heat transfer from the body's core to the surface, and that the combination of thymol and carvacrol greatly contributed to BST- and CBT-changes by WSV.
The addition of propylene glycol ester of alginic acid (PGA) or sodium alginate to wheat flour improved bread making properties such as bread height (mm) and specific volume (cm3/g). When PGA or sodium alginate/wheat flour and control bread dough were baked at 210°C for 10 min, the temperature of the dough (70 – 80°C) inactivates the yeast and thus gas production is stopped. However, the oven spring of PGA or sodium alginate/wheat flour bread dough continued for 30 min. The shrinkage of PGA or sodium alginate/wheat flour bread dough at 5 min of baking gradually decreased to zero at 30 min of baking; however, the shrinkage of the control decreased to almost zero at 15 min of baking. The larger addition of water in PGA or sodium alginate/wheat flour dough than in the control dough resulted in a longer time of gelatinization and protein denaturation than in the control dough during oven baking.
We developed a more convenient method for assaying polyamines and re-examined the variation of polyamine contents during each step of the natto production process. The steaming process slightly decreased spermidine in soybeans, and the subsequent fermentation process resulted in 41.1% increase of spermidine and 19.4% reduction of spermine compared with those of steamed soybeans. These results indicated that Bacillus subtilis (natto) produces spermidine during the fermentation process. Further, we determined that spermidine production differs among inoculum strains. It was also suggested that the selection of starter cultures with high spermidine productivity improves polyamine levels in natto.