Microbial dynamics and biochemical processes during suan cai fermentation were investigated. The pH decreased from 7.3 to 4.0 at day 12 of suan cai fermentation, and then remained at approximately 4.1. Water-soluble carbohydrate decreased from 15.1% to 4.5% of dry matter at day 18 of fermentation. Nitrite content comprised 54.6 mg kg−1 of fresh matter at day 6, and then decreased dramatically. Lactic acid, acetic acid and ethanol were the main volatile products identified, and concentrations were 6.8 g L−1, 0.78 g L−1 and 32.2 g L−1 at the end of fermentation, respectively. 16S rDNA clone libraries showed that bacteria during the fermentation included Acinetobacter sp., Pseudomonas fragi, Klebsiella sp., Citrobacter sp., Betaproteobacteria sp. and lactic acid bacteria, which included Leuconostoc mesenteroides, Lactobacillus curvatus, Lact. plantarum and Lact. oligofermentans. At day 6, LAB comprised 63.8% of the bacterial population. On day 30, all bacteria were LAB. Lact. curvatus dominated the fermentation. Lact. oligofermentans was found to be involved in the vegetable fermentation for the first time. 26S rDNA D1/D2 clone libraries revealed that eukaryotic microorganisms included Stramenopile sp. and soil fungus at day 12. Candida sake, Cystofilobasidium infirmominiatum, Claclosporium sp. and Tilletiopsis washingtonensis were also detected until day 30 of fermentation. This is the first study to focus on eukaryotic diversity during suan cai fermentation. These results provide a comprehensive understanding of the spontaneous suan cai fermentation process and a foundation for controlling suan cai fermentation and quality.
Soybeans and the processed food, soybean milk, have important health functions. A cheese-like food produced from soybean milk resembles casein protein in its mouthfeel and physical properties. The intracellular soybean milk curdling enzyme-producing Saccharomyces bayanus SCY003 strain was screened. The curdling enzyme is an intracellular protease, a 45 kDa monomer protein that degrades soy protein subunits, produced by this strain. The optimum temperature and pH of enzyme activity are 50°C and pH 7.5, respectively. The protease degrades β-conglycinin and parts of glycinin in soy protein to α’, α and β subunits. The rheological characteristics of the resultant curd were assessed, and revealed that elasticity differed from curd produced by glucono δ-lactone, which is used in tofu production. A new soy protein food having health-supporting functions will be developed using this protease.
Yoghurt has the strong flavour produced by adding Cheddar cheese into the milk and cold storage process before the fermentation. The flavour analysis of yoghurt was investigated by e-nose, e-tongue and gas chromatography-mass spectrometry (GC-MS). Yoghurt samples with adding Cheddar cheese or whole milk powder showed significant differences in their e-nose flavour profiles, but their e-tongue flavour profiles were roughly similar. Besides, neither e-nose nor e-tongue could accurately distinguish the yoghurt samples which were subjected to cold storage process before the homogenization or not. Among the detected volatile compounds, pentanal and dimethyl trisulfide were the most highly correlated with the cold storage process, and pentanal, ethyl butanoate, methanethiol, dimethyl disulfide and dimethyl trisulfide discriminated yoghurt samples adding Cheddar cheese or whole milk powder. This study showed the potential of adding Cheddar cheese in the yoghurt production to accelerate the flavour formation and increase the flavour compounds.
An imbalance of oxidation and antioxidation is one of the primary causes of atherosclerosis. The use of natural plant compounds with effects has been proven to have clinical relevance. 6-Gingerol, one of the major components of ginger, has diverse pharmacologic effects. In this study, the chemoprotective effect of 6-gingerol against hydrogen peroxide-induced DNA damage in human umbilical vein endothelia cells (HUVECs) was investigated. The comet assay was used to monitor DNA strand breaks. To further elucidate the underlying mechanisms, we tested lysosomal membrane stability, mitochondrial membrane potential, the intracellular generation of reactive oxygen species (ROS) and reduced glutathione (GSH). Our data revealed that 6-gingerol significantly reduced the DNA strand breaks caused by hydrogen peroxide. 6-Gingerol effectively suppressed hydrogen peroxide-induced intracellular ROS formation. The GSH depletion in HUVECs was also attenuated by 6-gingerol pretreatment. Moreover, lysosomal membrane stability was destroyed and mitochondrial membrane potential decreased after treated by hydrogen peroxide. Those effects can be protected by 6-gingerol. These firmly indicate 6-gingerol has a strong protective ability against the DNA damage caused by hydrogen peroxide in HUVECs, and the mechanism may relate to the antioxidant activity. Our data suggest 6-gingerol may be beneficial in the prevention of atherosclerosis.
BACKGROUND: Pen a1 is a major allergen in shrimp. It is a 284 amino acid protein member of the tropomyosin family with a molecular weight of 36 kDa. Irradiation and heat treatments have been previously shown to reduce the immunoreactivity of Pen a1, but since anaphylaxis is not induced by the whole protein but by epitopes within the protein, studying of the influence of these treatments on the epitopes of Pen a1 is helpful for understanding the sensitization mechanism. In this study, the immunoreactivity of the five epitopes of Pen a1 exposed to heat and irradiation treatments was detected by Ci-ELISA and western blot, using specific anti-sera generated from 5 synthesized epitope peptides of Pen a1. We examined the function of each epitope in the sensitization process by analyzing the variations of their immunoreactivity following irradiation, heat treatment, or a combination of both.RESULTS: Pen a1 was treated by gamma irradiation, heat at 100°C or a combination of irradiation and heat. The IC50 value for each of the five epitopes was detected. The IC50 value of epitopes 1, 2, and 4 decreased under all treatments, especially epitope 4; its IC50 value decreased sharply from 15.88 to 0.11 follwing 7 kGy irradiation and to 0.03 – 0.04 under 10 kGy or 7 kGy irradiation and heat. The IC50 value of epitope 3 increased from 1.49 to 5.32 under 7 kGy irradiation and to 10.03 under 7kGy and heat, but mildly decreased after 10 kGy irradiation. In contrast, the IC50 value of epitope 5 hardly changed following any treatments.CONCLUSION: The variation in the IC50 values of epitope 3 was consistent with the IC50 values measured from the whole Pen a1 protein, while epitope 5 was stable following irradiation and heat treatments. Since the variation of immunoreactivity of epitope 3 was consistent with Pen a1, this suggests that epitope 3 is the determinative epitope in the allergenicity of Pen a1; epitope 5 was stable with all treatment conditions, suggesting that it could be used in immunoassay kits for the detection of treated shrimp.
Foodborne illnesses associated with the consumption of fresh produce such as raw vegetables have become a major health concern worldwide in recent years. In the present study, we investigated the possible routes of Salmonella contamination in leafy lettuce via soil during cultivation. After 10-week cultivation of lettuce plants in soils inoculated with S. Enteritidis expressing green fluorescent protein (SE-EGFP), the bacterium was detected in soil inoculated with >104 cfu/g and from most lettuce leaves cultivated in soils inoculated with >4.4 × 107 cfu/g. As Salmonella was not detected in intact lettuce leaves or lettuce leaves with root injury cultivated in highly contaminated soils and after surface disinfection, the lettuce plants were not considered to internalize the bacterium. Overhead irrigation led to the contamination of one in 10 lettuce plants; however, all sets of three leaves of the plant were contaminated (>110 MPN/g). In an effort to prevent Salmonella contamination from soils, we investigated the effects of mulch on contamination levels during cultivation. Mulch effectively reduced Salmonella contamination levels of lettuce plants cultivated in highly contaminated soils.
The ginger rhizome (Zingiber officinale) is known to show a pale yellow color. However, the compounds responsible for the color are not known. In this study, 62 kinds of ginger rhizomes originating from different cultivars or different cultivation locations were collected for analysis of yellow pigment compounds. Ultra-performance liquid chromatography profiles at 420 nm for each sample were used for principal component analysis. Curcumin, demethoxycurcumin, and 6-dehydrogingerdione were identified as the main common compounds contributing to the yellow color, and their average amounts were 2.2 ± 0.1, 1.6 ± 0.1, and 20.0 ± 1.1 mg/100 g fresh weight, respectively. Curcumin and demethoxycurcumin were contained in cv. Kintoki samples at higher levels. However, their variation suggested that the yellow pigment of ginger rhizome is more dependent on the cultivation conditions and less on the cultivar. Comparative analysis of these amounts and the b-value between mature seed rhizomes and immature rhizomes from the same lines suggested that yellow pigments were synthesized during rhizome maturation.
Acrylamide is a toxic compound generated in processed foods prepared at high temperatures. To explore means by which food processing can reduce the acrylamide content in foods, we studied the reaction of acrylamide with lysine and cysteine, which carry nucleophilic functional groups, at temperatures below the initiation of acrylamide generation. The amino acid-mediated reduction of acrylamide content followed first-order reaction kinetics in aqueous solution below 120°C. The profile of acrylamide decrease correlated well with the formation of a 1:1 adduct of acrylamide with the respective amino acid, indicating that these amino acids reacted directly with acrylamide. The reactivity of acrylamide toward both amino acids was pH-dependent. In particular, the reactivity of cysteine toward acrylamide was remarkably enhanced by an increase in pH. These findings suggested the possibility of reducing acrylamide levels during food processing by treating foods with the appropriate amino acid(s) at moderate temperatures below 120°C.
The nutritional properties and health benefits of ice cream can be improved by substituting cow's milk with vegetable milks. In the present study cow's milk in ice cream was replaced by soy, coconut and composite milk (combinations of coconut or cow milks with soy milk). The changes in ice cream eating qualities and physical properties (melting rate, apparent viscosity, hysteresis, fat globule size and its zeta potential and freezing behavior) were evaluated. The use of vegetable milk to replace cow milk increased pH and decreased melting rate. Ice creams containing composite milk have reduced the melting rate, freezable water amount, particle size and total acceptability of ice creams whereas increased viscosity and hysteresis area with increasing soy milk content. The vegetable milks as composite milk can use to replace cow milk without markedly affecting the quality of ice cream.
The physicochemical properties and molecular structure of ginkgo and mung bean starch were investigated. Results showed that ginkgo starch (GBS) prepared in the laboratory had a good purity and displayed smaller granule particle size, higher gelatinization temperatures and lower average molecule weight (Mw) than mung bean starch (MBS). Ginkgo starch noodles (GBSN) and mung bean starch noodles (MBSN) were prepared and the quality evaluation among GBSN, MBSN, commercial mung bean and sweet potato starch noodles (c-MBSN and c-SPSN, respectively) revealed that cooking quality, and partial textural properties of GBSN were close to those of commercial products. The enzymatic digestion analysis of GBSN and MBSN conducted with α-amylase and β-amylase + pullulanase systems suggested that starch noodles were more resistant to β-amylase + pullulanase than α-amylase, and the starch in noodles might be composed of two parts: one part with relatively loose structure could be easily degraded, and the other with compact structure would be degraded more slowly.
In vitro fermentation of six functional oligosaccharides including fructooligosaccharides (FOS), galactooligosaccharides (GOS), xylooligosaccharides (XOS), isomaltooligosaccharides (IMOS), raffinose and stachyose was performed by using Clostridium butyricum TK2 and Clostridium butyricum CB8. Among the six oligosaccharides, IMOS revealed the strongest fermentability for both strains, which was supported by the highest viable cells (10.1 ± 1.05 and 9.8 ± 0.41 log (CFU / mL)) and the highest levels of SCFA or butyrate (11.77 ± 0.37 and 14.47 ± 1.05 mM) from fermentation with this functional oligosaccharide. The fermentability of GOS to two strains was better than raffinose or stachyose. The last groups were FOS and XOS. However, every oligosaccharide showed no significant difference in promoting the growth of both of C. butyricum (p > 0.05), and exerted some differences in the production of SCFA between two strains. This study provides a rational basis for establishing synbiotics with C. butyricum to improve the gut health.
We screened soil microorganisms with the potential to modify the structure of black rice anthocyanin. After culturing the microorganisms on PDA medium containing black rice anthocyanin, caffeic acid, p-hydroxybenzoic acid, ferulic acid, and malonic acid for 4 days at 30°C, one strain that changed the red medium to reddish purple was isolated. Anthocyanins present in the color-changed medium were extracted using 15% (w/v) acetic acid and their absorption spectra were then determined. The analysis revealed that the peak wavelength of the extracted anthocyanins was shifted to a shorter wavelength (500 nm) from that of black rice anthocyanin (520 nm). Further HPLC separation of the anthocyanins confirmed that four new species were present in the medium. Of the four pigments, two showed an absorption maximum at 500 nm. Analysis of their basic structure by acid hydrolysis showed that the two pigments had clearly different retention times from cyanidin, which is the main anthocyanidin in black rice, and were not malvidin or peonidin. A 16S rDNA homology search indicated that the isolated microorganism with the ability to modify the structure of black rice anthocyanin was an Enterobacter aerogenes strain.
Niihime is a sour Citrus fruit produced along the coast of the Sea of Kumano in the Mie prefecture of Japan. A novel ferulate derivative was isolated from niihime fruit. The structure of the compound was elucidated by spectroscopic analyses and identified as saccharic acid 1,4-lactone 3,5-di-O-ferulate by 1H-NMR, 13C-NMR, and MS analyses. The new compound exhibited significantly higher antioxidative activity than ferulic acid, a parent molecule of the compound, and trolox, a standard antioxidant, as measured by an ORAC assay (P < 0.05). Further, it was abundantly contained in the flavedo, albedo, and segment epidermis of the niihime peel. It was also found in the juice vesicles but not in the seeds.
The present study aimed to develop sericin-added bread in an effort to promote the effective consumption of the silk protein sericin and to evaluate bread-baking performance with sericin addition, with respect to effects on bread structure and palatability. Sericin supplementation resulted in decreased specific volume and darker crust color of the bread. No significant difference was observed in other physical properties. Sensory evaluation revealed that bread with up to 2 g of added sericin tended to be preferred. In a comprehensive evaluation of specific volume, crust color and preference rating by sensory evaluation, the optimal amount of added sericin was determined to be 2 g. Further, approximately 330 mg of sericin can be consumed in 1 slice of bread. We thus propose sericin-added bread as a desirable processed food that enables the effective ingestion of sericin.
This study investigated the flavonoid contents of the new lemon cultivar ‘Yellow Bell’ (YB) and its effects on fat metabolism in rats. YB contains neoeriocitrin, hesperidin, rhoifolin, neodiosmin and aurapten, and is high in neohesperidin (1020 – 1270 mg/100 g whole dry weight) and naringin (178 – 270 mg/100 g whole dry weight). The flavonoid pattern of YB differs from that of the conventional lemon cultivar. In experiment 1, rats were fed a high fat diet (HF) or HF containing 5% dry whole YB or conventional lemon cultivar Villafranca (Vil). Serum adiponectin was significantly increased by YB intake compared with control at 2 and 5 weeks (p < 0.05, p < 0.01, respectively). In experiment 2, rats were fed HF or HF containing 5% dry whole YB or dry peel YB. Serum adiponectin was significantly increased by whole YB intake compared with control at 5 weeks (p < 0.05). We revealed the novel effect of YB on increasing serum adiponectin.
The effect of thermal and ultrasound treatments on the physicochemical properties (pH, total soluble solids, titratable acidity, electrical conductivity, viscosity and color attributes), bioactive compounds (ascorbic acid, total pheolics and total anthocyanins) and antioxidant activity of strawberry puree was investigated. No significant difference in pH, total soluble solids and titratable acidity was observed among the treated and control samples whether thermal or ultrasound treatments were used. Ultrasound treatments significantly increased the electrical conductivity, while significantly reducing the viscosity of strawberry puree samples. Ultrasound treatments were found to better maintain or increase the bioactive compounds and the color attributes compared to the thermally treated samples. Ultrasound treatments significantly increased the radical scavenging activity compared to that of the control sample except when the ultrasound treatment was carried out at 0.42 W/mL for 20 and 30 min. These results indicate that ultrasound treatments can greatly improve the quality of strawberry puree.
This study was conducted to investigate the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of selected essential oils (EOs) against Escherichia coli O157:H7 under neutral and acidic pH conditions, and to evaluate the efficacy of EOs on the inactivation of E. coli O157:H7 in vegetable juice samples stored at 5, 20 and 35°C or heated at 55°C. The growth and survival of E. coli O157:H7 were significantly affected by pH adjustment, additive concentration, storage temperature and time. A synergistic or hurdle effect was observed within EOs at pH 4.0 and pH 4.5, or with heat treatment. The calculated decimal reduction times (D-value, min) varied with the EOs concentration. Star anise oil (0.05%, vol/vol) provided the maximum reduction in D55 value, from 5.69 min to 0.38 min. The combination of mild heat treatment and EOs may be used to enhance the safety of juice products.
Samples of red sea bream (Pagrus major) were grilled under far-infrared radiation heating. The last step of grilling, namely, carbonization, was analyzed. The temperature and color CIE L*a*b* at the center of the fish surface were measured during the entire grilling process. The color that developed during the carbonization was analyzed using a kinetic model based on the reduction rate of L* values and a computer vision system (CVS). Empirical equations for estimating a* and b* values were deduced based on the calculated L* values. During the carbonization step, the L* values of the surfaces decreased slowly. The L* values appeared to reach a constant value, the magnitude of which depends on the surface temperature. The color distribution across the entire surface during the grilling process was effectively estimated using the CVS. The effect of surface temperature on carbonization was analyzed by the CVS and successfully visualized using a two-dimensional simulation model.
The use of soymilk instead of water when making gluten-free rice flour bread significantly increases the dough volume after yeast fermentation. The soymilk solids function to increase the dough viscosity, reducing the amount of CO2 that is released through the dough's surface. Additionally, more CO2 is generated due to the sucrose content of soymilk. Dough made with soymilk rises better during baking than does dough made with water. We found that glycinin and β-conglycinin contained in soymilk prevent gas cells from merging or collapsing during yeast fermentation and baking. Therefore, this study suggests that the use of soymilk may affect the rising of gluten-free rice flour bread.
White breads with Yudane dough (Yudane bread) were made from commercial hard flour by the no first fermentation method. Yudane dough was prepared by mixing boiling water and flour at a ratio of 1:1. The dough at 20 and 40% (w/w, flour base) was added to the total bread dough. In the Yudane bread making method, an extended final proof, lower dough gas retention and gassing power, as well as specific loaf volume were observed compared to conventional bread making (control) without Yudane dough. Also, the moisture content of the Yudane breads increased with increasing water absorption for bread making. The total and reducing saccharide and maltose contents in the water-soluble fraction of Yudane bread also increased with the volume of added Yudane dough. The Yudane breads were very soft just after baking, and the staling (temporal changes in hardness) and starch retrogradation of the breads were somewhat reduced compared to the control. Further, the breads showed generally larger cohesiveness, i.e., the index of bread elasticity. Kinetic analysis indicated reduced bread staling and starch retrogradation rates compared to control. The data showed that the slow staling and unique texture of the Yudane breads were mainly due to the high moisture content, saccharide contents, and flour amylases-modification of swollen and gelatinized starch in the breads, which was related to the higher water absorption and starch swelling and gelatinization levels of the added Yudane dough.
Sulfiting agents have been used wide-spread for prolonging shelf life of berries, excessive of sulfur dioxide would cause food allergies to humans. Conventional methods mainly focus on the determination of free or total sulfite in liquid samples, and are not suitable to analyze berries with low level of sulfite. Here formaldehyde method and ion chromatography were coupled to determine the residues of the free and total sulfites in Red Globe grape. Both standard calibration curves showed good correlation between anion peak area and concentration. To free and total sulfite, limits of detection were 0.002 and 0.05 mg/L and recoveries ranged from 88 – 93% and 87 – 98%, respectively. Relative standard deviation values of repeatability and intraday precision for standard anions with the same sample were less than 3%. The method developed was well applicable to be used to determine free and total sulfite in barriers, especially to those with color.
Celiac disease is an immune-mediated enteropathy triggered by the ingestion of gluten in genetically susceptible individuals. Gluten is a complex mixture of storage proteins of wheat, rye and barley. However, pseudocereals do not contain gluten. Quinoa -one of three pseudocereals- has high level of protein, fat, fiber, vitamin, mineral and micro constituents, low level carbohydrate and it has good amino acid balance. The purpose of this study was to make gluten-free tarhana by using different ratios (40:30:30, 50:25:25 and 60:20:20%) quinoa flour (QF), rice flour and potato starch instead of wheat flour, and to determine the effects of QF addition levels on the some physical, chemical, nutritional, sensory properties of tarhana samples. The use of QF led to a decrease in fermentation loss values of the tarhana samples. Also, QF affected the colour (L*, a* and b*) of gluten-free tarhana. The tarhana samples containing 60% QF had the highest a* values, while tarhana samples containing 40% QF had the highest b* values. The use of high level QF (60%) increased crude protein, ash, crude fat, potassium, magnesium, calcium and iron contents in tarhana samples. Moreover, QF affected the scores of sensory properties of gluten-free tarhana soups. Tarhana soups prepared with 50% QF gave the highest scores for consistency and overall acceptability. In conclusion, gluten-free tarhana were satisfactorily improved in terms of chemical, nutritional and sensory properties nutritional properties by quinoa flour.
Standard methods for bacterial identification include culturing and biochemical identification. These methods are time-consuming because they require culturing in different media for at least a few days. Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has recently been demonstrated as a rapid, reliable method for bacterial identification. In this study, we developed an improved sample preparation method to accurately identify coliforms in processed soybean products using MALDI-TOF MS. Our method included harvesting bacterial cells using isoelectric precipitation and anionic surfactant treatment to eliminate food matrices such as proteins and fats. At least 107 colony-forming units (CFU) / mL of typical test strains of Escherichia coli, Klebsiella pneumoniae, and Citrobacter freundii were successfully identified in soy milk samples. After sample incubation steps at 37°C for 18 h, low levels of coliforms (101 CFU/mL) could be identified. Our proposed procedure was verified by accurately identifying coliforms in commercial processed soybean products.