scholarly journals Distribution and Quantification of 1,2-Propylene Glycol Enantiomers in Baijiu

Foods ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 3039
Author(s):  
Hao Xu ◽  
Yifeng Dai ◽  
Shuyi Qiu ◽  
Baoguo Sun ◽  
Xiangyong Zeng
Keyword(s):  
Propylene Glycol ◽  
Aging Time ◽  
Pure Water ◽  
Average Concentration ◽  
Soy Sauce ◽  
Downward Trend ◽  
Racemic Mixture ◽  
Enantiomeric Ratio ◽  
And Storage ◽  
Chiral Gas Chromatography

Enantiomers of 1,2-Propylene glycol (1,2-PG) were investigated in 64 commercial Chinese Baijiu including soy sauce aroma-type Baijiu (SSB), strong aroma-type Baijiu (STB), and light aroma-type Baijiu (LTB), via chiral gas chromatography (β-cyclodextrin). The natural enantiomeric distribution and concentration of 1,2-PG in various baijiu were studied to evaluate whether the distribution and content of the two isomers of 1,2-PG were correlated with the aroma type and storage year. The results showed that 1,2-PG has a high enantiomeric ratio and the (S)-configuration predominated in SSB. The average S/R enantiomeric ratio of this compound in SSB was approximately 87:13 (±3.17), with an average concentration of 52.77 (±23.70) mg/L for the (S)-configuration and 8.72 (±3.63) mg/L for the (R)-enantiomer. The (R)-configuration was predominant in the STB, whereas neither (S) nor (R)-form of 1,2-PG were detected in LTB. The content of the two configurations of 1,2-PG in the JSHSJ vintage of SSB showed a wave variation, with an average S/R enantiomeric ratio of 89:11 (±1.15). The concentration of (R)-1,2-PG in XJCTJ vintage liquors showed an upward and then downward trend with aging time, with an overall downward trend, and the concentration of (S)-form showed a wavy change with an overall upward trend. Except for the LZLJ-2019 vintage where both (R) and (S)-1,2-PG were present, all other samples only existed (R)-form, and a decreasing trend of (R)-enantiomer with aging time was observed. The enantiomeric ratio of 1,2-PG might be one of the potential markers for adulteration control of Baijiu as industrial 1,2-PG usually presented in the racemic mixture. Sensory analysis revealed olfactory thresholds of 4.66 mg/L and 23.92 mg/L for the (R)- and (S)-configurations in pure water respectively. GC-O showed both enantiomers exhibited different aromatic nuances.

scholarly journals Microtensile Bond Strength of Methacrylate and Silorane Resins to Enamel and Dentin

2014 ◽  
Vol 25 (4) ◽  
pp. 327-331 ◽  
Author(s):  
Gisele Rodrigues da Silva ◽  
Isabela Sousa Araújo ◽  
Rodrigo Dantas Pereira ◽  
Bruno de Castro Ferreira Barreto ◽  
Célio Jesus do Prado ◽  
...  
Keyword(s):  
Bond Strength ◽  
Aging Time ◽  
Storage Time ◽  
Composite Resin ◽  
Glass Plate ◽  
Composite Resins ◽  
Microtensile Bond Strength ◽  
Bonding Interaction ◽  
Significant Difference ◽  
And Storage

The aim of this study was to evaluate the microtensile bond strength (µTBS) of two substrates (enamel and dentin) considering two study factors: type of composite resin [methacrylate-based (Filtek Supreme) or silorane-based (Filtek LS)] and aging time (24 h or 3 months). Twenty human molars were selected and divided into 2 groups (n=10) considering two dental substrates, enamel or dentin. The enamel and dentin of each tooth was divided into two halves separated by a glass plate. Each tooth was restored using both tested composite resins following the manufacturer's instructions. The samples were sectioned, producing 4 sticks for each composite resin. Half of them were tested after 24 h and half after 3 months. µTBS testing was carried out at 0.05 mm/s. Data were analyzed by three-way ANOVA and Tukey's HSD tests at α=0.05. Significant differences between composite resins and substrates were found (p<0.05), but no statistically significant difference was found for aging time and interactions among study factors. The methacrylate-based resin showed higher µTBS than the silorane-based resin. The µTBS for enamel was significantly higher than for dentin, irrespective of the composite resin and storage time. Three months of storage was not sufficient time to cause degradation of the bonding interaction of either of the composite resins to enamel and dentin.

Survival and Growth of Vibrio cholerae O139 in Selected Malaysian Street Foods

1997 ◽  
Vol 60 (6) ◽  
pp. 644-648 ◽  
Author(s):  
GULAM RUSUL ◽  
CHONG KAM CHUN ◽  
SON RADU
Keyword(s):  
Vibrio Cholerae ◽  
Slow Growth ◽  
Food Poisoning ◽  
Rice Flour ◽  
Soy Sauce ◽  
Brown Sugar ◽  
Vibrio Cholerae O139 ◽  
Survival And Growth ◽  
Incubation Temperatures ◽  
And Storage

The growth of Vibrio cholerae O139 inoculated into cendol (a mixture of coconut milk, brown sugar, and green jelly from rice flour), rojak (prawn paste, sugar, soy sauce, spices, garlic, and peanut gravy), gravy, tofu, fried tofu, and wheat-flour noodles (all except rojak gravy containing the natural microbial flora) was examined at four incubation temperatures (7, 15,25, and 35°C). V. cholerae O139 grew well in cendol incubated at 25 and 35°C but not at 15°C or below. No growth of V. cholerae O139 in rojak gravy was detected at any temperature except for very slow growth at 35°C. V. cholerae O139 inoculated into tofu exhibited slow growth at 25 and 35°C and growth was not detected at 7 and 15°C. However, in fried tofu, the organism entered the growth phase after 12 h of incubation at 25 and 35°C. Growth of V. cholerae O139 was not demonstrated in noodles at any incubation temperatures. Nutrient broth with 1% NaCl added supported the growth of V. cholerae O139 at 25 and 35°C. At both of these incubation temperatures mean generation time was longer at pH 5 than at pH 8. The high variation in growth of V. cholerae O139 in the distinct foods examined might have been due to differences in pH, fat content, and aw. Proper sanitary practices and storage of foods at refrigeration temperatures will help to reduce the possibility of growth by Vibrio cholerae O139 in foods to levels which do not imply a risk for food-poisoning.

scholarly journals Partitioning of hydrogen peroxide in gas-liquid and gas-aerosol phases

2020 ◽  
Author(s):  
Xiaoning Xuan ◽  
Zhongming Chen ◽  
Yiwei Gong ◽  
Hengqing Shen ◽  
Shiyi Chen
Keyword(s):  
Hydrogen Peroxide ◽  
Liquid Phase ◽  
Gas Phase ◽  
Pure Water ◽  
Average Concentration ◽  
Effective Field ◽  
Urban Atmosphere ◽  
Ambient Atmosphere ◽  
Henry's Law ◽  
Henry’S Law

Abstract. Hydrogen peroxide (H2O2) is a vital oxidant in the atmosphere and plays critical roles in the oxidation chemistry of both liquid and aerosol phases. The partitioning of H2O2 between the gas and liquid phase or the aerosol phase could affect its abundance in these condensed phases and eventually the formation of secondary components. However, the partitioning processes of H2O2 in gas-liquid and gas-aerosol phases are still unclear, especially in the ambient atmosphere. In this study, field observations of gas-, liquid-, and aerosol-phase H2O2 were carried out in the urban atmosphere of Beijing during the summer and winter of 2018. The effective field-derived mean value of Henry's law constant (HAm, 2.1 × 105 M atm−1) was 2.5 times that of the theoretical value in pure water (HAt, 8.4 × 104 M atm−1) at 298 ± 2 K. The effective derived gas-aerosol partitioning coefficient (KPm, 3.8 × 10−3 m3 μg−1) was four orders of magnitude higher on average than the theoretical value (KPt, 2.8 × 10−7 M atm−1) at 270 ± 4 K. The partitioning of H2O2 in the gas-liquid and gas-aerosol phases in the ambient atmosphere does not only obey Henry's law or Pankow's absorptive partitioning theory but is also influenced by certain physical and chemical reactions. The average concentration of liquid-phase H2O2 in rainwater during summer was 44.12 ± 26.49 μM. In three-quarters of the collected rain samples, the measured H2O2 was greater than the predicted value in pure water calculated by Henry's law. In these samples, 46 % of the measured H2O2 was from gas-phase partitioning, and most of the rest may have come from residual H2O2 in raindrops. In winter, the level of aerosol-phase H2O2 was 0.093 ± 0.085 ng μg−1, which was much higher than the predicted value based on Pankow's absorptive partitioning theory. Almost all aerosol-phase H2O2 was not from the partitioning of the gas phase. The decomposition/hydrolysis of aerosol-phase organic peroxides could be responsible for 32 % of aerosol-phase H2O2 formation at the maximum rate of 3.65 ng μg−1. Furthermore, the heterogeneous uptake of H2O2 on aerosols contributed to less than 0.5 %.

scholarly journals Characterizing the effect of packaging material and storage temperature on the flavor profiles and quality of soy sauce

2019 ◽  
Vol 57 (4) ◽  
pp. 1544-1552
Author(s):  
Ru Liang ◽  
Jun Huang ◽  
Xueming Wu ◽  
Jun Fan ◽  
Yi Xu ◽  
...  
Keyword(s):  
Storage Temperature ◽  
Packaging Material ◽  
Soy Sauce ◽  
And Storage

scholarly journals Authenticity control of pine sylvestris essential oil by chiral gas chromatographic analysis of α-pinene

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Martina Allenspach ◽  
Claudia Valder ◽  
Daniela Flamm ◽  
Christian Steuer
Keyword(s):  
Gas Chromatography ◽  
Chromatographic Analysis ◽  
Enantiomeric Excess ◽  
Ionization Detector ◽  
Pine Oil ◽  
Flame Ionization ◽  
Enantiomeric Ratio ◽  
Chiral Gas Chromatography

AbstractNumerous terpenes present in essential oils (EOs) display one or more chiral centers. Within the same genus the enantiomeric ratio of these compounds can be different. Thus, the determination of enantiomers is a valuable tool to evaluate authenticity and quality of EOs. In here, the terpene profile of primary and commercial pine EOs was analyzed by conventional and chiral gas chromatography coupled to a flame ionization detector. The enantiomeric excess of ( ±)-α-pinene was determined and significant differences between primary and commercially available EOs were observed. Primary EOs of Pinus sylvestris L. showed a positive enantiomeric excess of (+)-α-pinene whereas commercial EOs labeled as P. sylvestris L. exhibited an enantiomeric excess of (−)-α-pinene. Thus, chiral analysis provides useful information on the authenticity of pine EOs and allows to uncover possible mislabeling, the use of the wrong herbal substance and sources of adulteration in pine oil.

scholarly journals Ethyl 2-hydroxy-3-methylbutanoate enantiomers: quantitation and sensory evaluation in wine

OENO One ◽  
2018 ◽  
Vol 52 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Marine Gammacurta ◽  
Sophie Tempere ◽  
Stéphanie Marchand ◽  
Virginie Moine ◽  
Gilles De Revel
Keyword(s):  
Red Wine ◽  
Detection Threshold ◽  
Sensory Characteristics ◽  
Detection Thresholds ◽  
White Wines ◽  
Enantiomeric Ratio ◽  
Potential Marker ◽  
Significant Difference ◽  
Sensory Tests ◽  
Chiral Gas Chromatography

Aim: To investigate chemical and sensory characteristics of ethyl 2-hydroxy-3-methylbutanoate in wines.Methods and results: Ethyl 2-hydroxy-3-methylbutanoate has been recently identified as a potential marker of lactic acid bacteria esterase activity. Enantiomers of this fruity ester were quantitated in 99 wines from various vintages and French regions using chiral gas chromatography (γ-cyclodextrin phase). Analyses revealed the predominant presence of the R enantiomer in red and white wines, with a maximum R/S enantiomeric ratio of 94/6 in a 1993 red wine. Results also highlighted greater levels of the ester in red than white wines, depending on grape origin. The detection thresholds of the R- and S-form were estimated at 4 µg/L and 1.5 µg/L in water and 51 mg/L and 21 mg/L in red wine, respectively. Moreover, ranking tests made with levels found in wines did not show significant sensory differences.Conclusion: The concentrations found in wines were considerably below the detection threshold, indicating no direct effect of these compounds on fruity aroma modulation. The absence of significant difference in sensory tests demonstrates that ethyl 2-hydroxy-3-methylbutanoate does not contribute significantly to the fruity aroma of red wine.Significance and impact of the study: To our knowledge, no previous research had determined the enantiomeric distribution and the sensory characteristics of this compound in wine.

Nucleate Boiling Performance of Azeotropic Binary Mixtures in a Saturate Pool Boiling System

2010 ◽  
Author(s):  
Kunihito Matsumura ◽  
Fumito Kaminaga
Keyword(s):  
Heat Transfer ◽  
Ethylene Glycol ◽  
Propylene Glycol ◽  
Binary Mixtures ◽  
Pure Water ◽  
Prediction Method ◽  
Nucleate Boiling ◽  
Transfer Coefficients ◽  
Process Industries ◽  
Nucleate Boiling Heat Transfer

Nucleate boiling of binary mixtures is of particular importance in chemical and process industries. The purpose of the present study is to provide experimental data and prediction method for nucleate boiling heat transfer in two types of anti-freeze solutions, Propylene-glycol (PG)/water and Ethylene-glycol (EG)/water, under atmospheric pressure. The experiments were performed in a saturated condition. The concentrations of solutions are varied from 10 to 40 wt%. It was found that the heat transfer coefficient gradually decreases as increasing the addition of anti-freeze. An addition of small amount of propylene-glycol and ethylene-glycol to water also decreases the CHF value far below that of pure water. It is concluded that the correlation proposed by Fujita for several binary mixtures can well predict the heat transfer coefficients within almost ±5% accuracy for every concentration of mixture solutions.

scholarly journals Hydrophobic lithiated titania floating film for efficient solar-driven water evaporation

2019 ◽  
Vol 20 (2) ◽  
pp. 478-486
Author(s):  
Miaomiao Ye ◽  
Xun Wang ◽  
Pei Zhou ◽  
Rong Chen ◽  
Qimao Gan ◽  
...  
Keyword(s):  
Storage Time ◽  
Pure Water ◽  
Solar Light ◽  
Water Evaporation ◽  
Water Parameters ◽  
Simulated Solar Light ◽  
New Process ◽  
New Research ◽  
And Storage

Abstract Recently, the development of new photothermal materials for seawater desalination based on air–water interfacial solar heating has become a new research hotspot. In this paper, hydrophobic lithiated titania was synthesized by lithium reaction with amorphous titania followed by surface modification with a thin 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) monolayer. The hydrophobic lithiated titania was used as a photothermal material for seawater evaporation based on this new process. A thin lithiated titania floating film was assembled under simulated solar light irradiance due to the combined actions of water surface tension and the water molecules' thermal motion. The formation of the thin floating film significantly promoted water evaporation. The water evaporation rate by the lithiated titania floating film was 0.87 kg·m−2·h−1 under 2.0 sun solar irradiance, which was 2.4 times higher than that of pure water. Parameters affecting the solar evaporation process such as lithiated titania dose, solar light intensity, and storage time were investigated. Finally, the quality of the condensed fresh water was tested to evaluate the potential application of the lithiated titania floating film in practical settings of seawater desalinization.

Encystment and excystment of the paramphistomid trematode Zygocotyle lunata

2010 ◽  
Vol 85 (3) ◽  
pp. 300-303 ◽  
Author(s):  
K.E. LeSage ◽  
B. Fried
Keyword(s):  
Acetic Acid ◽  
Sodium Chloride ◽  
Potassium Permanganate ◽  
Lemon Juice ◽  
Soy Sauce ◽  
Aluminium Foil ◽  
Chemical Factors ◽  
Physical And Chemical ◽  
And Storage ◽  
Do So

AbstractThis study reports further observations on encystment and excystment of the paramphistomid trematode Zygocotyle lunata. Of numerous substrates tested in the laboratory for cercarial encystment, i.e. plastic and glass dishes, Styrofoam™, aluminium foil, snail shells, and cheesecloth, all but cheesecloth allowed for 100% encystment within 4 h of cercarial release at 28°C. Numerous physical and chemical factors were tested to kill cysts, and their capacity to do so was determined by the subsequent inability of cysts to excyst within a chemical excystment medium. Vinegar, Italian salad dressing, soy sauce and 10% solutions of sucrose, acetic acid and sodium chloride were the most detrimental. Freezing, boiling and storage of cysts for more than 2 years also killed them. Several marinades such as lemon juice, Worcestershire sauce, and various concentrations of potassium permanganate, did not kill the majority of cysts tested. Since Z. lunata is a potential foodborne trematode for humans and animals, it is important to determine suitable ways to control or kill these cysts.

scholarly journals Chiral-Gas Chromatograpy-Selected Ion Monitoring-Mass Selective Detection Analysis of Secondary Alkaloids in Tobacco and Tobacco Smoke

1998 ◽  
Vol 18 (1) ◽  
pp. 35-42 ◽  
Author(s):  
TA Perfetti ◽  
WM Coleman
Keyword(s):  
Cigarette Smoke ◽  
Limiting Factor ◽  
Selective Detection ◽  
Methyl Radicals ◽  
Mainstream Smoke ◽  
Cigarette Smoke Condensate ◽  
Selected Ion Monitoring ◽  
Detection Analysis ◽  
Enantiomeric Ratio ◽  
Chiral Gas Chromatography

AbstractChiral gas chromatography-mass selective detection has been successfully employed in the analysis of secondary alkaloids in selected tobacco materials and cigarette smoke condensate. No extensive sample preparation is involved. A lower detection limit of ~2 % d-nornicotine, d-anabasine and d-anatabine in a mixture of l and d-isomers was achieved. The levels and the enantiomeric ratios of nicotine, nornicotine, anabasine and anatabine varied in different tobacco types. The enantiomeric ratios of nicotine, anabasine and anatabine in mainstream cigarette condensate also varied but were generally representative of the enantiomeric ratios for the alkaloids found in the leaf. The enantiomeric ratio for nornicotine in mainstream cigarette condensate also varied and was not representative of the enantiomeric ratios for the alkaloids found in the leaf. Preferential decomposition or racemization may account for the differences seen in the yields of isomers of nornicotine transferred to the mainstream smoke condensate. An experiment was conducted to determine if the d-nornicotine present in tobacco contributed to the yield of d-nicotine in mainstream smoke condensate. The results of that experiment indicated that the yield of d-nicotine transferred to mainstream smoke did not change significantly when either large levels of endogenous nornicotine were present in the leaf or when large levels of exogenous levels of d-, l-nornicotine were applied to the tobacco rod prior to smoking. The limiting factor in the production of d-nicotine in mainstream cigarette smoke condensate may be the concentration of methyl radicals present to react. Further work must be conducted to unravel the mechanism involved in the production of d-nicotine in cigarette smoke condensate.

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