Antioxidant Activity of Piceatannol in Canola Oil

Piceatannol has shown to be a strong antioxidant in vivo, however, its ability to suppress lipid oxidation in foods has not been examined. The present study is to examine the antioxidant effect of piceatannol on heated canola oil compared with that of butylated hydroxytoluene (BHT). The oxidation of canola oil is conducted at 60, 90, 120, and 150 °C by monitoring the depletion of oxygen, the decrease in unsaturated fatty acids, and the changes of primary and secondary oxidation products. Results demonstrated that piceatannol can suppress lipid oxidation of canola oil in a dose-dependent manner with its effect being more effective than BHT. Practical Applications: Lipid oxidation is a major factor in the deterioration of food quality. Synthetic antioxidants, such as BHT and butylated hydroxyanisole, are used to inhibit oxidation in foods, but their safety has been always concerned. Piceatannol has exhibited a strong antioxidant activity to attenuate lipid oxidation and it should be further explored for use as a natural antioxidant in foods.     

顶空-气相色谱法测定食品接触材料中14种溶剂残留量

建立顶空-气相色谱法测定食品接触材料（纸基食品接触材料和涂漆筷子等）中14种溶剂残留量的前处理分析方法。方法 通过优化溶剂基质和体积、氮气和空气、样品面积和碎片大小等前处理条件，实现了对14种溶剂残留量的常规、快速分析。结果 14种溶剂残留量在0.01~6.40 mg/m2浓度范围内, 线性相关系数均大于0.9970，方法检出限为0.01mg/m2。结论 建立了适用于纸基食品接触材料和涂漆筷子等食品接触材料前处理方法和仪器分析方法，对食品接触材料产品研究和提高企业产品质量提供依据。     

Headspace fingerprinting approach to identify the major pathway influencing volatile patterns of vinasse-cured duck processed by high pressure,as well as its impact on physicochemical and sensory attributes

As a decisive attribute, flavour could be influenced by HP treatments through multiple physical and chemical pathways within the high pressure (HP)-assisted meat curing process. This investigation aimed to identify the major pathway influencing volatile flavour patterns of two representative vinasse-cured duck (VCD) products with HP treatments (150–300 MPa/15 min), including wet and dry types, by employing headspace fingerprinting as an untargeted approach. Results suggested that HP treatments greatly lowered moisture contents and increased Warner-Bratzler shear force and thiobarbituric acid reactive substances of the cured samples. According to multivariate models, the volatile flavour patterns of the HP-processed VCD could be clearly separated from the unprocessed samples, but the VCD pressurised at different intensities represented similar volatile fingerprinting, which was validated by e-nose analysis. The discriminant analysis (OPLS-DA) model outlined vinasse-derived ethanol, acetic acid, 3-methyl-1-butanol, 2-methyl-1-butanol, phenethyl alcohol and 2-methyl-3-octanone as the major discriminant aromas across the unpressurised and pressurised samples.     

A reference isotope dilution headspace GC/MS method for the determination of nitrite and nitrate in meat samples

A novel method for the determination of nitrite and nitrate in meat products is presented. The samples were ground and extracted in hot water with the presence of and internal standards. The solution was buffered with sodium bicarbonate and reacted with triethyloxonium tetrafluoroborate to convert nitrite and nitrate into EtNO₂ and EtONO₂. Such derivatives could be detected by headspace GC/MS in positive chemical ionisation mode with 0.05 µg g⁻¹ and 1.0 µg g⁻¹ LOD. The method was used for and quantitation in the 0.5-300 and 2.5-300 µg g⁻¹ ranges. The method was applied for the analysis of fifteen meat products. Despite minimal sample preparation, the headspace sampling ensured a clean chromatography for over 135 analyses (throughput ten samples per hour). The proposed method offers selective GC/MS detection combined with high-precision isotope dilution calibration, it is suitable for metrological applications and can support regulations on meat safety (European Commission, 2011).     

酵子馒头与酵母馒头挥发性组分与香气特征分析

利用同时蒸馏萃取(SDE)和顶空固相微萃取(HS-SPME)收集酵子馒头(JSB)与酵母馒头(YSB)的挥发性物质,并结合气-质谱联用(GC/MS)和气相嗅闻(GC-O)技术,对其挥发性物质和香气特征进行分析。结果显示,SDE吸收液适合分馏和浓缩。HS-SPME最佳条件为吸附温度55℃,吸附时间30 min,解吸时间6 min。GC/MS分析发现,两种馒头共有组分23种,主要组分是乙醇、3-甲基-1-丁醇、正己醇、(E)-2-壬烯醛、2-正戊基呋喃、萘、苯甲醛、戊基苯、壬醛、香叶基丙酮,共有组分在JSB中相对含量较高(>60%),在YSB中含量较低(<50%),其中JSB中乙醇的相对含量最高(63%)。JSB中酸类、含苯环类、杂环类化合物的相对含量高于YSB,表现出醇香、果香和坚果香味。而YSB中烯烃类、醛类、酯类、酮类化合物高于JSB,其香气不如JSB浓郁。JSB与YSB的挥发性物质种类和相对含量差异明显,导致两者表现出不同的香气特征。     

HS-SPME/GC-MS测定石榴酒中香气组分的条件优化

该文使用气相质谱联用仪(gas chromatography-mass spectrometry,GC-MS)对石榴酒中的香气成分分析,在进样前对萃取纤维的种类,萃取的样品量,萃取时间,萃取温度4个条件进行优化,以期得到所测定的香气分子较多,重现性较好的GC-MS结果。试验结果表明对5.0 mL石榴酒样品,选取二乙烯基苯/碳分子筛/聚二甲基硅氧烷(divinylbenzene/carbon molecular sieve/dimethicone,DVB/CAR/PDMS)萃取纤维在45.0℃下萃取50 min,能够得到最优且重现性较好的GC-MS分析结果,定性出57种化合物,包括酯类、醇类、酸类、芳香族化合物等。为石榴酒的后续研究提供了基础。     

Identification of factors that accelerate hydrogen production by Clostridium butyricum RAK25832 using casamino acids as a nitrogen source

The ability of Clostridium butyricum RAK25832 to use casamino acids as a nitrogen source was investigated. Strain RAK25832 showed the capacity to utilize different types of carbon sources. With glucose as a carbon source (10 g/L), the preferred final concentration of casamino acids was 26.67 g/L, with a cumulative hydrogen production, production rate, and yield of 2505 mL H₂/L, 160 mL/h, and 1.81 mol H₂/mol glucose, respectively. Eighteen metal elements were screened to identify the most important metals for biohydrogen production, and four elements were optimized. The optimal medium composition was MgCl₂·6H₂O (0.1 g/L), K₂HPO₄·3H₂O (6.67 g/L), NaHCO₃ (2.6 g/L), and FeCl₂·4H₂O (0.002 g/L). Vitamin supplementation of the medium showed no significant effect on hydrogen production. Under the optimized conditions, cumulative hydrogen production reached 3074 mL H₂/L. This is the first study to demonstrate the use of casamino acids as a nitrogen source by C. butyricum.     

气相动态顶空进样同时分析饮用水源水中17种有机物

建立了对饮用水源水中乙醛、丙烯醛、丙烯腈、环氧氯丙烷、硝基苯、硝基氯苯、氯苯、二氯苯、三氯苯和四氯苯进行同时分析的气相动态顶空进样-气相色谱-质谱法(D-HS-GCMS),目标物均为集中式生活饮用水地表水源地特定项目。经过对比试验,确定了优化后的气相动态顶空进样法主要参数:样品盐度为35%、平衡温度为50℃、平衡时间为10 min、吹脱捕集气流速为60 mL/min、吹脱捕集时间为15 min。利用优化后的方法参数对乙醛等17种有机物进行分析,环氧氯丙烷和丙烯腈的方法检出限分别为7和19μg/L,乙醛、丙烯醛、硝基苯和硝基氯苯的方法检出限介于0.7~1.5μg/L,氯苯类化合物的检出限则为0.003~0.015μg/L。使用气相动态顶空进样法对饮用水源水实际样品进行监测,加标回收率均值介于78.7%~128%,对应的RSD为2.8%~23.0%(n=5)。     

北柴胡茎叶低温挥发性成分的气质联用分析

目的:顶空加热提取北柴胡茎叶的低温挥发性成分,建立其GC-MS快速分析方法,实现老药工采药感官经验的客观阐明。方法:选择北柴胡的茎叶,顶空提取结合气相色谱-质谱分析,确定低温挥发性成分的结构和相对含量。结果:顶空加热提取结合GC-MS分析,鉴定柴胡茎叶中24个挥发性化学成分。结论:顶空提取与GC-MS联用可以快速建立柴胡茎叶的低温易挥发性成分表征体系,初步实现了老药工采药经验"气味"的物质基础的阐明。     

蒸气顶空富集装置-自动顶空气相色谱法在海水中痕量苯系物检测中的应用

采用蒸气顶空富集-自动顶空气相色谱法,研究了海水中痕量苯系物(包括苯、甲苯、乙苯、对二甲苯、间二甲苯、邻二甲苯和苯乙烯)的测定方法,优化了蒸气富集作为海水中苯系物预处理方法的参数。对其精馏管长度、回收冷凝液体积、吸收介质等影响富集效果的关键因素进行了评价,并优化了色谱条件,考察方法的精密度和回收率。结果表明,大体积水样经过10 cm长度冷凝管的二次冷凝富集,以水作为吸收剂,1 L水样富集浓缩至10 mL后,可使原有自动顶空气相色谱分析苯系物的灵敏度提高1~2个数量级。采用蒸气顶空富集-顶空气相色谱法测定海水中的苯系物的平均加标回收率为83%~113%,相对标准偏差为1.1%~5.4%(n=3);苯系物的海水中检出限为0.02~0.1μg/L。本文建立的蒸气顶空富集-自动顶空气相色谱法简单快速,重现性好,回收率高,适用于海水中痕量苯系物的分析测定。