Sorption of Flavor Compounds by Low Density Polyethylene Film

The interactions of aldehydes, methyl ketones, methyl esters, sulfur compounds and alkylpyrazines with low density polyethylene (LDPE) were investigated. LDPE film, suspended on a stainless steel support, was immersed in simulated milk ultrafiltrate containing a flavor compound. After shaking the glass bottles containing the solutions and film samples for 24 hr at room temperature (24 ± 2°C), the flavor compound was extracted from both the LDPE samples and the SMUF, and quantitated using gas chromatography. The sorption was: aldehydes (C₇-C₁₀) 11% to 63%, methyl ketones (C₇-C₁₀) 1.5% to 43.0%, methyl esters (C₇-C₉) 6.0% to 42.0%, and sulfur compounds 8.5% to 21%. Insignificant levels of alkylpyrazines were sorbed. For all flavor compound classes, as carbon chain length increased, the quantity of sorbed flavor compounds increased.     

Oxygen Permeability of Low Density Polyethylene as a Function of Limonene Absorption: An Approach to Modeling Flavor "Scalping"

A procedure was developed to measure adsorption (scalping) of limonene by low density polyethylene. The polymer was mounted on an oxygen electrode. Limonene absorption produced an increase in oxygen permeability which appeared proportional to limonene concentration. Diffusion coefficients calculated from permeation curves were similar to diffusion coefficients calculated on a weight change basis.     

Oxidation of d-Limonene in Presence of Low Density Polyethylene

Headspace oxygen contents of sodium citrate-water buffers containing d-limonene with and without low density polyethylene (LDPE) were measured on a weekly basis for 10 wk. d-Limonene was readily sorbed into LDPE. Results indicated first order kinetics for limonene oxidation. GC/MS analyses determined production of limonene oxidation end-products, including d-carvone, carveol, limonene oxide, perrilaldehyde and linalool, as well as α-terpineol, a hydrolysis product. Headspace oxygen contents of the d-limonene/buffer (control) samples were lower thau that of the d-limonene/buffer/LDPE samples, suggesting a higher oxidation rate in the control than in LDPE. Oxidation rate constants and half-lives were 5.9 × 10^-3 log(%O₂) wk^-1, t_1/2= 116 wk for control and 1.2 × 10^-3 log(%O₂) wk^-1, t_1/2= 580 wk for LDPE samples, respectively.     

SAFE-GC-MS分析酸牛奶挥发性成分

采用溶剂辅助风味蒸发法萃取原味酸牛奶挥发性成分,利用气相色谱-质谱联用法结合保留指数、标准品对照对挥发性成分进行定性分析,采用面积归一化法加邻二氯苯作内标定量,共鉴定出挥发性成分52 种,其中酸12 种、醛2 种、酮5 种、醇2 种、酯3 种、内酯2 种、烯烃4 种、烷烃17 种、其他5 种。其中,对酸牛奶风味影响较大的可能有乙酸、丁酸、己酸、辛酸、癸酸、9-癸稀酸、乙偶姻、2-壬酮、2-十一酮、壬醛、香兰素、3-甲基-2-丁烯-1-醇、十六硫醇、丁位癸内酯、丁位十二内酯等。     

柑橘乳化香精的稳定性研究

选用柠檬油为原料,纯胶为乳化剂,以乳化香精的吸光度变化率为评价指标,借助单因素试验和正交试验,优化制备稳定乳化香精的工艺条件.对于纯胶的乳化来说,影响最大的是乳化剂浓度,其次是均质转速,然后是增稠剂浓度,影响最小的是均质时间.纯胶乳化稳定性最佳的务件是:6%的纯胶作乳化剂,0.5%的卡拉胶作增稠剂,在数显高速分散均质机的转速为4500r/min下均质25min,乳化香精的吸光度变化率为10.13%,变化率最小,乳化效果最好.     

新型反应型鸡肉香精的制备及其挥发物的分析

以鸡肉酶解物和HVP液为主要原料,在pH5.0下,125℃反应40min制得了鸡肉味较强、总体香气较好的鸡肉味香精,该香精的挥发物经分离、浓缩和GC/MS分析后,鉴定出的40种化合物中有8种是在煮鸡肉中鉴定出的关键香味化合物。     

Analysis of Volatiles Related to Warmed over Flavor of Cooked Chevon

The development of warmed over flavor (WOF) in cooked chevon was monitored from its Tenax trapped volatiles by direct gas chromatography (GC). WOF markers, pentanal, hexanal, heptanal, 2,-3-octanedione and nonanal were identified from volatile profiles obtained with packed poly MPE coated Tenax-GC column. These volatile markers as well as the total volatiles increased over 6 days storage of cooked chevon at 4°C. Increase in hexanal was more rapid than the other WOF markers. Results suggest WOF development in cooked chevon is more rapid than reported rates for other cooked meats.     

Evaluation of the Contribution of Flavor Volatiles to the Aroma of Beef by Surface Response Methodology

The contribution to beef aroma of some compounds previously identified in the flavor volatiles from cooked beef was estimated by surface response methodology. In general, heterocyclic compounds containing oxygen, nitrogen and/or sulfur and unsaturated alcohols gave higher predicted scores and had lower optimum concentrations than ketones, aldehydes, alkanes or saturated alcohols. It was further demonstrated that hydrophilic compounds are more likely to contribute to meat aroma than hydrophobic compounds, thus, verifying a more important role for water-soluble compounds in contributing to meat flavor. On testing mixtures of compounds, the optimum concentrations were generally lower, but there was a greater range in maximum scores. Special significance is given to the fact that highest scoring two-component mixture (2-acetyl-3-methylpyrazine and H₂S) resulted from combining the two single compounds that scored highest alone. Furthermore, the reaction mixture of H₂S with 4-hydroxy-5-methyl-3(2H)-furanone gave the highest predicted score in the entire study. Thus, results indicate that the surface response method offers promise for unraveling the complexity of the meat flavor system.     

大米经不同包装方式贮藏后蒸煮风味物质的变化

采用顶空固相微萃取(HS-SPME)与气相色谱-质谱联用(GC-MS)的方法,对在37℃、60%相对湿度的贮藏条件下,采用4种不同包装方式(自然密闭、充CO2、充N2或抽真空)的大米蒸煮后风味物质进行了比较研究。研究表明,自然密闭包装方式储藏后醛类、醇类和酮类物质较其他包装方式增加量均最为显著,这说明采用自然密闭包装方式贮藏的保鲜效果最差。通过对抽真空、充CO2或充N2这3种包装的醛类、醇类、酮类和2-戊基呋喃总量进行比较,发现抽真空包装或充CO2包装这两种包装方式可以较好的延缓米饭风味物质的劣变,保持大米的品质,充N2包装次之。     

Effect of Heat Treatment on Antioxidant Capacity and Flavor Volatiles of Mead

ABSTRACT: The objective of this study was to evaluate the effects of heat processing on the antioxidant capacity of mead (honey wine). Soy and buckwheat honey musts were subjected to 2 heat treatments and fermented into wine. Total phenolic concentration was determined. High-performance liquid chromatography (HPLC) phenolic profiling was performed on the methanol fraction of Amberlite extraction. Antioxidant capacity was evaluated using the oxygen radical absorbance capacity (ORAC) assay. Changes in volatile components were evaluated by headspace-solid phase microextraction/gas chromatography-mass spectrometry (H-SPME/GC-MS). ORAC values of experimental meads (3.62 m M Trolox equivalent) were comparable to those of commercial white wine (3.66 m M Trolox equivalent). No significant difference in antioxidant capacity due to heat treatment or honey type was observed. There was no difference in total phenolics between heat treatments in buckwheat mead; however, soy mead made from high-heated must had significantly greater phenolic concentration than the gently heated mead (α= 0.05). Linear regression analysis indicated a strong positive correlation between total phenolic concentration and antioxidant capacity by ORAC ( r = 0.9077; P < 0.0001). HPLC analysis of phenolic profiles in the methanol fractions of Amberlite extraction of the meads indicated significantly higher levels of certain phenolics as a result of the high-heat process in buckwheat mead, but not in soy mead. Differences in volatile components that potentially impact flavor were noted between high and low heat treatments. Results of this study suggest dramatic heat treatments that are often avoided because their flavor impact in mead production have the potential to alter the antioxidant capacity of mead by changing phenolic profiles.     

低密度聚乙烯袋厚度对杏鲍菇减压贮藏品质的影响

为了探寻杏鲍菇减压贮藏适宜的包装材料厚度,以杏鲍菇为试材,分别采用0.03、0.05、0.07 mm低密度聚乙烯袋(low density polyethylene,LDPE)抽真空减压至0.06 MPa包装后,置于4℃冷藏30 d,探究不同厚度包装材料对减压贮藏条件下杏鲍菇的生理生化指标及品质的变化规律.结果表明:到...     

风味物质初始质量分数与储存温度对LDPE吸附性能的影响

包装材料对食品风味化合物的吸附会引起食品感官品质变化,甚至产生食品包装安全问题,其中风味物质本身的浓度和食品储存条件将直接影响包装材料的吸附特性。采用GC法测定塑料薄膜LDPE对不同种类风味化合物(己醛、乙酸丁酯、戊酮、辛醇)的吸附量,分析食品风味化合物不同的初始质量分数与储存温度对薄膜吸附过程的影响。结果表明,LDPE对风味物质平衡吸附量随着食品模拟液中的物质初始质量分数(10~1 000 mg/kg)的上升而增大;高温加剧风味物质分子运动,降低LDPE结晶度,以及改变模拟液中风味物质含量,从而促进吸附程度;但高温同时将促使乙酸丁酯等物质发生分解,一定程度上造成吸附量的减少。     

石墨炉原子吸收法测定烟用香精中的镉

建立了硝酸-过氧化氢微波消解、纵向塞曼自动背景校正、石墨炉原子吸收法测定烟用香精中镉(Cd)含量的方法,并采用该方法测定了30个烟用香精样品中的Cd含量。结果表明:①Cd含量测定的适宜条件为:硝酸钯作为基体改进剂,灰化温度600℃,原子化温度1300℃;②镉的检出限0.029μg/L,回收率96.5%～102.0%,RSD≤2.9%;③5个香精样品中未检出Cd,11个样品的Cd含量为0.08～0.18mg/kg,10个样品的Cd含量为0.21～0.38mg/kg,4个样品的Cd含量为0.41～0.53mg/kg。     

Reduction of Warmed-Over Flavor Volatiles from Freeze-Dried Lean by Supercritical CO2 Extraction

Supercritical carbon dioxide (SC-CO₂) was used to extract warmed-over flavor (WOF) volatiles from cooked, freeze-dried beef at 40°C and pressures of 10.3 MPa or 30 MPa after 2 days storage. WOF markers, hexanal, heptanal, octanal, nonanal, and 2,3-octanedione, were identified in the volatiles profile of precooked beef by dynamic headspace extraction and gas chromatography-mass spectrometry before and after CO₂ extraction. TBARS and levels of WOF markers increased over 2 days storage. There was a reduction in WOF markers at both extraction pressures. The higher pressure led to greater reduction of WOF markers (e.g., hexanal: 73.5%) than the lower pressure (e.g., hexanal: 60.3%), notably for heptanal and nonanal. SC-CO₂ may be applicable for reducing WOF volatiles from precooked meats.     

Volatiles in Skin of Low Dose Irradiated Fresh Chicken

Fresh chickens were irradiated with up to 1200 krad at 0–5°C. Volatile compounds from the skin and subcutaneous fat of these chickens, and from unirradiated controls, were analyzed by gas chromatography. Acceptability of the odor of the chickens was also evaluated. Other samples (0 and 300 krad) were evaluated by chemical and sensory analysis after storage at 4°C. Analysis of volatiles indicated that levels of octane, l-octene, hexanal, and nonane increased regularly with radiation dose. Amount of total volatiles was greater in unstored irradiated samples than in controls, but this was reversed after storage. After 14 days, the irradiated sample still had acceptable odor, while the control ahd severely deteriorated.     

热反应对鸡肉味香味料挥发性成分影响初探

用同时蒸馏提取技术对由半胱氨酸、硫胺素、味精、葡萄糖、I +C、甘氨酸、丙氨酸组成的经热反应产生的鸡肉味香味料的挥发性成分进行了分离和浓缩 ,所得到的浓缩物用GC MS技术定量分析 ,共鉴定出 40余种化合物 ,并计算出它们的含量。其中 ,重要的肉味化合物如 2 甲基 3 呋喃硫醇、二 (2 甲基 3 呋喃基 )二硫、(2 甲基 3 呋喃基 ) (2 甲基 4,5 二氢 3 呋喃基 )二硫、二 (2 甲基 4,5 二氢 3 呋喃基 )二硫、呋喃、噻吩等被鉴定出来 ,并对其感觉特性及形成途径进行了简略说明     

Interactions of Citrus Flavor Compounds with Polypropylene Films of Varying Crystallinities

Equilibrium sorption levels at 23°C were determined individually for two citrus flavor components (d-limonene and 1-carvone) into ground and unground polypropylene films of different crystallinities. Sorption levels at equilibrium were also determined for a mixture of the two flavor compounds. Aqueous solutions of the flavor compounds (200 ppm carvone and 1000 ppm limonene) were employed. Concentrations of flavors remaining in solution before and after exposure were measured by high performance liquid chromatography (HPLC). Results indicated flavor compound polarity, polymer crystallinity and the presence of other flavor compounds in a mixture influenced sorption behavior.