Flavor chemistry of 2-methyl-3-furanthiol,an intense meaty aroma compound

Volatile compounds containing sulfur make very important contributions to the aromas associated with various foods, and often define the characteristic flavor of the food. Thiols are especially potent; some have the lowest aroma thresholds of any food odorant. In this review, we focused on 2-methyl-3-furanthiol (MFT) which is a potent meaty flavor. We summarized the natural occurrence of MFT in a variety of meat products, together with its common isolation and detection techniques. MFT is generated in food processing in different pathways, among which Maillard reaction between carbohydrates and cysteine is the most common. Other than that it can also be formed from thiamin degradation or enzymatic reactions. Being unstable, MFT readily reacts with different components in food systems including forming disulfides through radical reactions or interacting with melanoidins through ionic reactions. MFT also has good antioxidant activities, in both aqueous and organic systems and can protect from lipid peroxidation. The metabolism of MFT in rat liver is also discussed.     

尿素对抗坏血酸-半胱氨酸模式反应形成香味化合物的影响

以固相微萃取-气相色谱-质谱联用(SPME-GC-MS)技术对抗坏血酸与半胱氨酸(ASA-Cys)的模式反应产物进行鉴定,考察了尿素对模式反应形成香味化合物的影响。鉴定出了呋喃、吡嗪、噻吩、噻唑、噻吩并噻吩及脂环硫化物在内的47个香味化合物,其中,含硫化合物(噻吩、噻吩并噻吩、脂环硫化物)是最为丰富的香味成分。尿素加入到模式体系中(pH=8.00),一方面使一些含硫化合物的产量显著降低,甚至消失;另一方面却促进了几个含氮化合物,如吡嗪、甲基吡嗪、乙基吡嗪、2,6-二甲基吡嗪及其他烷基吡嗪的生成。表明在模式反应中,尿素受热能够释放出NH3,NH3与H2S和ASA降解产物发生竞争反应形成含氮化合物如烷基吡嗪,从而导致含硫化合物的产量降低。     

Application of headspace analysis to the study of aroma compounds-lipids interactions

Taking into account interactions between aroma compounds and food components is necessary to better manage the flavoring of food products. These interactions occur at a molecular level and reflect changes, at a macroscopic level, in thermodynamic equilibria, such as solubility or volatility. The rate of transfer of an aroma compound from the liquid to the vapor phase can be affected as well. The behavior of aroma compounds in water and lipid solutions was studied in two complementary ways, a thermodynamic and a kinetic approach (head-space analysis). The transfer rate of volatiles at the liquid-water interface does not only depend on the hydrophobicity of the aroma compounds. Vapor-liquid partition and activity coefficients show the presence of solute-solvent interactions. The Gibbs free energy values indicate their physicochemical nature.     

Dynamic Accumulation of Volatile Compounds Between Olive Pulps and Stones and Its Relation with the Fatty Acids Content During the Oil Extraction Process of Ouslati and Chemlali Olive Fruits

The characterization of both volatiles and fatty acids of Tunisian olive varieties (Ouslati and Chemlali) is achieved in order to understand their correlation with the aroma accumulation via the lipoxygenase (LOX) pathway. The main identified volatiles in both crushed pulps and crushed stones are hexanal, E‐(2)‐hexenal, (Z)‐3‐hexen‐1‐ol, 1‐hexanol, and hexyl acetate. With regard to their fatty acid composition, results show that both de‐stoned (DOO) and conventional (COO) olive oils contain mainly unsaturated fatty acids. The results also show that oleic acid (C18:1) is the main fatty acid in both DOO and COO. Meanwhile, linoleic acid (C18:2) is present in a relatively higher percentage (5.2% and 19.8%, respectively, for Ouslati and Chemlali DOI) than linolenic fatty acid (C18:3) (<2%). The analysis of volatiles shows that more than 80% of total LOX‐compounds from both crushed pulps and crushed stones have linolenic acid as synthesis precursor despite its lower level (2%). Moreover, the contribution of olive parts in generating aroma is much higher in crushed pulps (more than 80%) than in crushed stones, which explains the fact that DOO, extracted from crushed pulps, contains the dominant amount of volatiles. Therefore, the obtained results promote both the consumption and the marketing of DOO. Practical Applications: The aroma and the organoleptic properties of olive oil are strictly correlated with both the olives quality and the extraction techniques used. Many technologies are developed to extract olive oil with highest quality. De‐stoned olive oil extraction process is one of these technical procedures. In the present work, the characterization of volatiles in pulp and stone separately provides important information about the contribution of olive constitutive parts on the accumulation of olive oil aroma during the oil extraction process.     

Interactions between volatiles and lipids in complex systems

Partition equilibria of three aroma compounds in three different biphasic systems were studied by a liquid/liquid partition technique to investigate interactions that occur between volatiles and lipids in biphasic solutions. The lipids used were linoleic acid and ricinoleic acid and tetradecane as a model. The three aroma compounds were ethyl acetate, 2,5-dimethylpyrazine, and oct-1-en-3-ol. The results showed that the intermolecular forces involved were weak. Infrared spectroscopy was then performed on binary systems (tetradecane and linoleic acid or aroma compound) and on ternary systems (tetradecane, linoleic acid, and aroma compound) to determine the nature of the interactions. This method confirmed the presence of hydrogen bonds between linoleic acid and 2,5-dimethylpyrazine or oct-1-en-3-ol and also between molecules of oct-1-en-3-ol when the latter are present at high concentrations in lipids. The observations provided sufficient information to explain the behavior of oct-1-en-3-ol in biphasic solutions, but further work is needed to fully elucidate the nature of interactions between ethyl acetate or 2,5-dimethylpyrazine and lipids and also to explain the behavior of these compounds in biphasic solutions.     

Volatile Profiles of Rapeseed Oil Flavored with Basil,Oregano, and Thyme as a Function of Flavoring Conditions

The flavoring of oils with herbs gives a specific taste and aroma to the oils and may increase their antimicrobial and antioxidant activity. The volatile aroma compounds in flavored rapeseed oil were studied as a function of flavoring conditions, by means of headspace solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis. Rapeseed oils were flavored with dried basil, oregano, and thyme at two different concentrations (3 and 6%) and were heated at different temperatures and for various time intervals, followed by filtration. In the headspace of flavored oils, the main volatiles of the dried herbs were detected. In general, the share of monoterpenes in the headspace of flavored oil was higher than in the original dried herbs, while sesquiterpenes and phenolic compounds were detected to a considerably lower extent in the oil than in the herbs. The concentrations of the volatiles detected in the oil increased with increasing heating time and temperature.     

Oxidative stability of fermented meat products

Meat and meat products, which form a major part of our diet, are very susceptible to quality changes resulting from oxidative processes. Quality of fermented food products depends on the course of various physicochemical and biochemical processes. Oxidation of meat components in raw ripening products may be the result of enzymatic changes occurring as a result of activity of enzymes originating in tissues and microorganisms, as well as lipid peroxidation by free radicals. Primary and secondary products of lipid oxidation are extremely reactive and react with other components of meat, changing their physical and chemical properties. Oxidised proteins take on a yellowish, red through brown hue. Products of lipid and protein degradation create a specific flavour and aroma ; furthermore, toxic substances (such as biogenic amines or new substances) are formed as a result of interactions between meat components, e.g. protein-lipid or protein-protein combinations, as well as transverse bonds in protein structures. Oxidation of meat components in raw ripening products is a particularly difficult process. On the one hand it is essential, since the enzymatic and non-enzymatic lipid oxidation creates flavour and aroma compounds characteristic for ripening products; on the other hand excessive amounts or transformations of those compounds may cause the fermented meat product to become a risk to health.     

植物性天然香料的研究进展

介绍了植物性天然香料的重要成分萜烯类、酚类、生物碱类的生物功效与毒副性,探讨了影响其组成的环境因素,对比说明了水蒸气蒸馏法、超临界萃取法、溶剂萃取法、压榨法、微波辐射诱导萃取法的优缺点。对植物性天然香料的分离原理与技术、现代仪器分析方法进行了综述,介绍了顶空分析法、固相富集法,并列出了植物性天然香料在各行业中的具体应用情况。指出今后植物性天然香料的研究方向是应用生物反应工程及微波技术等,以提高香料的提取收率,综合利用,进一步分离精制,开发出具有特效功能的高附加值产品。     

Influence of heat pump drying on tomato flavor

ABSTRACT

Tomato flavor from a heat pump dehumidifier dryer was characterized and compared to fresh and freeze-dried tomato samples for the retention of fresh flavor compounds. The monitored quality parameters were nonvolatile, volatile, and odor intensity. There were no differences in nonvolatile profiles; however, significant changes in key odor-impact volatiles were observed. Commercial spray-dried tomato was also evaluated to examine thermally induced volatile changes. The volatile and sensory profiles of heat pump dried tomato were comparable to freeze-dried tomato, with good retention of fresh aroma. In contrast, loss of compounds contributing to fresh green aroma ((E)-2-hexenal, 1-penten-3-one, 1-hexanol) and presence of heat-induced compounds (dimethyl sulfide, furfural, pyrrole derivatives) were detected in the spray-dried tomato.     

固始鸡/A-A鸡鸡汤中香味物质的比较

河南固始鸡 /华都肉鸡 (A A鸡 )分别经过同时蒸馏提取及高压蒸煮—常压蒸馏—溶剂萃取 ,香气提取物用Vigreux柱浓缩 ,然后用气 质联用仪对其进行分析。结果表明 ,重要的鸡肉味香味化合物反 ,顺 2 ,4 癸二烯醛、反 ,反 2 ,4 癸二烯醛还有反 2 辛烯醛、壬醛、反 2 壬烯醛、顺 2 癸烯醛、反 2 十一烯醛均从本实验的两种方法中分离鉴定出 ;而在高压蒸煮—常压蒸馏—溶剂萃取法中 ,固始鸡含有华都肉鸡所没有的重要香味物质如壬醛、1 甲氧基 4 ( 1 丙烯基 )苯 (反式茴香醚 )、十六醛、9 十八烯醛、1 十八醇等 ;反 ,反 2 ,4 癸二烯醛的含量固始鸡是A A鸡的 7倍还多     

Influence of Prolonged Deep-Frying Using Various Oils on Volatile Compounds Formation of French Fries Using GC–MS,GC-O,and Sensory Evaluation

Flavor is a decisive sensory characteristic to determine the popularity of French fries (FF). To investigate the effect of prolonged deep-frying using various oils on volatiles formation of FF, the FF were prepared in the palm oil (PO), soybean oil (SO), and high-oleic rapeseed oil (RO) for 24 hours intermittent frying. The effect of oil types was found to be more significant than the frying time on the volatiles of FF indicated from the clusters of the fried FF by chemometric analysis. A total of 26 key aroma-active compounds were identified by aroma extract dilution analysis, in which aldehydes were predominant. The FF fried in SO revealed higher desirable aroma compounds, i.e., (E, E)-2,4-decadienal and it increased to maximum value at 12 hours, and left the deep-fried odor in FF. Meanwhile, a significant increase in metallic off-flavor was observed in FF fried in SO and PO at 20 hours, indicating that oil quality reduction resulted in FF with unappealing flavor. The above results showed that frying process had an optimum frying window (approximately 4–16 hours with total polar compounds content below 22.2%), and the French fries prepared in this period obtained higher flavor scores. The study will provide insights into the effect of oil types and oxidation degree on obtaining the ideal flavors for fried food.     

Effect of processing on flavor precursor amino acids and volatiles of sesame paste (tehina)

The content of flavor precursor free amino acids in dehulled sesame seeds, subjected to roasting (R), steaming (S), roasting plus steaming (RS) and microwaving (M), was determined and compared with those of the raw (RW) seeds. R, RS, and S had major effects in reducing the content of free amino acids from 2360 μg/g to 582, 795 and 884 μg/g, respectively; M had no effect on the content of free amino acids. Meanwhile, flavor volatiles of the raw and processed seeds were compared by means of a dynamic headspace analyzer/gas chromatograph-mass spectrometer. Volatiles of RW seeds contained 85 compounds, whereas under the analytical conditions employed, seeds subjected to R, RS, S, and M had 117, 97, 93 and 87 compounds, respectively. Among volatiles identified in the RW seeds were 36 hydrocarbons, 8 aldehydes, 4 ketones, 8 alcohols, 2 acids, 2 esters, and 1 pyrazine. The only pyrazine identified in the RW seeds was 2,5-dimethylpyrazine. Pyrazines, generally recognized as contributors to the roasted aroma of foods, were more numerous (10 in R, 6 in RS, 2 in S, and 2 in M) and prevalent (8.71% in R, 2.97% in RS, 2.04% in S, 0.53% in M, and 0.25% in RW) in the volatiles of processed sesame seeds. The chemical nature of pyrazines also depended on the process employed. Multivariant analysis indicated a highly negative correlation between the loss of free amino acids and production of volatile flavor compounds in the R and RS samples, while the M sample remained unchanged. Furthermore, both R and RS seeds contained dimethyl sulfide and dimethyl disulfide, whereas no sulfur-containing compounds were present in other samples. Of the processed seeds, the flavors of R and RS samples were considered as acceptable, and the flavor intensity of the former was deemed stronger than that of the latter by the experimenters.     

Characterization of Aroma-Active Compounds in Iranian cv. Mari Olive Oil by Aroma Extract Dilution Analysis and GC–MS-Olfactometry

Aroma, aroma‐active compounds and fatty acid profiles of Iranian olive oil obtained from the cv. Mari were investigated for the first time in the current study. Aroma extracts were isolated from the oil by using a purge and trap extraction system and their compositions were analyzed by gas chromatography‐mass spectrometry‐olfactometry (GC–MS‐O). A total of 35 aroma compounds comprising alcohols, aldehydes, acids, esters, ketones, terpenes and volatile phenols were identified and quantified in the assayed samples. Aldehydes were present at the highest levels, followed by ketones and alcohols. (E)‐2‐Hexenal was quantitatively (1589 µg kg^?1) the main aroma compound in the analyzed oils, followed by hexanal and (E)‐2‐heptenal. The aroma‐active volatiles were elucidated in the aromatic extract by applying aroma extract dilution analysis (AEDA). The results of AEDA revealed 17 aroma‐active compounds. Under these condition it was possible to completely identify 16 of these compounds. Regarding to the flavor dilution (FD) factor, the most potent odorants with the highest FD factor were (E)‐2‐hexenal (512), followed by hexanal, 6‐methyl‐5‐hepten‐2‐one, (E)‐2‐decenal and one unknown compound (LRI = 1871). The fatty acid profile of the tested oils was composed of thirteen compounds. Oleic acid was the main fatty acid (76.01 %) followed by palmitic acid.     

3-Alkyl-2-Methoxypyrazines: Overview of Their Occurrence,Biosynthesis and Distribution in Edible Plants

Pyrazines are ubiquitous in nature – biosynthesized by microorganisms, insects, and plants. Due to their great structural diversity, they own manifold biological functions. Alkyl- and alkoxypyrazines for instance play a key role as semiochemicals, but also as important aroma compounds in foods. Especially 3-alkyl-2-methoxypyrazines (MPs) have been of great research interest. MPs are associated with green and earthy attributes. They are responsible for the distinctive aroma properties of numerous vegetables. Moreover, they have a strong influence on the aroma of wines, in which they are primarily grape-derived. Over the years various methods have been developed and implemented to analyse the distribution of MPs in plants. In addition, the biosynthetic pathway of MPs has always been of particular interest. Different pathways and precursors have been proposed and controversially discussed in the literature. While the identification of genes encoding O-methyltransferases gave important insights into the last step of MP-biosynthesis, earlier biosynthetic steps and precursors remained unknown. It was not until 2022 that in vivo feeding experiments with stable isotope labeled compounds revealed l -leucine and l -serine as important precursors for IBMP. This discovery gave evidence for a metabolic interface between the MP-biosynthesis and photorespiration.     

Aroma‐Relevant Volatile Compounds as Markers for the Sensory Quality of Argan Oil

The aim of the present work is to identify and characterize the most important aroma active compounds of argan oil from unroasted and roasted argan almonds as well as roasted almonds obtained from goat‐digested fruits by dynamic headspace GC and GC‐olfactometry with aroma dilution analysis to classify samples from the market according to their processing. While fresh ground argan almonds are characterized by only seven aroma active compounds, in argan oil from unroasted and roasted almonds, 22 and 35 aroma active compounds are found, respectively. As a result of the roasting process, 14 aroma active compounds with dilution factors >64 are detected in the oil by GC‐olfactometry. 17 aroma active compounds show significant differences between the three different argan oil qualities. These compounds are used to differentiate the quality of argan oil from the market. Practical Application: Argan oil belongs to the high‐price oils on the market but sometimes the sensory quality of the oil contradicts the positive image that has been built up for oil by unpleasant cheese‐like and fusty sensory attributes. Although some information about the composition of the volatile compounds of cold‐pressed argan oil from unroasted and roasted kernels is available, the knowledge about compounds that are typical for the aroma of argan oil is important in order to develop analytical methods for the classification of different argan oil qualities. This reduces the work for a panel group that is often time and labor consuming and sometimes the results are not reliable. The present paper demonstrates which volatile compounds show significant differences between argan oil from unroasted and roasted argan almonds as well as roasted almonds obtained from goat‐digested fruits allowing a differentiation of these oils.     

The impact of processing on the profile of volatile compounds in sesame oil

The flavor of sesame oil significantly depends on the roasting conditions and the relative concentrations of volatiles. In the present study, volatile components from three varieties of sesame oil produced by roasting the seeds under different conditions were analyzed and profiled using GC–mass chromatography. The results showed that the roasting temperature had an obvious effect on the aroma of the oils since there was an increase in the concentration of the volatiles responsible for aroma such as pyrazines, furans, and sesamol as the temperature at which the seeds were roasted was increased. However, the concentration of some components such as alcohols and aldehydes, decreased with an increase in the roasting temperature. The roasting conditions have an important effect on the characteristic aroma of sesame oil. Other methods used to process sesame oil, such as solvent extraction, mechanical pressing and hot water flotation, were also investigated. Sesame oil produced using the Chinese traditional hot water flotation method had the most preferred flavor. There was good consistency between the principal components analysis (PCA) and sensory evaluation. The results of the present study suggested that production of sesame oil with the most acceptable aroma was dependent on the appropriate processing method.     

Adsorbents for the recovery of aroma compounds in fermentation processes

Using a model solution of 12 aroma compounds, representative of microbial volatiles, 31 different adsorptive materials were investigated with regard to their solid phase extraction and desorption properties. Well known styrene—divinylbenzene-based resins and alternative adsorbents including zeolites, β-cyclodextrin and modified activated carbon were compared. Adsorption/desorption rates in aqueous solution were determined for each adsorbent. Isotherms and adsorption kinetics were determined for the most effective adsorbents.     

芳香疗法研究中使用的各种方法

论述了芳香疗法研究中使用的各种方法。使用这些方法的目的是增加人们对香料和精油的各种功效的了解以及这些芳香化合物作用于人体后产生的各种作用等的知识。论述并讨论了动物实验和人健康受试者试验中 ,香料化合物具有各种生理和药理作用的新成果 ,还强调了芳香疗法的正确定义     

Wechselwirkungen zwischen Aromastoffen und Lipiden 2. Mitteilung: Sorption ausgewählter Aromastoffe an Kakaobutter

Interactions Between Aroma Compounds and Lipids, 2. Sorption of Some Selected Aroma Compounds on Cocoa Butter The specific retention volumes and retention indices of 30 aroma compounds on cocoa butter have been determined at some temperatures between 90° and 130° C or between 130° and 170° C. The linear correlations between the logarithms of the specific retention volumes or the retention indices and the boiling points proved to be the best ones of several correlations. They can serve for the estimation of the reversible sorbed amounts of not tested aroma compounds. Possibilities of extrapolation to other temperatures are discussed. The retention values depend on the relation of aroma compound to cocoa butter. Another linear relationship exists between the sorption heats and the boiling points.