HS-SPME/GC-MS Method to Characterise the Flavour of Italian Pasta: Potential Application to Assess the Quality of the Products

Food flavour, consisting of a large number of volatile compounds, has great influence on consumer acceptability and, when safety and nutritional value are guaranteed, sensory parameters become the discriminating factor in the product quality assessment which determines the differentiation on the market. The present work combines head space-solid phase micro-extraction and gas chromatography mass spectrometry techniques to analyse the volatile fraction of Italian durum wheat pasta. The aim was the optimization of an analytical method suitable to show possible differences in pasta flavour richness and identify compounds that could be used as food quality markers. Twenty-three odorants were identified and confirmed by comparing their mass spectra with those of 27 standard substances. The optimum conditions for extraction temperature and time, respectively, resulted from 70 °C and 90 min; the best recoveries were achieved with 10.5 g of sample. The developed method was applied for the relative quantitative analysis of different priced pasta to verify the technique capability to highlight possible quality differences.     

Measurement of transport phenomena of volatile compounds: A review

Measurement of the transport phenomena of volatile compounds is a central preoccupation in food flavour and is the subject of the present paper. After a theoretical reminder concerning transport phenomena, the methods used for the measurement of diffusion and mass transfer of volatile compounds are described with their principles, main advantages and drawbacks. These methods are illustrated by some results obtained for flavoured model food products.

Several methods characterized by the type of diffusion coefficient measured, the method basis, the scale at which diffusion is measured and the means used to detect the diffusing molecule, are available to determine diffusion coefficients.

To study the impact of the different factors influencing aroma release, kinetic parameters extracted from release curves obtained by sampling and analysis of the gas phase can be measured and compared. The coherence between experimental conditions and mathematical models used to estimate the parameters is of major importance.     

Flavour release in the mouth

Eating is the stage at which food flavour is released, sensed and judged by consumers. The relationships between flavour compounds and sensory perception are still not entirely clear. Analysing the total flavour composition of a food does not reflect the flavour profile experienced during eating; however, new methods of analysis that model flavour release in-mouth have been developed. Recently, direct analysis of volatiles in the air expired through the nose and mouth has been achieved during eating, confirming that the volatile profile changes over time, as had been suspected from results produced by time-intensity sensory analysis. Data from these analyses may explain the link between perception and food composition as well as providing a tool for optimizing the formulation of flavours in low-fat foods.     

Food matrices – determination of odorant partition coefficients and application of models for their prediction

Foods are complex multi-component systems which are composed of volatile and non-volatile substances. The flavour profile of a food is an important criterion for the selection of our foodstuffs. The main objective of this study was the clarification of the complex relationships of the flavour release as a function of the composition of the food matrix at molecular level. Therefore the influence of matrix effects onto the odorants partition coefficients in oil–water model systems and a custard sample were investigated. The studies included a series of lactones, ester and alcohols (γ- and δ-octalactone, γ- and δ-nonalactone, γ- and δ-decalactone, ethyl hexanoate, 3-methyl-1-butanol and 2-phenylethanol). The partition coefficients were determined using static headspace gas chromatography (SH-GC). The results indicated that the custard/air partition coefficients of selected odorants are located between the water/air- and miglyol/air partition coefficients. Furthermore the mass transfer rates of selected odorants were investigated in custard- and milk powder–water samples. The values of the mass transfer rate were found higher in milk powder/water systems than in custard model. Nevertheless the results indicated that the viscosity of the matrix did not significantly influence the values of mass transfer rate of selected flavour compounds.     

不同品种浓香亚麻籽油的呈香特征解析

目的 选取全国不同产区的28个主栽品种为对象制备浓香亚麻籽油,并对其风味特征进行分类。方法 运用评估适合项目法(rate-all-that-apply method,RATA)法建立亚麻籽油感官描述词并进行感官评价,采用顶空固相微萃取-气相色谱-质谱法(headspace solid phase microextraction-gas-chromatography-mass,HS-SPME-GC-MS)分析浓香亚麻籽油挥发性风味物质,使用正交偏最小二乘法(orthogonal projections to latent structures,OPLS)将关键挥发性风味物质与感官评价结果进行关联。结果 浓香亚麻籽油主要呈现出焦糊味、油脂味、烤香味、海鲜味和香油味,从28种浓香亚麻籽油中共检测出86种挥发性物质,其中48种物质具有香气贡献,关键挥发性风味物质有29种(气味活性值(odor activity value,OAV)＞1),不同的香气属性与不同的关键挥发性风味物质具有一定的关联性。结论 基于风味导向可以将28种浓香亚麻籽油大致分为三类,第一类(晋亚24号、坝选3号等)哈喇味较重,主要与(E)-2-戊醇、己醇、1-戊烯-3-醇等醇类物质有关,第二类(陇亚13号、坝亚13号等)主要呈现烤香味和海鲜味,第三类(晋亚10号、宁亚21号、陇亚10号等)主要呈现出谷物味、焦糊味和油脂味,焦糊味、烤香味主要由2-乙基-6-甲基吡嗪、2,6-二乙基吡嗪、2-乙酰基-3-甲基吡嗪等吡嗪类风味物质构成,油脂味、海鲜味主要由(E,E)-2,4-庚二烯醛、(E)-2-己烯醛、(E)-2-辛烯醛、1-戊烯-2-酮、2(5H)-呋喃酮等醛酮类风味物质构成,谷物味主要与二甲基二硫醚关系最密切。     

Volatile constituents from a guava (Psidium guajava L.) natural flavour concentrate

The volatile constituents of a commercially produced guava natural flavour concentrate were isolated by simultaneous distillation-extraction with diethyl ether. The resultant essence was analyzed by capillary gas chromatography and GC-MS technique. A total of 29 compounds was identified, from which 10 substances could be described for the first time as guave fruit constituents.     

Effect of Browning Reactions on the Formation of Flavour Substances

Nonenzymic browning reactions are usually accompanied by side reactions resulting in the formation of various flavour substances. The amount of volatile flavour compounds is very low in comparison with that of brown pigments. Flavour compounds are formed from intermediary reaction products by several secondary reactions: 1. cyclization of oligosubstituted hydroxylic, thiol, amine, carboxylic and carbonylic derivatives; 2. condensation of volatile carbonylic derivatives with amine, sulphur, or other carbonylic derivatives; 3. Strecker degradation of amino acids and peptides by quinones, osones, and triosones; 4. aldolization of aldehydes, especially in presence of amines; 5. spontaneous or thermic decomposition of macromolecular brown pigments or intermediary Schiff bases; 6. binding of flavour compounds into flavour-neutral or modified-flavour derivatives. By modifying the composition of ingredients or by adjusting the processing and storage conditions it is possible to obtain desirable flavour properties.     

食品接触材料中挥发性气味物质分析技术的研究进展

目前食品接触材料安全性日益受到关注。食品接触材料产生的挥发性物质,常常具有异常的气味,可能通过气相传质或直接接触迁移至食品中,不但会引发食品感官特性的变化,影响消费者的使用体验,削弱消费者购买欲望,过量摄入后还会危及人体健康。因此,准确识别和检测食品接触材料产生的异味物质,对确保食品接触材料的合规以及保护消费者健康安全显得尤为重要。本文对国内外关于挥发性物质气味评估和检测技术及其在食品接触材料领域的运用进行综述。重点介绍了顶空、顶空-固相微萃取、热脱附、电子鼻等气味分析技术,及其与气相色谱、气相色谱/质谱或气相色谱-嗅闻-质谱仪等结合的联用分析技术,并梳理和展望了食品接触材料中挥发性气味物质分析技术发展前景,为有效管控食品接触材料异味问题提供技术参考。     

Analysis of Daqu produced in different seasons

This investigation undertook a systematic analysis of two kinds Daqu (Tao‐hua qu and Fu‐qu) made by same method, but in different seasons (spring and summer). The analysis determined the content of microorganisms, enzyme activity and flavour component of the Daqu. From the results, it was noted that the prokaryotic microbial species present in Daqu were much more complex than the eukaryotic microorganisms; from the results of Operational Taxonomic Units, prokaryotic microorganisms were about 6–8 times greater than eukaryotic microorganisms. With regards to eukaryotic microorganisms, Fu‐qu contained a more complex consortium than Tao‐hua qu, but Tao‐hua qu contained a more complex prokaryotic population than Fu‐qu. The saccharification and liquefaction of Daqu were achieved by the mould and a saccharifying enzyme, which was secreted by the mould. The growth temperature of the mould was 20–30 °C and from the analysis results it can be seen that the saccharification and liquefaction of Tao‐hua qu produced in the spring was higher than that of Fu‐qu produced in the summer. A qualitative analysis of the volatile flavour substances in Daqu was performed using the methods of the NIST data‐base and relative retention indices. Approximately 26 kinds of volatile flavour substances were detected in the Tao‐hua qu compared with approximately 22 kinds of volatile flavour substances in the Fu‐qu. A specific observation of the volatile flavour substances of the two was that Tao‐hua qu and Fu‐qu had about 13 volatile flavour compounds that were common to both. Copyright © 2016 The Institute of Brewing & Distilling     

Two-film theory of flavour release from solids

A new theory for flavour release from solid or semi-solid foods is is proposed which uses twolayer, stagnant film theory to calculate the mass transfer coefficient for the flavour across the food-saliva interface. The theory is applied to the simple case of flavour release from a boiled sweet. By using the colours which dye the sweet as a substitute for flavour, the theoretical predictions are compared with experiment, both for simple solution of the dye into stirred water and for the more realistic case of mass loss on sucking in the mouth. The role of changing food-saliva interfacial area is explicitly incorporated into the theory and used as a basis for classifying flavour release from other types of food.     

The Influence of Yeast Strains on the Volatile Flavour Compounds of Chinese Rice Wine

In order to assess the influence of yeast strains on volatile flavour profiles of Chinese rice wine, small‐scale Chinese rice wine brewing was carried out with eight yeast strains from three different typical Chinese rice wine brewing regions. The volatile flavour compounds were extracted by headspace solid phase microextraction (HS‐SPME) and analyzed by gas chromatography‐mass spectrometry (GC‐MS). The volatile flavour profiles of the different Chinese rice wines showed statistically significant differences depending on the yeast strains used. Yeast strains from the Shaoxing region showed a higher capacity to produce the esters 2‐phenylethanol and 3‐methylthiopropanol, while yeast strains from the Shanghai region stood out for their production of branched‐chain higher alcohols. Chinese rice wine fermented with a yeast strain from the Jiangsu region had the highest levels of organic acids. Using principal component analysis of the Chinese rice wine volatile flavour compounds, the eight yeast strains could be classified into three groups according to their origins. This is the first report about the volatile flavour characteristics of Chinese rice wine yeast. The data obtained in this work shows that the yeast strains contributed significantly to the flavour differences of the Chinese rice wines from the different regions.     

Headspace concentration of selected dry-cured aroma compounds in model systems as affected by curing agents

The effect of curing agents (sodium chloride, nitrate, nitrite, glucose, and ascorbic acid) on the headspace concentration of six volatile compounds (2-methyl-butanal, 3-methyl-butanal, 2-pentanone, hexanal, methional, and octanal) has been studied. These volatile compounds were selected based on their presence and contribution to the flavour of typical Spanish dry-cured meat products. The release of volatile compounds to the headspace has been studied by using solid-phase microextraction (SPME) and gas chromatography analysis. The main effect was produced by sodium chloride, because it produced a salting-out effect on all the volatile compounds studied. Furthermore, the presence of nitrite, nitrate, and ascorbic acid in the solution also produced an increase in the headspace concentration of the volatile compounds while glucose decreased the headspace concentration of octanal and hexanal. The changes in the relative proportions of volatile compounds due to the effect of curing agents should be taken into account as they may change the flavour perception of dry-cured meat products.     

Chemical tainting of foods

Taints and off-flavours in food are a major cause of consumer rejection of the food product, and consequently the occurrence of such flavour defects is of great concern also to the manufacturer. Unacceptable flavours in foods may develop within the food through chemical or microbial action on food components, or they may be inadvertently introduced into the food during processing or storage, by absorption of chemicals from airborne, waterborne or packaging-related sources. The chemicals responsible for taints and off-flavours are usually volatile organic compounds, which are frequently found at concentrations of less than 1 μg kg⁻¹, and cause flavour problems because of their low odour-threshold values. This paper discusses the possible origins of off-flavours and taints in foods, and describes some incidents in which food taints have been caused by chemical contamination from the environment.     

Flavour release from rehydrated French beans (Phaseolus vulgaris) influenced by composition and volume of artificial saliva

Influence of saliva composition and volume on flavour release from rehydrated French beans (Phaseolus vulgaris) was studied in three types of mouth model systems; dynamic headspace (DH), dynamic headspace and mastication (DHM) and a purge-and-trap (PT) model system. Volatile compounds were analysed by gas chromatography, using flame ionization detection (FID), mass spectrometry and sniffing port detection. Areas of FID peaks were largest in the PT system, followed by those of the DHM and DH systems, respectively. Saliva composition as well as volume influenced the release of volatile compounds from rehydrated French beans. Generally, FID data showed a decrease in release by the saliva component mucin, because of interactions between volatile compounds and protein, and an increase in release by its α-amylase, probably due to degradation of inclusion complexes of starch. The decrease in flavour release by the enlarged saliva volume was evaluated by a model study. Sniffing patterns of odour active compounds were barely influenced by either saliva composition or volume.     

Volatile profiles of aromatic and non-aromatic rice cultivars using SPME/GC–MS

Rice (Oryza sativa L.) is enjoyed by many people as a staple food because of its flavour and texture. Some cultivars, like scented rice, are preferred over others due to their distinctive aroma and flavour. The volatile profile of rice has been explored by other investigators, some of whom have also determined a corresponding aroma using GC/olfactometry. However, little research has been done to determine if different aromatic rice cultivars produce different flavour volatiles that would make them more desirable than others when cooked. In this study, seven aromatic and two non-aromatic cultivars were examined for their volatile profiles both before and after storage using solid phase microextraction (SPME) fibres in conjunction with gas chromatography/mass spectrometer (GC–MS). Ninety-three volatile compounds were identified, 64 of which had not been previously reported in rice. Differences were found in the volatile compounds of aromatic and non-aromatic rice besides 2-acetyl-1-pyrroline (2-AP). Most of the volatile compounds were present in freshly harvested rice and rice following storage, with very few new compounds being identified only after storage. Dellrose, an aromatic cultivar, and Cocodrie, a non-aromatic cultivar, had the most complex volatile profiles (over 64 volatiles). Sixteen compounds were found only in the aromatic cultivars, and some volatiles were found to be unique to specific aromatic cultivars. However, no distinctive pattern was observed that would identify a cultivar as being derived from Basmati, Khao Dawk Mali 105 (i.e. jasmine), or other sources of aroma. This study showed that there is a great diversity of volatiles in both aromatic and non-aromatic rice cultivars and, with further research, this may lead to a better understanding of the combination of compounds that gives a cultivar a unique flavour.     

酱中挥发性风味物质的研究进展

酱是日常生活中重要的调味品,风味是影响酱品质的重要指标之一。近年来对酱中挥发性风味成分的研究发展迅速,从提取、分离、鉴定、主要特征香气成分及其影响因素等方面对酱的挥发性风味物质进行综述,并对今后酱中挥发性风味成分的深入研究提出了一些建议。     

Flavour release from rehydrated French beans (Phaseolus vulgaris) influenced by composition and volume of artificial saliva

Influence of saliva composition and volume on flavour release from rehydrated French beans (Phaseolus vulgaris) was studied in three types of mouth model systems; dynamic headspace (DH), dynamic headspace and mastication (DHM) and a purge-and-trap (PT) model system. Volatile compounds were analysed by gas chromatography, using flame ionization detection (FID), mass spectrometry and sniffing port detection. Areas of FID peaks were largest in the PT system, followed by those of the DHM and DH systems, respectively. Saliva composition as well as volume influenced the release of volatile compounds from rehydrated French beans. Generally, FID data showed a decrease in release by the saliva component mucin, because of interactions between volatile compounds and protein, and an increase in release by its -amylase, probably due to degradation of inclusion complexes of starch. The decrease in flavour release by the enlarged saliva volume was evaluated by a model study. Sniffing patterns of odour active compounds were barely influenced by either saliva composition or volume.     

The role of rheological behaviour in flavour perception in model oil/water emulsions

Decreasing the fat content of a food produces changes in a range of physical, chemical and sensory properties that are important in flavour perception. The aim of this paper was to study the role of rheological behaviour in flavour perception in model oil/water emulsions, using a series of samples with different hydroxypropyl methyl cellulose (HPMC) and oil content. The composition of the emulsions was adjusted to deliver iso-release aroma in vivo and to produce samples with the same viscosity in-mouth (measured as the Kokini oral shear stress). The results showed that there was no significant difference in perceived thickness between the three samples providing further evidence that the Kokini oral sheer stress is well correlated with in-mouth thickness. However, there was a significant difference in perceived volatile fruity flavour and sweetness. Samples containing the highest oil content were perceived as significantly less fruity and sweet despite having the same volatile release and in-mouth thickness.     

Activated carbon added to recycled paperboard to prevent migration into food: approach for determining efficacy,and first results

Catcherboard MB12® from Smurfit Kappa is a recycled paperboard incorporating activated carbon to reduce the release of contaminants into food. An approach is proposed to determine the efficacy of the activated carbon. Sorption into activated carbon increases the concentration ratio paperboard/food (distribution coefficient) and reduces the migration rate, i.e. prolongs the time for equilibration. Using silicone paper as food simulant, the concentration ratio was increased by a factor of at least 1000 compared to recycled paperboard without activated carbon, which is sufficient to meet the 1% criterion proposed for barriers. Sorbents have limited capacity. A load with in total 4000 mg surrogate substances/kg paperboard (in addition to the material from the paperboard) exceeded the capacity: concentration ratios were reduced and the release of paperboard constituents increased. Capacity is consumed by constituents from the printing inks and the packed food. Total amounts of substances in dry foods of sufficient volatility to potentially migrate into the paperboard through the gas phase at ambient temperature were determined by GC-FID. For the large majority of the dry foods, these amounts were clearly below the capacity limit even under the exaggerated assumption of total transfer. Migration of mineral oil hydrocarbons into cat food over up to 1 year was not detectable at 1 mg/kg. It is concluded that recycled paperboard with activated carbon is promising for respecting the 1% criterion stipulated for functional barriers to avoid food contamination from recycled paperboard.     

Monitoring of warmed-over flavour in pork using the electronic nose - correlation to sensory attributes and secondary lipid oxidation products

Sensory analysis of meatballs was carried out to monitor the warmed-over flavour (WOF) development in cooked, cold-stored (at 4 °C for 0, 2 and 4 days) and reheated meatballs derived from M. longissimus dorsi (LD) and M. semimembranosus (SM) of pigs fed a standard diet supplemented with either 3% of rapeseed oil or 3% of palm oil. This was performed in combination with measurement of volatile compounds using a solid-state-based gas sensor array system (electronic nose) and gas chromatography/mass spectrometry together with measurement of thiobarbitoric acid reactive substances (TBARS). Subsequently, to elucidate the relations and predictability between the obtained data, the gas sensor responses were correlated with chemical (volatile and non-volatile secondary lipid oxidation products) and sensory data (flavour and odour attributes), using partial least squares regression modelling (PLSR). The TBARS, hexanal, pentanal, pentanol and nonanal all correlated to the sensory attributes associated to WOF formation. Moreover, the responses from eight of the MOS (metal oxide semiconductor) sensors within the electronic nose proved to be significantly related to WOF characteristics detected by both sensory and chemical analysis, while six of the MOSFET (metal oxide semiconductor field effect transistor) sensors were related to freshly cooked meat attributes determined by sensory analysis. The obtained results show the potential of the present gas sensor technology to monitor WOF formation in pork.