Characterization of volatile aroma compounds after in-vial cooking of foxtail millet porridge with gas chromatography-mass spectrometry

Changes in the grain quality of foxtail millet released in China from the 1970s to the 2020s

Foxtail millet (Setaria italica (L.) P. Beauv.) is popular for its medicinal and edible properties and is an important strategic reserve crop for future complex climates. In this study, the genetic diversity of 5 representative foxtail millet genotypes released from the 1970s to the 2020s was examined for their appearance quality, nutritional quality, amino acid contents, culinary quality and aroma profiles. The trend of these indicators over the 60 years of cultivar release was revealed. The results revealed that the genetic gains of b*, yellow pigment content (YPC), breakdown viscosity (BD), setback viscosity (SB), and consistency (CS) were 0.45 %, 0.93 %, 0.34 %, -1.97 %, and - 0.68 %, respectively. The replacement of foxtail millet cultivars improved their appearance quality, culinary quality, and aroma and decreased their nutritional quality. Overall, a compensation effect exists between nutritional quality and organoleptic quality. The transitional foxtail millet variety has advantages over both the old varieties and modern varieties. Therefore, breeders need to focus on improving the nutritional quality of foxtail millet and utilize the quality advantages of the transitional variety in the future.

Metabolite profiling of foxtail millet varieties from Qingyang using GC-MS and LC-MS analysis

Foxtail millet has been cultivated in Gansu Province for centuries, with several dominant cultivars; however, the metabolic differences among these varieties remain unclear. Therefore, the volatile and non-volatile metabolites of five different millets cultivars were analyzed using GC-MS and LC-MS techniques. A total of 64 volatile compounds were detected by GC-MS, among which aldehydes were the main contributors to foxtail millet flavor. A total of 1512 metabolites were detected by LC-MS. Comparison of HMDB (Human Metabolome Database) showed that the proportion of lipids and lipid-like molecules among the metabolites of JG21, ZZ13, and JF107 was the highest, while those of HM and JG1 predominantly consisted of organic acids and their derivatives. Additionally, 16 differential metabolites of polyphenols were screened and the biosynthetic pathways of flavonoids such as apigenin, luteolin, and phloretin were identified through KEGG (Kyoto Encyclopedia of Genes and Genomes) annotation. This study can provide a reference for the processing and quality control of downstream products of foxtail millet.

Uncovering the Differences in Flavour Volatiles from Hybrid and Conventional Foxtail Millet Varieties Based on Gas Chromatography-Ion Migration Spectrometry and Chemometrics

The flavour of foxtail millet (Setaria italica (L.) P. Beauv.) is an important indicator for evaluating the quality of the millet. The volatile components in steamed millet porridge samples were analysed using electronic nose (E-Nose) and gas chromatography-ion mobility spectrometry (GC-IMS) techniques, and characteristic volatile fingerprints were constructed to clarify the differences in the main flavour substances in different foxtail millet varieties (two hybrids and two conventional foxtail millets). After sensory evaluation by judges, Jingu 21 (JG) scored significantly higher than the other varieties, and the others were, in order, Jinmiao K1 (JM), Changzagu 466 (CZ) and Zhangzagu 3 (ZZ). E-Nose analysis showed differences in sulphides and terpenoids, nitrogen oxides, organosulphides and aromatic compounds in different varieties of millet porridge. A total of 59 volatile components were determined by GC-IMS in the four varieties of millet porridge, including 23 aldehydes, 17 alcohols, 9 ketones, 4 esters, 2 acids, 3 furans and 1 pyrazine. Comparative analyses of the volatile components in JG, JM, ZZ and CZ revealed that the contents of octanal, nonanal and 3-methyl-2-butenal were higher in JG; the contents of trans-2-butenal, 2-methyl-1-propanol, trans-2-heptenal and trans-2-pentenal were higher in JM; and the contents of 2-octanone, hexanol, 1-octen-3-ol, 2-pentanone and butyraldehyde were higher in ZZ. The contents of 2-butanol, propionic acid and acetic acid were higher in CZ. A prediction model with good stability was established by orthogonal partial least squares discriminant analysis (OPLS-DA), and 25 potential characteristic markers (VIP > 1) were screened out from 59 volatile organic compounds (VOCs). These volatile components can be used to distinguish the different varieties of millet porridge samples. Moreover, we found conventional foxtail millet contained more aldehydes than the hybridised foxtail millet; especially decanal, 1-nonanal-D, heptanal-D, 1-octanal-M, 1-octanal-D and 1-nonanal-M were significantly higher in JG than in the other varieties. These results indicate that the E-Nose combined with GC-IMS can be used to characterise the flavour volatiles of different foxtail millet, and the results of this study may provide some information for future understanding of the aroma characteristics of foxtail millet and the genetic improvement of hybrid grains.

Analysis of dynamic flavor changes of volatile and non-volatile fractions analysis of black qingke (Hordeum vulgare L. var. nudum Hook. f.) during steaming process

Qingke (Hordeum vulgare L. var. nudum Hook. f.) is a cereal of Gramineae, and it is an indispensable food crop for people in the Qinghai-Tibetan Plateau of China. This work focused on the dynamic changes of volatile and non-volatile fractions of qingke (Heilaoya), that is, black qingke, during steaming, and the flavor variations were discussed combined with their correlation. According to the results of sensory analysis, it revealed that the rice and sweet aroma of black qingke increased with the extension of steaming time and reached the maximum at 60 min, whereas the grassy aroma decreased. Besides, a total of 43 aroma fractions were identified by gas chromatography-olfactometry-mass spectrometry, with the largest quantity showing up at 60 min. In addition, the overall flavor of black qingke became more abundant after steaming for 40-60 min. Furthermore, combined with the changes of the non-volatile substances, it was inferred that Maillard and Strecker reactions occurred between reducing sugars and amino acids, and the fractions, such as 2-acetylthiazole, 2-methylpyrazine, 2-pentylfuran, and furfural, were generated. These components mainly presented notes of baked, rice, and grain. In addition, the fatty acids undergo oxidative degradation to generate hexanal and (E,E)-2,4-decadienal. These results can provide a theoretical basis for the flavor quality control and industrial production of qingke.

Food-Grade Pickering Emulsions Stabilized by Ultrasound-Treated Foxtail Millet Prolamin: Characterization and In Vitro Release Behavior of Curcumin

To date, extensive studies have focused on developing proteins as stabilizers to fabricate food-grade emulsions for encapsulating bioactive compounds aimed at targeted delivery. This paper aimed to develop a novel stabilizer using foxtail millet prolamin (FMP) to fabricate medium internal-phase Pickering emulsions (MIPEs) and investigate the stability and in vitro release behavior of curcumin (Cur) encapsulated within the MIPEs. Ultrasound treatment modified the secondary and tertiary structures of FMP, along with its particle size, zeta potential, and wettability, enhancing its functionality as a stabilizer for MIPEs. The MIPEs stabilized by 65% ultrasound-treated FMP (FMP-U) exhibited better rheological properties and stability, significantly improving the storage stability and antioxidant activity of Cur. In vitro digestion results demonstrated that the MIPEs delayed the release of Cur, achieving a final release rate of 84.0 ± 1.47% after 4 h of gastrointestinal digestion and the DPPH radical scavenging activity (RSA) of 39.9 ± 1.31%, which was notably higher than the RSA of free Cur in oil at only 5.8 ± 1.37%. Moreover, MIPEs with Cur increased the bioaccessibility of Cur. This study provides new insights into a novel delivery system designed with FMP-U for encapsulating hydrophobic compounds, thereby enhancing their stability, sustained release, and bioaccessibility.

Influence of phospholipid structures on volatile organic compounds generation in model systems

To investigate the regularities and differences in oxidation products of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) by gas chromatography-mass spectrometry (GC-MS), and examine the influence of variations in fatty acid compositions and head groups on the kinds and contents of volatile organic compounds (VOCs) generated. A total of 42 VOCs were identified from PE (16:0-18:2), PC (16:0-18:2), and PC (16:0-18:1), with aldehydes and ketones being the main VOCs in three phospholipids (PLs). The content of most VOCs produced by PE (16:0-18:2), PC (16:0-18:2), and PC (16:0-18:1) increases with the increase of oxidation temperature and time. Reached peak at 175 °C for 60 min. The total VOCs contents generated by PE (16:0-18:2) and PC (16:0-18:2) were higher than those produced by PC (16:0-18:1), with PC (16:0-18:2) showing the highest total VOCs contents. PLs exhibited three mass loss processes with increasing temperature, namely stability, reduction, and stabilization. PC (16:0-18:2) experienced the highest mass loss, followed by PE (16:0-18:2), while PC (16:0-18:1) showed the least mass loss. These findings showed that polyunsaturated fatty acids were more susceptible to oxidation and degradation during oxidation, and the presence of choline groups in the form of PE may enhance the oxidative stability of fatty acyl groups compared to PC.

Improvement in Taste Quality of Rice Porridge Using Konjac Glucomannan

Improving the taste quality of rice porridge in a scientific way is essential to guiding residential and commercial production. This study aimed to determine the impact of konjac glucomannan (KGM) on the taste quality of rice porridge. The obtained results showed that the optimal concentration of KGM added to rice porridge is 1%. This was primarily observed via the reduction in water absorption, swelling power, and iodine blue value, thus increasing the hardness of rice porridge. At the same time, KGM also reduced the free water content and improved the water-holding capacity of rice porridge. Nevertheless, the pasting properties showed that the high viscosity of KGM raised the pasting viscosity of rice flour, thereby enhancing the stickiness of rice porridge with the increase in the KGM concentration. In addition, KGM gave the rice porridge a stronger aroma. Sensory evaluations further confirmed significant improvements in the color, odor, palatability, and overall acceptability of KGM-supplemented rice porridge (p < 0.05). To summarize, adding an appropriate amount of KGM was beneficial in forming a richer flavor and improving the taste quality of rice porridge. The findings offer valuable insights into the scientific processing of rice porridge products.

Influence of germination and roasting on the characteristic volatile organic compounds of quinoa using sensory evaluation, E-nose, HS-GC-IMS, and HS-SPME-GC-MS

This study aimed to investigate the effects of germination and roasting on the flavor of quinoa. Firstly, the aroma of quinoa and germinated quinoa roasted under different conditions was analyzed using sensory evaluation and electronic nose (E-nose). Results showed that the best favorable aroma of quinoa and germinated quinoa was obtained when roasted at 160 °C for 15 min. Then, a total of 34 and 80 volatile organic compounds (VOCs) of quinoa and germinated quinoa roasted at 160 °C for 15 min were determined using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Germination and roasting effectively reduced the contents of VOCs that produced undesirable flavor. Moreover, germination improved the floral aromas, while roasting mainly produced caramel, cocoa, and roasted nut aromas of quinoa. This study indicated that germination and roasting treatments might serve as promising processing methods to improve the flavor of quinoa.

Effect of cooking methods on volatile compounds and texture properties in maize porridge

To investigate the optimal processing of maize porridge, the volatile compounds and texture under different cooking methods and time have been studied. A total of 51 volatile compounds were identified in maize porridge. Notably, the major volatiles, aldehydes and esters exhibited a relatively high content in electric pressure cooker (EPC), and esters tend to significantly increase after cooking. Among aldehydes, nonanal and hexanal played a great role in flavor due to their relatively high content. Volatile compounds of maize porridge in different cooking methods could be clearly distinguished by multiple chemometrics. Furthermore, texture analysis revealed that almost all the indicators in the EPC can reach the lowest value at 60 min. To summarize, different cooking methods had a more significant influence on the volatile compounds and texture compared to time. This study helps to improve the sensory attributes of maize porridge, and thus contributes to healthier and more sustainable production.

Insights into the Volatile Flavor Profiles of Two Types of Beef Tallow via Electronic Nose and Gas Chromatography-Ion Mobility Spectrometry Analysis

In the current study, an electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS) were employed to investigate the volatile flavor compounds (VFCs) of intense flavor beef tallow (L) and ordinary beef tallow (P). The study results indicate that an E-nose combined with an LDA and GC-IMS combined with an OPLS-DA can effectively distinguish between the two types of beef tallow. Compared with ordinary beef tallow, the E-nose sensors of intense flavor beef tallow have stronger response signals to sulfides, terpenes, and nitrogen oxides. A total of 22 compounds contribute to making the flavor of intense flavor beef tallow more typical and richer; in contrast, ethyl acetate was the main aroma-active compound found in the ordinary beef tallow. Sulfur-containing compounds and terpenoids might be the key substances that cause sensory flavor differences between the two types of beef tallow. In conclusion, the results of this study clarify the characteristics and differences of the two types of beef tallow and provide an enhanced understanding of the differences in the flavors of the two types of beef tallow.

Uncovering the differences in flavor volatiles of different colored foxtail millets based on gas chromatography-ion migration spectrometry and chemometrics

The differences of volatile organic compounds in commercially available foxtail millets with different colors (black, green, white and yellow) were assayed through gas chromatography-ion migration spectrometry (GC-IMS) to explore their volatile flavor characteristics. Fifty-five volatile components were found in various colored foxtail millets, including 25 kinds of aldehydes (accounting for 39.19-48.69%), 10 ketones (25.36-32.37%), 15 alcohols (20.19-24.11%), 2 ethers (2.29-2.45%), 2 furans (1.49-2.95%) and 1 ester (0.27-0.39%). Aldehydes, alcohols and ketones were the chief volatiles in different colored foxtail millet, followed by furans, esters and ethers. These identified volatile flavor components in various colored foxtail millets obtained by GC-IMS could be well distinguished by principal components and cluster analysis. Meanwhile, a stable prediction model was fitted via partial least squares-discriminant analysis (PLS-DA), in which 17 kinds of differentially volatile components were screened out based on variable importance in projection (VIP>1). These findings might provide certain information for understanding the flavor traits of colored foxtail millets in future.

Characterization and discrimination of flavor volatiles of different colored wheat grains after cooking based on GC-IMS and chemometrics

Changes in flavor volatiles of three colored wheat grains (black, green, and yellow) after cooking were detected via gas chromatography-ion migration spectrometry (GC-IMS) to explore corresponding volatile flavor traits. A total of 52 volatile chemicals were spotted among these cooked wheat grains, including 30 aldehydes (accounting for 73.86-83.78%), 11 ketones (9.53-16.98%), 3 alcohols (0.88-1.21%), 4 furans (4.82-7.44%), 2 esters (0.28-0.42%), and 2 pyrazines (0.18-0.32%). Aldehydes, ketones, and furans were the main volatile compounds in three different cooked wheat. For black-colored wheat, the relative contents of benzene acetaldehyde, benzaldehyde, 2-methyl butanal, and 3-methyl butanal were much higher (p < 0.05). For green-colored wheat, the relative contents of nonanal, 2-pentyl furan, (E)-hept-2-enal, 2-butanone, and acetone were significantly higher (p < 0.05). For yellow-colored wheat, the relative amounts of heptanal, hexanal, and pentanal were much higher (p < 0.05). The overall volatile substances of the three cooked wheat grains might be classified by GC-IMS data coupled with principal component analysis and heatmap clustering analysis. A reliable forecast set was established through orthogonal partial least squares-discriminant analysis (OPLS-DA), and 22 differential volatile compounds were screened out based on variable importance in projection (VIP) being higher than 1.0, as flavor markers for distinguishing the three cooked wheat grains. These results suggest that GC-IMS could be used for characterizing the flavor volatiles of different colored wheat, and the findings could contribute certain information for understand the aroma traits in different colored cooked wheat and related products in the future.

Characterization of volatile organic compounds of different pigmented rice after puffing based on gas chromatography-ion migration spectrometry and chemometrics

The distinctness in volatile profiles of pigmented rice with various colors (black, green, purple, red, and yellow) after puffing were assayed through gas chromatography-ion migration spectrometry (GC-IMS) to explore their odor characteristics. Fifty-two volatile components were found in those puffed rice, including 27 kinds of aldehydes (accounting for 59.69-64.37 %), 9 ketones (25.55-29.73 %), 5 alcohols (2.45-5.29 %), 4 pyrazines (1.38-2.36 %), 3 ethers (0.81-1.27 %), 2 furans (0.95-1.39 %), 1 pyridine (1.0-1,16 %), and 1 pyrrole (0.59-0.71 %). Aldehydes and ketones were the two chief volatiles in different pigmented puffed rice. These identified volatile flavor components in various pigmented puffed rice obtained by GC-IMS might be well differentiated by principal component and cluster interpretation. Meanwhile, a stable prediction model was fitted via orthogonal partial least squares-discriminant analysis, and 19 differentially volatile components were screened out based on variable importance projection (VIP) above 1. These findings could add certain information for understanding the flavor profiles of pigmented puffed rice and related products.

Overview of advanced technologies for volatile organic compounds measurement in food quality and safety

Food quality and nutrition have received much attention in recent decades, thanks to changes in consumer behavior and gradual increases in food consumption. The demand for high-quality food necessitates stringent quality assurance and process control measures. As a result, appropriate analytical tools are required to assess the quality of food and food products. VOCs analysis techniques may meet these needs because they are nondestructive, convenient to use, require little or no sample preparation, and are environmentally friendly. In this article, the main VOCs released from various foods during transportation, storage, and processing were reviewed. The principles of the most common VOCs analysis techniques, such as electronic nose, colorimetric sensor array, migration spectrum, infrared and laser spectroscopy, were discussed, as well as the most recent research in the field of food quality and safety evaluation. In particular, we described data processing algorithms and data analysis captured by these techniques in detail. Finally, the challenges and opportunities of these VOCs analysis techniques in food quality analysis were discussed, as well as future development trends and prospects of this field.

Volatile compounds, bacteria compositions and physicochemical properties of 10 fresh fermented rice noodles from southern China

To clarify the discrepancy in characteristic flavor and bacteria composition of 10 fresh fermented rice noodles from southern China, the volatile and bacteria composition were determined by headspace-gas chromatography ion mobility spectrometry and 16SrRNA sequencing methods. The potential relationship between volatile compounds and bacterial composition has also been further revealed using spearman's correlation analysis. The contents of proximate composition, cooking properties and texture properties of 10 fresh fermented rice noodles exhibited significant different among them (p ＜ 0.05). The flavor analysis showed that a total of 54 compounds were detected. 1-Octen-one, ethyl 3-methylbutanoate, 3-methylbutanal, n-nonanal, hexanal, amyl acetate, ethanol and 2-pentyl furan were the key volatiles among them. The bacterial analysis showed that Leuconostoc and Lactococcus were the core bacteria at the genu level of all samples. Amyl acetate, 2-butanone and methyl-2-methylpropanoate were positively related to Lactococcus while ethanol was negatively correlated with Lactococcus. And Leuconostoc was positively related to 3-methylbutanal and acetone, while was negatively correlated with hexanal. Results indicated that key volatiles and textural properties of different fresh fermented rice noodle samples were associated with bacterial composition.

Identification of the volatile profiles of 22 traditional and newly bred maize varieties and their porridges by PTR-QiTOF-MS and HS-SPME GC-MS

BACKGROUND

Low adoption of maize varieties bred to address the nutritional needs of the growing African population limits their impact. Aroma is essential in consumer preference, but has hitherto hardly been studied. We analysed the volatile organic compounds of flours and porridges of 22 maize varieties belonging to four nutritionally distinct groups, namely provitamin A maize, quality protein maize, yellow and white maize.

RESULTS

Proton-transfer-reaction quadrupole ion time-of-flight mass spectrometry (PTR-QiTOF-MS) analysis generated 524 mass peaks ranging from 16.007 to 448.089 m/z. Principal component analysis separated the varieties belonging to the four groups. With headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME GC-MS), 48 volatile compounds were identified in maize flour and 21 in maize porridge, including hexane, nonane, pentanoic acid, 1-octen-3-ol, 1-hexanol, hexanal, nonanal, 2-pentylfuran and 2-heptanone. Volatile compounds such as 1,2,4-trimethyl benzene, associated with thermal degradation of carotenoids, increased in the porridge of yellow and provitamin A maize.

CONCLUSION

The results indicate that PTR-QiTOF-MS and HS-SPME GC-MS combined with multivariate analysis are instrumental to study the volatile aroma compounds of different maize varieties.

Characterization of volatile compounds in differently coloured Chenopodium quinoa seeds before and after cooking by headspace-gas chromatography-ion mobility spectrometry

Aroma is an important feature of quinoa that influences consumer preferences. Differently coloured quinoa seeds exhibit diverse nutritional characteristics; however, their aromatic profile differences are poorly investigated. The volatile components of 11 quinoa samples were characterized by headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). A total of 120 peaks were detected, with 61 compounds identified. White quinoa liberated a high concentration of volatiles with grass (n-hexanol) and green ((E)-2-octenal, (E)-2-heptenal, etc.) aromas before and after cooking, respectively. Raw flaxen samples uniquely released a caramel compound (cyclotene) and exhibited several sweet and caramel volatiles (decanal, 5-methyl-furfural, and 2-furfural) after cooking. Additionally, cooked black quinoa exerted more fruity substances (methyl hexanoate and phenylacetaldehyde). Orthogonal partial least square discriminant analysis clearly distinguished the samples before and after cooking and differentiated the seeds into different colours. The results confirm the potential of HS-GC-IMS to evaluate volatiles in quinoa and are meaningful for quinoa consumption.

Policosanol profiles and adenosine 5'-monophosphate-activated protein kinase (AMPK) activation potential of Korean wheat seedling extracts according to cultivar and growth time

Policosanols is a health promoting aliphatic alcohol known as lipid-lowing agent. To enable maximising the functional properties of wheat, this research investigates the policosanol profiles and adenosine 5'-monophosphate-activated protein kinase (AMPK) activation potential of Korean wheat seedlings according to cultivars and growth times. GC-MS revealed six policosanols that differed markedly in content between 17 cultivars, especially, octacosanol (8) showed the most predominant component (49-83%), varying significantly in average concentrations with growth times as 361.4 (3 days) → 613.0 (6 days) → 203.1 (9 days) → 196.5 (12 days) → 50.9 mg/100 g (19 days). The highest average policosanol (738.7 mg/100 g) exhibited after 6 days, while the lowest was 104.4 mg/100 g on 19 days. Moreover, the wheat cultivars including Shinmichal 1, Anbaek, Namhae, and Joah at 6 days may be recommended as potential sources because of high policosanols (921.7-990.6 mg/100 g). Western blot analysis revealed markedly higher AMPK activation in cells treated with the hexane extracts (150-370% at 100 μg/ml) and octacosanol (8) possessed potent AMPK activator (control; 100 → 280% at 200 μg/ml). It is confirmed that the AMPK activation by wheat seedlings are positively related to the highest policosanol content at the 6 days of growth time, independent of the cultivar. Our results may be contributed to enhance the wheat value regarding development of new cultivars and functional foods.

Variation Patterns of the Volatiles during Germination of the Foxtail Millet (Setaria Italic): The Relationship between the Volatiles and Fatty Acids in Model Experiments

Functional and nutritional compounds are increased during foxtail millet germination while bad smell is produced due to the fatty acid oxidation. To eliminate the unpleasant aroma, the origins of the volatiles must be known. A comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry showed forty-nine volatiles containing 8 ketones, 10 aldehydes, 20 alkanes, 4 alcohols, 5 alkenes, and 2 furans were tentatively identified, and they increased during the germination of the foxtail millet. To identify the origin of some volatiles, model experiments by adding 6 fatty acids to the crude enzymes of the foxtail millet was designed, and 17 volatiles could be detected. The saturated fatty acids (palmitic acid and stearic acid) had no contributions to the formation of the volatiles, whereas the unsaturated fatty acid played important roles in the formation of volatiles. Among the unsaturated fatty acids, palmitoleic acid and linoleic acid produced most aldehydes, alcohols, and ketones, while linolenic acid produced the most alkanes and alkenes. This study will be helpful for controlling the smell of germinated seeds from the raw material selection.

Volatile Profiles from Traditional Chinese Oat Meal Varied Significantly from Oat Porridge and Differed with Cultivars and Locations

Volatile profiles of oat-based foods are mainly analyzed on the oat flakes and porridge as snack or breakfast, whereas the volatile characteristics of the traditional Chinese oat meal (TCOM), a popular main food in some regions of northern China, with special strong aroma, are not known. Here, we compared the volatile profiles from headspace solid phase microextraction gas chromatography-mass spectrometry analysis of oat porridge (OP) and TCOM, which were of different processing and cooking methods, from those of different cultivars, and analyzed the effect of cultivation locations on oat volatile features. Apart from the 35 volatiles shared by OP and TCOM, there were 23 and 24 volatiles specific to OP and TCOM, respectively, with the later showing more toasting and frying-related volatiles due to the dry frying process of the grains before milling. Principle component analysis of the volatiles of OP and TCOM from 16 cultivars showed that they were clustered into two groups, and four cultivars were clustered together, independent of processing and cooking methods. The oat volatile profiles of cultivars grown in three regions of north China were dependent on the cultivation locations rather than cultivars, regardless of OP or TCOM, with those from Datong of Shanxi Province and Zhangjiakou of Hebei Province clustered together. The location effect could be due to significant less precipitation in the two regions above than the other region Ulanqab of Inner Mongolia. PRACTICAL APPLICATION: The volatile compounds in oat are closely related to cultivation regions, which could be applied as a key factor by oat producers for marketing. The four cultivars showed similar and stable volatile profiles, which could be used as reference cultivars for breeding of high-quality oat with better flavor.

Identification of volatile compounds and odour activity values in quinoa porridge by gas chromatography-mass spectrometry

BACKGROUND

Quinoa porridge is becoming popular among Asian for its nutritional values; hence, it is important to understand its aroma characteristics.

RESULTS

Volatile compounds in porridge of 30 quinoa varieties were determined by gas chromatography-mass spectrometry combined with headspace-solid phase micro-extraction. In total, 53 volatile compounds were detected and grouped into 14 alkanals, four alcohols, seven ketones, 10 alkanes, 10 acids and esters, and eight heterocycles. The relative content of alkanes (22.97%), acids and esters (44.33%) was comparatively high, although alkanals (11.75%) may dominate the aroma. Most of the compounds were similar with respect to types and numbers, although they varied in amount, whereas 11 compounds varied significantly among different varieties. The 30 varieties could be divided into eight groups based on the concentrations of volatile compounds, although the same varieties would be divided into four groups if based on the relative odour activity values of twelve variable aroma compounds.

CONCLUSION

Nine compounds were identified as the main contributors to the quinoa porridge aroma, including hexanal, 1-octen-3-ol, 2-pentylfuran, nonanal, (E,E)-2,4-decadienal and 6,10-dimethyl-5,9-undecadien-2-one. Heptanal, benzeneacetaldehyde and decanal may play roles in harmonizing the overall aroma. It is also interesting to note that 6,10,14-trimethyl-2-pentadecanone, with a slightly fatty aroma, showed a high content in all varieties. © 2019 Society of Chemical Industry.