Mechanism of aroma compounds changes from sea cucumber peptide powders (SCPPs) under different storage conditions

Characterization of aroma characteristics of silver carp mince glycated with different reducing sugars

The purpose of this study was to investigate the volatile flavor changes in silver carp mince (SCM) gel glycated with different reducing sugars (glucose, L-arabinose, and xylose) based on E-nose, GC-IMS, and sensory evaluation. These results showed that glycation reduced the fishy smell of SCM gel and increased the meaty, toasty, and burnt smell. A total of 10 volatile compounds were considered as characteristic flavor compounds and potential markers. Among them, the main contributors of fishy included hexanal, heptanal, n-nonanal, octanal, etc. Toasty and burnt were mainly related to the production of 3-methylbutanal and furfurol. These results heralded that glycation could be used to improve the volatile flavor of SCM. This research provided a theoretical basis and technical support for glycation in aquatic food flavor quality control, aquatic pre-made food development, and aquatic leisure food processing.

Effects of different hot-air drying methods on the dynamic changes in color, nutrient and aroma quality of three chili pepper (Capsicum annuum L.) varieties

The effects of constant and variable temperature hot-air drying methods on drying time, colors, nutrients, and volatile compounds of three chili pepper varieties were investigated in this study. Overall, the variable temperature drying could facilitate the removal of water, preserve surface color, and reduce the loss of total sugar, total acid, fat and capsaicin contents. Electronic-nose (E-nose) and gas chromatography-ion mobility spectroscopy (GC-IMS) analyses found that aldehydes, ketones, alcohols and esters contributed to the aroma of chili peppers. The drying process led to an increase in acids, furans and sulfides contents, while decreasing alcohols, esters and olefins levels. In addition, the three chili pepper varieties displayed distinct physical characteristics, drying times, chromatic values, nutrients levels and volatile profiles during dehydration. This study suggests variable temperature drying is a practical approach to reduce drying time, save costs, and maintain the commercial appeal of chili peppers.

The selective adsorption mechanism of V-type starches for key off-odors of sea cucumber intestinal peptides

The off-odors of sea cucumber intestinal peptide (SCIP) severely limit its application. In this study, the V-type starches were derived from high amylose maize starch to adsorb odors of SCIP and the adsorption mechanism was explored. The inclusion complexes formed by V-type starches and volatile compounds of SCIP were characterized by X-ray diffraction and Fourier transform infrared spectroscopy. The electronic nose results revealed a decreasing trend in response values of SCIP, with significant differences before and after deodorization (p < 0.05). Furthermore, 82 volatiles were identified from SCIP, and six were determined as key volatiles using gas chromatography-mass spectrometry. The V6- and V7-type starches with smaller cavity sizes selectively adsorb butyric acid, isobutyric acid and nonaldehyde, and V8-type starches with a larger cavity size selectively adsorb trimethylamine. This study proved that using V-type starches for deodorization could effectively improve SCIP flavor.

Comparative Analysis of Characteristic Volatile Compounds in Five Types of Infant Nutrition Powders by HS-GC-IMS and GC-MS

This study employed the headspace-gas chromatography-ion migration spectrum (HS-GC-IMS) in conjunction with the gas chromatography-mass spectrometer (GC-MS) technique for the assessment of the flavor quality of complementary food powder intended for infants and young children. A total of 62 volatile compounds were identified, including aldehydes, esters, alcohols, ketones, pyrazines, and furans, among which aldehydes were the most abundant compounds. Based on the principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) models, infant nutritional powder (YYB) from different manufacturers could be clearly distinguished. Among them, 2-hydroxybenzaldehyde, 1, 2-dimethoxyethane, 2-isobutyl-3-methoxypyrazine, and methyl butyrate were the four most critical differential volatiles. In addition, these differences were also manifested in changes in fatty acids. The reason for this phenomenon can be attributed to the difference in the proportion of raw materials used in nutrition powder, micronutrient content, and the packaging process. In conclusion, this study provides comprehensive information on the flavor quality of YYB, which can be used as a basis for quality control of YYB.

Adsorption characteristics of V-type starch for off-odors of sea cucumber intestinal peptides in solid-phase environment

With the concern of the strong fishy odor of sea cucumber intestinal peptides, the deodorization potential of V-type starch with a flexible cavity was investigated. By gas chromatography-mass spectrometry and electronic nose, it was confirmed that V-type starch effectively deodorized key off-odor compounds (isobutyric acid, butanoic acid, 1-octen-3-ol, nonanal, and trimethylamine), and the optimum deodorization performance (adsorption ratio of 92.45%) was achieved after 8 h adsorption at the sea cucumber intestinal peptide to starch ratio of 1:15 (w/w). In the Fourier transform infrared spectrum of the V-type starch inclusion complexes, a new characteristic peak was observed at 1563 cm-1 when the sea cucumber intestinal peptide to starch ratio was 1:1 (w/w). The presence of this peak was attributed to the complexation between V-type starch and trimethylamine. For the first time, we demonstrated that the V-type starch could deodorize aquatic products, and this study contributes to the application of starch materials.

Effect of Stable Chlorine Dioxide and Vacuum-Packing Treatments on the Physicochemical and Volatile Flavor Properties of Pike Eel (Muraenesox cinereus) during Chilled Storage

The effects of vacuum-packaging and stable chlorine dioxide treatments on the quality of pike-eel fillets were investigated during chilled storage for a period of up to 10 days. The results reveal that the sensory scores, total volatile basic nitrogen (TVB-N) content, total viable count (TVC), malondialdehyde (MDA) content, and the myofibrillar protein (MP) content of pike-eel fillets with different packing treatments all decreased significantly over 10 days of storage. However, the vacuum-packaging and stable chlorine dioxide pretreatment showed positive effects on the protein stability of pike-eel samples. Compared with the simple packaging (SP) and vacuum packing (VP) treatments, the combination treatments (CP) significantly inhibited the rapid increases in the TVB-N content, TVC values, and MDA content. Moreover, the comparative stability in the MP and its carbonyl content were maintained. Furthermore, our volatile organic compounds (VOCs) analysis confirmed that the combined packaging treatments significantly hindered protein and lipid oxidation, inhibited the growth of spoilage bacteria, and maintained the volatile flavors of pike-eel samples during chilled storage.

Effects of antioxidants on physicochemical properties and odorants in heat processed beef flavor and their antioxidant activity under different storage conditions

Heat processed beef flavor (HPBF) is a common thermal process flavoring, whose flavor properties can be affected by lipid oxidation during storage. Addition of antioxidants is an option to avoid the changes of HPBF induced by lipid oxidation. In this study, the effects of three antioxidants, tert-butylhydroquinone (TBHQ), tea polyphenol (TP), and L-ascorbyl palmitate (L-AP), on volatile components, physicochemical properties, and antioxidant activities of HPBF were studied over 168 days at different temperatures (4, 20, and 50°C). Although all three antioxidants had little effect on browning, acidity, water activity, and secondary lipid oxidation products, L-AP and TBHQ showed greater capabilities to prevent the formation of primary lipid oxidation products than TP. According to the results of oxidation reduction potential and DPPH radical scavenging experiments, TBHQ had better antioxidant ability compared to L-AP and TP during the storage. Of note, TBHQ affected the flavor profiles of HPBF, mainly on volatile odorants produced by lipid degradation. TBHQ could mitigate the development of unfavorable odorants. This study indicated TBHQ would enhance lipid oxidation stability and maintain physicochemical properties and flavor profiles of HPBF during storage. It suggested that TBHQ could be applied as an alternative additive to improve the quality of HPBF related thermal process flavorings.

Insight into the Characterization of Volatile Compounds in Smoke-Flavored Sea Bass (Lateolabrax maculatus) during Processing via HS-SPME-GC-MS and HS-GC-IMS

The present study aimed to ascertain how the volatile compounds changed throughout various processing steps when producing a smoke-flavored sea bass (Lateolabrax maculatus). The volatile compounds in different production steps were characterized by headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS). A total of 85 compounds were identified, and 25 compounds that may be considered as potential key compounds were screened by principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Results indicated that aldehydes were the major volatile compounds throughout the processing. The characteristic volatile compound in fresh samples was hexanol, and curing was an effective method to remove the fishy flavor. The concentration of volatile compounds was significantly higher in dried, smoked, and heated samples than in fresh and salted samples. Aldehydes accumulated because of the drying process, especially heptanal and hexanal. Smoke flavoring was an important stage in imparting smoked flavor, where phenols, furans and ketones were enriched, and heating leads to the breakdown of aldehydes and alcohols. This study will provide a theoretical basis for improving the quality of smoke-flavored sea bass products in the future.

Gas-phase ion migration spectrum analysis of the volatile flavors of large yellow croaker oil after different storage periods

The large yellow croaker, a species of fish found in the northwestern Pacific, is favored by consumers because of its prevalence in saltwater bodies, golden yellow abdomen, high calcium content, high protein, high fat content, and a flavor that originates from its lipids and volatile components. Volatile organic compounds significantly affect the aroma of food. In this work, electronic nose and headspace gas chromatography-ion mobility spectrometry were applied to analyze the flavor differences in fish oil durations. Through electronic nose system analysis, sensors W1C, W3S, W6S, and W2S directly affected fish oil flavor, and their flavor components were different. Gas chromatography-ion mobility spectrometry identified 26 volatile components (19 aldehydes, 3 ketones, 2 alcohols, 1 furan, and 1 olefin). (E,E)-2,4-hexadienal (D), (E,E)-2,4-hexadienal (M), 2,4-heptadienal (M), (E)-2-octenal, 2-propanone, 2-heptanone (M), 3-pentanone (D), and 1-octen-3-ol were the key flavor components of the fish oil. In conclusion, the combination of GC-IMS and PCA can identify the differences in flavor changes of large yellow croaker oil during 0–120 days storage. After 60 days storage, the types and signals of 2-propanone, 2-heptanone (M) components increase significantly. When 120 days storage, at this time, (E,E)-2,4-hexadienal (D), (E,E)-2,4-hexadienal (M), 2,4-heptadienal (M), (E)-2-octenal,(E)-2-octenal significantly. It has become the main flavor substance of fish oil. In summary, as the storage period increases, the components increase, and the oxidizing substances will increase, resulting in the deterioration of fish oil.

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The oxidation state of Large yellow croaker oil in different storage periods was investigated.

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The volatile compounds of Large yellow croaker oil were studied by GC-IMS.

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The effects of storage period on the composition of large yellow croaker oil samples were tested.

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We believe GC-IMS will play a crucial role in controlling the flavor of fish oil.

Validation Study on the Simultaneous Quantitation of Multiple Wine Aroma Compounds with Static Headspace-Gas Chromatography-Ion Mobility Spectrometry

A new quantitative method based on static headspace-gas chromatography-ion mobility spectrometry (SHS-GC-IMS) is proposed, which enables the simultaneous quantitation of multiple aroma compounds in wine. The method was first evaluated for its stability and the necessity of using internal standards as a quality control measure. The two major hurdles in applying GC-IMS in quantitation studies, namely, nonlinearity and multiple ion species, were also investigated using the Boltzmann function and generalized additive model (GAM) as potential solutions. Metrics characterizing the model performance, including root mean squared error, bias, limit of detection, limit of quantitation, repeatability, reproducibility, and recovery, were investigated. Both nonlinear fitting methods, Boltzmann function and GAM, were able to return desirable analytical outcomes with an acceptable range of error. Potential pitfalls that would cause inaccurate quantitation, that is, effects of ethanol content and competitive ionization, were also discussed. The performance of the SHS-GC-IMS method was subsequently compared against that of a currently established method, namely, GC-MS, using commercial wine samples. These findings provide an initial validation of a GC-IMS-based quantitation method, as well as a starting point for further enhancing the analytical scope of GC-IMS.

In Situ Quality Assessment of Dried Sea Cucumber (Stichopus japonicus) Oxidation Characteristics during Storage by iKnife Rapid Evaporative Ionization Mass Spectrometry

Sea cucumber (Stichopus japonicus) is one of the most luxurious and nutritious seafoods in Asia. It is always processed into dried products to prevent autolysis, but its quality is easily destructed during storage. Herein, an extremely simplified workflow was established for real-time and in situ quality assessment of dried sea cucumbers (DSCs) during storage based on the lipid oxidation characteristics using an intelligent surgical knife (iKnife) coupled with rapid evaporative ionization mass spectrometry (REIMS). The lipidomic phenotypes of DSCs at different storage times were acquired successfully, which were then processed by multivariate statistical analysis. The results showed that the discrepancy in the characteristic ions in different DSCs was significant (p < 0.05) with high R²(Y) and Q² values (0.975 and 0.986, respectively). The receiver operating characteristic curve revealed that the ions of m/z 739.5, m/z 831.5, m/z 847.6, and m/z 859.6 were the most specific and characteristic candidate biomarkers for quality assessment of DSCs during accelerated storage. Finally, this method was validated to be qualified in precision (RSD_intraday ≤ 9.65% and RSD_interday ≤ 9.36%). In conclusion, the results showed that the well-established iKnife-REIMS method was high-throughput, rapid, and reliable in the real-time quality assessment of DSCs.

Changes in volatile organic compounds and lipid oxidation in traditional Chinese bacon during cold smoking

The smoking time of cold-smoked traditional Chinese bacon (TCB) in northeast Chongqing is not precisely controlled. In this study, the accumulation of, and changes in, volatile organic compounds (VOCs) during smoking were investigated by gas chromatography–ion mobility spectrometry (GC-IMS). Simultaneously, the lipid oxidation and sensory attributes of TCB were assessed. Thirty-nine VOCs were identified in samples, most of which were alcohols, aldehydes, ketones, and esters. Samples smoked for 12 and 15 days contained characteristic VOCs, mainly comprising phenols, esters, and heterocyclic compounds, which produce the flavor of mature TCB. Odorous substances other than characteristic VOCs reached their maximum or sub-maximum on day 12, which was consistent with the sensory assessment results. The peroxide value of TCB increased continuously with smoking; while 2-thiobarbituric acid reactive substances test (TBARS) values were at a lower level between days 9 and 12. Therefore, the recommended smoking time should be about 12 days.

Influence of Frying Methods on Quality Characteristics and Volatile Flavor Compounds of Giant Salamander (Andrias davidianus) Meatballs

Effects of deep fat frying and hot air frying on texture, color difference, sensory score, yield, fat content, and volatile flavor compounds of giant salamander meatballs before and after frying were investigated. The results showed that, compared with the deep fat frying group, hot air-fried giant salamander meatballs had higher hardness, elasticity, and L ${}^{\ast }$ ( $p<0.05$ ), but lower a ${}^{\ast }$ , b ${}^{\ast }$ value, fat content, and yield ( $p<0.05$ ). There was little distinction in sensory score, cohesiveness, and chewiness between the two frying methods ( $p>0.05$ ). Gas chromatography ion migration chromatography (GC-IMS) was used for flavor compound analysis, and 50 flavor compounds were analyzed, containing 22 aldehydes, 11 ketones, 6 olefins, 4 acids, 3 esters, 3 alcohols, and 1 phenol. Compared with the samples before frying, the relative contents of aldehydes and ketones of fried giant salamander meatballs increased significantly, while the relative contents of esters and alkenes decreased significantly. Principal component analysis showed that the GC-IMS spectra of volatile flavor compounds before and after deep fat frying and hot air frying varied greatly, and the cumulative contribution rate of the two principal components reached 86.1%, indicating that the GC-IMS technology might be used to distinguish giant salamander meatballs before and after frying, or with different frying methods. These results may offer a note for development and quality control of the precooked giant salamander meatballs in the future.

Evaluation of volatile metabolites as potential markers to predict naturally-aged seed vigour by coupling rapid analytical profiling techniques with chemometrics

Rapid volatile detection methods for seed vigour rely heavily on artificial ageing (AA), however the comparability of volatile organic compounds (VOCs) to natural ageing (NA) and practicability of the detection models were not well known. In this study, VOCs between AA and NA sweet corn seeds were compared and Partial Least Squares Regression (PLS-R) modelswere constructed based on AA to predict the seed vigour of NA. A total of 33 VOCs were identified, among which aldehydes showed the highest consistency between NA and AA. Furthermore, a AS-PLS-R model with variable importance in projection (VIP > 1) and Pearson Correlation Coefficient (r > 0.9) algorithms, which was built on 3 volatile markers: benzaldehyde monomer, n-nonanal, 1-butanol monomer, achieved the best performance (R²p of 0.901 and RMSEP of 0.050). Therefore, coupling Gas Chromatography- Ion Mobility Spectrometry (GC-IMS) with chemometrics can be an effective way to monitor and predict stored seeds vigour.

Aroma characteristics of traditional Huangjiu produced around Winter Solstice revealed by sensory evaluation, gas chromatography-mass spectrometry and gas chromatography-ion mobility spectrometry

Traditional Huangjiu (a kind of traditional Chinese rice wine) produced around Winter Solstice has higher quality and a more harmonious aroma than those produced during other periods. To determine the specific differences in aroma characteristics, sensory evaluation, gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS) were used to analyze the volatile profiles of the traditional Huangjiu samples produced under different ambient temperature conditions. The sensory evaluation results showed that the aroma attributes of wheat, sweet, ester, alcoholic and sauce were stronger for the samples fermented near Winter Solstice than those for the other samples. GC-MS combined with heatmap analysis showed that with the decrease in average ambient temperature, the contents of esters such as diethyl succinate and ethyl butanoate gradually increased, and the contents of alcohols such as phenylethyl alcohol, 2-methylpropanol and 3-methylbutanol gradually decreased. Some key aroma compounds, such as ethyl butyrate (OAV: 97-151), nonanal (OAV: 189-200), ethyl octanoate (OAV: 859-1134) and ethyl phenylacetate (OAV: 307-353), were more abundant in the samples fermented near Winter Solstice than the other samples. The visualization of GC-IMS suggested that isoamyl acetate, 2-methylpropyl acetate, ethyl 3-methylbutyrate, and ethyl 2-methylbutanoate were enriched near Winter Solstice. Together, the results suggested that the traditional Huangjiu produced around Winter Solstice contained more flavor volatiles and had better aroma quality than those produced during other periods.

Amino Acid Profiling with Chemometric Analysis as a Feasible Tool for the Discrimination of Marine-Derived Peptide Powders

Marine-derived peptide powders have suffered from adulteration via the substitution of lower-price peptides or the addition of adulterants in the market. This study aims to establish an effective approach for the discrimination and detection of adulterants for four representative categories of marine-derived peptide powders, namely, oyster peptides, sea cucumber peptides, Antarctic krill peptides, and fish skin peptides, based on amino acid profiling alongside chemometric analysis. The principal component analysis and orthogonal partial least squares discriminant analysis results indicate that four categories of marine-derived peptides could be distinctly classified into four clusters and aggregated with the respective raw materials. Taurine, glycine, lysine, and protein contents were the major discriminants. A reliable classification model was constructed and validated by the prediction dataset, mixture sample dataset, and unclassified sample dataset with accuracy values of 100%, 100%, and 100%, respectively.

Effect of Frying Conditions on Self-Heating Fried Spanish Mackerel Quality Attributes and Flavor Characteristics

In this study, we investigated the effects of different frying conditions on the quality characteristics of fried Spanish mackerel (Scaberulous niphonius) to address the food quality degradation of self-heating fish products after frying, sterilization, and reheating. Furthermore, the effect of different moisture contents (65%, 60%, 55%, and 50%) of fried Spanish mackerel on texture, color, and microstructure after sterilization and self-heating were examined. The flavor fingerprints of different frying temperatures (140 °C, 160 °C, 180 °C, and 200 °C) coupled with the optimal moisture content were identified; furthermore, volatile organic compounds (VOCs) were studied using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) with principal component analysis (PCA). The results indicated that the shear force value significantly increased, while the hardness and chewiness significantly decreased simultaneously with decreasing moisture content. Samples containing 65% moisture content showed the highest L*, a*, and W values, while their b* value was the lowest, and the most clearly visible fibrous veins with tiny cracks could be observed in them. Samples fried at 160 °C and 65% moisture content exhibited the richest VOCs, with a greasy or fried aroma. Based on the PCA, there were significant differences in the sample VOCs under different frying conditions. In summary, among all treatments, frying at 160 °C with 65% moisture content resulted in the highest food quality of fish filets. The results of this study could provide a theoretical basis for improving the food quality of self-heated fish products.