Flavor characteristics of shrimp sauces with different fermentation and storage time

Effect of CO2 on the spoilage potential of Shewanella putrefaciens target to flavour compounds

To investigate the regulation mechanism of CO₂ (0% CO₂, 20% CO₂, 60% CO₂, and 100% CO₂) on the spoilage potential of S. putrefaciens target to flavour compounds, the metabolic activity of S. putrefaciens and the changes in flavour compounds extracted from inoculated large yellow croakers were evaluated. Results showed that CO₂ significantly reduced biofilm formation capacity and suppressed synthesis of intracellular adenosine triphosphate (ATP). The production of unpleasant flavour compounds, such as total volatile basic nitrogen (TVB-N), trimethylamine (TMA), inosine (HxR), hypoxanthine (Hx), histidine, lysine, histamine, putrescine, 1-octen-3-ol, hexanal and benzaldehyde, was inhibited by CO₂. The hydrolysis and oxidation of lipid in CO₂-treated samples were alleviated and unsaturated fatty acids (UFAs) were in a higher percentage. In summary, CO₂ efficiently reduced the spoilage potential of S. putrefaciens and contributed to better flavour quality of samples during 4 °C storage. A more effective inhibition by 100% CO₂ was observed.

Changes in protease activity during fermentation of fish sauce and their correlation with antioxidant activity

BACKGROUND

Antioxidant activity has been found in fermented fish sauce. In this experiment, the properties of endogenous protease and antioxidant activity were studied in anchovy sauce during fermentation. The correlation between protease activity and antioxidant activity in fermented anchovy sauce was analyzed using the partial least squares (PLS) method.

RESULTS

The results showed that at least four proteases were present in the endogenous enzyme solution, and the optimum pH values were 2.5, 5.5, 9.0, and 12.5, respectively. The maximum inhibition rate of endogenous protease, from high to low, was: serine protease inhibitor > trypsin inhibitor > aspartic protease inhibitor (pepsin inhibitor) > cysteine protease inhibitor > metalloprotease inhibitor. At the sixth month of fermentation, fish sauce had stronger trypsin, pepsin-like activity, and antioxidant activity. At the ninth month of fermentation, the cathepsin activity was greater. A model correlating changes in protease activity with antioxidant activity suggested that the trypsin and serine protease were the main factors affecting antioxidant activity.

CONCLUSION

This study reports a model correlating changes in protease activity with the antioxidant activity of fish sauce. It lays a foundation for further exploration of the formation of antioxidant substances and antioxidant effects during the process of fish sauce fermentation. © 2021 Society of Chemical Industry.

Novel insight into the role of processing stages in nutritional components changes and characteristic flavors formation of noble scallop Chlamys nobilis adductors

Processing stages play critical role in the nutrition and flavor changes of marine products. This study investigated the nutrition and flavor profiles in noble scallop Chlamys nobilis adductor during boiling, rinsing, baking and drying processing stages by high performance liquid chromatography, headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry. The results showed that the overall processing stages favorably preserved the essential amino acids. Drying obviously increased the umami and sweet amino acids contents by 72.08%, 67.77%, respectively (P < 0.05), and promoted the production of flavor nucleotides. In addition, the overall processing stages significantly increased the protein and lipid oxidation degree by (1.49-3.01)-fold and (4.25-5.81)-fold, respectively, compared with raw group (P < 0.05). Moreover, alcohols were the major volatiles in raw group, while the aldehydes, alcohols, and hydrocarbons predominated in rinsing, baking and drying stages. In conclusion, the processing maintained the nutrition value and improved the flavor of scallop adductors.

Differentiation of Penaeus vannamei from different thermal processing methods in physico-chemical, flavor and sensory characteristics

Differentiation in physico-chemical, flavor and sensory characteristics of shrimps (Penaeus vannamei) after direct roasting (DR, 200 °C), boiling (100 °C/2 min) + roasting (BR), steaming (100 °C/2 min) + roasting (SR) and microwaving (280 W/2 min) + roasting (MR) was investigated. BR, SR, and MR endowed shrimps with better texture to varying degrees and significantly (P < 0.05) increased lightness when compared to DR, which closely related to their different water status. High correlations between nuclear magnetic resonance data and quality properties were found by partial-least-squares regression (PLSR). Shrimps possessed by SR significantly (P < 0.05) increased the proportion of sweet amino acids (63.89 ± 0.92%), with superior umami and richness detected by electronic tongue. Compared with DR, both SR and MR endowed shrimps with richer ester, while BR endowed shrimps with richer hydrocarbons. Roasting combined with other thermal processing would favor improving the quality of shrimp products.

Progress of Research on the Application of Nanoelectronic Smelling in the Field of Food

In the past 20 years, the development of an artificial olfactory system has made great progress and improvements. In recent years, as a new type of sensor, nanoelectronic smelling has been widely used in the food and drug industry because of its advantages of accurate sensitivity and good selectivity. This paper reviews the latest applications and progress of nanoelectronic smelling in animal-, plant-, and microbial-based foods. This includes an analysis of the status of nanoelectronic smelling in animal-based foods, an analysis of its harmful composition in plant-based foods, and an analysis of the microorganism quantity in microbial-based foods. We also conduct a flavor component analysis and an assessment of the advantages of nanoelectronic smelling. On this basis, the principles and structures of nanoelectronic smelling are also analyzed. Finally, the limitations and challenges of nanoelectronic smelling are summarized, and the future development of nanoelectronic smelling is proposed.

Regulation of microbial metabolism on the formation of characteristic flavor and quality formation in the traditional fish sauce during fermentation: a review

Fish sauce is a special flavored condiment formed by traditional fermentation of low-value fish in coastal areas, which are consumed and produced in many parts of the world, especially in Southeast Asia. In the process of fish sauce fermentation, the diversity of microbial flora and the complex metabolic reactions of microorganisms, especially lipid oxidation, carbohydrate fermentation and protein degradation, are accompanied by the formation of flavor substances. However, the precise reaction of microorganisms during the fersmentation process is difficult to accurately control in modern industrial production, which leads to the loss of traditional characteristic flavors in fermented fish sauces. This paper reviews the manufacturing processes, core microorganisms, metabolic characteristics and flavor formation mechanisms of fermented fish sauces at home and abroad. Various methods have been utilized to analyze and characterize the composition and function of microorganisms. Additionally, the potential safety issues of fermented fish sauces and their health benefits are also reviewed. Furthermore, some future directions and prospects of fermented fish sauces are also reviewed in this paper. By comprehensive understanding of this review, it is expected to address the challenges in the modern production of fish sauce thereby expanding its application in food or diet.

Metabolic Footprint Analysis of Volatile Organic Compounds by Gas Chromatography-Ion Mobility Spectrometry to Discriminate Mandarin Fish (Siniperca chuatsi) at Different Fermentation Stages

Chinese fermented mandarin fish (Siniperca chuatsi) have unique aroma characteristics that are appreciated by local consumers. In this study, electronic nose (E-nose) and gas chromatography–ion mobility spectrometry analyses were combined to establish a volatile fingerprint of fermented mandarin fish during fermentation. Clear separation of the data allowed mandarin fish samples at different fermentation stages to be distinguishing using E-nose analysis. Forty-three volatile organic compounds were identified during fermentation. Additionally, partial least squares discrimination analysis was performed to screen for different VOC metabolites in the fermented mandarin fish; the levels of six VOCs changed significantly during fermentation (variable importance in projection >1; p < 0.05). Three VOCs, i.e., hexanal-D, nonanal, and limonene were identified as potential biomarkers for fermentation. This study provided a theoretical basis for flavor real-time monitoring and quality control of traditional mandarin fish fermentation.

Quality and volatile compound analysis of shrimp heads during different temperature storage

This study aimed to investigate volatile compounds and quality traits of shrimp heads stored at 20 °C, 4 °C, -3 °C, and -18 °C. With increased storage time, sensory scores gradually decreased, while pH and TVB-N content showed a gradually increase trend. L* showed a decreasing and then increasing tendency. The radar chart and principal component analysis showed variation changes. Three compounds including 2-decanone, dimethyl disulphide and dimethyl tetrasulphide, four compounds including 2-pentanone, 3-methyl-1-butanol, 2-methylbutyric acid, and 2,3,5-trimethylpyrazine, and 3-methylbutyraldehyde were the characteristic volatiles for the samples stored at 20 °C, 4 °C, and -3 °C, respectively. Twenty-five volatile compounds were key volatile compounds, among which nine were potential classification compounds with high variable importance in projection values. Trimethylamine and 2-nonanol were selected as potential markers of spoilage. The study provides the theoretical basis for quality and volatile compound investigations for shrimp heads with further high-quality utilization.

Formation of colloidal micro-nano particles and flavor characteristics of Greenland halibut bone soup

In this study, halibut bone, a byproduct of Greenland halibut processing, was prepared into a thick soup through a non-frying process. The formation of colloidal micro-nano particles and flavor characteristics in halibut bone soup was explored. The results showed that the nutrients in halibut bones migrated to the soup continuously with the cooking process and reached the highest concentration (total sugars, 38.16 mg/100 ml; water-soluble proteins, 25.71 mg/ml; fatty acids, 2.15 g/100 ml; solids, 1.14 g/100 ml) at 150 min. Taste substances such as organic acids, 5'-nucleotides and total free amino acids (TFAAs) content in halibut bone soup also reached maximum at 150 min. At this time, results for particle size showed that MNPs with uniform size (725.62 nm) were formed, which made the bone soup milky white, stable, and had good tasting. Headspace-gas chromatography-ion mobility spectrometry results showed that a total of 59 volatile substances were detected from the halibut bone soup. The content of volatile flavor substances in the 150 min group was lower than that in the 90-120 min group. Meanwhile, aldehydes and ketones gradually became esters. PRACTICAL APPLICATION: Soup is an indispensable part of the world food culture. In order to increase the added value of Greenland halibut, halibut bone soup was studied in this paper. This study found that halibut bone soup that had not been fried, formed the MNPs and has a more harmonious and pleasant flavor. Thus, non-fried halibut bone soup is a good processing method and can improve economic efficiency.

Inhibition of Advanced Glycation End Products in Yogurt by Lotus Seedpod Oligomeric Procyanidin

The basic ingredients of yogurt include lactose and protein. Yogurt undergoes the Maillard reaction easily, producing many advanced glycation end products (AGEs) that cause some chronic diseases. Lotus seedpod oligomeric procyanidin (LSOPC) have demonstrated a strong inhibitory effect on AGE formation in simulated models; however, the inhibition of procyanidin on AGE formation and the subsequent effects on yogurt quality remains unknown. Our study demonstrated that LSOPC had a good inhibitory effect on the formation of fluorescent AGEs and Nε-carboxymethyl lysine (P < 0.05). The inhibitory capacity on AGEs and antioxidant activity of yogurt were positively correlated with the concentration of LSOPC. The effect of LSOPC on the physicochemical properties of yogurt was also evaluated. Bound water content, viscosity, and flavor of yogurt were significantly increased after LSOPC addition (P < 0.05). Therefore, LSOPC may lead to significant benefits for controlling AGE formation and improving the quality of yogurt.

Effects of thermoultrasonic treatment on characteristics of micro-nano particles and flavor in Greenland halibut bone soup

In order to investigate the effects of thermoultrasonic treatment (TUT) on the formation of colloidal micro-nano particles (MNPs) and the quality of halibut bone soup, nutrients, particle characteristics, and flavor characteristics were analyzed. The morphology of MNPs was studied using an optical microscope. Results showed that TUT could increase the nutrient content (total sugars, 22.15 mg/100 mL; water soluble proteins, 173.24 mg/mL; fatty acids, 1779.7 mg/100 mL; solids, 3.16 g/100 mL), reduce the particle size (605.92 nm) and interfacial tension. Meanwhile, TUT make the halibut bone soup has better emulsifying characteristics and stability. The contents of flavor substances, such as esters, 5'-nucleotides, organic acids in the halibut bone soup were more abundant, while the contents of hexanal and 1-octen-3-ol and fishy off-flavor were reduced in TUT group. The overall odor and taste outline were more harmonious. Therefore, TUT can be used in the production of high quality fish bone soup, and TUT could be considered as a good deep processing technology for halibut bone and improve economic efficiency.

Evaluation of flavor characteristics of bacon smoked with different woodchips by HS-SPME-GC-MS combined with an electronic tongue and electronic nose

This study investigated the effects of different woodchip types (beech, oak, pear, and apple) on the volatile compounds and sensory characteristics of smoked bacon. The volatile compounds were influenced by woodchip types and the total content of ketones and phenols in pear-smoked bacon were higher than in bacon smoked with other woodchips (P < 0.05). The E-tongue combined with E-nose can effectively distinguish the difference in the flavor of bacon smoked with different woodchip types by the signal intensities. Sensory analysis showed that smoking increased bacon's redness, saltiness, and smoky flavor compared with the control (unsmoked bacon) (P < 0.05) and it had little impact on off-odor (P > 0.05). Correlation analysis showed that the E-nose and E-tongue data were highly correlated with contents of alcohols, aldehydes, and ketones. This study revealed that the different smoked materials greatly influenced the flavor and sensory properties of bacon.

Characterization and structure-activity relationship of novel umami peptides isolated from Thai fish sauce

Fish sauce has a prominent umami flavor. In this study, umami peptides were isolated, purified and identified from Thai fish sauce, and their structure-activity relationships were analyzed. Six novel umami peptides were characterized and verified by using sensory evaluation and a electronic tongue. Molecular docking with T1R1/T1R3 receptors showed that the interaction forces were mainly hydrogen bonds, electrostatic interaction and van der Waals force. In the constructed three dimensional quantitative structure-activity relationship model (3D-QSAR) model, the regression coefficient (R2) for the degree of dispersion between the predicted molecular and the experimental values of the six peptides was 0.976. The association between the structure and activity of umami peptides was revealed through 3D-QSAR. Results showed that the spatial effect was significant for long chain peptides.

Identification, taste characterization and molecular docking study of novel umami peptides from the Chinese anchovy sauce

BACKGROUND

Fish sauce has a subtle flavor with prominent umami and salty taste, and is accompanied by a certain sweetness and bitterness. In order to identify a wider range of umami peptides, Chinese southern and northern anchovy sauce were selected for the study.

RESULTS

Seventeen peptides were obtained by separation and purification, and their taste activity was predicted. Through the taste characterization and descriptive analysis, it was found that the synthesized peptides were umami and umami-enhancing peptides. Seventeen umami peptides were simulated and embedded into the umami receptor T1R1/T1R3 by inserting into the Venus flytrap domain (VFTD) of the T1R3 subunit; the interaction forces were mainly hydrogen bonding, electrostatic interaction, van der Waals force and hydrophobic interaction. According to the docking interaction energies, long-chain peptides may be easier to bind to the receptor than short-chain peptides. Asp196, Glu128 and Glu197 were the main binding sites for docking, and could affect umami synergism.

CONCLUSION

For the first time, novel umami peptides in Chinese anchovy sauce have been reported. This study is helpful for discovering umami marine resource peptides, and can provide a basis for further understanding the flavor system of anchovy sauce. © 2020 Society of Chemical Industry.

Change Regularity of Taste and the Performance of Endogenous Proteases in Shrimp (Penaens vannamei) Head during Autolysis

This study evaluated the food safety and proximate composition of shrimp head (SH). Potentially toxic elements in SH were below European Union legislation limits. SH had a high content of tasting amino acids (sweet and umami amino acids was 57%) and a high content of functional amino acids (essential amino acids was 37%). Moreover, the changes of flavor and key umami molecules in SH were studied by sensory evaluation, electronic tongue, electronic nose, automated amino acid analyzer, and high performance liquid chromatography (HPLC). The results showed that the significant difference of flavor in SH happened during autolysis. SH with autolysis had the best umami taste at 6 h, which may result from the synergistic work of free amino acids and nucleotide related compounds. Additionally, the performance of endogenous proteases in SH was investigated to efficiently analyze autolysis. The optimum pH and temperature of endogenous proteases in SH were 7.5 and 50 °C, respectively. The autolysis of SH depends on two endogenous proteases (~50 kDa and ~75 kDa). These results suggest that the formation of flavor in SH during autolysis can be controlled, which could provide guidance for SH recycle. SH could consider as one of the food materials for producing condiments.

Changes in taste substances during fermentation of fish sauce and the correlation with protease activity

Anchovy sauce shows different taste profiles under different fermentation time. The change rules of free amino acids was measured by amino acid analyzer, and other taste substances, such as nucleotides and organic acids in anchovy sauce under different fermentation time were also investigated. Moreover, the correlation between protease activity and taste substances in anchovy sauce fermentation was analyzed by orthogonal partial least squares. Throughout the fermentation process, the taste substances in anchovy sauce increased during early months and then decreased as time increased. The content of amino acid nitrogen, TCA-soluble peptides, 5'-nucleotides (AMP, GMP, IMP) and organic acids (lactic acid, succinic acid) in anchovy sauce increased by 26%, 33%, (45%, 35%, 68%) and (27%, 2%) respectively in comparison with 6 months fermentation. Total amino acid content reached its maximum after 18 months fermentation. Results of electronic tongue demonstrated that the umami of anchovy sauce after 12 months fermentation increased by 17% in comparison with 6 months fermentation. A model correlating changes in protease activity with taste formation suggested that protease activity impacted the content of Ala, Glu, Lys, Asp, Leu, TCA-soluble peptides and succinic acid. This study can provide empirical evidence to guide the efficient processing of anchovy sauce.

Novel insight into physicochemical and flavor formation in naturally fermented tilapia sausage based on microbial metabolic network

The quality and flavor formation in fermented fish sausages are based on the complex metabolism of microbial community. In this study, the dynamic changes of physicochemical characteristics, volatile compounds, and microbial communities in the naturally fermented tilapia sausage were studied during the fermentation process. The main physical indexes (gel strength, whiteness, and hardness), dominant flavor free amino acids (glycine, alanine, and glutamic acid) and characteristic volatile flavor compounds (hexanal, heptanal, octanal, benzaldehyde, (E)-2-octenal, 4-ethylbenzaldehyde, (E)-2-heptenal, (E,E)-2,4-decadienal, 1-octen-3-ol, 2-pentylfuran, and 2-ethyl-furan) were significantly enhanced after fermentation, and were positively correlated with Lactococcus, Pediococcus, Enterococcus, and Lactobacillus. The microbial metabolic network showed that Lactococcus, Pediococcus, and Enterococcus played a significant role in the formation of physicochemical and flavor characteristics, while the accumulation of biogenic amines might result from the metabolism of Enterococcus, Enterobacter, and Citrobacter. Isolation of lactic acid bacteria in Lactococcus and Pediococcus might be suitable to improve the fermented tilapia sausage. Microbial metabolic network has revealed the physicochemical and flavor formation of tilapia sausage and can provide guidance for future research on screening of starters.

Virgibacillus halodenitrificans ST-1 for fermentation of shrimp paste and hydrolysates of its protease

The nutrition and flavor of shrimp paste came from hydrolyzation by enzymes that were produced by microorganisms. The salt-tolerant strain Virgibacillus halodenitrificans ST-1 isolated from shrimp paste was studied and used in the fermentation of shrimp paste. The strain and the protease produced by ST-1 were investigated. The optimum pH of the protease was 8.0, and the reaction temperature was 30°C. The protease showed high activity in the range of pH (5.0-11.0) and NaCl concentration (1%-15%). Divalent cations such as Ba2+, Ca2+, Mg2+, Mn2+, and Si2+ could enhance the protease activity. Residual activity of protease was more than 90% when it was incubated with PMSF and H2O2. Also, the enzyme retained more than 90% of initial activity after it was incubated with organic solvents. Variety of natural proteins could be substrates of the protease. By analyzing the release rate of free amino acids, it was predicted that the cleavage sites of the protease were mainly Glu, Asp, Gly, Leu, and Lys. Moreover, the hydrolysates of the protease had antioxidant activity, especially for DPPH and superoxide anion radical scavenging. The strain ST-1 and the protease both were excellent candidates for food industries.

Comparative aroma and taste profiles of oil furu (soybean curd) fermented with different mucor strains

The effects of different mucor strains (Mucor racemosus, Actinomucor, and Mucor wutungkiao) on aroma and taste profiles based on proteolysis, lipolysis, and their catabolism in oil furu were studied. Gas chromatography-mass spectrometry and relative odor activity were used to monitor the changes of key volatile compounds and the differences in the characteristic aroma contents of oil furu. Using principal component analysis, the different fermentation strains had an effect on aroma profiles. The volatile compounds from metabolism of protein and fatty acid contributed to the aroma of oil furu with different contribution from the different strains, presumably due to their different enzymes. The electronic tongue and free amino acid profiles also showed strain differences of taste. Based on these results, optimization of the amount of each of the different mucor strains during cofermentation might achieve better flavor.

Novel insight into the formation mechanism of volatile flavor in Chinese fish sauce (Yu-lu) based on molecular sensory and metagenomics analyses

Complex microbial metabolism is the basis for flavor formation in traditional fish sauce. To guide the targeted regulation of production quality, we used molecular sensory and metagenomics analyses to determine dynamic changes in volatile flavor compounds and microbial communities of fish sauce as fermentation progressed. In total, 56 volatile compounds were identified; of these, 3-methylthiopropanal had the highest average odor activity value. Twelve volatile compounds, key for fish sauce flavor development, were identified. Bidirectional orthogonal partial least squares analysis was applied to investigate the correlation between microorganisms and flavor substances. Five microbial genera including Halanaerobium, Halomonas, Tetragenococcus, Halococcus and Candidatus Frackibacter constituted the core microbial flora responsible for flavor formation. The microbial metabolic pathways degraded raw materials into primary metabolites, such as glucose, amino acids, and fatty acids. This study provides novel insights into the flavor formation mechanism of traditional fish sauce fermentation.