Flavor Molecules Research Articles

Black soldier fly larvae replace traditional iced trash fish diet to enhance the delicious flavor of Chinese mitten crab (Eriocheir sinensis)

Chinese mitten crabs (Eriocheir sinensis) are traditionally fed iced trash fish, but the industry is facing problems such as low breeding safety. Black soldier fly (Hermetia illucens) is an alternative protein source in animal diets, including diets for aquatic animals, due to its high nutritional value. However, studies on the effects of black soldier fly on the flavor characteristics of aquatic animals are still limited. In the present study, we investigated the effects of the complete replacement of iced trash fish with black soldier fly larvae during the fattening period of Chinese mitten crab on the flavor molecule contents and evaluation indices. The levels of free amino acids and nucleotides were determined in three edible parts (muscle, hepatopancreas, and gonads) of crab. Taste activity value analysis showed that glutamic acid, glycine, alanine, and arginine were the main amino acids contributing to the umami taste and sweetness, while histidine, lysine, valine, and methionine were the main amino acids contributing to the bitterness. Equivalent umami concentration (EUC) analysis showed that female gonads had the strongest umami taste, followed by the hepatopancreas and muscle. Sweetness value (SWT) analysis showed that the sweetness of muscle was the highest. Feeding black soldier fly larvae affected the flavor characteristics of crabs with tissue and sex differences. The EUC of the female gonads and SWT of the muscle were significantly increased. Meanwhile, the EUC of the hepatopancreas and SWT of the gonads were slightly decreased in male crabs. Our results indicate that the complete replacement of iced trash fish with black soldier fly larvae during the fattening period significantly enhances the flavor characteristics of crabs based on the contents of flavoring amino acids and nucleotides. It is important for sustainable aquaculture to replace animal protein with alternative protein sources such as black soldier fly larvae.

High-spatial-resolution multi-spectroscopic provides insights into the interaction and release of δ-decanolactone and decanoic acid with β-lactoglobulin

Flavor retention during processing and stability in processed products is a major concern in the goat dairy products. Herein a novel strategy, combined with high-spatial-resolution multi-spectroscopic and molecular docking techniques, was developed and applied to investigate the non-covalent binding interactions in δ-decanolactone and decanoic acid to the β-lactoglobulin. Direct mass spectrometry and proteomics identified that both δ-decanolactone and decanoic acid bound to β-lactoglobulin in 1:1 stoichiometric ratio, and were localized on LSFNPTQLEEQCHI and YLLFCMENSAEPEQSLACQCLVR, respectively. Fluorescence experiments proved that the binding of δ-decanolactone and decanoic acid to β-lactoglobulin was state quenching with good affinity at 298 K. The binding constant values were 5.36 × 105 L mol−1 and 6.85 × 105 L mol−1, implied decanoic acid had stronger binding affinity toward β-lactoglobulin than δ-decanolactone. Molecular docking elucidated that decanoic acid and δ-decanolactone competed for the binding of the Val43 and Thr18 of β-lactoglobulin, causing the decrease in fluorescence intensity. The cooperativity made the δ-decanolactone and decanoic acid release stably in the model system. Therefore, this experiment systematically evaluated the binding effect of δ-decanolactone and decanoic acid on β-lactoglobulin, provided foundations for reasonable stable release of flavor molecules in the goat dairy products.

Flavor encapsulation into chitosan-oleic acid complex particles and its controlled release characteristics during heating processes

Encapsulation of a highly volatile, hydrophobic flavor compound, l-limonene (LIM), and its release behavior during simulated cooking experiments under various heating conditions were investigated using chitosan-oleic acid (CHI-OA) complex particles as a colloidal carrier for flavor encapsulation. An aqueous solution of CHI and ethanolic solution of OA containing LIM were mixed, and the complex particles with homogeneous diameter distribution with a mean diameter of ∼1 μm were formed in a self-assembly manner. The flavor release behavior under different heating conditions using conventional or microwave heating devices was analyzed via the Avrami equation. The results revealed that the flavor release rate from the CHI-OA complex particles was significantly affected by temperature and heating methods, indicating that the release behavior of the encapsulated flavor was tunable by controlling the heating conditions. The complex particle suspension containing flavor molecules could be autoclaved and spray-dried while retaining their colloidal dispersibility and controlled release ability.

Development of vegan meat flavour: A review on sources and techniques

The inclination towards naturalness and "clean label" products amongst the consumers has encouraged the development of novel processes for the production of vegan meat flavour. Many basic investigations indicate that acid, enzymatic, or fermentation reactions can be used to produce specific flavour molecules or more complicated flavour formulations. This review summarises recent basic research and development on meat flavour by using different vegan sources. The combination of acid or enzymatic treatment or fermentation of raw materials with heat-induced food processes (e.g., extrusion) represents an elegant approach for generating meat flavour. The current review illustrates the different raw materials, techniques, and challenges in producing vegan meat flavour.

Microbial ecology and functional coffee fermentation dynamics with Pichia kudriavzevii

Specialty coffee can be developed by the application of explicit microorganisms or starters to obtain desired fermentation. In the present study, natural fermentation (NF) of Arabica coffee was carried out spontaneously, the other set was inoculated with Pichia kudriavzevii (Y) starter culture (isolated, identified and mass cultured). The effect of microbial fermentation, metagenomics, production of functional metabolites, volatiles and their sensorial aspects were studied. The bioprocess illustrated cohesive interface of coffee nutrients and microbial communities like Mycobacterium, Acinetobacter, Gordonia, etc., in NF, Lactobacillus and Leuconostoc were prevailing in Y. The Pichia and Rhodotorula dominated in both the groups. The bioactivity of bacteria and fungi induced complex changes in physicochemical features like pH (4.2–5.2), Brix° (9.5–3.0), and metabolic transition in sugar (3.0–0.7%), alcohol (1.4–2.7%), organic acids modulating flavour precursors and organoleptics in the final brew. In the roasted bean, Y exhibited higher sugar (42%), protein (25%), polyphenol (3.5%), CGA (2.5%), caffeine (17.2%), and trigonelline (2.8%) than NF. The volatile profile exhibited increased flavour molecules like furans, ketones, and pyrazines in Y, besides lactone complexes. The organoleptics in Y were highlighted with honey, malt and berry notes. P. kudriavzevii coffee fermentation could be beneficial in specialty coffee production and enhancement of distinct characteristic flavours.

Predicting individual perceptual scent impression from imbalanced dataset using mass spectrum of odorant molecules

Predicting odor impression is considered an important step towards measuring the quality of scent in the food, perfume, and cosmetic industries. In odor impression identification and classification, the main target is to predict scent impression while identifying non-target odor impressions are less significant. However, the effectiveness of predictive models depends on the quality of data distribution. Since it is difficult to collect large scale sensory data to create an evenly distributed positive (target odor) and negative (non-target odor) samples, a method is necessary to predict the individual characteristics of scent according to the number of positive samples. Moreover, it is required to predict large number of individual odor impressions from such kind of imbalanced dataset. In this study, we used mass spectrum of flavor molecules and their corresponding odor impressions which have a very disproportioned ratio of positive and negative samples. Thus, we used One-class Classification Support Vector Machine (OCSVM) and Cost-Sensitive MLP (CSMLP) to precisely classify target scent impression. Our experimental results show satisfactory performance in terms of AUCROC to detect the olfactory impressions of 89 odor descriptors from the mass spectra of flavor molecules.

Quality Evaluation of Drinks Based on Liposome Shape Changes Induced by Flavor Molecules.

The flavors of ethyl caproate and isoamyl acetate and their precursors are crucial in sake brewing for fermentation and evaluation of the corresponding quality of drinks. However, the quality evaluation of drinks containing these flavors is challenging. Therefore, sake quality was evaluated via dynamic membrane transformation on cell-sized liposomes while adding flavor-containing solutions. Flavor varieties have been reported to influence dynamic shape change patterns. This study reports the observed difference in the dynamic shape change of each flavor. Based on these results, proper quality evaluation of drinks is expected.

Synthesis, odor characteristics and biological evaluation of N-substituted pyrrolyl chalcones.

A novel approach for converting N-substituted acetylpyrroles and primary alcohols into N-substituted pyrrolyl chalcones in air with the assistance of t-BuOK is reported, and several prominent flavor and bioactive molecules were obtained. The process entails oxidizing the alcohols to the corresponding aldehydes, and t-BuOK is crucial to the effective production of CC bonds by aldol condensation. Gas chromatography-mass spectrometry-olfactometry (GC-MS-O) was used to examine the odor properties of pyrrolyl chalcones, which are usually different from those of the associated acetylpyrroles and alcohols. The biological evaluation assay showed that the products (E)-3-(3-fluorophenyl)-1-(1-methyl-1H-pyrrol-2-yl)prop-2-en-1-one (3j), (E)-1-(1-ethyl-1H-pyrrol-2-yl)-3-phenylprop-2-en-1-one (4a), (E)-3-(4-bromophenyl)-1-(1-ethyl-1H-pyrrol-2-yl)prop-2-en-1-one (4e), (E)-3-(4-chlorophenyl)-1-(1-ethyl-1H-pyrrol-2-yl)prop-2-en-1-one (4f) and (E)-1-(1-ethyl-1H-pyrrol-2-yl)-3-(4-fluorophenyl)prop-2-en-1-one (4g) exhibited excellent inhibitory activity against R. solani with EC50 values from 0.0107 to 0.0134 mg mL-1. Molecular docking of 3j with SDH (succinate dehydrogenase) was performed to reveal the binding modes in the active pocket and analyze the interactions between the molecules and the SDH protein. Meanwhile, they have good thermal stability according to the results of thermogravimetry (TG) analysis.

Interactions between recrystallized rice starch and flavor molecules

Two flavor compounds in cooked rice—2,3-butanedione and 2-acetyl-1-pyrroline were selected as representative flavors that could respectively form B- and V-type crystal complexes with starch. Interactions between recrystallized starch and these flavor compounds were systematically investigated using Fourier-transform infrared (FT-IR), laser confocal micro-Raman (LCM-Raman) spectroscopy and 13C cross-polarization/magic angle spinning nuclear magnetic resonance (13C CP/MAS NMR). Results of FT-IR and LCM-Raman showed that 2,3-butanedione and 2-acetyl-1-pyrroline molecules could interact with recrystallized starch via hydrogen bonding affecting the molecular water environment of starch but with different modes of action. 13C CP/MAS NMR results further indicated that flavor molecules affect the water distribution microenvironment and starch chains conformations in the recrystallized region. The 2-acetyl-1-pyrroline molecules could potentially enter the hydrophobic cavities of B- and V-type crystals, whereas 2,3-butanedione could only interact with the starch chains. These results could enrich knowledge on the flavor retention mechanisms of recrystallized starch.

Characterization of Basil Volatile Fraction and Study of Its Agronomic Variation by ASCA.

Basil is a plant known worldwide for its culinary and health attributes. It counts more than a hundred and fifty species and many more chemo-types due to its easy cross-breeds. Each species and each chemo-type have a typical aroma pattern and selecting the proper one is crucial for the food industry. Twelve basil varieties have been studied over three years (2018–2020), as have four different cuts. To characterize the aroma profile, nine typical basil flavour molecules have been selected using a gas chromatography–mass spectrometry coupled with an olfactometer (GC–MS/O). The concentrations of the nine selected molecules were measured by an ultra-fast CG e-nose and Principal Component Analysis (PCA) was applied to detect possible differences among the samples. The PCA results highlighted differences between harvesting years, mainly for 2018, whereas no observable clusters were found concerning varieties and cuts, probably due to the combined effects of the investigated factors. For this reason, the ANOVA Simultaneous Component Analysis (ASCA) methodology was applied on a balanced a posteriori designed dataset. All the considered factors and interactions were statistically significant (p < 0.05) in explaining differences between the basil aroma profiles, with more relevant effects of variety and year.

Surface-Enhanced Raman Scattering (SERS) Taster: A Machine-Learning-Driven Multireceptor Platform for Multiplex Profiling of Wine Flavors.

Integrating machine learning with surface-enhanced Raman scattering (SERS) accelerates the development of practical sensing devices. Such integration, in combination with direct detection or indirect analyte capturing strategies, is key to achieving high predictive accuracies even in complex matrices. However, in-depth understanding of spectral variations arising from specific chemical interactions is essential to prevent model overfit. Herein, we design a machine-learning-driven "SERS taster" to simultaneously harness useful vibrational information from multiple receptors for enhanced multiplex profiling of five wine flavor molecules at parts-per-million levels. Our receptors employ numerous noncovalent interactions to capture chemical functionalities within flavor molecules. By strategically combining all receptor-flavor SERS spectra, we construct comprehensive "SERS superprofiles" for predictive analytics using chemometrics. We elucidate crucial molecular-level interactions in flavor identification and further demonstrate the differentiation of primary, secondary, and tertiary alcohol functionalities. Our SERS taster also achieves perfect accuracies in multiplex flavor quantification in an artificial wine matrix.

FlavorGraph: a large-scale food-chemical graph for generating food representations and recommending food pairings

Food pairing has not yet been fully pioneered, despite our everyday experience with food and the large amount of food data available on the web. The complementary food pairings discovered thus far created by the intuition of talented chefs, not by scientific knowledge or statistical learning. We introduce FlavorGraph which is a large-scale food graph by relations extracted from million food recipes and information of 1,561 flavor molecules from food databases. We analyze the chemical and statistical relations of FlavorGraph and apply our graph embedding method to better represent foods in dense vectors. Our graph embedding method is a modification of metapath2vec with an additional chemical property learning layer and quantitatively outperforms other baseline methods in food clustering. Food pairing suggestions made based on the food representations of FlavorGraph help achieve better results than previous works, and the suggestions can also be used to predict relations between compounds and foods. Our research offers a new perspective on not only food pairing techniques but also food science in general.

Co-culturing fructophilic lactic acid bacteria and yeast enhanced sugar metabolism and aroma formation during cocoa beans fermentation

Glucose and fructose are the main fermentable sugars in cocoa pulp. During fermentation, glucose is consumed within 48–72 h and fructose only after 120 h, mainly associated with the preferential use of glucose by microorganisms. In the first stage of this study, the complete genome sequence of a lactic acid bacterium with high fructose consumption capacity (Lactobacillus plantarum LPBF35) was reported. The notable genomic features of L. plantarum LPBF35 were the presence of alcohol/acetaldehyde dehydrogenase gene and improved PTS system, confirming its classification as a “facultatively” fructophilic bacterium. Subsequently, this bacterium was introduced into cocoa fermentation process in single and mixed cultures with Pediococcus acidilactici LPBF66 or Pichia fermentans YC5.2. Community composition by Illumina-based amplicon sequencing and viable counts indicated suppression of wild microflora in all treatments. At the beginning of the fermentation processes, cocoa pulp consisted of approximately 73.09 mg/g glucose and 73.64 mg/g fructose. The L. plantarum LPBF35 + P. fermentans YC5.2 process showed the lowest levels of residual sugars after 72 h of fermentation (7.89 and 4.23 mg/g, for fructose and glucose, respectively), followed by L. plantarum LPBF35 + Ped. acidilactici LPBF66 (8.85 and 6.42 mg/g, for fructose and glucose, respectively), single L. plantarum LPBF35 treatment (4.15 and 10.15 mg/g, for fructose and glucose, respectively), and spontaneous process (22.25 and 14.60 mg/g, for fructose and glucose, respectively). The positive interaction between L. plantarum LPBF35 and P. fermentans YC5.2 resulted in an improved formation of primary (ethanol, lactic acid, and acetic acid) and secondary (2-methyl-1-butanol, isoamyl acetate, and ethyl acetate) metabolites during fermentation. The primary metabolites accumulated significantly in cocoa beans fermented by P. fermentans YC5.2 + L. plantarum LPBF35, causing important reactions of color development and key flavor molecules formation. The results of this study suggest that fructophilic lactic acid bacteria and yeast is a microbial consortium that could improve sugar metabolism and aroma formation during cocoa beans fermentation.

RecipeDB: a resource for exploring recipes.

Cooking is the act of turning nature into the culture, which has enabled the advent of the omnivorous human diet. The cultural wisdom of processing raw ingredients into delicious dishes is embodied in their cuisines. Recipes thus are the cultural capsules that encode elaborate cooking protocols for evoking sensory satiation as well as providing nourishment. As we stand on the verge of an epidemic of diet-linked disorders, it is eminently important to investigate the culinary correlates of recipes to probe their association with sensory responses as well as consequences for nutrition and health.RecipeDB (https://cosylab.iiitd.edu.in/recipedb) is a structured compilation of recipes, ingredients and nutrition profiles interlinked with flavor profiles and health associations. The repertoire comprises of meticulous integration of 118 171 recipes from cuisines across the globe (6 continents, 26 geocultural regions and 74 countries), cooked using 268 processes (heat, cook, boil, simmer, bake, etc.), by blending over 20 262 diverse ingredients, which are further linked to their flavor molecules (FlavorDB), nutritional profiles (US Department of Agriculture) and empirical records of disease associations obtained from MEDLINE (DietRx). This resource is aimed at facilitating scientific explorations of the culinary space (recipe, ingredient, cooking processes/techniques, dietary styles, etc.) linked to taste (flavor profile) and health (nutrition and disease associations) attributes seeking for divergent applications. Database URL: https://cosylab.iiitd.edu.in/recipedb

Gelation characteristics of sodium alginate in presence of flavor molecules

Gelation properties of alginate in the presence of flavor molecules were investigated using small amplitude oscillatory shear tests at temperatures from 10 to 40°C. The apparent gelation time (AGT) was 72 min for plain alginate at 10°C. The AGT was 85 min in the presence of 2-acetyl pyridine and 56 min in the presence of eugenol. Flavor molecules affected dynamic elastic modulus (Gʹ) to a different extent depending upon the gelation temperature. At 10°C, Gʹ was higher for samples with eugenol and 2-acetyl pyridine in comparison to the plain version. At 40°C, Gʹ was generally lower for all flavored samples in comparison to the plain version. This study revealed surfactant properties of flavor molecules, with eugenol having the largest activity by reducing the surface tension of water from 73 to 49 mN/m. The compression force was most affected by the gelation temperature; increasing significantly at 40°C for all flavored gels. Practical applications Most of the available literature focuses on the effect of hydrocolloids on flavor release and perception. However, from industrial point of view, it is equally important to know the influence of flavor molecules on the behavior of hydrocolloids. Studies focusing on this issue are scarcely reported in the literature. This work demonstrates that flavor molecules influence significantly the gelation kinetics and other properties of alginate dispersions. The findings of this work are expected to help process engineers better understand and regulate the alginate gelation process in the presence of flavor molecules.

Effects of thermal processing on the flavor molecules of goat by-product hydrolysates

The aim of this study was to obtain flavor molecules from goat by-product hydrolysates, emphasizing the thermal action during processing. A mixture of by-products submitted or not to the inactivation of endogenous enzymes was used, followed by hydrolysis with the proteolytic enzyme Alcalase® (Bacillus licheniformis), and autoclaving after hydrolysis. The production of hydrolysates provided both quantitative and qualitative data on the precursors involved in the aromatic formation of protein hydrolysates. The inactivation process of endogenous enzymes resulted in hydrolysates with a higher degree of hydrolysis and greater protein content. The autoclaving process produced a significant increase in the concentration of free amino acids and maltose and a reduction in the glucose content. Application of the two heat treatments resulted in the production of goat by-product protein hydrolysates with different volatile profiles. The goat by-product protein hydrolysate without heat treatment but with autoclaving (HCA), showing a higher concentration of flavor precursors and the formation of heterocyclic volatiles, is expected to impact the aroma quality of goat hydrolysates.

Development of Green and Clean Processes for Perfumes and Flavors Using Heterogeneous Chemical Catalysis

Background: In this review, different heterogeneous catalysts based on acid, base, metal and enzymes are discussed for the synthesis of industrially relevant perfumes and flavor compounds. These molecules are mainly produced by a variety of reaction pathways such as esterification, isomerization, hydration, alkylation, hydrogenation, oxidation, etc. All these reactions are discussed thoroughly for the synthesis of vital aromatic compounds. The review also summarizes various recent technologies applied for designing new catalysts to obtain the maximum yield of the desired product. Overall, this review highlights the green, clean and eco-friendly processes which can be industrially accepted for the synthesis of perfumes, flavors and fragrances. Objective: The objective of the current review was to emphasize on the synthesis of industrially important perfumes and flavor molecules such as α-terpineol, cyclohexyl esters, thymol, raspberry ketone, etc. using heterogeneous catalysts. Results: Three hundred and eight papers are reported in this review, the majority of which are on heterogeneous catalysis for the synthesis of molecules which impart flavor or possess perfumery characteristics. Among all, the preparation of esters is highlighted as they represent an imperative functional group in aroma chemicals. Conclusion: The review confirms the need for heterogeneous catalysis in pollution-free and costeffective synthesis of flavor and perfumery compounds.

Structural Characterization of a Cyclodextrin/l-menthol Inclusion Complex in the Solid-state by Solid-state NMR and Vibrational Circular Dichroism.

Hydrophobic and volatile flavor molecules can be encapsulated inside cyclodextrins (CyDs). Inclusion complexes are frequently used in solid or dispersed states in preserved food and cosmetics. In this study, the solid-state structures of spray-dried inclusion complexes of l-menthol in α-CyD and β-CyD were analyzed using 13C solid-state NMR and vibrational circular dichroism (VCD). The NMR signals of l-menthol and CyDs were identified in the physical mixture and the l-menthol inclusion complex of α- and β-CyD. The NMR signal of the isopropyl-methyl group of menthol in the α-CyD inclusion complex exhibited a large low-field shift, which suggested a steric hindrance between menthol and α-CyD. VCD exhibited specific changes in the intensity of bands corresponding to C-C vibrations in α-CyD and O-C stretching vibrations in l-menthol. Our results indicated that l-menthol specifically fitted the narrow space within α-CyD. The combined solid-state NMR and VCD analysis provided structural insights into the flavor inclusion complex in the solid-state.

Covalent Adduct Formation Between Flavor Compounds of Various Functional Group Classes and the Model Protein β-Lactoglobulin.

The formation of covalent bonds between 47 flavor compounds belonging to 13 different classes of functional groups and β-lactoglobulin (BLG) has been evaluated using electrospray ionization protein mass spectrometry. Covalent bond formation was determined by the appearance of ions in the mass spectra corresponding to BLG + flavor molecule(s). The observed processes for covalent bond formation were Schiff base, Michael addition, and disulfide linkages. Some reactions resulted in protein cross-linking. Aldehydes, sulfur-containing molecules (especially thiols), and functional group-containing furans were the most reactive flavor components. The thiol-containing compounds cleaved one or both electrophilic disulfide linkages in BLG to form disulfide linkages and the sulfides formed covalent bonds with the free cysteine group. Ketones were generally stable, but α-diketones (e.g., diacetyl) were reactive. Some bases (e.g., pyrazines and pyridines) were interactive, while the nucleophilic allylamine was reactive. Hydrocarbons, alcohols, acids, esters, lactones, and pyrans did not give observable levels of adduct formation within the period studied. The formation of covalent bonding (flavor protein) is potentially responsible for the loss of flavor, limiting the shelf-life of many foods.

Effects of pulsed electric field treatment on the preparation and physicochemical properties of porous corn starch derived from enzymolysis

Porous corn starch preparation by enzymolysis and pulsed electric field treatment (PEF) and its physicochemical characterizations were investigated in this study. The best processing parameters of enzymolysis and PEF treatment designed by response surface methodology were 3.9 hr, 11.5 kV/cm applied for 18 ms, respectively, resulting in the highest oil absorption value of 130%. The solubility and transparency of native corn starch were increased after enzymolysis or PEF treatment, and the values were the highest when starch was treated with the combined method. Pasting temperature and gelatinization enthalpy of porous starch were higher than that of native starch, but then decreased significantly after PEF treatments. Scanning electron microscope images, specific surface area as well as X-Ray Diffraction directly reflected the reinforcement effect of PEF treatment on the micropores formation of porous starch. These results indicate that PEF is expected to be used to assist the production of porous starch. Practical applications Starch materials are able to dehydrate water from ethanol due to the existence of numerous hydroxyl groups on the surface, porous starch granules possesses larger specific surface area, which increases the total number of hydroxyl groups on starch particles’ surface. Increased surface area provides more reactive sites at which functionalized groups can be grafted to improve starch properties as well. In addition, numerous small pores enable porous starch to encapsulate compounds of several times its weight by the absorption and capillary flow of micropores, especially heat-liable compounds like flavor molecules, plant essential oils, biologically functional compounds, for example, liquid flavors are unstable under heat processing, mixtures of which could be spry-dried with porous starch to obtain flavor powder, prolonging the storage time of flavor compounds. And the combination of enzymolysis and PEF treatment is good for the micropores formation of porous starch, which could be used to produce porous starch for industrial application.