Flavor Binding Research Articles

Molecular interactions by thermodynamic and computational molecular docking simulations of selected strawberry esters and pea protein isolate in an aqueous model system

The objective of this study was to determine the interactions between selected strawberry esters and pea protein isolate (PPI) in a protein-containing aqueous model system, utilizing modified ultrafiltration and equilibrium dialysis techniques. Strawberry esters, including ethyl butanoate, ethyl isopentanoate, ethyl hexanoate, and methyl anthranilate, demonstrated different binding parameters to the PPI. Overall flavor binding affinities (nK) of all esters decreased as the temperature increased from 5 °C to 25 °C. Among these compounds, ethyl hexanoate exhibited the highest affinity to PPI at 25 °C. Thermodynamic parameters revealed that all ester-PPI interactions were spontaneous and enthalpy-driven, primarily involving van der Waals forces or hydrogen bonding. In addition, computational molecular docking studies also identified alkyl hydrophobic interactions in ester-PPI complexes. These findings illustrated that understanding the interactions between esters and PPIs can assist in determining the optimal proportions of compounds for flavorings in high-protein beverages from pea protein.

Plant protein flavor chemistry fundamentals and techniques to mitigate undesirable flavors

AbstractMany plant protein ingredients have unpleasant flavor (e.g., green, beany, bitterness) characteristics. Isolation of the protein fraction will reduce the intensity of the undesirable flavors but in most cases the flavor issue is not eliminated. The objective of this review is to provide information about undesirable flavors associated with plant proteins and approaches to mitigate these flavors. The focus of the review will be on flavor associated with plant proteins from pulses, soybean, and oilseeds (e.g., hempseed, flaxseed). While other plant proteins exist, they will not be covered extensively in this limited review. The undesirable flavors are defined as volatile organic compounds (VOCs) and non‐volatile organic compounds (non‐VOCs). Example VOCs include aldehydes, ketones, and isobutyl pyrazines whereas saponins, bitter peptides, and phenolics are among the most common non‐VOCs. The raw material used as the source for the protein dictates the undesirable flavors remaining in the protein ingredient. The intensity of the binding of the VOCs and non‐VOCs to protein serves as the basis for the detection and difficulty in removing these compounds from the protein. A discussion about flavor binding and processing methods to mitigate unwanted flavors in protein ingredients will be provided. Methods presented will focus on extraction and thermal treatment. Although flavor masking is an approach to minimize undesirable, this topic will not be covered. Understanding the compounds responsible for the flavor issues and methods to minimize their impacts on sensory characteristic of protein ingredients can provide manufacturers with solutions to addressing flavor issues inherent to plant proteins.

Unraveling the Role of Flavor Structure and Physicochemical Properties in the Binding Phenomenon with Commercial Food Protein Isolates.

Food protein-flavor binding influences flavor release and perception. The complexity of the binding phenomenon lies in the flavor and protein properties. Thus, molecular interactions between commercial whey- or plant-based protein isolates (PI) such as pea, soy, and lupin, with carbonyl and alcohol flavor compounds were assessed by static headspace (HS) GC-MS. HS results showed that not only the displacement of the carbonyl group from the inner part of the flavor structure toward the edge promoted binding up to 52.76% ± 4.65 but also the flavor's degree of unsaturation. Similarly, thermal treatment led to a slight increase in hexanal-protein binding because of possible protein conformational changes. Protein's residual fat (<1%) seemed insufficient to promote significant flavor binding to PI. Despite the complexity of commercial food protein isolates, the results displayed that binding is predominantly influenced by the flavor structure and physicochemical properties, with the protein source and residual fat playing a secondary role.

Characterization of the interaction between capsaicin and porcine myofibrillar proteins

Flavor binding or release behavior acts as an important role in the sensory characteristics of meat products. The interaction between capsaicin and porcine myofibrillar proteins (MPs) was investigated using spectroscopic methods and molecular docking simulations. The capsaicin quenched the fluorescence of MPs via static quenching mechanisms, indicating the interaction between MPs and capsaicin. The binding constant (1.20 × 105, 3.98 × 105 and 16.98 × 105 L/mol for 298, 303 and 310 K, respectively) and the number of binding sites (1.57, 1.74 and 2.01 for 298, 303 and 310 K, respectively) for capsaicin binding to MPs increased with the increase of temperature. Fluorescence and Raman spectroscopic analyses suggested that capsaicin exhibited no obvious effect on the conformation of MPs. The thermodynamic analysis revealed that interactions between capsaicin and MPs were spontaneous processes. The positive ΔH (169.05 kJ/mol) and ΔS (0.66 kJ/(mol·K)) indicated that the binding of capsaicin to MPs was predominantly driven by hydrophobic force, which was further corroborated by molecular docking simulations. The study provides insights into the mechanism of the interaction between capsaicin and MPs, which can guide the modulation of the spicy flavor during the meat processing to improve the sensory characteristics of meat products.

Flavor-food ingredient interactions in fortified or reformulated novel food: Binding behaviors, manipulation strategies, sensory impacts, and future trends in delicious and healthy food design.

With consumers gaining prominent awareness of health and well-being, a diverse range of fortified or reformulated novel food is developed to achieve personalized or tailored nutrition using protein, carbohydrates, or fat as building blocks. Flavor property is a critical factor in the acceptability and marketability of fortified or reformulated food. Major food ingredients are able to interact with flavor compounds, leading to a significant change in flavor release from the food matrix and, ultimately, altering flavor perception. Although many efforts have been made to elucidate how food matrix components change flavor binding capacities, the influences on flavor perception and their implications for the innovation of fortified or reformulated novel food have not been systematically summarized up to now. Thus, this review provides detailed knowledge about the binding behaviors of flavors to major food ingredients, as well as their influences on flavor retention, release, and perception. Practical approaches for manipulating these interactions and the resulting flavor quality are also reviewed, from the scope of their intrinsic and extrinsic influencing factors with technologies available, which is helpful for future food innovation. Evaluation of food-ingredient interactions using real food matrices while considering multisensory flavor perception is also prospected, to well motivate food industries to investigate new strategies for tasteful and healthy food design in response to consumers' unwillingness to compromise on flavor for health.

Improvement of the gel properties and flavor adsorption capacity of fish myosin upon yeast β-glucan incorporation

The potential effects of yeast β-glucan (YG) on heat-induced gel properties, microstructure and flavor adsorption capacity of fish myosin at different NaCl concentrations were investigated in this study. The incorporation of YG significantly improved the texture properties, gel strength, water holding capacity (WHC), storage modulus and loss modulus of myosin gels, especially at a high salt level, whereas the whiteness declined. Furthermore, myosin gels containing YG displayed a more compact and ordered three-dimensional network structure, accompanied by the increasing immobilization of water in gels. The binding abilities of gels to selected flavor compounds at high salt content were inferior to those at the low salt content. Regardless of the salt level, YG addition boosted the flavor binding capacity of gels, which might be attributed to the unfolding of the protein conformation by exposing more flavor-binding sites, as well as the porous sponge structure of YG with unique adsorption capacity.

Effect of deacetylated konjac glucomannan on heat-induced structural changes and flavor binding ability of fish myosin

This work investigated the effects of deacetylated konjac glucomannan (DKGM) on heat-induced structural changes and flavor binding in bighead carp myosin. DKGM could cross-link with fish myosin to form a thermostable complex and improve the gel strength of myosin. The incorporation of DKGM increased the surface hydrophobicity and total sulfhydryl content of heat-induced myosin. Increasing DKGM concentrations resulted in a decrease in the absolute zeta potential and a continuous increase in particle size. DKGM addition significantly reduced the α-helical content of myosin with a concomitant increase in β-sheet, β-turn, and random coil content. The binding abilities of myosin to flavors were significantly enhanced by increasing amounts of DKGM, attributing to the accelerative unfolding of myosin secondary structures and the exposure of additional hydrophobic and thiol binding sites. Increased numbers of available hydroxyl groups after DKGM treatment could also cause an increase of flavor adsorption by hydrogen bonding.

Improving the cake quality by using red kidney bean applied different traditional processing methods

This study aimed to evaluate the effects of adding red kidney bean flour subjected to soaking with dehulling, cooking, and roasting substituted with wheat flour on functional, physical, qualitative, and sensorial properties of cake and as compared with control cake. Traditional processing methods affect the functional properties of red kidney bean flour, as emulsion capacity and foaming capacity values increased but oil absorption capacity values decreased. Cooked (CKB) and roasted red kidney bean (RKB) flour samples gave higher water and oil absorption capacity values than raw (R) and soaked and dehulled red kidney bean flour (SDKB). The highest emulsion capacity values were determined with CKB samples, and the highest foaming capacity values determined were with R and RKB samples. Treatments also affected the batter pH of cake; CKB-added cake batter gave the highest pH, but the lowest pH value of cake batter was obtained with R added formula. Cooking treatment showed the highest volume index values in cake samples. SDKB, CKB, and RKB addition in cake formulation gave higher volume index compared with control and R-added cake. Desirable uniformity index values were obtained with R, CKB, and RKB cake samples. All treatments of red kidney bean showed a decrease in firmness values. Red kidney bean flour addition increased the ash and protein amount and decreased the carbohydrate content. Treatments resulted in a decrease in the fat content of cake samples. Control cake sample, CKB, and RKB-added cake samples were found more acceptable according to taste and odor by panelists. In conclusion, due to their beneficial effects, CKB and SDKB might be recommended to be used in cake formulations successfully. Practical applications Processing techniques such as soaking, autoclaving, dehulling, boiling, irradiation, cooking, germination, fermentation, and ultrasound improves the nutritional quality and digestibility of dry beans by reducing the content of anti-nutritional factors and, at the same time, diversifies their use as ingredients by altering their functional properties. There is limited information about bean flour's functional and physico-chemical properties and ultimately affecting product properties and therefore sensory quality and consumer acceptability. Functional properties of flours are important for the development of new food products besides their stability of storage (oxidative rancidity and flavor binding). In this study, three different treatments (soaking–dehulling, cooking, and roasting) on red kidney bean flour were applied and-added cake formulation to compare the physical, chemical, sensorial properties of cake samples with control (wheat flour) and raw red kidney bean flour.

Heavy flavor dissociation in framework of multi-body Dirac equations * * Supported by the NSFC (11575093, 11890712), and the Natural Sciences and Engineering Research Council of Canada

We study heavy flavor properties at finite temperature in the framework of a relativistic potential model. Using an improved method to solve the three-body Dirac equation, we determine a universal set of model parameters for both mesons and baryons by fitting heavy flavor masses in vacuum. Taking heavy quark potential from lattice QCD simulations in hot medium, we systematically calculate heavy flavor binding energies and averaged sizes as functions of the temperature. The meson and baryons are separately sequentially dissociated in the quark-gluon plasma, and the mesons can survive at higher temperatures owing to the stronger potential between quark-antiquark pairs than that between quark-quark pairs.

Flavor binding property of coconut protein affected by protein-glutaminase: Vanillin-coconut protein model

Flavor compounds added to food products can interact with protein and may result in a reduction in flavor intensity. The objective of this study was to study the effect of enzymatic deamidation by protein-glutaminase (PG) on the flavor-binding potential of coconut protein (CP) using a vanillin flavor model. Vanillin was allowed to interact with either 3 g/100 mL of untreated or deamidated CP (DCP) suspended in 0.05 mol/L phosphate buffer. The results showed that deamidation by PG decreased overall flavor-binding affinity of vanillin to the protein from 586 to 985 ( × 104) L/mol to 435–803 ( × 104) L/mol. Thermodynamic parameters indicated that the vanillin-protein interactions were spontaneous and the interactions were driven by enthalpy. Beside Schiff-base formation, van der Waals forces or hydrogen bonding were suggested to be involved in the binding mechanism. The lower binding affinity for vanillin for DCP than for CP was confirmed by a sensory threshold study, which showed that vanillin had about a 2 fold lower odor detection threshold in DCP solution than in CP solution.

Binding of volatile aroma compounds to can linings with different polymeric characteristics.

Flavor compounds have been shown to interact with packaging materials either by scalping, the movement of flavorings from the food product to the package, or by flavor release, movement of flavorings from the package to the food. Work has elucidated the parameters important for the scalping of flavor compounds to polyolefin packaging materials, but very little work has been conducted examining the scalping of flavor compounds by can lining materials. Can linings composed of three different polymers, polyolefin, acrylic, epoxy, were studied for binding of volatile flavor compounds (octanal, nonanal, decanal, eugenol, d‐limonene) at room temperature over a 2‐week period. Solid phase microextraction (SPME) was used with gas chromatography mass spectrometry to identify and quantify volatile compounds. Flavor compounds were studied at concentrations around 4–1,000 ppb. Fourier transform infrared spectroscopy was used to verify can lining polymer chemistry. Almost complete binding of all five of the volatile compounds studied was observed over 9–14 days at room temperature for each of the can lining chemistries. The number of time data points limited our ability to determine the order and rate constants of binding. This model system appears to be a valuable for investigating flavor binding of polymeric can lining materials.

Effect of trypsin treatments on the structure and binding capacity of volatile compounds of myosin

In order to investigate the mechanism between flavor binding and proteins degradation during meat processing, the influence of different trypsin contents on the structure of myosin and the adsorption capacity on aldehydes and ketones was determined. The 1% treatment produced subfragment 2 (S2), light meromyosin (LMM) and decreased 18 and 16kDa light chains; 5% and 10% treatments produced 100 and 65kDa new bands and more S2, LMM and cleaned light chains. With the rising trypsin contents, β-sheet, β-turn, random coil, hydrophobicity and total sulfydryl content increased; solubility, α-helix and free percentages of aldehydes and ketones decreased. The increase of absorbing capacity could be attributed to the increased hydrophobicity and total sulphydryl and the unfolding of secondary structures by exposing reactive amino and thiol groups and hydrophobic sites; the decreased solubility was related to the increased hydrophobicity. The trypsin-dose dependent proteolysis of myosin increased the retention of volatile compounds.

Food Protein Functionality--A New Model.

Proteins in foods serve dual roles as nutrients and structural building blocks. The concept of protein functionality has historically been restricted to nonnutritive functions--such as creating emulsions, foams, and gels--but this places sole emphasis on food quality considerations and potentially overlooks modifications that may also alter nutritional quality or allergenicity. A new model is proposed that addresses the function of proteins in foods based on the length scale(s) responsible for the function. Properties such as flavor binding, color, allergenicity, and digestibility are explained based on the structure of individual molecules; placing this functionality at the nano/molecular scale. At the next higher scale, applications in foods involving gelation, emulsification, and foam formation are based on how proteins form secondary structures that are seen at the nano and microlength scales, collectively called the mesoscale. The macroscale structure represents the arrangements of molecules and mesoscale structures in a food. Macroscale properties determine overall product appearance, stability, and texture. The historical approach of comparing among proteins based on forming and stabilizing specific mesoscale structures remains valid but emphasis should be on a common means for structure formation to allow for comparisons across investigations. For applications in food products, protein functionality should start with identification of functional needs across scales. Those needs are then evaluated relative to how processing and other ingredients could alter desired molecular scale properties, or proper formation of mesoscale structures. This allows for a comprehensive approach to achieving the desired function of proteins in foods.

Why does the sense of smell vanish in the mouth? Testing predictions from two accounts.

When participants perceive flavor they do not recognise the role of smell. We examined two possible accounts of why: (1) a common attentional channel activated by taste; and (2) prior learning between taste and smell. Participants were asked to sniff food-related odors with a fluid in their mouth and profile each odor after expectorating. This process was later repeated for each odor, with some odors experienced with water on both occasions, and others with water on one occasion and sucrose (weak or strong) on the other. We investigated how reliable these odor profiles were and whether they were influenced by prior odor-taste learning (indexed by odor sweetness). For non-sweet smells, the presence of a tastant significantly improved profile reliability relative to water in the mouth. For sweet smells, tastant had no effect, which we suggest represents a cancelling out of the beneficial effects of the common attentional channel by the detrimental effects of prior learning. Thus, both mechanisms may contribute to masking the modal identity of smell thereby contributing to flavor binding.

Flavor binding: Its nature and cause.

The brain binds inputs from multiple senses to enhance our ability to identify key events in the environment. Understanding this process is based mainly on data from the major senses (vision and audition), yet compelling examples of binding occur in other domains. When we eat, in fact taste, smell, and touch combine to form flavor. This process can be so complete that most people fail to recognize that smell contributes to flavor. The flavor percept has other features: (a) it feels located in the mouth, even though smell is detected in the nose and taste on the tongue, and (b) it feels continuous, yet smell is delivered in pulses to the nose during eating. Furthermore, tastes can modify smell perception and vice versa. Current explanations of these binding-related phenomena are explored. Preattentive processing provides a well-supported account of taste-to-tongue binding. Learning between taste and smell can explain perceptual interactions between these senses and perhaps localization of smell to the mouth. Attentional processes may also be important, especially given their role in binding the major senses. Two are specifically examined. One claims that the failure to recognize smell's role in flavor stems from the role of involuntary attention's "defaulting" to the mouth and taste (i.e., binding by ignoring). Another claims that taste and smell form a common attentional channel in the mouth, in effect becoming one sense. Except for preattentive processing, the mechanisms involved in flavor binding differ markedly from those proposed for the major senses. This distinction may result from functional differences, with flavor supporting future food choice but not current identification.

Effect of Enzymatic Protein Deamidation on Protein Solubility and Flavor Binding Properties of Soymilk

The effect of enzymatic deamidation by protein-glutaminase (PG) on protein solubility and flavor binding potential of soymilk was studied. Treatment of soymilk with PG for 2 h (temperature of 44 °C and enzyme:substrate ratio (E/S) of 40 U/g protein) resulted in high degree of protein deamidation (66.4% DD) and relatively low degree of protein hydrolysis (4.25% DH). Deamidated (DSM) and control soymilks (CSM) did not differ with respect to aroma, but differed in taste characteristics by sensory evaluation. Protein solubility in DSM was enhanced at weakly acidic conditions (pH 5.0), but did not differ from non-deamidated soymilk at pH values of 3.0 and 7.0. Odor detection thresholds for the flavor compounds vanillin and maltol were approximately 5 and 3 fold lower, respectively, in DSM than in CSM. Dose-response curves (Fechner's law plots and n exponents from Stevens's power law) further demonstrated that DSM had a lower flavor binding potential than CSM. PG deamidation has the potential to reduce flavor binding problems encountered in high protein-containing foods and beverages. The findings of this study can help lead to the development of technology to produce protein-containing foods with improved functional properties, especially protein solubility, and potentially decreased flavor fade problems associated with flavor-protein interactions, especially with carbonyl containing flavor compounds.

In Silico Homology Modeling To Predict Functional Properties of Cruciferin

Cruciferin is the major storage protein in Brassicaceae family oilseeds. The predominant cruciferin isoforms in Arabidopsis thaliana were investigated using homology modeling (HM) for their molecular structures and functional properties. The structure of Brassica napus procruciferin was used as the template for HM to determine the molecular structures and hypervariable regions. Hydrophobicity and electrostatic surface potential distribution on the intradisulfide-containing face (IA) and the interdisulfide-containing face (IE) indicated favorable interfacial and solubility properties. More heat-induced structural changes were predicted for the CruC homotrimer than for the CruA or CruB homotrimers. Structural features that facilitate flavor binding and limit proteolytic digestion were more readily observed in CruA and CruB than in CruC. On the basis of these comparative models, structural differences among cruciferin isoforms and their relevance to potential technofunctionalities were identified. This approach of functional property prediction will link protein structure to utilities and will be valuable in designing proteins for targeted applications.

The impact of mediodorsal thalamic lesions on olfactory attention and flavor perception

Olfactory attention may be important in generating odor-induced tastes – an arguably universal form of synesthesia – by ensuring that the taste concurrent is captured by the nose and olfaction, not by the mouth and gustation (oral-capture). To examine the role of olfactory attention in generating odor-induced tastes and oral capture we tested a small sample ( n = 4) of participants with likely impairments in olfactory attention – individuals with mediodorsal thalamic nucleus (MDNT) lesions. These participants were compared to two sets of controls on tests of olfactory attention, oral capture, odor and flavor perception, and control tasks. MDNT participants demonstrated impaired olfactory attention and enhanced oral capture. Greater oral capture was associated with greater olfactory attentional impairment. These findings imply that olfactory attention may be important in attributing odor-induced tastes to the olfactory modality. However, unlike for visual binding and for the neurodevelopmental synesthesias, where attention may be necessary to demonstrate both phenomena, olfactory attention deficits did not impair flavor binding or the experience of odor-induced tastes.

The role of attention in the localization of odors to the mouth

Odors can be perceived as arising from the environment or as part of a flavor located in the mouth. One factor that may dictate where an odor is perceived to be is concurrent gustatory stimulation in the mouth. A taste may impair the ability to attend to an odor, especially if they are perceptually similar. Alternatively, salient mouth-based features of a flavor might command attention at the expense of smell. Experiment 1 and 2, using different stimulus sets, explored the impact of perceptually similar and dissimilar pairings of tastes in the mouth and odors at the nose. In each case, these were followed by judgments of the odor's location (mouth vs. nose). Perceptual similarity had no impact on localization judgments. Experiment 3 then manipulated the salience of the olfactory and gustatory cues and showed that each could independently shift the perceived location of an odorant-salient olfactory cues toward the nose and gustatory cues toward the mouth. These findings suggest that the salient features of a flavor may command attention at the expense of olfaction and, thereby, contribute to oral localization, with implications for flavor binding.

Short communication: Low-fat ice cream flavor not modified by high hydrostatic pressure treatment of whey protein concentrate

The purpose of this study was to examine flavor binding of high hydrostatic pressure (HHP)-treated whey protein concentrate (WPC) in a real food system. Fresh Washington State University (WSU, Pullman) WPC, produced by ultrafiltration of separated Cheddar cheese whey, was treated at 300MPa for 15min. Commercial WPC 35 powder was reconstituted to equivalent total solids as WSU WPC (8.23%). Six batches of low-fat ice cream were produced: A) HHP-treated WSU WPC without diacetyl; B) and E) WSU WPC with 2 mg/L of diacetyl added before HHP; C) WSU WPC with 2 mg/L of diacetyl added after HHP; D) untreated WSU WPC with 2 mg/L of diacetyl; and F) untreated commercial WPC 35 with 2 mg/L of diacetyl. The solution of WSU WPC or commercial WPC 35 contributed 10% to the mix formulation. Ice creams were produced by using standard ice cream ingredients and processes. Low-fat ice creams containing HHP-treated WSU WPC and untreated WSU WPC were analyzed using headspace-solid phase microextraction-gas chromatography. Sensory evaluation by balanced reference duo-trio test was carried out using 50 untrained panelists in 2 sessions on 2 different days. The headspace-solid phase microextraction-gas chromatography analysis revealed that ice cream containing HHP-treated WSU WPC had almost 3 times the concentration of diacetyl compared with ice cream containing untreated WSU WPC at d 1 of storage. However, diacetyl was not detected in ice creams after 14 d of storage. Eighty percent of panelists were able to distinguish between low-fat ice creams containing untreated WSU WPC with and without diacetyl, confirming panelists’ ability to detect diacetyl. However, panelists were not able to distinguish between low-fat ice creams containing untreated and HHP-treated WSU WPC with diacetyl. These results show that WPC diacetyl-binding properties were not enhanced by 300-MPa HHP treatment for 15min, indicating that HHP may not be suitable for such applications.