The Enhancement of the Perception of Saltiness by Odorants Selected from Chinese Douchi in Salt Solution

Research Progress in Saltiness Perception and Salty Substitutes

Salty taste in foods is a key sensory attribute for appetite enhancement, however, consumption of a high salt diet is associated with a high risk of hypertension, stroke, and heart diseases. To address this issue, the World Health Organization (WHO) has recommended reducing the global per capita salt consumption by 30% by 2025, with adults optimally consuming less than 5 g/day of salt. Therefore, the search for new salty substitutes to reduce salt intake in foods has become a research hotspot. Despite the ongoing endeavors of global research, multiple studies have focused on the application of a single category of salty alternatives or food processing quality (such as preservative effects and process characteristics), and there is still little comprehensive evaluation of these alternatives in terms of nutritional value, health impact, and consumer acceptance in the literature. This review will first outline the urgency of global salt reduction, followed by thorough discussion of salty substitutes and associated mechanisms from the perspective of human salty taste perception. Second, the present review will explore the potential application of salty substitutes and highlight the interaction between taste and odor in foods. Additionally, the potential impacts of salty substitutes on human health will be discussed. The present review will provide a scientific basis for the development of low salt products by food industry.

Computational approaches for decoding structure-saltiness enhancement and aroma perception mechanisms of odorants: From machine learning to molecular simulation

The unclear relationship between structure and saltiness enhancement limits the development and application of savory odorants. The structure characteristic-saltiness enhancement perception (SEP) mechanisms of savory odorants were investigated by machine learning, molecular docking, and site-directed mutagenesis simulations. The XGBoost model (R2 = 0.96) showed better prediction on the maximum saltiness-enhancement ability of odorants based on their structures. The important features of the odorants contributing to SEP were analyzed by Shapley additive explanations (SHAP). Results showed that phenyl and aldehyde groups had significant positive contributions to SEP, with SHAP values of + 2.94 and + 0.74, respectively. Molecular docking and site-directed mutagenesis simulations elucidated the interaction region, forces, and key sites between savory odorants and olfactory receptors. Results showed TM3, TM5 and TM6 were the main interaction regions of the savory odorants prioritize binding with OR1A1 and OR1D2, resulting in the characteristic aromas. Hydrogen bonding and hydrophobic interactions were the key driving forces. Phe203, Asn109, and Asn155 of OR1A1 were partially important residues involved in the interactions with savory odorants. These findings presented a quick screening approach for savory odorants and revealed their SEP mechanism, providing theoretical guidance to facilitate the application of odor-induced salt reduction in food industry.

Decoding of the enhancement of saltiness perception by aroma-active compounds during Hunan Larou (smoke-cured bacon) oral processing

The enhancement of saltiness induced by odrants perceived from the retronasal cavity during Larou oral processing was analyzed. During the oral processing of Xiangtan Larou, the smoky attribute was the dominant when chewing 0-15 times, followed by the savory (15-24 times) and meaty (24-42 times). Partial least squares analysis predicted 33 aroma compounds from the retronasal cavity significantly (p < 0.05) contributing to the aroma perception. A total of 12 aroma compounds with saltiness-enhancement ability were confirmed by odorant-NaCl mixture model experiments. Results revealed that 2-methoxy-4-vinylphenol (1.00-1000.00 μg/L) had the strongest enhancing effect on saltiness at NaCl (2969.85 mg/L), followed by diallyl sulfide (0.156-2.50 μg/L), 2,5-dimethylthiophene (0.156-50.00 μg/L), 2,6-dimethylphenol (1.00-100.00 μg/L), 2,5-dimethylpyrazine (0.391-50.00 μg/L), and 2,3-butanedione (0.50-100.0 μg/L). The sulfur-containing, nitrogen-containing, and phenolic odorants with savory, roasty, sulfide, meaty or smoky, attributes showed the better ability in saltiness enhancement.

Effectively saltiness enhanced odorants screening and prediction by database establish, sensory evaluation and deep learning method

Odor-taste interaction has gained success in enhancing saltiness perception. This work aimed to provide candidate odorants for saltiness enhancement. Volatile compounds and their frequencies in salty foods were systematically analyzed. The compounds with higher frequency were incorporated into the savory aroma compounds database. The saltiness enhancement concentrations of representative aroma compounds at the NaCl solution (3.00 g/L) were detected by sensory evaluation. SELF-referencing Embedded Strings-based representation leaning and graph attention network combined with Backpropagation Neural Network classifier was utilized to predict the saltiness-enhancing ability of odorants. Results showed that ketones, pyrazine and sulfur-containing compounds showed higher saltiness-enhancing ability. Mushroom and fatty attributes contributed to the saltiness-enhancing ability of aroma compounds. Deep learning model showed excellent generalization ability and accuracy (95.93 %), which provided rapid screening method for selecting savory aroma compounds. This study would provide new pathways for food industry to achieve salt reduction goals.

Key aroma compounds associated with umami perception of MSG in fried Takifugu obscurus liver

Monosodium glutamate (MSG) is a basic representative of umami taste, but it exerts adverse effects as reported in several studies. Enhancing umami perception through aroma-taste interactions is a potentially useful approach as a flavor enhancer to reduce future MSG intake. We identified the aroma compounds in fried Takifugu obscurus liver, then studied the effect of aroma compounds on perceived umami taste using the sensomics approach. A total of 117 volatile compounds were identified from the fried liver. Thereinto, 30 volatile compounds related to five basic tastes were detected by gas chromatography/olfactometry-associated taste analysis. Aroma compounds associated umami, sweet and salty perception in the fried Takifugu obscurus liver showed the potential to enhance umami perception of MSG solutions. Three aldehydes, i.e. heptanal, (Z)-4-heptenal and 2-methylbutanal, significantly enhanced the umami intensity perception of an MSG solution (p < 0.05). The use of aroma compounds to enhance umami perception is considered as a promising tool, further broadening the research area of umami science for application as flavor enhancers in the food industry. In addition, this study also provides an insight into revealing aroma-taste interaction.

A comprehensive review of plant-derived salt substitutes: Classification, mechanism, and application

The diseases caused by excessive sodium intake derived from NaCl consumption have attracted widespread attention worldwide, and many researchers are committed to finding suitable ways to reduce sodium intake during the dietary process. Salt substitute is considered an effective way to reduce sodium intake by replacing all/part of NaCl in food without reducing the saltiness while minimizing the impact on the taste and acceptability of the food. Plant-derived natural ingredients are generally considered safe and reliable, and extensive research has shown that certain plant extracts or specific components are effective salt substitutes, which can also give food additional health benefits. However, these plant-derived salt substitutes (PSS) have not been systematically recognized by the public and have not been well adopted in the food industry. Therefore, a comprehensive review of PSS, including its material basis, flavor characteristics, and taste mechanism is helpful for a deeper understanding of PSS, accelerating its research and development, and promoting its application.

Umami and saltiness enhancements of vegetable soup by enzyme-produced glutamic acid and branched-chain amino acids

Introduction

One major challenge of reducing salt content in food is the risk of the overall taste becoming bland. Enhancing saltiness is an effective strategy for salt reduction, and the development of salt-reduced foods using these saltiness-enhancing flavorants as food additives is underway. However, an increasing number of consumers demand a reduction in additives in clean-label foods.

Objective

Enzyme processing of food is an attractive strategy for developing clean-label foods because enzymes are not considered additives. We aimed to improve the saltiness and umami intensity of vegetable soups by enzyme treatment while meeting clean-label requirements. We first optimized the enzymatic reaction conditions of a protease and glutaminase blend and then investigated the synergistic effects of this enzyme blend on the taste of vegetable soup.

Results

Sensory evaluations indicated that the reaction products (e.g., protein hydrolysates or amino acids) could enhance the umami, kokumi, and saltiness intensity of vegetable soup supplemented with 0.5% NaCl. Notably, the saltiness intensity ratio of the enzyme-treated soup with 0.50, 0.45, and 0.40% NaCl were increased by 1.31-, 1.16-, and 0.99-fold, respectively, when this ratio for the control soup with 0.50% NaCl was set to 1.0. This indicates a 20% salt reduction rate can be achieved by enzyme treatment. Moreover, we found that these enhancements were synergically caused by enzyme-produced glutamic acid and branched-chain amino acids.

Conclusion

Our findings suggest that using enzyme blends of bacterial and fungal proteases and glutaminase is an effective approach to enhancing the saltiness levels of vegetable soups while meeting clean-label requirements.

Evaluation of aroma characteristics of Penaeus vannamei with different drying methods using HS-SPME-GC-MS, MMSE-GC-MS, and sensory evaluation

The effects of microwave drying (MD), hot air drying (HAD), vacuum hot air drying (VD), and vacuum freeze drying (VFD) on the volatile profiles of Penaeus vannamei were investigated. A total of 89 and 94 volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and monolithic material sorptive extraction gas chromatography-mass spectrometry (MMSE-GC-MS), respectively. Orthogonal partial least squares-discriminant analysis (OPLS-DA) and variable influence on projection (VIP) models were utilized to select characteristic volatiles and key marker compounds (e.g., octanal, 1-octen-3-ol, 2-methyl-butanal, 2-ethyl-furan, and trimethyl-pyrazine) to discriminate among four drying methods. Based on synthesis of odor descriptions and sensory evaluation, it was found that P. vannamei via MD, HAD, and VD greatly reduced the fishy and generated roasted, fatty, and smoked odors. This study systematically analyzed the aroma characteristics of four traditional dried P. vannamei products, which may provide theoretical guidance for industrial production.

Effects of polyols at low concentration on the release of sweet aroma compounds in model soda beverages

This study investigated the effect of polyols erythritol, d-mannitol, and maltitol on the volatility of aroma compounds γ-butyrolactone, 3-methyl-1-butanol, and 2-phenylethanol in aqueous solution. Headspace solid-phase microextraction/gas chromatography and diffusion-ordered nuclear magnetic resonance techniques were used to obtain information on aroma-food matrix interaction. Results demonstrated that adding polyols at final low concentrations of 5% or 10% (w/w) to an aqueous solution of 2-phenylethanol reduced the release of vapor-phase aromas, except in the case of 3-methyl-1-butanol, which was not affected by the presence of polyols in the liquid matrix. Polyols also reduced the diffusion coefficients of all three aroma compounds, probably due to friction between the molecules. At low polyol concentrations, aroma compound volatility and diffusion coefficient values were altered compared to those of aromas released from pure water. This observation is related to the physicochemical properties of the aroma compounds. These insights may help guide the use of the combination of aroma compounds and polyols in the formulation of sugar-free and reduced-sugar beverages.

Chemical compounds

γ-butyrolactone (PubChem CID: 7302), 3-methyl-1-butanol (PubChem CID: 31260), 2-phenylethanol (PubChem CID: 6054), erythritol (PubChem CID: 222285), d-mannitol (PubChem CID: 6251), maltitol (PubChem CID: 493591).

Could the aroma of spices produce a cross-modal enhancement of food saltiness and contribute to reducing salt intake?

BACKGROUND

As a result of its correlation with cardiovascular diseases, salt intake must be reduced. According to multi-sensory integration, aroma plays an important role in saltiness enhancement; this could enable a food's salt content to be reduced without losing acceptance. We therefore studied the effect of three spices, Curcuma longa, Laurus nobilis L. and Petroselinum crispum L., on saltiness enhancement through sensory tests on consumers. This was followed by olfactometric analysis with the aim of relating the effect to the spices' aromatic composition.

RESULTS

According to the odour-induced salty taste enhancement (OISE) mean values, bay leaf and turmeric had the highest effect on saltiness enhancement, at a similar level to dry-cured ham aroma, wherwas parsley had a significantly lower OISE value. Only one odour-active compound (OAC), eugenol, showed a direct correlation with the spices' OISE values. Turmeric primarily had OACs with sweet aroma, whereas bay leaf had more OACs belonging to the spicy-aroma category.

CONCLUSION

The three spices, turmeric, bay leaf and parsley, investigated in the present study appear to enhance the salty taste of mashed potato with a low salt content. The results suggest that an interaction effect among OACs with different aromatic ranges may exist. Therefore, when the global OAC modified frequency value, grouped according to aroma range, was considered, the sweet range appears to counteract the effect of the spicy aroma on saltiness. © 2024 Society of Chemical Industry.

Odorants Identified in Chinese Dry-Cured Ham Contribute to Salty Taste Enhancement

Jinhua dry-cured ham (JDH) is a traditional fermented Chinese meat product. We studied the dynamic sensory and emotional profiles of JDHs obtained by five preparation methods and the corresponding release of sodium ions (Na+), potassium ions (K+), and volatile organic compounds (VOCs) during oral processing. The VOCs with salty taste enhancement abilities were screened based on the correlations of VOCs with salty flavor and concentration of Na and K ions with salty flavor. A trained sensory panel evaluated the saltiness enhancements of selected VOCs by using static and dynamic sensory methods. The results revealed that Na+, K+, and selected VOCs were mainly released during 0-10 s of the chewing process. The release of Na+ and K+ in JDH residue samples exhibited consistently decreasing trends, while in saliva, their concentrations increased. The VOCs showing a high correlation with Na+ and K+ and salty flavor have saltiness enhancement abilities in both NaCl solutions and NaCl + MSG mixtures. Odor-induced saltiness was pronounced at low salt concentrations (0.2% NaCl). The investigation demonstrated 16 VOCs exhibiting saltiness enhancement abilities, including 4 pyrazines, 5 acids, 4 sulfur-containing compounds, and 3 other compounds. The sensory evaluation suggested pyrazines and sulfur-containing compounds as good saltiness enhancers. 2-Furfuryl mercaptan significantly enhanced the salty sensation in the NaCl + MSG solutions when compared with MSG alone (p < 0.05). This research provides evidence that certain odorants identified in JDHs exhibit salty-enhancing properties, indicating their potential for salt reduction at the industrial level.

Food Perception: Taste, Smell and Flavour

Flavor is the most important sensory quality in food [...].

Study on the taste active compounds in Douchi using metabolomics method

Douchi is a traditional famous seasoning in China. This study adopted electronic tongue and metabolomics to analyze the taste characteristics and taste active compounds of 12 samples from three most famous types of Douchi (Liuyang Douchi, Yangjiang Douchi, Yongchuan Douchi). Thirty-six differential metabolites mainly enriched from the arginine biosynthesis were identified among these Douchis. Umami and bitterness are considered as two taste that bring positive and negative perceptions for Douchi. The succinic acid was found to be responsible for the umami in LY, YJ and YC Douchi, with the TAVs of 2054, 643, 174, respectively, rather than the glutamic acid and aspartic acid. The leucine was identified as the main metabolite for bitterness, with the TAVs of 9, 9, 7 respectively. KEGG enrichment analysis found that the umami, sourness and saltiness might be related to alanine, aspartate and glutamate metabolism and the bitterness might be related to aminoacyl-tRNA biosynthesis pathway.

Role of Aromatic Herbs and Spices in Salty Perception of Patients with Hyposmia

Herbs and spices represent a possibility for the improvement of anosmia and ageusia. In this work we evaluated the role of Mediterranean aromatic herbs and spices in the salty taste perception of patients with hyposmia compared to healthy controls. To this goal, the salty taste perception in response to pure salt and different types of commercial flavored sea salt was assessed in patients with hyposmia, with or without a post-acute coronavirus syndrome, and healthy controls. Myrtle berries and leaves, a mixture of Mediterranean herbs and plants such as helichrysum, rosemary, liquorice, fennel seeds and myrtle leaves, oranges and saffron were used as salt flavoring ingredients. Differences in gustatory perception between 57 patients with hyposmia and 91 controls were evaluated considering the rate of the gustatory dimensions of pleasantness, intensity, and familiarity, using a 7-point hedonic Likert-type scale. At a dose of 0.04 g/mL, saline solutions of flavored salts, with an average 15% less NaCl, were perceived by patients with hyposmia as equally intense but less familiar than pure salt solution, with similar scores in the pleasantness dimension. Our study highlighted the central role of Mediterranean aromatic plants in the enhancement of salty perception in patients with hyposmia.