Improved extraction methods for simultaneous recovery of umami compounds from six different mushrooms

Effects of umami substances as taste enhancers on salt reduction in meat products: A review

Sodium is one of the essential additives in meat processing, but excessive sodium intake may increase risk of hypertension and cardiovascular disease. However, reducing salt content while preserving its preservative effect, organoleptic properties, and technological characteristics poses challenges. In this review, the mechanism of salt reduction of umami substances was introduced from the perspective of gustation-taste interaction, and the effects of the addition of traditional umami substances (amino acids, nucleotides, organic acids(OAs)) and natural umami ingredients (mushrooms, seaweeds, tomatoes, soybeans, tea, grains) on the sensory properties of the meat with reduced-salt contents were summarized. In addition, the impacts of taste enhancers on eating quality (color, sensory, textural characteristics, and water-holding capacity (WHC)), and processing quality (lipid oxidation, pH) of meat products (MP) and their related mechanisms were also discussed. Among them, natural umami ingredients exhibit distinct advantages over traditional umami substances in terms of enhancing quality and nutritional value. On the basis of salt reduction, natural umami ingredients improve the flavor, texture, WHC and antioxidant capacity. This comprehensive review may provide the food industry with a theoretical foundation for mitigating salt consumption through the utilization of umami substances and natural ingredients.

Effect of Steaming and Microwave Heating on Taste of Clear Soup with Split-Gill Mushroom Powder

Salt is widely overconsumed. Among the strategies used in low-salt foods, the addition of flavor enhancers to improve saltiness perception through an umami taste is a viable and promising technique. This study investigated using split-gill mushroom (SGM) powder containing umami taste to increase saltiness in a clear soup for two different heating conditions: steaming under high pressure and microwave heating. According to the E-tongue results, the addition of 0.2-0.8% SGM produced a different taste in the soup compared to the addition of salt, and the addition of 0.2-0.8% SGM yielded a similar taste to the addition of 0.4-0.6% MSG in a plain, clear soup. In flavored soup, SGM at a high concentration had a taste-enhancing impact comparable to 0.4% MSG, whereas SGM at a low concentration had no taste-enhancing effect. The flavored soups containing 0.4 or 0.8% SGM consisted of two umami 5'-nucleotides: adenosine 5'-monophosphate (5'-AMP) and guanosine 5'-monophosphate (5'-GMP); however, inosine 5'-monophosphate (5'-IMP) was not detected. The major umami amino acids were glutamic acid, aspartic acid, and arginine. Microwave heating increased the salinity and total nucleotides and could maintain the umami amino acids, whereas aspartic acid (one of the umami amino acids) was reduced by 8.23% after steaming under high pressure. Thus, after microwave heating and steaming under high pressure, the equivalent umami concentration was reduced by 43.11 and 44.53%, respectively. In conclusion, the addition of SGM and volumetric heating using microwaves could be an alternative method for reducing the amount of salt in soup by increasing the umami taste intensity and salinity.

Comparative Study of Different Protein Extraction Technologies Applied on Mushrooms By-products

Mushroom production is a growing sector as the demand for this product is increasing. The quantity of waste and by-products generated along the supply chain is however considerable (about 20% of the fresh weight is disposed). Although the recovery of chitosan from mushrooms has been extensively studied, little has been done to optimize the recovery of proteins, which make up to 20% of dry weight. In the present work, six different by-products were studied for their crude composition and their protein fraction was characterized in detail. Then, a comparative study was conducted on three different extraction techniques (environmentally friendly aqueous extraction, ultrasound-assisted extraction, and enzyme-assisted extraction). Enzyme-assisted extraction has proven to be the most efficient technique in terms of protein extraction yield, even though the protein fraction is extracted in the form of peptides and not whole proteins. The lowest degree of hydrolysis is instead given by the ultrasound-assisted extraction, which however shows a rather high degree of racemization which decreases the quality of the proteins. The aqueous extraction, despite the low extraction yield, gave the purest protein extracts.

Effect of Novel High-Intensity Ultrasound Technique on Physio-Chemical, Sensory Attributes, and Microstructure of Bovine Semitendinosus Muscle

The present study aimed to evaluate the effects of high-intensity ultrasound (HIU) application on meat quality traits, sensory parameters, and the microstructure of semitendinosus muscle from Hanwoo cattle. The samples were treated in an ultrasonic bath (35 kHz) at an intensity of 800 W/cm² for 60 min, followed by aging at 1°C for 0, 3, and 7 days. The application of ultrasound resulted in lower Warner-Bratzler shear force and higher myofibrillar fragmentation index values during the storage period. HIU also enhanced the tenderness, flavor, umami, and overall acceptability of cooked beef muscle. However, the electronic tongue evaluation results showed higher umami values in the control treatment on the seventh day of storage. The microstructure of sonicated meat showed disorganized myofibrillar architecture and swelling in the A-band region of sarcomeres during the storage period, which led to greater meat tenderness. The heatmap illustrated the high abundance of α-linolenic acid (C20:5n3) and eicosapentaenoic acid (C18:3n3) in sonicated meat samples on the third day of the storage. These results showed that HIU is a potential method for tenderizing and improving the sensory attributes of beef without compromising other quality aspects.

Comparison of Nutrition and Flavor Characteristics of Five Breeds of Pork in China

To characterize the quality of widely consumed pork in China, the chemical compositions and other indexes of five breeds of pork were compared. The results indicated that the moisture content, sensory flavor, and overall acceptability of Pipa pork (PPP) were superior to other breeds. The fat content and essential amino acids (EAA) of Yihao native pork (YNP) were significantly (p < 0.05) higher than in other breeds. The protein content, the total amount of amino acids, and perceptible flavor of Tibetan black pork (TBP) were higher than in other breeds. The protein nutrition profiles of manor black pork (MBP) and TBP were better than in others. The equivalent umami concentration (EUC) value of white pork (WP) was significantly (p < 0.05) higher than in others; however, the health risk of its fatty acid content was higher. There were unique protein and flavor chemicals in YNP, TBP, and PPP, which may be useful for distinguishing their authenticity.

Storage Stability and Flavor Change of Marinated Pork

To evaluate the storage stability and flavor changes of marinated pork treated with chili and pepper essential oils, the contents of total sulfhydryl, malondialdehyde, total volatile base nitrogen (TVBN), Ca²⁺ATPase activity, and total viable counts of marinated pork were determined. Further, the non-volatile (umami, numb, and spicy) and volatile flavor compounds of marinated pork were analyzed. Based on the results, the chili and pepper essential oils had limited effects on the storage stability of marinated pork. However, these essential oils could inhibit the oxidation of lipids and proteins and reduce the number of microorganisms and TVBN in marinated pork within 6 days. The non-volatile flavors of the marinated pork decreased as the refrigeration time increased. It was concluded that the decomposition of umami-enhancing nucleotides (GMP, IMP, XMP), the number of flavor substances (hydroxyl-α-sanshool, hydroxyl-β-sanshool), and spicy (capsaicin) tasting compounds caused the decrease in non-volatile flavors.

Gastrophysical and chemical characterization of structural changes in cooked squid mantle

Squid (Loligo forbesii and Loligo vulgaris) mantles were cooked by sous vide cooking using different temperatures (46°C, 55°C, 77°C) and times (30 s, 2 min, 15 min, 1 h, 5 h, 24 h), including samples of raw tissue. Macroscopic textural properties were characterized by texture analysis (TA) conducted with Meullenet-Owens razor shear blade and compared to analysis results from differential scanning calorimetry. The collagen content of raw tissues of squid was quantified as amount of total hydroxyproline using ultra-high-performance liquid chromatography. Structural changes were monitored by Raman spectroscopy and small-angle X-ray scattering and visualized by second harmonic generation microscopy. Collagen in the squid tissue was found to be highest in arms (4.3% of total protein), then fins (3.0%), and lowest in the mantle (1.5%), the content of the mantle being very low compared to that of other species of squid. Collagen was found to be the major protein responsible for cooking loss, whereas both collagen and actin were found to be key to mechanical textural changes. A significant decreased amount of cooking loss was obtained using a lower cooking temperature of 55°C compared to 77°C, without yielding significant textural changes in most TA parameters, except for TA hardness which was significantly less reduced. An optimized sous vide cooking time and temperature around 55-77°C and 0.5-5 h deserves further investigation, preferably coupled to sensory consumer evaluation. PRACTICAL APPLICATION: The study provides knowledge about structural changes during sous vide cooking of squid mantle. The results may be translated into gastronomic use, promoting the use of an underutilized resource of delicious and nutritious protein (Loligo vulgaris and Loligo forbesii).

Recent insights in flavor-enhancers: Definition, mechanism of action, taste-enhancing ingredients, analytical techniques and the potential of utilization

The consumers' demand for clean-label food products, lead to the replacement of conventional additives and redesign of the production methods in order to adopt green processes. Many researchers have focused on the identification and isolation of naturally occurring taste and flavor enhancers. The term "taste enhancer" and "flavor enhancer" refer to umami and kokumi components, respectively, and their utilization requires the study of their mechanism of action and the identification of their natural sources. Plants, fungi and dairy products can provide high amounts of naturally occurring taste and flavor enhancers. Thermal or enzymatic treatments of the raw materials intensify taste and flavor properties. Their utilization as taste and flavor enhancers relies on their identification and isolation. All the above-mentioned issues are discussed in this review, from the scope of listing the newest trends and up-to-date technological developments. Additionally, the appropriate sensory analysis protocols of the naturally occurring taste-active components are presented. Moreover, future trends in using such ingredients by the food industry can motivate researchers to study new means for clean-label food production and provide further knowledge to the food industry, in order to respond to consumers' demands.

Analysis of umami taste substances of morel mushroom (Morchella sextelata) hydrolysates derived from different enzymatic systems

Seven enzyme groups were applied to hydrolyze broken fruiting bodies of morel mushroom (Morchella sextelata) to extract umami substances. Physical-chemical properties, as well as compositions and concentrations of quintessential umami compounds of morel hydrolysates were analyzed. Electronic tongue and electronic nose were used to evaluate the sensory characteristics. The results suggested that peptides below 3 kDa showed the highest correlation with umami taste. Morel hydrolysate obtained from Neutrase-Flavourzyme (NF) combination contained the most contents of small peptides (<3 kDa), free amino acids (224.83 ± 0.87 mg/g), as well as flavor 5'-nucleotides (4.84 ± 0.32 mg/g), giving the best overall flavor properties. The reaction conditions of NF were optimized by response surface methodology (RSM). The highest degree of hydrolysis (DH) was up to 36.64%. An enzymatic hydrolysis approach was established to develop novel flavor products with high umami and low bitter taste from morel mushroom.

Green extraction of proteins, umami and other free amino acids from brown macroalgae Ascophyllum nodosum and Fucus vesiculosus

Seaweeds are a valuable potential source of protein, as well as free amino acids (FAAs) with umami flavour which are in high demand by the food industry. The most commonly used flavouring agents in the food industry are chemically synthesised and therefore are subject to concerns regarding their safety and associated consumer resistance. This study focuses on the effects of extraction time (1 and 2 h) and solvents (0.1 M HCl, 1% citric acid and deionised water) on the extraction of protein and FAAs including umami FAAs from Irish brown seaweeds (Ascophyllum nodosum and Fucus vesiculosus). Extraction yields were influenced by both the extraction solvent and time, and also varied according to the seaweed used. Both seaweeds investigated were found to be good sources of protein, FAAs including umami FAAs, demonstrating potential application as flavouring agents in the food industry. Overall, the use of green solvents (deionised water and citric acid) resulted in higher recoveries of compounds compared to HCl. The results of this study will facilitate the use of more sustainable solvents in industry for the extraction of proteins and flavouring agents from seaweed.

Umami synergy as the scientific principle behind taste-pairing champagne and oysters

Food and flavour pairing are commonly used as an empirically based phenomenology by chefs and food innovators for creating delicious dishes. However, there is little if any science behind the pairing systems used, and it appears that pairing is determined by food culture and tradition rather than by chemical food composition. In contrast, the pairing implied by the synergy in the umami taste, elicited by free glutamate and free nucleotides, is scientifically founded on an allosteric action at the umami receptor, rendering eggs-bacon and cheese-ham delicious companions. Based on measurement of umami compounds in champagnes and oysters we suggest that a reason why champagne and oysters are considered good companions may be the presence of free glutamate in champagne, and free glutamate and 5′-nucleotides in oysters. By calculations of the effective umami potential we reveal which combinations of oysters and champagnes lead to the strongest umami taste. We also show that glutamate levels and total amount of free amino acids are higher in aged champagnes with long yeast contact, and that the European oyster (Ostrea edulis) has higher free glutamate and nucleotide content than the Pacific oyster (Crassostrea gigas) and is thus a better candidate to elicit synergistic umami taste.

Green Tea Extract Decreases Arg-Derived Advanced Glycation Endproducts but Not Lys-Derived AGEs in UHT Milk during 1-Year Storage

Epigallocatechin gallate (EGCG)-enriched green tea extract (GTE) was added to lactose-reduced UHT-treated milk to evaluate its role in perturbing the Maillard reaction and the formation of advanced glycation endproducts (AGEs) during 1-year storage. The UHT processing caused epimerization of EGCG into gallocatechin gallate (GCG). For milk samples with added 0.1% w/v GTE, a EGCG/GCG loss of 26% was found soon after the UHT treatment and the loss increased to 64% after the 1-year of storage. LC-MS/MS analysis revealed the presence of various EGCG/GCG-α-dicarbonyl adducts and EGCG/GCG-hydroxymethylfurfural adducts in milk samples, while EGCG/GCG-amino acid adducts were not detected. Although EGCG/GCG trapped α-dicarbonyl compounds including glyoxal, methylglyoxal, 3-deoxyglucosone/3-deoxygalactosone, and diacetyl, it did not lower their net steady-state concentrations, except of 3-deoxyglucosone. The addition of GTE reduced the formation of Arg-derived AGEs by 2- to 3-fold, but surprisingly enhanced the accumulation of furosine and lysine-derived AGEs [Nε-(carboxymethyl)lysine and Nε-(carboxyethyl)lysine)] by 2-4-fold depending on the concentration of the added GTE and storage time. The present study shows that trapping of α-dicarbonyl compounds by EGCG may not be the major pathway for inhibiting the formation of AGEs in milk.

Ultrasound processing of coffee silver skin, brewer's spent grain and potato peel wastes for phenolic compounds and amino acids: a comparative study

Awareness towards utilizing food-processing by-products are increasing in health as well as environmental purview. Coffee silver skin (CSS), potato peel (PP) and brewer's spent grain (BSG) are voluminous by-products in their respective processing industries. The present study compared these three by-products for their prospective utilization in producing polyphenols-rich aqueous extracts by using ultrasound-assisted extractions (UAE). A probe-type sonicator was used for ultrasound treatments. The total phenolic contents in the extracts were assessed by Folin-Ciocalteu assay, while the phenolic profiles of the extract was characterized by LC-Q-TOF mass spectrometry. The microstructure of the samples after UAE was evaluated by scanning electron microscopy (SEM). Ultrasound treatment enhanced the rate of extraction and recovered 2.79, 2.12 and 0.66 mg gallic acid equivalents/g of TPC from CSS, PP and BSG, respectively in 30 min, which correspond to recoveries of 97.6%, 84.5% and 84.6%, respectively, compared to conventional solid-liquid extractions carried out for 24 h. The extraction yield was dependent on the particle size of the raw materials and the highest yield was obtained from the materials with 100-250 µm particle size. The SEM imaging revealed that ultrasound treatment caused prominent tissue damage. Extracts contained mainly hydroxycinnamic acid derivatives of phenolic acids. PP and CSS had the highest amounts of umami free amino acids (0.13 mg/g in each), while BSG contained the highest amount of essential amino acids (92 mg/g). The present work shows that CSS, PP and BSG are good sources of polyphenols and UAE can be employed to enhance the extraction efficiency as means of a green approach.

Umami Ingredient: Flavor enhancer from shiitake (Lentinula edodes) byproducts

An alternative use of shiitake stipes, usually treated as waste, was proposed for the production of a powder ingredient, rich in umami compounds, aiming its application in food. The extraction of umami compounds was optimized through the Response Surface Methodology (RSM), in order to obtain an extract with high umami taste intensity. From the optimized condition, a comparative analysis of shiitake stipes dehydration method was performed. Stipes were dehydrated by hot air drying (HD) and freeze drying (FD), submitted to extraction and the umami compounds in the extracts were compared. The comparative analysis showed that the 5' - nucleotides are more sensitive to prolonged heating, while the release of free amino acids (FAA) was favored by hot air drying. The HD samples extract showed higher Equivalent Umami Concentration (EUC). The spray drying of the HD samples extract allowed the production of a newly powder ingredient rich in umami compounds (Umami Ingredient) that can be applied in diverse food matrices. Due to the presence of umami compounds, Umami Ingredient can be a potential alternative to help in the process of sodium reduction by enhancing food flavor.

Cleavage of Disulfide Bonds in Cystine by UV-B Illumination Mediated by Tryptophan or Tyrosine as Photosensitizers

Photolytic cleavage of disulfide bonds in proteins by UV light will influence their structure and functionality. The present study aimed to investigate the efficiency of disulfide cleavage by UV-B light in a system without a protein backbone consisting of combinations of cystine (a disulfide) and tryptophan (Trp) or tyrosine (Tyr) under anaerobic and aerobic conditions and to identify oxidation products formed by UV-B light. Cystine was reduced to cysteine (Cys) almost with a 1:1 stoichiometry by photoexcited Trp for anaerobic equimolar aqueous solutions (each 200 μM; pH 7.0), while photoexcited Tyr provided lower concentrations of Cys. The calculation of apparent quantum yields allowed for a comparison between the efficiency of reactions and showed that formation of Cys from disulfide cleavage of cystine was more efficient by photoexcited Trp than by photoexcited Tyr and of cystine alone and that Trp was more sensitive to photodegradation than Tyr and cystine under both aerobic and anaerobic conditions. Increasing the ratio between cystine and Trp to a 1:2 ratio did not increase the efficiency of free thiol formation but caused a more efficient photodegradation of Trp. The free thiol formed from disulfide cleavage of cystine was further oxidized to other unidentified compounds. Trp oxidation products (3-hydroxykynurenine (3-OH-Kyn) and tryptamine) were only identified in minor concentrations following light exposure of cystine and Trp in 1:1 and 1:2 ratios under both aerobic and anaerobic conditions, indicating further photodegradation to unidentified compounds. 3,4-Dihydroxyphenylalanine (DOPA) was formed from the oxidation of Tyr in the illuminated samples of cystine and Tyr in a 1:1 ratio under both aerobic and anaerobic conditions.

Reduction of Salt and Fat in Frankfurter Sausages by Addition of Agaricus bisporus and Pleurotus ostreatus Flour

The reduction of fat and salt and the incorporation of fiber-rich compounds in frankfurters is a trend to improve their nutritional profile. The objective of this study was to evaluate the partial replacement of 30 and 50% of pork backfat and 50% of salt by adding edible mushroom flour (2.5 and 5%) from Agaricus bisporus (Ab) and Pleurotus ostreatus (Po) on physicochemical, microbiological and sensory properties of frankfurters sausages during cold storage. The addition of flours increased the moisture, and the dietary fiber contents in frankfurters, keeping the amino acid profile. Lipid oxidation remained under acceptable values despite not antioxidant effect was observed by mushrooms flours. Only spore-forming bacteria were found during cold storage. Color and texture was modified by addition of mushroom, being the Ab samples darker, while Po flour addition resulted in softer and less cohesive sausages. Although lower color, flavor, and taste scores were given to the mushroom samples than the control, they ranked in the acceptable level confirming that the inclusion of 2.5 and 5% of Ab and Po flours in fat- and salt-reduced frankfurter sausages resulted a feasible strategy to enhance the nutritional profile these products.

Controlling Surface Oxygen Concentration of a Nanocarbon Film Electrode for Improvement of Target Analytes

A nanocarbon film consisting of nanocrystallites with mixed sp² and sp³ bonds formed by unbalanced magnetron sputtering, was studied with respect to changes in the characteristics caused by the surface oxygen concentration. An electrochemical pretreatment (ECP) was conducted to change the surface oxygen concentration of the nanocarbon film. X-ray photoelectron spectroscopy (XPS) measurements revealed that nanocarbon films with different amounts of surface oxygen could be prepared. In addition, we observed no significant increase of surface roughness (R_a) at the angstrom level after ECP, owing to a stable structure containing 40% of sp³ bonds. The electrode characteristics, including the potential window, and electrochemical properties for some redox species, such as Ru(NH₃)₆^3+/2+, Fe(CN)₆^3-/4- and some biomolecules, were investigated. The anodic potential limit became wider and ΔE_p of Fe(CN)₆^3-/4- became smaller at the treated nanocarbon film electrode than those of the as-deposited nanocarbon film electrode. Based on these results, we realized to measure uridylic acid (UMP) and inosine triphosphate (ITP) with a high oxidation potential by direct oxidation, which was difficult to measure at the as-deposited nanocarbon film electrode.

The effect of cooking on umami compounds in wild and cultivated mushrooms

The effect of cooking on the taste compounds of five mushroom species Agaricus bisporus, Lactarius trivialis, Cantharellus cibarius, Cantharellus tubaeformis and Suillus variegatus were assessed with a special focus on the compounds responsible for the umami taste. Liquid chromatography was used to analyse free amino acids (FAAs) and 5'-nucleotides from fresh and sous vide (SV) cooked mushroom samples and cooking juice. The SV technique enabled analysis of entire mushrooms, including the liquid released during cooking. FAA content decreased when cooking temperature increased, indicating their further chemical reactions. S. variegatus contained highest concentrations of FAAs in analysed wild mushrooms. The umami-enhancing nucleotide 5'-GMP was detected only in cooked samples, concentration being likely dependent on enzymatic activity. The highest concentration of 5'-GMP was detected in cooked L. trivialis samples (17 mg/100 g fw). To our knowledge, the analysed taste compounds of L. trivialis and S. variegatus are documented for the first time.