Combined ultrasound and heat pretreatment improve the enzymatic hydrolysis of clam (Aloididae aloidi) and the flavor of hydrolysates

Impact of thermal ultrasound on enzyme inactivation and flavor improvement of sea cucumber hydrolysates

In this study, the effects of the thermal ultrasonic enzyme inactivation process on flavor enhancement in sea cucumber hydrolysates (SCHs) and its impact on the inactivation of neutral proteases (NPs) were investigated. The body wall of the sea cucumber was enzymatically hydrolyzed with NPs. On the one hand, the structure of NPs subjected to different enzyme inactivation methods was analyzed using ζ-potential, particle size, and Fourier transform infrared (FT-IR) spectroscopy. On the other hand, the microstructure and flavor changes of SCHs were examined through scanning electron microscopy, E-nose, and gas chromatography-ion mobility spectrometry (GC-IMS). The results indicated that thermal ultrasound treatment at 60 °C could greatly affect the structure of NPs, thereby achieving enzyme inactivation. Furthermore, this treatment generated more pleasant flavor compounds, such as pentanal and (E)-2-nonenal. Hence, thermal ultrasound treatment could serve as an alternative process to traditional heat inactivation of enzymes for improving the flavor of SCHs.

Sequential Enzymatic Hydrolysis and Ultrasound Pretreatment of Pork Liver for the Generation of Bioactive and Taste-Related Hydrolyzates

In the study of protein-rich byproducts, enzymatic hydrolysis stands as a prominent technique, generating bioactive peptides. Combining exo- and endopeptidases could enhance both biological and sensory properties. Ultrasound pretreatment is one of the most promising techniques for the optimization of enzymatic hydrolysis. This research aimed to create tasteful and biologically active pork liver hydrolyzates by using sequential hydrolysis with two types of enzymes and two types of ultrasound pretreatments. Sequential hydrolyzates exhibited a higher degree of hydrolysis than single ones. Protana Prime hydrolyzates yielded the largest amount of taste-related amino acids, enhancing sweet, bittersweet, and umami amino acids according to the Taste Activity Value (TAV). These hydrolyzates also displayed significantly higher antioxidant activity. Among sequential hydrolyzates, Flavourzyme and Protana Prime hydrolyzates pretreated with ultrasound showed the highest ferrous ion chelating activity. Overall, employing both Alcalase and Protana Prime on porcine livers pretreated with ultrasound proved to be highly effective in obtaining potentially tasteful and biologically active hydrolyzates.

Unraveling the effects of drying techniques on chaya leaves: Metabolomics analysis of nonvolatile and volatile metabolites, umami taste, and antioxidant capacity

Chaya (Cnidoscolus chayamansa) leaves are known for their strong umami taste and widespread use as a dried seasoning. This study aimed to assess the impact of different drying methods [freeze drying (FD), vacuum drying, oven drying at 50 °C and 120 °C (OD120) and pan roasting (PR)] on the metabolome using mass spectrometry, umami intensity, and antioxidant properties of chaya leaves. The predominant volatile compound among all samples, 3-methylbutanal, exhibited the highest relative odor activity value (rOAV), imparting a malt-like odor, while hexanal (green grass-like odor) and 2-methylbutanal (coffee-like odor) are the second highest rOAV in the FD and PR samples, respectively. OD120 and PR samples possessed the highest levels of umami-tasting amino acids and 5'-ribonucleotides as well as the most intense umami taste, whereas FD samples exhibited the highest antioxidant capacity. These findings enhance our understanding of the aroma characteristics, umami taste, and antioxidant potential of processed chaya leaves.

Effects of Low Temperature-Ultrasound-Papain (LTUP) Combined Treatments on Purine Removal from Pork Loin and Its Influence on Meat Quality and Nutritional Value

A combined pretreatment method of "low temperature-ultrasound-papain" (LTUP) was proposed to remove the purine of pork loins. Compared with untreated pork loin, under optimal conditions (temperature 58 °C, ultrasound density 100 W/cm2, and papain concentration 0.085%), the purine removal rate of treated pork loin could reach 59.29 ± 1.39%. The meat quality of pork loin treated with the LTUP method such as hardness and chewiness decreased by 58.37% and 64.38%, respectively, and the in vitro protein digestibility was increased by 19.64%; the cooking loss was decreased by 15.45%, compared with the simulated household blanching process (HT). In view of the high purine removal rate, the losses of free amino acids and soluble peptides were acceptable and reasonable. SEM and LF-NMR results showed that low temperature and ultrasound combined with papain treatment opened a channel for purine transfer and promoted purine dissolution by affecting the protein structure of pork loin. In addition, the migration of water within the muscle tissue was also related to purine removal. In summary, LTUP is recommended as an efficient and green way for the meat industry to remove purine.

Efficient preparation of oyster hydrolysate with aroma and umami coexistence derived from ultrasonic pretreatment assisted enzymatic hydrolysis

In the study, an efficient protease Neutrase®-Flavourzyme® (NF) was screened to prepare the umami-aroma flavor oyster hydrolysate. The effect of protease and ultrasonic pretreatment (UP) assisted by the optimal protease on the flavor substances was investigated. The results demonstrated that the optimal UP-NF (450 W) showed a higher amino acid nitrogen content of 0.34 g/100 mL compared to the NF, and 19 major aroma compounds including octanal, decanal, nonanal, benzaldehyde, 2-undecanone, and 1-octen-3-ol were obtained. Additionally, the free amino acid and fatty acid spectrum indicated that the formation of flavor compounds was primarily due to the oxidation of linoleic and linolenic acids and the degradation of amino acids. Furthermore, taste analysis proved that increased umami and saltiness resulted from the accelerated release of Glu, Asp and 5'-IMP. Overall, UP-NF proved to be an effective method for producing umami-aroma flavor, facilitating further processing of oyster products for the application.

Optimization of cold plasma combined treatment process and its effect on the quality of Asian sea bass (Lates calcarifer) during refrigerated storage

BACKGROUND

Cold plasma exhibits broad applicability in the realm of fish sterilization and preservation. The combination process of plasma-activated water and dielectric barrier discharge (PAW-DBD) was optimized, and its disinfection effects on bass fillets were studied.

RESULTS

The best conditions for disinfection of PAW-DBD were as follows. Bass fillets were soaked in PAW for 150 s, and then treated by DBD system at 160 kV for 180 s. The total viable count (TVC) reduced by 1.68 log CFU g-1 . On the 15th day of refrigerated storage, TVC of PAW-DBD group was 7.01 log CFU g-1 , while the PAW and DBD group exhibited a TVC of 7.02 and 7.01 log CFU g-1 on day 12; the TVC of the control group was 7.13 log CFU g-1 on day 6. The sensory score, water-holding capacity, and 2-thiobarbituric acid reactive substance values of the PAW-DBD group were significantly higher than those of PAW and DBD group (P < 0.05), whereas the TVC, Pseudomonas spp. count, and pH of the group were significantly lower (P < 0.05) during refrigerated storage.

CONCLUSION

PAW-DBD treatment can enhance the disinfection effect, maintain good quality, and extend the storage period of bass fillets. © 2023 Society of Chemical Industry.

Research progress of fishy odor in aquatic products: From substance identification, formation mechanism, to elimination pathway

Fishy odor in aquatic products has a significant impact on the purchasing decisions of consumers. The production of aquatic products is a complex process involving culture, processing, transportation, and storage, which contribute to decreases in flavor and quality. This review systematically summarizes the fishy odor composition, identification methods, generation mechanism, and elimination methods of fishy odor compounds from their origin and formation to their elimination. Fishy odor compounds include aldehydes (hexanal, heptanal, and nonanal), alcohols (1-octen-3-ol), sulfur-containing compounds (dimethyl sulfide), and amines (trimethylamine). The mechanism of action of various factors affecting fishy odor is revealed, including environmental factors, enzymatic reactions, lipid oxidation, protein degradation, and microbial metabolism. Furthermore, the control and removal of fishy odor are briefly summarized and discussed, including masking, elimination, and conversion. This study provides a theoretical basis from source to elimination for achieving targeted regulation of the flavor of aquatic products, promoting industrial innovation and upgrading.

Improving the Flavour of Enzymatically Hydrolysed Beef Liquid by Sonication

Beef potentiator is an important flavour enhancer in the food industry, while it is prone to generating insufficient compounds with umami and sweet tastes and compounds with a fishy odour during enzymatic hydrolysis of beef, resulting in poor flavour of beef potentiator. It has been extensively reported that sonication is capable of improving food flavour. However, the effect of sonication on the flavour of enzymatically hydrolysed beef liquid (EHBL) was scarcely reported. Herein, we investigated the effect of sonication on the flavour of EHBL using quantitative descriptive analysis (QDA), physicochemical analysis and SPME-GC-olfactometry/MS. QDA showed that sonication had a significant effect on taste improvement and off-odour removal of EHBL. Compared with the control, sonication (40 kHz, 80 W/L) increased the contents of total nitrogen, formaldehyde nitrogen, total sugars, reducing sugars, free amino acids (FAAs) and hydrolysis degree of EHBL by 19.25%, 19.80%, 11.83%, 9.52%, 14.37% and 20.45%. Notably, sonication markedly enhanced the contents of sweet FAAs, umami FAAs and bitter FAAs of EHBL by 19.66%, 14.04% and 9.18%, respectively, which contributed to the taste improvement of EHBL. SPME-GC-olfactometry/MS analysis showed that aldehydes and alcohols were the main contributors to aroma compounds of EHBL, and sonication significantly increased the contents of key aroma compounds and alcohols (115.88%) in EHBL. Notably, sonication decreased the contents of fishy odorants, hexanoic acid and nonanal markedly by 35.29% and 26.03%, which was responsible for the aroma improvement of EHBL. Therefore, sonication could become a new potential tool to improve the flavour of EHBL.

Insights into application progress of seafood processing technologies and their implications on flavor: a review

Seafood tends to be highly vulnerable to spoilage and deterioration due to biochemical reactions and microbial contaminations, which requires appropriate processing technologies to improve or maintain its quality. Flavor, as an indispensable aspect reflecting the quality profile of seafood and influencing the final choice of consumers, is closely related to the processing technologies adopted. This review gives updated information on traditional and emerging processing technologies used in seafood processing and their implications on flavor. Traditional processing technologies, especially thermal treatment, effectively deactivate microorganisms to enhance seafood safety and prolong its shelf life. Nonetheless, these methods come with limitations, including reduced processing efficiency, increased energy consumption, and alterations in flavor, color, and texture due to overheating. Emerging processing technologies like microwave heating, infrared heating, high pressure processing, cold plasma, pulsed electric field, and ultrasound show alternative effects to traditional technologies. In addition to deactivating microorganisms and extending shelf life, these technologies can also safeguard the sensory quality of seafood. This review discusses emerging processing technologies in seafood and covers their principles, applications, developments, advantages, and limitations. In addition, this review examines the potential synergies that can arise from combining certain processing technologies in seafood processing.

Physicochemical and structural changes of myofibrillar proteins in muscle foods during thawing: Occurrence, consequences, evidence, and implications

Myofibrillar protein (MP) endows muscle foods with texture and important functional properties, such as water-holding capacity (WHC) and emulsifying and gel-forming abilities. However, thawing deteriorates the physicochemical and structural properties of MPs, significantly affecting the WHC, texture, flavor, and nutritional value of muscle foods. Thawing-induced physicochemical and structural changes in MPs need further investigation and consideration in the scientific development of muscle foods. In this study, we reviewed the literature for the thawing effects on the physicochemical and structural characters of MPs to identify potential associations between MPs and the quality of muscle-based foods. Physicochemical and structural changes of MPs in muscle foods occur because of physical changes during thawing and microenvironmental changes, including heat transfer and phase transformation, moisture activation and migration, microbial activation, and alterations in pH and ionic strength. These changes are not only essential inducements for changes in spatial conformation, surface hydrophobicity, solubility, Ca2+ -ATPase activity, intermolecular interaction, gel properties, and emulsifying properties of MPs but also factors causing MP oxidation, characterized by thiols, carbonyl compounds, free amino groups, dityrosine content, cross-linking, and MP aggregates. Additionally, the WHC, texture, flavor, and nutritional value of muscle foods are closely related to MPs. This review encourages additional work to explore the potential of tempering techniques, as well as the synergistic effects of traditional and innovative thawing technologies, in reducing the oxidation and denaturation of MPs and maintaining the quality of muscle foods.

Application of ultrasound and its real-time monitoring of the acoustic field during processing of tofu: Parameter optimization, protein modification, and potential mechanism

Tofu is nutritious, easy to make, and popular among consumers. At present, traditional tofu production has gradually become perfect, but there are still shortcomings, such as long soaking time, serious waste of water resources, and the inability to realize orders for production at any time. Moreover, tofu production standards have not yet been clearly defined, with large differences in quality between them, which is not conducive to industrialized and large-scale production. Ultrasound has become a promising green processing technology with advantages, such as high extraction rate, short processing time, and ease of operation. This review focused on the challenges associated with traditional tofu production during soaking, grinding, and boiling soybeans. Moreover, the advantages of ultrasonic processing over traditional processing like increasing nutrient content, improving gel properties, and inhibiting the activity of microorganisms were explained. Furthermore, the quantification of acoustic fields by real-time monitoring technology was introduced to construct the theoretical correlation between ultrasonic treatments and tofu processing. It was concluded that ultrasonic treatment improved the functional properties of soybean protein, such as solubility, emulsifying properties, foamability, rheological properties, gel strength, and thermal stability. Therefore, the application of ultrasonic technology to traditional tofu processing to optimize industrial parameters is promising.

Synergistic modification of collagen structure using ionic liquid and ultrasound to promote the production of DPP-IV inhibitory peptides

BACKGROUND

Dual modification of collagen was performed using ionic liquid (IL) and ultrasound (US) to modulate the activity of collagen hydrolyzed peptides and reveal the production mechanism of cowhide-derived dipeptidyl peptidase (DPP-IV) inhibitory peptides.

RESULTS

The results revealed that dual modification (IL + US) significantly improved the hydrolytic degree of collagen (P < 0.05). Meanwhile, IL and US tended to promote the break of hydrogen bonds, but inhibit the crosslinking between collagens. The double modification reduced the thermal stability and accelerated the exposure of tyrosine and phenylalanine of collagen, and improved the proportion of small molecular (< 1 kDa) peptides in collagen hydrolysates. Interestingly, the hydrophobic amino acid residues and DPP-IV inhibitory activity of collagen peptides with small molecular weight (< 1 kDa) was increased further under the combination of IL and US.

CONCLUSION

Enhanced hypoglycemic activity of collagen peptides can be attained through the dual modification of IL and US. © 2023 Society of Chemical Industry.

Flavor characteristics of semi-dried yellow croaker (Pseudosciaena crocea) with KCl and ultrasound under sodium-reduced conditions before and after low temperature vacuum heating

This study investigated the flavor characteristics of semi-dried yellow croaker made by KCl instead of partial NaCl combined with ultrasound treatment before and after low temperature vacuum heating. The electronic tongue, electronic nose, free amino acids, 5'-nucleotides, and gas chromatography-ion mobility spectrometry were employed. Electronic nose and electronic tongue results showed that different treatment groups had different sensitive signals to smell and taste. The odor and taste of each group were mainly affected by Na⁺ and K⁺. The difference between the groups becomes larger after thermal treatment. Ultrasound and thermal treatment both changed the content of taste components. In addition, each group contained 54 volatile flavor compounds. Among them, the combined treatment method gave semi-dried large yellow croaker pleasant flavor characteristics. Besides, it also improved the content of flavor substances. In conclusion, the semi-dried yellow croaker under sodium-reduced conditions showed better performance in flavor characteristics.

Effects of Ultra-High Pressure Synergistic Enzymatic Hydrolysis on Flavor of Stropharia rugoso-annulata

In this study, using gas chromatography-mass spectrometry (HS-SPME-GC-MS), electronic nose (E-nose), high performance liquid chromatography (HPLC), and electronic tongue (E-tongue) to analyze the effect of ultra-high pressure (UHP) synergistic enzymatic hydrolysis on the flavor compounds of enzymatic hydrolysates of S. rugoso-annulata. The results demonstrated that 38 volatile flavor substances were identified in the enzymatic hydrolysates of S. rugoso-annulata treated at atmospheric pressure and 100, 200, 300, 400, and 500 MPa, mainly 6 esters, 4 aldehydes, 10 alcohols, 5 acids, and 13 other volatile flavor substances, and the most kinds of flavor substances reached 32 kinds when the pressure was 400 MPa. E-nose can effectively distinguish the overall changes of enzymatic hydrolysates of S. rugoso-annulata treated with atmospheric pressure and different pressures. There was 1.09 times more umami amino acids in the enzymatic hydrolysates at 400 MPa than in the atmospheric pressure enzymatic hydrolysates and 1.11 times more sweet amino acids at 500 MPa than in the atmospheric pressure enzymatic hydrolysates. The results of the E-tongue indicate that the UHP treatment increased umami and sweetness and reduced bitterness, which was also confirmed by the results of amino acid and 5'-nucleotide analysis. In conclusion, the UHP synergistic enzymatic hydrolysis can effectively improve the overall flavor of the enzymatic hydrolysates of S. rugoso-annulata; this study also lays the theoretical foundation for the deep processing and comprehensive utilization of S. rugoso-annulata.

Metabolomics investigation on the volatile and non-volatile composition in enzymatic hydrolysates of Pacific oyster (Crassostrea gigas)

To investigate the differences of volatile and non-volatile metabolites between oyster enzymatic hydrolysates and boiling concentrates, molecular sensory analysis and untargeted metabolomics were employed. "Grassy," "fruity," "oily/fatty," "fishy," and "metallic" were identified as sensory attributes used to evaluate different processed oyster homogenates. Sixty-nine and 42 volatiles were identified by gas chromatography-ion mobility spectrometry and gas chromatography-mass spectrometry, respectively. Pentanal, 1-penten-3-ol, hexanal, (E)-2-pentenal, heptanal, (E)-2-hexenal, 4-octanone, (E)-4-heptenal, 3-octanone, octanal, nonanal, 1-octen-3-ol, benzaldehyde, (E)-2-nonenal, and (E, Z)-2,6-nonadienal were detected as the key odorants (OAV > 1) after enzymatic hydrolysis. Hexanal, (E)-4-heptenal, and (E)-2-pentenal were significantly associated with off-odor, and 177 differential metabolites were classified. Aspartate, glutamine, alanine, and arginine were the key precursors affecting the flavor profile. Linking sensory descriptors to volatile and nonvolatile components of different processed oyster homogenates will provide information for the process and quality improvement of oyster products.

Contribution of Lipids to the Flavor of Mussel (Mytilus edulis) Maillard Reaction Products

Lipid oxidation and the Maillard reaction are two of the most important reactions affecting the flavor of foods that have been heat-processed. To investigate the contribution of lipids to the mussel’s flavor, the mussel’s Maillard reaction products (MRPs) were prepared with polar lipids (mainly phospholipids) and nonpolar lipids (mainly glycerides), respectively. The effects of polar and nonpolar lipids on the flavor of the MRPs were investigated by sensory evaluation, electronic tongue, electronic nose, ultra-performance liquid chromatography-mass-spectrometry (UPLC-MS) and gas chromatography-mass-spectrometry (GC-MS). From the sensory evaluation results, the polar lipid MRPs had the highest scores. The tastes of polar lipid MRPs and nonpolar lipid MRPs were mainly umami, saltiness and sourness, and there were significant differences in their sour tastes. The flavor compounds in the MRPs were mainly inorganic sulfides, organic sulfides and nitrogen oxides. The odor of polar lipid MRPs was stronger than that of nonpolar lipid MRPs, and the seafood flavor was more obvious. A total of 37 volatile compounds were detected by GC-MS, mainly aldehydes, alcohols and ketones. The addition of polar lipids helped the MRPs to produce more volatile compounds. A total of 177 non-volatile compounds (including amino acids and their derivatives and oligopeptides, etc.) were detected in the samples using UPLC-MS. The non-volatile compounds contained in the no-lipid MRPs, polar lipid MRPs and nonpolar lipid MRPs were significantly different. This study provides a theoretical basis and technical support for the production of mussel MRPs.

Vibration mill-assisted complex enzyme hydrolysis for flavoring of freeze-dried sea cucumber powder

This study aims to analyze the flavor differences of freeze-dried sea cucumber powder, processed for different time intervals, under vibration mill-assisted complex enzyme hydrolysis using electronic nose (E-nose) and gas chromatography-ion mobility spectrometry (GC-IMS). The results of principal component analysis by E-nose showed distinction among the four groups of freeze-dried sea cucumber powder (papain-neutral protease (PN) and flavorzyme-neutral protease (FN), processed for 60 and 80 min). The GC-IMS revealed 35 volatile compounds. Subsequently, based on the fingerprint and heat map results, the flavor differences among the samples were clearly distinguished. When compared to the other three groups, the 60-FN group exhibited a greater variety and quantity of volatile compounds such as octanal, heptanal, hexanal, (E, Z)-2,6-nonadienal, and nonanal. The 80-PN group exhibited high amounts of 2-propanone, ethylbenzene, ethyl acetate, and 2,5-dimethylpyrazine. In addition, the vibration mill technique was considered to be a mild enzyme-assisted method. PRACTICAL APPLICATIONS: This study found that different enzyme types and physical technology operation time can affect the different volatile flavor compounds of freeze-dried sea cucumber powder, which can be quickly and effectively be identified by E-nose and GC-IMS technology to improve the flavor and quality of the product, while facilitating the rapid adjustment and development of the industry. Meanwhile, the results of the study could provide a reference for the deep processing and flavor improvement of the sea cucumber industry and make an important contribution to the related literature. In addition, this could also promote the development and application of non-thermal processing technologies such as vibratory mill in the freeze-dried sea cucumber powder industry.

Quality characteristics and non-volatile taste formation mechanism of Lentinula edodes during hot air drying

In this paper, the changes of non-volatile taste substances and the formation mechanism of taste quality of Lentinula edodes during hot air drying at 50 °C were studied. The results showed that with the increase of drying time, the moisture content gradually decreased, volume shrinkage, color deepening, chewiness and viscosity first increased and then decreased. After drying for 8 h, when the moisture content reached 28.68%, the appearance, taste and the overall quality of L.edodes were better. After 12 h drying, the content of free amino acids and organic acids increased significantly, while the content of 5'-nucleotide and soluble sugar decreased significantly, and the EUC value was higher. Succinic acid has the highest TAV value, which contributes the most to the taste of dried L.edodes products. Comprehensive quality analysis of drying process and the guidance for rehydration of dried L.edodes were also predicted.

Study on the Flavor Compounds of Fo Tiao Qiang under Different Thawing Methods Based on GC–IMS and Electronic Tongue Technology

“Fo Tiao Qiang” is a famous dish with Chinese characteristics. It is delicious, rich in materials, and high in nutritional value. Through physical and chemical analysis, electronic tongue, gas chromatography–ion mobility spectroscopy, and other technologies, the present study explored the quality characteristics and flavor differences of Fo Tiao Qiang by using different thawing methods (natural thawing, ultrasonic thawing, microwave thawing, and water bath thawing). The results show that the protein content was slightly higher in Fo Tiao Qiang with ultrasonic thawing than others. The fat content of the microwave-thawed Fo Tiao Qiang was significantly lower than the other three kinds of samples. After ultrasonic thawing, the number of free amino acids in the samples were the highest and the umami taste was the best. Compared with natural thawing, most of the flavor substances decreased in ultrasonic thawing, microwave thawing, and water bath thawing. However, several substances increased, such as alpha-terpineol, beta-phenylethyl alcohol, phenylacetaldehyde, cis-rose oxide, isobutyl acetate, and 2–3-pentanedione. This study revealed the changing laws of different thawing methods on the quality characteristics and flavor characteristics of Fo Tiao Qiang. It provides theoretical guidance for the industrial production and quality control of Fo Tiao Qiang.