Emerging applications of nano-optical sensors combined with near-infrared spectroscopy for detecting tea extract fermentation aroma under ultrasound-assisted sonication

The current innovative work combines nano-optical sensors with near-infrared spectroscopy for rapid detection and quantification of polyphenols and investigates the potential of the nano-optical sensor based on chemo-selective colorants to detect the dynamic changes in aroma components during the fermentation of tea extract. The procedure examined the influence of different ultrasound-assisted sonication factors on the changes in the consumption rate of polyphenols during the fermentation of tea extract versus non-sonication as a control group. The results showed that the polyphenol consumption rate improved under the ultrasound conditions of 28 kHz ultrasound frequency, 24 min treatment time, and 40 W/L ultrasonic power density. The metal–organic framework based nano-optical sensors reported here have more adsorption sites for enhanced adsorption of the volatile organic compounds. The polystyrene-acrylic microstructure offered specific surface area for the reactants. Besides, the employed porous silica nanospheres with higher porosity administered improved gas enrichment effect. The nano-optical sensor exhibits good performance with a “chromatogram” for the identification of aroma components in the fermentation process of tea extract. The proposed method respectively enhanced the consumption rate of polyphenol by 35.57%, 11.34% and 16.09% under the optimized conditions. Based on the established polyphenol quantitative prediction models, this work demonstrated the feasibility of using a nano-optical sensor to perform in-situ imaging of the fermentation degree of tea extracts subjected to ultrasonic treatment.     

Effect of ultrasound combined with exogenous GABA treatment on polyphenolic metabolites and antioxidant activity of mung bean during germination

Mung bean seeds were treated by a combination of ultrasound and γ-aminobutyric acid (GABA). Effect of these treatments on the free polyphenols content, antioxidant activity, and digestibility of mung bean sprouts was evaluated. Additionally, phenolic compounds were analyzed and identified using a metabolomics approach. The combined ultrasound and GABA treatments significantly enhanced the free polyphenols and flavonoids content (P < 0.05) of mung bean sprouts depending on sprouting duration. Besides, a positive correlation (P < 0.05) was found between the polyphenols content and in vitro antioxidant activity of mung bean sprouts. Moreover, a total number of 608 metabolites were detected, and 55 polyphenol compounds were identified, including flavonoids, isoflavones, phenols, and coumarins. Also, the KEGG metabolic pathway analysis revealed 10 metabolic pathways of phenols, including flavonoid, isoflavone, and phenylpropanoid biosynthesis. Powder of 48 h sprouted mung bean released polyphenols during simulated gastric digestion and possessed antioxidant activity.     

Antioxidant and anti-inflammatory polyphenols in ultrasound-assisted extracts from salvilla (Buddleja scordioides Kunth)

Salvilla is a widely distributed plant used in treatments against gastrointestinal disorders due to its phenolic antioxidant and anti-inflammatory potential. Major yield and quality of bioactive polyphenols must be obtained with no degradation during suitable processes such as Ultrasound-Assisted Extraction (UAE), which allows an efficient extraction of metabolites at appropriate parameter conditions. Salvilla extractions were made using UAE and aqueous ethanolic solutions. Variables used in UAE were sonication time, wave amplitude and percentage of ethanol in solvent. Extracts were tested for total flavonoids, antioxidant activity (ABTS, FRAP and ORAC) and an identification and quantification of phenolic compounds was carried out by UPLC-PDA-ESI-MS/MS. Once elected the better extraction conditions, an anti-inflammatory test was performed for this treatment. As a result, total flavonoids content in extracts was 147 to 288 µg catechin equivalents/mg of dry salvilla extract. All extracts have shown good antioxidant activity (86 to 280 mM Trolox eq/mg dry salvilla extract). Flavonoids contents by chromatography were higher than hydroxybenzoic and hydroxycinnamic acids specially the flavone, flavanol and flavanone groups. Treatment T6 (75% ethanol, 30% amplitude and 10 min extraction time) was the best extract in terms of significant flavonols, antioxidant activity, and higher anti-inflammatory potential.     

Ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. and their antioxidant activity

Bay leaves (BL) (Laurus nobilis L., Family: Laureceae) are traditionally used to treat some symptoms of gastrointestinal problems, such as epigastric bloating, impaired digestion, eructing and flatulence. These biological properties are mainly attributed to its phenolic compounds. In this paper, ultrasound-assisted extraction of phenolic compounds from Laurus nobilis L. (Laureceae) was studied.Effects of several experimental factors, such as sonication time, solid/liquid ratio and concentration of solvent on extraction of phenolic compounds were evaluated through a randomized complete block design with factorial treatment arrangement (3³). The best extraction conditions were: 1 g plant sample with 12 mL of 35% ethanol, for 40 min, obtaining a yield of phenolic compounds of 17.32 ± 1.52 mg g^?1 of plant. In addition, free radical-scavenging potential of DPPH and lipid oxidation inhibition, by linoleic acid peroxidation of the selected extract was measured in order to evidence their antioxidant properties. Results indicated that high amounts of phenolic compounds can be extracted from L. nobilis by ultrasound-assisted extraction technology.     

Intensification of bio-actives extraction from pomegranate peel using pulsed ultrasound: Effect of factors,correlation, optimization and antioxidant bioactivities

Pomegranate peel (PP) is one of the interesting agri-food by-products because of its abundant bioactive phytochemicals. However, the bioactivity of valuable compounds is affected due to the extraction method used. A pulsed ultrasound-assisted extraction (PUAE) was carried out to intensify the extraction efficacy with reduced power and time. Influence of several process variables viz. peel solids/ solvent ratio, sonication power, duty cycle, and extraction time was studied using empirical quadratic models followed by multicriterial numerical optimization with respect to face-centered composite design. Power-duty cycle combination was found to be most significant (p < 0.05) for process intensification. The optimal process conditions of 2.17 g/100 mL S/S ratio at 116 W power with 80% duty cycle for 6 min resulted into 0.48 g/g yield, 177.54 mg GAE/g total phenolics content, 35.71 mg QE/g total flavonoids, 160.54 mg GAE/g antioxidant capacity, 21.65 mg cyn-3-glc/100 g anthocyanin content with 54.92 browning index in dry pomegranate peel. Significant Pearson correlation analysis was established in all responses with potent phenols and flavonoid relation with highest coefficient (r) 0.931. All response models were significantly validated with regression coefficient (R²) above 0.965. Remarkable antioxidant bioactivities were recorded for the resultant peel extract. Hence, it is strongly recommended that PUAE could be successfully applied for the intensification of the extraction process of bioactive from any peel and or plant systems with minimal process time and power consumption with a green label.     

Ultrasound-assisted green extraction methods: An approach for cosmeceutical compounds isolation from Macadamia integrifolia pericarp

This study aimed was to examine the potential of several green extraction methods to extract cosmetic/cosmeceutical components from Macadamia integrifolia pericarps, which were a by-product of the macadamia nut industry. M. integrifolia pericarps were extracted by conventional solvent extraction process using 95% v/v ethanol and various green extraction methods, including infusion, ultrasound, micellar, microwave, and pulsed electric field extraction using water as a clean and green solvent. The extracts were evaluated for total phenolic content using Folin-Ciocalteu method. The antioxidant activities were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), ferric reducing/antioxidant power, and ferric-thiocyanate method. The anti-skin ageing activities were investigated by means of collagenase, elastase, and hyaluronidase inhibition using enzyme-substrate reaction assay. The irritation profile of the extracts was evaluated by the hen’s egg test-chorioallantoic membrane (HET-CAM) test. The results noted that ultrasound-assisted extraction yielded the significantly highest extract amount with the significantly highest total phenolic content (p < 0.05), especially when the extraction time was 10 min. The aqueous extract from ultrasound-assisted extraction possessed the most potent antioxidant and anti-skin ageing activities (p < 0.05). Its antioxidant activities were comparable to ascorbic acid and Trolox, whereas the anti-skin ageing activities were equivalent to epigallocatechin-3-gallate and oleanolic acid. Besides, the extract was safe since it induced no irritation in the HET-CAM test. Therefore, ultrasound-assisted extraction was suggested as an environmentally friendly extraction method for M. integrifolia pericarp extraction and further application in the cosmetic/cosmeceutical industries.     

Ultrasonic-assisted enzymatic improvement of polyphenol content,antioxidant potential,and in vitro inhibitory effect on digestive enzymes of Miang extracts

The aims of this research were to optimize the ultrasonic-assisted enzymatic extraction of polyphenols under Miang and tannase treatment conditions for the improvement of antioxidant activity of Miang extracts via response surface methodology. Miang extracts treated with and without tannase were investigated for their inhibitory effects on digestive enzymes. The optimal conditions for ultrasonic-assisted enzymatic extraction of the highest total polyphenol (TP) (136.91 mg GAE/g dw) and total flavonoid (TF) (5.38 mg QE/g dw) contents were as follows: 1 U/g cellulase, 1 U/g xylanase, 1 U/g pectinase, temperature (74 °C), and time (45 min). The antioxidant activity of this extract was enhanced by the addition of tannase obtained from Sporidiobolus ruineniae A45.2 undergoing ultrasonic treatment and under optimal conditions (360 mU/g dw, 51 °C for 25 min). The ultrasonic-assisted enzymatic extraction selectively promoted the extraction of gallated catechins from Miang. Tannase treatment improved the ABTS and DPPH radical scavenging activities of untreated Miang extracts by 1.3 times. The treated Miang extracts possessed higher IC₅₀ values for porcine pancreatic α-amylase inhibitory activity than those that were untreated. However, it expressed approximately 3 times lower IC₅₀ values for porcine pancreatic lipase (PPL) inhibitory activity indicating a marked improvement in inhibitory activity. The molecular docking results support the contention that epigallocatechin, epicatechin, and catechin obtained via the biotransformation of the Miang extracts played a crucial role in the inhibitory activity of PPL. Overall, the tannase treated Miang extract could serve as a functional food and beneficial ingredient in medicinal products developed for obesity prevention.     

Towards the industrial production of antioxidants from food processing by-products with ultrasound-assisted extraction

Apple pomace, a by-product of the cider production, has been studied as a potential source of polyphenols, compounds of great interest for the industry. Ultrasound has been used to improve extraction efficiency in terms of time needed and total polyphenol content. A preliminary study has been first investigated to optimize ethanol proportion of aqueous extractant (50%, v/v) and solid/liquid ratio (<15%, w/v). A response surface methodology has then been used to maximize total polyphenol content of extracts and investigate influence of parameters involved in extraction procedures for both total polyphenols content and composition of extracts. Optimal settings reached from a central composite design were applied for ultrasound-assisted extraction and were compared to conventional procedure: yields were increased by more than 20%. Ultrasound-assisted polyphenols extraction from apple pomace appears to be a relevant, rapid, sustainable alternative to conventional procedure, and that scale up of the process is possible.     

Comparison of ultrasound-assisted extraction with conventional extraction methods of oil and polyphenols from grape (Vitis vinifera L.) seeds

Ultrasound-assisted extraction (US) carried out at 20 KHz, 150 W for 30 min gave grape seed oil yield (14% w/w) similar to Soxhlet extraction (S) for 6 h. No significant differences for the major fatty acids was observed in oils extracted by S and US at 150 W. Instead, K₂₃₂ and K₂₆₈ of US- oils resulted lower than S-oil. From grape seeds differently defatted (S and US), polyphenols and their fractions were extracted by maceration for 12 h and by ultrasound-assisted extraction for 15 min. Sonication time was optimized after kinetics study on polyphenols extraction. Grape seed extracts obtained from seeds defatted by ultrasound (US) and then extracted by maceration resulted the highest in polyphenol concentration (105.20 mg GAE/g flour) and antioxidant activity (109 Eq αToc/g flour).     

Phytochemicals in Capsicum oleoresin from different varieties of hot chilli peppers with their antidiabetic and antioxidant activities due to some phenolic compounds

Due to its wide use in nutritional therapy, a capsicum oleoresin extraction from hot chilli pepper was optimized using ultrasound assisted extraction. Under optimal conditions, a 0.1 g sample in 10 mL of a 20% water in methanol solution was extracted at 50 °C for 20 min to remove phytochemicals consisting of oleoresin, phenolics, carotenoids, flavonoids, capsaicinoids (pungency level), reducing sugars. Antioxidant and antidiabetic activities of the crude extracts from 14 chilli pepper varieties were examined. The antioxidant and antidiabetic activities of some phenolic compounds were also tested individually. The results showed that these chilli pepper samples are a rich source of phytochemicals with antioxidant and antidiabetic activities. High antioxidant activity of the extracts was evaluated using the 2,2-diphenyl-1-picrylhydrazyl, N,N-dimethyl-p-phenylenediamine dihydrochloride, 2,2′-azino-bis(3-ethylbenzothiazolin-6-sulfonic acid) and ferric ion reducing antioxidant power assays. The crude extracts had a lower level of sugars induced by the inhibitory effect of α-amylase activity. Thus, their enzymatic inhibitory effect might have resulted from a synergism among the phytochemicals concerned. Therefore, a diet with this type of food may have beneficial health effects.     

Solubility study and intensification of extraction of phenolic and anthocyanin compounds from Oryza sativa L. ‘Violet Nori’

Oryza sativa L. ‘Violet Nori’ is an Italian cultivar of spontaneous growing aromatic purple rice which is particularly rich in polyphenolic compounds, especially anthocyanins, conferring it an excellent antioxidant capacity. The present study aimed at increasing the extraction yields of its antioxidant compounds with green strategies and it is divided into two steps. The first step concerned a solubility study of the targeted polyphenols in different ethanol:water mixtures by means of a theoretical prediction method, using the simulation program COSMO-RS, and the subsequently confirmation of the computational results by practical experiments. Once the best extraction mixture was identified, the second step of the work was performed, with the purpose of intensifying the extraction yield. Therefore, various innovative green extraction techniques, including ultrasound, using both the probe system and the ultrasonic bath, bead milling, microwave and accelerated solvent extractions were tested and compared to conventional maceration.Results, expressed in terms of total phenolic and total monomeric anthocyanin contents, showed that the best extracting solvent for ‘Violet Nori’ rice was the mixture ethanol:water (60:40 v/v), being COSMO-RS computational predictions in good correlation with the experimental results. Moreover, the most efficient techniques to extract the antioxidant compounds resulted to be both ultrasound-assisted extraction probe and bead milling, that in only 5 min got the same extractive efficiency obtained after 3 h of conventional maceration.     

Optimized ultrasound-assisted extraction of phenolic compounds from Thymus comosus Heuff. ex Griseb. et Schenk (wild thyme) and their bioactive potential

An optimized ultrasound-assisted extractive method was developed to obtain a polyphenol-enriched extract from the aerial parts of Thymus comosus Heuff. ex Griseb. et Schenk. Optimization process was conducted based on Design of Experiment (DoE) principles, determining the influence of three independent variables (time, ultrasound amplitude, ethanol concentration) on the total phenolic content of the extract (dependent variable). Additionally, the phenolic composition of the extract was characterized through UHPLC-HRMS, revealing beside the most abundant flavonoid-type compounds the presence of salvianolic acids C, D and L in high amounts. Phytochemical profile of the extract was correlated with its antioxidant activity (tested through five complementary assays) and enzyme-inhibitory potential, showing important antiglucosidase and anticholinesterase effects. Overall, it was concluded that the developed method is suitable for obtaining a good recovery of both phenolic and non-phenolic compounds from Thymus comosus aerial parts, and their presence in the optimized extract is responsible for its pharmacological potential.     

Bioactive characterization of ultrasonicated ginger (Zingiber officinale) and licorice (Glycyrrhiza Glabra) freeze dried extracts

Ginger (Zingiber officinale) and Licorice (Glycyrrhiza glabra L.) are one of the most popular spices having a wide range of bioactive compounds that have varied biological and pharmacological properties. The study was aimed to extract polyphenols from Himalayan medicinal herbs ginger and licorice in different solvents using ultra-sonication technique. The extraction efficiency (EE) was determined, and the extracts were characterized for physical properties (particle size, colour values), total phenolics, flavonoids, antioxidant properties, and structural and morphological features. Ultra-sonicated ginger in aqueous phase had the highest EE of polyphenols (15.27%) as compared to other solvents. Similar trend was observed in licorice with EE of 30.52 % in aqueous phase followed by ethanol: water (50: 50), and methanol: water (50:50) with 28.52% and 26.39%, respectively. The preliminary screening showed the presence of tannins, phenolics, flavonoids, saponins and carbohydrates, steroids and alkaloids in all the extracts. The phenolic and flavonoid content of dried ginger was found higher in ethanolic extracts compared to fresh ones as revealed by HPLC. Similarly, for licorice, the ethanolic fractions had the highest polyphenolic content. The representative samples of ginger (ethanol: water 75:25 and ethylacetate: water 75:25) and licorice (ethanol: water 70:30 and methanol: water 50:50) were studied for FESEM and particle size. The results showed the agglomerated extract micro-particles with a diameter of 0.5–10 µm and increased particle size (ginger: 547 and 766 nm), and (licorice: 450 and 566 nm). The findings could be beneficial for the advancement of ginger and licorice processing, for the comprehension of these herbs as a source of natural antioxidants in different food formulations.     

Optimization of ultrasound-assisted extraction of bioactive compounds from coffee pulp using propylene glycol as a solvent and their antioxidant activities

In the cosmetic and pharmaceutical industries, it has been increasingly popular to use alternative solvents in the extraction of bioactive compounds from plants. Coffee pulp, a by-product of coffee production, contains different phenolic compounds with antioxidant properties. The effects of polyols, amplitude, extraction time, solvent concentration, and liquid–solid ratio on total phenolic content (TPC) using ultrasound-assisted extraction (UAE) were examined by single-factor studies. Three main factors that impact TPC were selected to optimize the extraction conditions for total phenolic content (TPC), total flavonoid content (TFC), total tannin content (TTC), and their antioxidant activities using the Box-Behnken design. Different extraction methods were compared, the bioactive compounds were identified and quantified by liquid chromatography triple quadrupole mass spectrometer (LC-QQQ), and the cytotoxicity and cellular antioxidant activities of the extract were studied. According to the response model, the optimal conditions for the extraction of antioxidants from coffee pulp were as follows: extraction time of 7.65 min, liquid–solid ratio of 22.22 mL/g, and solvent concentration of 46.71 %. Under optimized conditions, the values of TPC, TFC, TTC, 1,1-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging assay, 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging assay, and Ferric reducing antioxidant power assay (FRAP) were 9.29 ± 0.02 mg GAE/g sample, 58.82 ± 1.38 mg QE/g sample, 8.69 ± 0.25 mg TAE/g sample, 7.56 ± 0.27 mg TEAC/g sample, 13.59 ± 0.25 mg TEAC/g sample, and 10.90 ± 0.24 mg FeSO₄/g sample, respectively. Compared with other extraction conditions, UAE with propylene glycol extract (PG-UAE) was significantly higher in TPC, TFC, TTC, DPPH, ABTS, and FRAP response values than UAE with ethanol (EtOH-UAE), maceration with propylene glycol (PG-maceration), and maceration with ethanol (EtOH -maceration) (p < 0.05). Major bioactive compounds detected by LC-QQQ included chlorogenic acid, caffeine, and trigonelline. At higher concentrations starting from 5 mg/ml, PG-UAE extract showed higher cell viability than EtOH-UAE in both cytotoxicity and cellular antioxidant assays. The researcher expects that this new extraction technique developed in this work could produce a higher yield of bioactive compounds with higher biological activity. Therefore, they can be used as active ingredients in cosmetics (anti-aging products) and pharmaceutical applications (food supplements, treatment for oxidative stress-related diseases) with minimal use of chemicals and energy.     

Ultrasound-assisted extraction of bioactive compounds from palm pressed fiber with high antioxidant and photoprotective activities

This work is focused on the optimization of the ultrasound-assisted extraction of antioxidant compounds with photoprotective effect from palm pressed fiber. The influence of ultrasound intensity and pulse cycle was investigated by means of a central composite rotational design. The optimized condition was ultrasound intensity of 120 W.cm⁻² and pulse factor of 0.4, yielding 3.24 wt%. Compounds such as fatty acids, β-sitosterol, α-tocopherol, squalene, total phenolics and carotene were identified. The extract presented antioxidant activity towards synthetic (2,2-diphenyl-1-picrylhydrazyl – DPPH, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) – ABTS) and biological radicals (Hydroxyl – OH), besides a sun protection factor of 15.01. Polar extracts from palm pressed fiber are promising candidates for use in cosmetic and pharmaceutical formulation since they present high antioxidant activity towards different radicals, combined with the high sun protection factor.     

Optimization of ultrasound extraction of functional compound from makiang seed by response surface methodology and antimicrobial activity of optimized extract with its application in orange juice

An ultrasound-assisted extraction (UAE) was optimized for the extraction of bioactive compound (total phenolic compound and total flavonoid content) with antioxidant activity (DPPH and FRAP assays) using response surface methodology based on Box-Behnken design (BBD). The effect of extraction temperature (X₁: 30–70 °C), extraction time (X₂: 25–45 min) and amplitude (X₃: 30–50%) were determined. In addition, antimicrobial activity and application of optimized makiang seed extract (MSE) were also evaluated. Results showed that the optimum condition of UAE were X₁: 51.82 °C, X₂: 31.87 min and X₃: 40.51%. It was also found that gallic acid was the major phenolic compound of optimized MSE and its minimum inhibitiory concentration (MIC) and minimum bactericidal concentration (MBC) was between 1.56 - 6.25 and 25–100 mg/mL respectively. The addition of MSE could enhance the stability of orange juice and shelf life extension was also obtained. This research finding suggests the beneficial opportunities for ultrasound-assisted extraction for the production of bioactive compound from makiang seed with antioxidant activity leading to an application in medicinal and functional food industry.     

Effect of ultrasound,heating and enzymatic pre-treatment on bioactive compounds in juice from Berberis amurensis Rupr.

The aim of the study was to assess the influence of ultrasound (frequency 20 kHz, amplitude 70%, power 140 W for 10 min), heating (80 °C, 5 min) and enzymatic pre-treatment of mash (50 °C, Rohapect 10L at a dose of 0.23 g/1000 g, maceration time 60 min) on the yield, the content of phenolic compounds (including anthocyanins), ascorbic acid, and the antioxidative capacity of Berberis amurensis juice. Additionally, the polyphenols profile of this raw material and juices was identified. 25 phenolic compounds were identified in the fruit and 24 in juices. The content of phenolics in the fruit was 636 mg/100 g. Chlorogenic acid, 4-hydroxybenzoate and quercetin-3-O-glicoside were predominant. The content of anthocyanins in the fruit was 217 mg/100 g f.w., where peonidin-3-O-glucoside (98%) was predominant. The content of ascorbic acid amounted to 16.60 mg/100 g. The yield of the barberry juice pressing process ranged from 56% to 60% – there were no differences between the mash treatment methods. The enzymatic and thermal treatment of the mash resulted in the highest content of phenolic compounds in the juice. The sonication resulted in the highest content of anthocyanins, including peonidin-3-O-glucoside, as the main anthocyanin. The thermal treatment of the mash resulted in a lower loss of ascorbic acid than the other methods. The juice from the mash subjected to pectinolysis or heat treatment exhibited the highest antioxidative capacity.     

Ultrasound-assisted extraction of polyphenols from native plants in the Mexican desert

Several plants that are rich in polyphenolic compounds and exhibit biological properties are grown in the desert region of Mexico under extreme climate conditions. These compounds have been recovered by classic methodologies in these plants using organic solvents. However, little information is available regarding the use of alternative extraction technologies, such as ultrasound. In this paper, ultrasound-assisted extraction (UAE) parameters, such as the liquid:solid ratio, solvent concentration and extraction time, were studied using response surface methodology (RSM) for the extraction of polyphenols from desert plants including Jatropha dioica, Flourensia cernua, Turnera diffusa and Eucalyptus camaldulensis. Key process variables (i.e., liquid:solid ratio and ethanol concentration) exert the greatest influence on the extraction of all of the phenolic compounds (TPC) in the studied plants. The best conditions for the extraction of TPC involved an extraction time of 40 min, an ethanol concentration of 35% and a liquid:solid ratio ranging from 8 to 12 ml g⁻¹ depending on the plant. The highest antioxidant activity was obtained in the E. camaldulensis extracts. The results indicated the ability of UAE to obtain polyphenolic antioxidant preparations from desert plants.     

Effects of ultrasound-assisted heating on aroma profile,peptide structure,peptide molecular weight,antioxidant activities and sensory characteristics of natural fish flavouring

This study deals with the production of natural fish flavouring using ultrasound-assisted heating process. The effect of ultrasound pretreatment at different amplitudes (0, 15, 30, and 45%) on the Maillard reaction rate, antioxidant activities, flavour profile, and sensory characteristics of fish flavouring was investigated. Results showed that sonication markedly accelerated the Maillard reaction (MR) rate, as evidenced by the modification of peptide structure, a decrease in pH value, free amino acid content coupled with a rise in browning intensity. Also, ultrasound pretreatment significantly enhanced the antioxidant activities of fish flavouring (p ≤ 0.05). Moreover, sonication increased the type and content of aroma compounds significantly. Sensory analysis revealed that ultrasound pretreatment increased the fish-like and toasty aroma as well as umami and mouthfulness attributes coupled with the reduction of the bitter taste of the fish flavouring. This result was consistent with the GC–MS, electronic nose, cluster, and Partial Least Squares Regression (PLSR) analyses, which clearly showed that ultrasound pretreatment enhanced the fish-like aroma, which was associated with the increase in aldehydes, ketones, alcohols, thiophenes, pyrazine, and furans contents. Thus, it could be concluded that ultrasound pretreatment, coupled with the thermal process, could be a promising process for the production of natural fish flavouring with higher antioxidant activities.