Characterization of the Key Aroma Constituents in Fried Tilapia through the Sensorics Concept

Combined of plasma-activated water and dielectric barrier discharge atmospheric cold plasma treatment improves the characteristic flavor of Asian sea bass (Lates calcarifer) through facilitating lipid oxidation

To explore the combination effects of plasma-activated water and dielectric barrier discharge (PAW-DBD) cold plasma treatment on the formation of volatile flavor and lipid oxidation in Asian sea bass (ASB), the volatile flavor compounds and lipid profiles were characterized by gas chromatography-ion mobility spectrometry and LC-MS-based lipidomics analyses. In total, 38 volatile flavor compound types were identified, and the PAW-DBD group showed the most kinds of volatile components with a significant (p < 0.05) higher content in aldehydes, ketones, and alcohols. A total of 1500 lipids was detected in lipidomics analysis, phosphatidylcholine was the most followed by triglyceride. The total saturated fatty acids content in PAW-DBD group increased by 105.02 μg/g, while the total content of unsaturated fatty acids decreased by 275.36 μg/g. It can be concluded that the PAW-DBD processing increased both the types and amounts of the volatile flavor in ASB and promoted lipid oxidation by altering lipid profiles.

Changes in volatile compounds and lipid oxidation in various tissues of Nile tilapia (Oreochromis niloticus) during ice storage

Changes in the lipid oxidation and volatile compounds of a variety of tilapia tissues (Oreochromis niloticus) including the muscle, gills, and skin during ice storage were investigated by evaluating peroxide values (PVs), lipoxygenase (LOX) activity, fatty acid (FA) composition, and volatile substances. LOX activity and PV were determined in the gills, skin, and muscles throughout 9 days of storage in ascending order to the extended storage time. The highest level of LOX activity was found in the gills, whereas the highest PV was determined in the skin. FA content of all tissues decreased during the storage period. Oleic acid was the predominant monounsaturated fatty acid, whereas linoleic acid and docosahexaenoic acid were the main polyunsaturated fatty acids and omega-3 in all tissues. The fish gills were shown to have the highest level of volatile compounds followed by the skin and muscle, based on headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry. Principal component analysis indicated gradual changes in the volatile compound composition with increasing storage time. 2-Butanone and nonanal in the muscle, 6-methyl-2-heptanone and 2-nonenal in the gills, and 1-heptanol, and 1-nonanol in the skin were found to be the potential freshness indicators. In addition, hexanal could be a general potential marker for measuring the degree of lipid oxidation in all tissues. PRACTICAL APPLICATION: Understanding the volatile compound formation related to lipid oxidation within storage time at various tissues of tilapia could be critical to the side-stream processing to yield the desired quality.

Improving the flavor of tilapia fish head soup by adding lipid oxidation products and cysteine

Deodorization and umami enhancement are important challenges in promoting and consuming fish products. The aim of this study was to establish whether exogenous addition of oxidized lipids and cysteine can improve the fishy, umami and create a characteristic flavor in tilapia fish head soup. The results revealed that adding oxidized lipids and cysteine enhanced the sensory attributes of fish head soup and promoted the production of pleasant-tasting amino acids and fewer bitter amino acids in the Maillard reaction. Additionally, the combination increased the levels of well-flavored aldehydes, esters, heterocyclic compounds and less hydrocarbons in the fish head soup. Among the 13 volatile compounds screened, nine were identified as characteristic aromas of fish head soup, including nonanal, (E,E)-2,4-decadienal, 1-octen-3-ol, (E)-2-decenal, acetic acid, hexanal, heptanal, 2-octenal, and decanal. Exogenous lipid oxidation products, fatty acid oxidation, and Maillard reaction can improve the aroma and umami of tilapia fish head soup.

Aroma characterization and consumer acceptance of four cookie products enriched with insect (Ruspolia differens) meal

This research aims to advance knowledge on the impact of four processing methods on volatile compounds from insect-based baked products (cookies) to provide insights on consumer acceptance. Samples were exposed to double step enzyme digestive test, volatiles characterized through headspace analysis, while semi-trained panelists were recruited for the sensory test. Blanched and boiled samples of R. differens had considerably higher digestibility (83.42% and 81.61%, respectively) (p < 0.05) than toasted and deep-fried samples. Insect-based cookie products integrated with blanched and boiled R. differens meal expressed higher digestibility (80.41% and 78.73%, respectively) that was comparable to that of commercial cookie products (control cookies-CTRC with 88.22%). Key volatile compounds common between the various cookie products included, nonanal, octanal, methyl-pyrazine, hexanal, tetradecane, 2-pentylfuran, 2-heptanone, 2E-octenal, 2E-heptenal and dodecane. Among the volatile compounds, pleasant aromas observed were 2E,4E-dodecadienal, pentanal, octanal, methyl pyrazine, furfurals, benzaldehyde, and 2-pentyl furan, which were more pronounced in cookies fortified with boiled, toasted and deep-fried R. differens meal. There was a greater resemblance of sensory characteristics between control cookies and those fortified with deep-fried R. differens. These findings underscore the significant influence of aroma compounds on consumer acceptability and preference for insect-based baked food products, which allows for future process-modification of innate aromas of insect-based meals to produce high-valued pleasant consumer driven market products.

Correlation between physicochemical properties and volatile compound profiles in tilapia muscles subjected to four different thermal processing techniques

This work studied the physicochemical properties and odor profiles of tilapia muscles after exposure to four types of thermal processing methods: microwaving, roasting, boiling, or steaming. The effect of thermal processing on textural properties followed a pH-water state-water content-tissue microstructure-mass loss-textural properties route, expressed in the following manner: microwaving > roasting > steaming ≈ boiling. After processing, muscle pH increased from 6.59 ± 0.10 to 6.73 ± 0.04-7.01 ± 0.06, and hardness changed from 1468.49 ± 180.77 g to 452.76 ± 46.94-10723.66 ± 2898.46 g. Gas chromatography-based E-nose analysis confirmed that these methods had significant odor fingerprint effects on the tilapia muscles. Finally, the combined analysis of headspace solid-phase microextraction-gas chromatography-mass spectrometry, statistical MetaboAnalyst, and odor activity value showed that the microwaved, roasted, steamed, and boiled tilapia muscles had, respectively, three (hexanal, nonanal, and decanal), four (2-methyl-butanal, 3-methyl-butanal, decanal, and trimethylamine), one (2-methyl-butanal), and one (decanal) relatively important volatile compounds.

Physicochemical and Volatile Flavor Properties of Fish Skin under Conventional Frying, Air Frying and Vacuum Frying

The aim of this study was to investigate the physicochemical characteristics and volatile flavor of fried tilapia skins under three frying methods. Conventional deep-fat frying usually increases the oil content of the fried fish skin and leads to lipid oxidation, which reduces the product quality. Alternative frying methods, such as air frying for 6 and 12 min under 180 °C (AF6, and AF12) and vacuum frying at 0.085 MPa for 8 and 24 min under 120 °C (VF8, and VF24) were compared to conventional frying for 2 and 8 min under 180 °C (CF2, and CF8) for tilapia skin. Physical properties of fried skin, such as the moisture content, water activity, L* values and breaking force decreased under all frying methods, while the lipid oxidation and a*, b* values increased with the increase in frying time. In general, VF offered higher hardness of product compared to AF which had a lower breaking force. Especially AF12 and CF8 had the lowest breaking force, which indicated higher crispness. For the oil quality inside the product, AF and VF reduced conjugated dienes formation and retarded oxidation compared to CF. The results of the flavor compositions of fish skin measured using gas chromatography mass spectrometry (GC/MS) with solid phase microextraction (SPME) showed that CF obtained higher unpleasant oily odor (nonanal, 2,4-decadienal, etc.), while AF presented greater grilling flavor (pyrazine derivatives). Because fish skin fried by AF only relied on hot air, Maillard reaction derived compounds, such as methylpyrazine, 2,5-dimethylpyrazine, and benzaldehyde were the leading flavors. This made the aroma profiles of AF very different from VF and CF. Among all the approaches, AF and VF developed lower oil content, mild fat oxidation and better flavor attributes, which proves their practical applications for frying tilapia fish skin.

Development of Flavor and Taste Components of Sous-Vide-Cooked Nile Tilapia (Oreochromis niloticus) Fillet as Affected by Various Conditions

This study aims to shed light on the association between non-volatile and volatile compounds related to flavor/taste characteristics as well as sensory acceptability of Nile tilapia fillet (Oreochromis niloticus) cooked by various sous-vide (SV) conditions (50−60 ℃, 30−60 min), with fish cooked with boiling water used as control. Higher temperatures and longer processing times of SV cooking led to greater protein and lipid oxidation as indicated by the increase in total sulfhydryl (-SH), carbonyl, free fatty acid (FFA) contents as well as peroxide values (PV) and thiobarbituric acid reactive substance (TBARS) values. The differences in flavor/taste components including adenosine triphosphate (ATP)-related compounds, free amino acids (FAAs) and volatiles were also obtained, which directly affect sensory acceptability as evaluated by using the hedonic scale. Based on principal component analysis (PCA) results, the acceptability score was strongly correlated with inosine monophosphate (IMP) and acetoin, which seem to be the most crucial flavor enhancers for cooked tilapia. Among all samples, tilapia processed at 60 °C for 45 and 60 min, which contained significantly higher IMP and acetoin (p < 0.05) than others, had significantly higher flavor-liking and overall-liking scores, with a more than 7.5 meaning for high acceptability (p < 0.05), indicating the optimal SV conditions for tilapia fillet. Overall, the present finding indicated that the SV-cooking technique, at the optimal conditions, can improve the meat quality of cooked fish, in terms of flavor/taste characteristics, compared with traditional cooking (control).