Effect of the fish oil, oxidation status and of heat treatment temperature on the volatile compounds of the produced fish feeds

Elucidation of key fatty aroma compound contributing to the hepatopancreas of Eriocheir sinensis using sensomics approach by GC-IMS and GC-MS-O

Aroma is one of the most noticeable characteristics when consuming Chinese mitten crab (Eriocheir sinensis) and is crucial for consumer satisfaction and the development of industry. In this study, we utilized fingerprints and the sensomics approach to analyze volatiles in the hepatopancreas of E. sinensis from Chongming and Taixing. GC-IMS indicated that the odor profile was dominated by pungent (-), buttery (+), and fruity (+) from Chongming and was more prone to alcoholic (-), solvent (-), and aldehydic (+) in Taixing. Moreover, PLS-DA modeling identified 2-acetylthiazole and toluene as the primary differential compounds. Subsequently, fifteen active-aroma compounds with FD values of >4 was recombined in an odorless matrix to simulate the odor profile of the hepatopancreas. Notably, removing methional may significantly decrease the intensity of the fatty and toasted odors. The findings reveal the odor profile of hepatopancreas and establish a theoretical foundation for subsequent studies on flavor.

Effects of Bacterioruberin-Rich Haloarchaeal Carotenoid Extract on the Thermal and Oxidative Stabilities of Fish Oil

This study aimed to assess the efficacy of a bacterioruberin-rich carotenoid extract (HAE) derived from the halophilic archaea Halorubrum ezzemoulense DSM 19316 in protecting crude fish oil against thermal oxidation. The research used fish oil derived from anchovies, which had a peroxide value (PV) of 6.44 ± 0.81 meq O2 kg-1. To assess the impact of HAE on the thermal stability and post-oxidation characteristics of fish oil, several concentrations of HAE were added to the fish oil samples: 0 ppm (no additive) (HAE0), 50 ppm (HAE50), 100 ppm (HAE100), 500 ppm (HAE500), and 1000 ppm (HAE1000). Furthermore, a control group was established with the addition of 100 ppm butylated hydroxytoluene (BHT100) in order to evaluate the effectiveness of HAE with a synthetic antioxidant that is commercially available. Prior to the fast oxidation experiment, thermogravimetric analysis was conducted on samples from all experimental groups. At the conclusion of the examination, it was seen that the HAE500 and HAE1000 groups exhibited a delay in the degradation temperature. The experimental groups underwent oxidation at a temperature of 55.0 ± 0.5 °C for a duration of 96 h. The measurement of PV was conducted every 24 h during this time. PV in all experimental groups exhibited a time-dependent rise (p < 0.05). However, the HAE500 group had the lowest PV measurement at the conclusion of the 96 h period (p < 0.05). Significant disparities were detected in the fatty acid compositions of the experimental groups at the completion of the oxidation experiment. The HAE500 group exhibited the highest levels of EPA, DHA, and ΣPUFA at the end of oxidation, with statistical significance (p < 0.05). Through the examination of volatile component analysis, specifically an oxidation marker, it was shown that the HAE500 group exhibited the lowest level of volatile components (p < 0.05). Consequently, it was concluded that the addition of HAE to fish oil provided superior protection compared to BHT at an equivalent rate. Moreover, the group that used 500 ppm HAE demonstrated the highest level of performance in the investigation.

Anti-Inflammatory and Antioxidative Phytogenic Substances against Secret Killers in Poultry: Current Status and Prospects

Chronic stress is recognized as a secret killer in poultry. It is associated with systemic inflammation due to cytokine release, dysbiosis, and the so-called leaky gut syndrome, which mainly results from oxidative stress reactions that damage the barrier function of the cells lining the gut wall. Poultry, especially the genetically selected broiler breeds, frequently suffer from these chronic stress symptoms when exposed to multiple stressors in their growing environments. Since oxidative stress reactions and inflammatory damages are multi-stage and long-term processes, overshooting immune reactions and their down-stream effects also negatively affect the animal's microbiota, and finally impair its performance and commercial value. Means to counteract oxidative stress in poultry and other animals are, therefore, highly welcome. Many phytogenic substances, including flavonoids and phenolic compounds, are known to exert anti-inflammatory and antioxidant effects. In this review, firstly, the main stressors in poultry, such as heat stress, mycotoxins, dysbiosis and diets that contain oxidized lipids that trigger oxidative stress and inflammation, are discussed, along with the key transcription factors involved in the related signal transduction pathways. Secondly, the most promising phytogenic substances and their current applications to ameliorate oxidative stress and inflammation in poultry are highlighted.

The Preparation and Identification of Characteristic Flavour Compounds of Maillard Reaction Products of Protein Hydrolysate from Grass Carp (Ctenopharyngodon idella) Bone

This study aims at preparing the Maillard reaction products of protein hydrolysate from grass carp (Ctenopharyngodon idella) bone and identifying its characteristic flavour compounds. Meanwhile, bioactivities and amino acids composition of hydrolysates and its Maillard reaction products were compared with the thermal degradation reaction as one positive control. Single factor experiment was applied to optimize the enzymolysis parameters of grass carp bone protein using flavourzyme, under which the highest degree of hydrolysis (40.1%) was obtained. According to the response surface methodology, the top predicted value (70.45%) of degree of graft of Maillard reaction was obtained with initial pH of 7.07, temperature of 118.33°C, and time of 1.75 h. Moreover, the results of Maillard reaction products illustrated a significant increase in DPPH radical scavenging activity ( $p<0.05$ ) compared to that of hydrolysate and its thermal degradation products, which was accompanied by the decreased ACE inhibitory activity. Besides, the umami-sweet taste amino acid ratio in free amino acids of Maillard reaction products climbed considerably compared to those of hydrolysate and its thermal degradation products, which proved that Maillard reaction is an effective way to improve the flavour taste of protein hydrolysate. The GC-MS results showed that 37, 40, and 62 kinds of volatile compounds were detected in hydrolysate, thermal degradation products, and Maillard reaction products, respectively. The Maillard reaction products contained more flavour volatile compounds of aldehydes, alcohol, ketone, pyrazine, and other compounds that contribute to pleasant aromas. These results suggested that the grass carp bone protein hydrolysate after Maillard reaction could potentially have a wide range of applications as antioxidant and flavour substances.

Volatile components of American silver carp analyzed by electronic nose and MMSE-GC-MS-O

We evaluated the characteristic odor substances in Asian carp meat, which are prevalent in the Great Lakes, to provide a foundation for resource utilization and removing its fishy smell. Three Mono Trap RCC18 adsorbents were used to extract samples. Volatile components were analyzed by gas phase-olfaction-mass spectrometry. The main odor-active substances were identified by aroma extraction dilution analysis. The overall odor profile was analyzed by electronic nose. Overall sensory evaluation showed that metallic and grassy in Chinese carp were heavier than those in American. Trimethylamine, ketones, aldehydes, and alcohols were the main odor components in the two species. Flavor dilution factors indicated that hexanal (grassy), 1-octen-3-ol (mushroom-like), and 2,3-pentanedione (milky) were important. Trimethylamine, 1-pentene-3-ol, 2,3-pentanedione, pentanal, 3-methyl-1-butanol, hexanal, 1-Hexanol, heptanal, 1-heptanol, 1-octen-3-ol, octanal, 2,3-pentanedione. D-limonene, nonanal, decanal, and naphthalene were the main flavor substances. The contents and intensities of volatile substances are generally higher in American than in Chinese silver carp. PRACTICAL APPLICATIONS: The large numbers of American silver carp are problematic in the Great Lakes. Pollution of the water environment may cause contamination in the fish body and the smell of freshwater fish is heavy and unacceptable. This study focuses on the odor of American silver carp to provide a foundation for later deodorization to increase utilization of the American silver carp.

The use of factorial design to evaluate the oxidation of oils containing different types of omega-3 fatty acids

BACKGROUND

Omega-3 fatty acids (n3 FA) promote beneficial effects on cardiovascular diseases, but they are highly susceptible to oxidation, which leads to the formation of potentially toxic secondary products. In this study, the antioxidant capacity of natural compounds (sinapic acid and rutin) was evaluated using an accelerated model to oxidize the oils. Five inducers (temperature, Fe²⁺ , 2,2'-azobis(2-amidinopropane) dihydrochloride, ascorbyl palmitate and the hydrophobic 2,2'-azobis-2,4-dimethylvaleronitrile (AMVN)) were combined in a factorial design to accelerate the oxidation of three oils (flaxseed, echium and fish) containing different sources of n3 FA.

RESULTS

Lipid hydroperoxide (LOOH) and thiobarbituric acid reactive substance (TBARS) concentrations estimated using the regression models did not differ from the observed values. AMVN + Fe²⁺ increased TBARS in all samples.

CONCLUSION

The values for the oxidative markers obtained 48 h after induction were similar to those obtained when the oils were heated at 60 ° C for 15 days. Of a number of volatile compounds formed from the oxidation of different n3 FA sources, (E,E)-2,4-heptadienal, (E,E)-2,4-decadienal, decanal, undecanal and (E)-2-undecenal were identified in all samples and could be used as more specific oxidative markers. Using the accelerated model, rutin improved the oxidative stability of fish oil, probably due to the presence of a catechol group in its chemical structure. © 2017 Society of Chemical Industry.

A Comprehensive Approach to Assess Feathermeal as an Alternative Protein Source in Aquafeed

The effect of partially replacing fishmeal in aquafeed with feathermeal (FTH) at three levels (0%: FTH0, 8%: FTH8, 24%: FTH24) and two extrusion temperatures (100 and 130 °C) was evaluated in rainbow trout (Oncorhynchus mykiss) with respect to growth performance, metabolism response, and oxidative status of the feed proteins. Multivariate data analyses revealed that FTH24 correlated positively with high levels of oxidation products, amino acids (AA) racemization, glucogenic AAs level in liver, feed intake (FI), specific growth rate (SGR), and feed conversion ratio (FCR); and low AAs digestibility. Both FI and SGR were significantly increased when 8 and 24% feathermeal was included in the feed extruded at 100 °C, while there was a negative effect on FCR in fish fed FTH24. In conclusion, higher oxidation levels in FTH24 may give rise to metabolic alterations while lower levels of FTH may be considered as fishmeal substitute in aquafeed for rainbow trout.

Hepatic transcriptome analysis and identification of differentially expressed genes response to dietary oxidized fish oil in loach Misgurnus anguillicaudatus

RNA sequencing and short-read assembly were utilized to produce a transcriptome of livers from loaches (Misgurnus anguillicaudatus) fed with three different diets respectively containing fresh fish oil (FO group), medium oxidized fish oil (MO group) and high oxidized fish oil (HO group). A total of 60,663 unigenes were obtained in this study, with mean length 848.74 bp. 50,814, 49,584 and 49,814 unigenes were respectively obtained from FO, MO and HO groups. There were 2,343 differentially expressed genes between FO and MO, with 855 down- and 1,488 up-regulated genes in the MO group. 2,813 genes were differentially expressed between FO and HO, including 1,256 down- and 1,552 up-regulated genes in the HO group. 2,075 differentially expressed genes were found in the comparison of MO and HO, including 1,074 up- and 1,001 down-regulated genes in the MO group. Some differentially expressed genes, such as fatty acid transport protein (fatp), fatty acid binding protein (fabp), apolipoprotein (apo), peroxisome proliferator activated receptor-gamma (ppar-γ), acetyl-CoA synthetase (acs) and arachidonate 5-lipoxygenase (alox5), were involved in lipid metabolism, suggesting these genes in the loach were responsive to dietary oxidized fish oil. Results of transcriptome profilings here were validated using quantitative real time PCR in fourteen randomly selected unigenes. The present study provides insights into hepatic transcriptome profile of the loach, which is a valuable resource for studies of loach genomics. More importantly, this study identifies some important genes responsible for dietary oxidized fish oil, which will benefit researches of lipid metabolism in fish.