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The research is aimed at investigating the effects of dietary protein and lipid levels on adult triploid rainbow trout growth performance, feed utilization, digestive and metabolic enzyme activities, antioxidative capacity, and fillet quality. Nine diets containing three dietary protein levels (DP) (300, 350, and 400 g kg-1) and three dietary lipid levels (DL) (200, 250, and 300 g kg-1) were prepared using a 3 × 3 factorial design. In freshwater cages, 13,500 adult female triploid rainbow trout (3.2 ± 0.1 kg) were cultured for 77 days. Triplicate cages (500 fish per cage) were used as repetitions of each experimental diet. The findings revealed that as DP increased to 400 g kg-1 and DL raised to 300 g kg-1, the weight gain ratio (WGR) elevated significantly (P < 0.05). However, when DP ≥ 350 g kg-1, WGR was similar in the DL250 and DL300 groups. As DP raised to 350 g kg-1, the feed conversion ratio (FCR) notably decreased (P < 0.05). In the DP350DL300 group, lipids had a protein-sparing impact. High DP diet (400 g kg-1) generally improved fish health status by increasing antioxidant capacity in the liver and intestine. A high DL diet (300 g kg-1) showed no harmful effect on hepatic health based on plasma levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and antioxidant capacity in the liver. For fillet quality, a high DP diet could increase fillet yield, improve fillet hardness, springiness, and water-holding capacity values, and inhibit the production of off-flavors caused by n-6 fatty acids. A high DL diet could increase odor intensity, and EPA, DHA, and n-3 fatty acid concentrations decrease the thrombogenicity index value. The maximum fillet redness value was discovered in the DP400DL300 group. Overall, for adult triploid rainbow trout (≥3 kg), the minimum recommended DP and DL according to growth performance were 400 and 250 g kg-1, respectively; DP and DL based on feed utilization were 350 and 200 g kg-1, respectively; DP and DL based on fillet quality were 400 and 300 g kg-1, respectively.
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A twelve-week feeding experiment was undertaken to explore the impact of substituting dietary fish meal (FM) and fish oil (FO) with complex protein (CP) and canola oil (CO) in the diet of triploid rainbow trout on the quality of their fillets. The control diet (F100) contained FM (60%) and FO (18.6%) as the main protein and lipid sources. Based on this, 50% and 100% of FM and FO were substituted by CP and CO and they were named as F50 and F0, respectively. The results showed that there were no significant differences in the specific growth rates, condition factors, gutted yields, fillet yields and yellowness values as the substitution levels increased (p > 0.05). The F50 treatment obtained the highest values of fillet springiness and chewiness, improved the umami and bitter taste of the fillets by increasing the contents of inosine-5'-monophosphate and histidine, and increased lipid, protein, C18: 1n-9 and C18: 2n-6 contents (p < 0.05). The F0 treatment obtained the highest values of fillet hardness and pH, attenuated the sweet taste of the fillets by decreasing the content of glycine, and decreased the contents of EPA and DHA (p < 0.05). Both F50 and F0 treatments could increase the redness value, decrease the lightness and hue values of fillets, and increase the odor intensity, resulting in the typical fillet odors of green, fatty, orange and fishy (p < 0.05). In general, 50% and 100% of FM and FO substitution did not affect the growth of trout, but it did affect quality. Compared to the F100 treatment, the fillet quality of the F0 treatment was similar to the F50 treatment and could improve the appearance and odor intensity of the fillets. However, the difference was that the F50 treatment increased the springiness, umami, bitterness and lipid nutritional value of the fillets, but the F0 treatment increased the hardness, decreased the sweetness, and decreased the lipid, EPA and DHA contents of the fillets.
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Herein, for the first time, we have successfully constructed a novel near-infrared (NIR) emission fluorescent probe Dpyt for ultrafast detecting (within 5 s) bisulfate and organic amines based on a 1,2-dihydrocyclopenta[b]chromene-barbiturate conjugation system. Upon addition of bisulfate or organic amines, Dpyt displayed a distinct color change from blue to colorless or from purple to blue, respectively, suggesting that the Dpyt can be used to detect two analytes by the naked eye. Based on quantum chemistry calculations, the fluorescence quenching of Dpyt after the addition of HSO3- is caused by the photoinduced electron transfer (PET) process of the adduct Dpyt-HSO3-. The fluorescence enhancement of Dpyt caused by most organic amines is due to the enhanced intramolecular charge transfer (ICT) process of deprotonated Dpyt. Notably, Dpyt can be applied for detecting HSO3- in actual food samples such as red wine and sugar, as well as for imaging of HSO3- and representative propylamine in living cells. And more importantly, indicator labels constructed by filter paper loaded with Dpyt can visually monitor the freshness of salmon in real-time by daylight and fluorescence dual-mode. The comparison with national standard method of China manifests that indicator labels are a valid tool to assess the freshness of seafood.
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Aminas , Corantes Fluorescentes , Animais , Corantes Fluorescentes/química , Colorimetria/métodos , Sulfitos , PeixesRESUMO
At least 10 million tons of seafood products are spoiled or damaged during transportation or storage every year worldwide. Monitoring the freshness of seafood in real time has become especially important. In this study, four machine learning algorithms were used for the first time to develop a multi-objective model that can simultaneously predict the shelf-life of five marine fish species at multiple storage temperatures using 14 features such as species, temperature, total viable count, K-value, total volatile basicnitrogen, sensory and E-nose-GC-Ms/Ms. as inputs. Among them, the radial basis function model performed the best, and the absolute errors of all test samples were <0.5. With the optimal model as the base layer, a real-time prediction platform was developed to meet the needs of practical applications. This study successfully realized multi-objective real-time prediction with accurate prediction results, providing scientific basis and technical support for food safety and quality.
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Peixes , Armazenamento de Alimentos , Aprendizado de Máquina , Alimentos Marinhos , Animais , Alimentos Marinhos/análise , Cromatografia Gasosa-Espectrometria de Massas , Temperatura , Nariz EletrônicoRESUMO
Economic loss due to fish spoilage exceeds 25 billion euros every year. Accurate and real-time monitoring of the freshness of fish can effectively cut down economic loss and food wastage. In this study, a dual-functional hydrogel based on sodium alginate-co-pigment complex with volatile antibacterial and intelligent indication was prepared and characterized. The characterization results indicated that the sodium alginate-co-pigment complex successfully improved the stability and color development ability of blueberry anthocyanins and bilberry anthocyanins at different temperatures and pH. The double cross-linking network inside the hydrogel conferred it with excellent mechanical properties. During rainbow trout storage, the hydrogel indicated a color difference of 73.55 on the last day and successfully extended the shelf-life of rainbow trout by 2 days (4 °C). Additionally, four dual-channel monitoring models were constructed using machine learning. The validation error of the genetic algorithm back propagation model (GA-BP) was only 5.6e-3, indicating that GA-BP can accurately monitor the freshness of rainbow trout. The rainbow trout real-time monitoring platform built based on GA-BP model can monitor the freshness of rainbow trout in real time through the images uploaded by users. The results of this study have broad applicability in the food industry, environmental conservation, and economic sustainability.
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Antocianinas , Oncorhynchus mykiss , Animais , Antocianinas/química , Polissacarídeos , Oncorhynchus mykiss/microbiologia , Alimentos Marinhos/análise , Embalagem de Alimentos/métodos , Alginatos , Aprendizado de Máquina , Concentração de Íons de HidrogênioRESUMO
Global seafood consumption is estimated at 156 million tons annually, with an economic loss of >25 billion euros annually due to marine fish spoilage. In contrast to traditional smart packaging which can only roughly estimate food freshness, an intelligent platform integrating machine learning and smart aerogel can accurately predict remaining shelf life in food products, reducing economic losses and food waste. In this study, we prepared aerogels based on anthocyanin complexes that exhibited excellent environmental responsiveness, high porosity, high color-rendering properties, high biocompatibility, high stability, and irreversibility. The aerogel showed excellent indication properties for rainbow trout and proved suitable for fish storage environments. Among the four machine learning models, the radial basis function neural network and backpropagation network optimized by genetic algorithm demonstrated excellent monitoring performance. Also, the two-channel dataset provided more comprehensive information and superior descriptive capability. The three-layer structure of the monitoring platform provided a new paradigm for intelligent and sophisticated food packaging. The results of the study might be of great significance to the food industry and sustainable development.
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Alginatos , Embalagem de Alimentos , Armazenamento de Alimentos , Géis , Alimentos Marinhos , Alimentos Marinhos/análise , Qualidade dos Alimentos , Aprendizado de Máquina , Oncorhynchus mykiss , Géis/química , Alginatos/análise , Antocianinas/análise , Congelamento , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X , Sistemas ComputacionaisRESUMO
The corruption of refrigerated marine fish results in global economic losses exceeding 25 billion euros annually. However, conventional preservatives present challenges, including singular functionality, potential toxicity, and high cost. In response, we developed multifunctional, safe, cost-effective, and environmentally friendly carbon dots derived from radish residues (R-CDs) by using the one-pot hydrothermal method. The surface of R-CDs is enriched with hydroxyl groups, conferring broad-spectrum antioxidant and antibacterial characteristics. R-CDs exhibited a notable 72.92 % inhibition rate on lipid peroxidation, surpassing the effectiveness of vitamin C (46 %). Additionally, R-CDs demonstrated impressive scavenging rates of 93.8 % for 2,2-diphenyl-1-picrylhydrazyl free radicals and 99.36 % for 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid-free radicals. In combating spoilage bacteria such as Aeromonas sobria and Hafnia alvei, R-CDs disrupted cell structures and influenced intracellular substance content. Importantly, co-cultivation with R-CDs showed no significant cytotoxicity. Further incorporating R-CDs into films using starch and chitosan (S/CS/R-CDs films) for efficient and convenient use in salmon fillets preservation. S/CS/R-CDs films effectively inhibited the growth of spoilage bacteria, lipid oxidation, and protein decomposition in salmon fillets, thereby extending shelf life by 4 days. This combination of antioxidant and antibacterial properties in R-CDs, along with the functional films, presents a promising approach for enhancing salmon fillet preservation.
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Antibacterianos , Antioxidantes , Carbono , Quitosana , Embalagem de Alimentos , Raphanus , Salmão , Amido , Animais , Antibacterianos/farmacologia , Antibacterianos/química , Antioxidantes/farmacologia , Antioxidantes/química , Embalagem de Alimentos/métodos , Carbono/química , Raphanus/química , Quitosana/química , Quitosana/farmacologia , Amido/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Pontos Quânticos/química , Peroxidação de Lipídeos/efeitos dos fármacosRESUMO
Triploid rainbow trout can adapt to various dietary lipid levels; however, the mechanisms of systematic adaptation are not well understood. To investigate how adult triploid rainbow trout maintains lipid hemostasis under different exogenous lipid intake, a 77-day feeding trial was conducted. Diets with lipid contents of 20%, 25%, and 30% were formulated and fed to triploid rainbow trout with an initial weight of 3 ± 0.02 kg, and they were named L20, L25, and L30 group, respectively. Results showed that the condition factor, hepatosomatic index, liver color, and plasma triglyceride were comparable among three groups (p > 0.05), whereas the value of specific growth rate, viscerosomatic index, and liver glycogen content gradually increased with increasing dietary lipid level (p < 0.05). A significantly highest value of plasma glucose and nonesterified fatty acids were found in the L30 group (p < 0.05), whereas the significantly higher content of plasma total cholesterol, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol was found in the L25 group compared with those in L20 group (p < 0.05). As for lipid deposition, abdominal adipose tissue, and muscle were the main lipid storage place for triploid rainbow trout when tissues' weight is taken into consideration. Overall quantitative PCR showed that the lipid transport and glycolysis were upregulated, and fatty acids oxidative was downregulated in liver when fish were fed low lipid diets. It meant that the liver was the primary lipid metabolizing organ to low lipid diet feeding, which could switch energy supply between glycolysis and fatty acids oxidation. Fish fed with a moderate dietary lipid level diet could increase lipid uptake and promote lipogenesis in muscle. Abdominal adipose tissue could efficiently uptake excess exogenous free fatty acid through upregulating fatty acid uptake and synthesis de novo and then storing it in the form of triglyceride. Excess lipid uptake is preferentially stored in abdominal adipose tissue through coordinated fatty acid uptake and fatty acid synthesis de novo as dietary lipid levels increased. In summary, triploid rainbow trout can adapt to various dietary lipid levels by coordinating metabolism in different tissues.
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Organoleptic properties and nutritional value are the most important characteristics of fish fillet quality, which can be determined by a series of quality evaluation indexes and closely related to fish nutrition. Systematic organoleptic and nutritional quality evaluation indexes consisting of 139 indexes for physical properties and chemical compositions of triploid rainbow trout were established. Besides, effects of dietary lipid levels (6.6%, 14.8%, 22.8% and 29.4%) on the quality of triploid rainbow trout were analyzed in the study. The main results showed that, for fillet appearance quality, fish fed diets with lipid levels above 22.8% had higher fillet thickness and redness but lower gutted yield and fillet yield (p < 0.05). For fillet texture, fish fed the diet with a 6.6% lipid level had the highest fillet hardness (5.59 N) and lowest adhesiveness (1.98 mJ) (p < 0.05), which could be related to lipid, glycogen, water soluble protein and collagen contents of the fish fillet. For fillet odor, the odor intensity of "green, fatty and fishy" significantly increased with the increase of the dietary lipid level (from 1400 to 2773 ng/g muscle; p < 0.05), which was related to the degradation of n-6 and n-9 fatty acids. For fillet taste, a high lipid diet (≥22.8%) could increase the umami taste compounds contents (from 114 to 261 mg/100 g muscle) but decrease the bitterness and sourness taste compounds contents (from 127 to 106 mg/100 g muscle and from 1468 to 1075 mg/100 g muscle, respectively) (p < 0.05). For nutritional value, a high lipid diet could increase the lipid nutrition level (such as the content of long chain polyunsaturated fatty acids increased from 3.47 to 4.41 g/kg muscle) but decease tryptophan and selenium content (from 2.48 to 1.60 g/kg muscle and from 0.17 to 0.11 g/kg muscle, respectively). In total, a high lipid diet could improve the quality of triploid rainbow trout. The minimum dietary lipid level for triploid rainbow trout should be 22.8% to keep the better organoleptic and nutritional quality.
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This experiment simulated the hypoxic environment caused by actual production operations in fish farming (i.e., catching, gathering, transferring, and weighting) to study the effects of acute hypoxic conditions on the physiological and metabolic responses of triploid rainbow trout (O. mykiss). Two groups of fish weighting 590 g were sampled in the normoxia group (dissolved oxygen above 7 mg/L) and hypoxia group (dissolved oxygen ranged from 2 to 5 mg/L for 10 min). The results showed that 1) regarding stress response, hypoxia increased plasma levels of cortisol, heat shock protein 70 (HSP-70), lysozyme, alanine aminotransferase (ALT), aspartate aminotransferase (AST) and creatine phosphokinase (CPK); induced the expression of hepatic genes encoding nuclear factor erythroid 2 related factor 2 (Nrf2), interferon γ (IFN-γ) and interleukin-1ß (IL-1ß). 2) Regarding metabolism response, hypoxia increased plasma levels of globulin (GLOB), glucose (GLU), triglyceride (TG) and lactate dehydrogenase (LDH); upregulated the hepatic gene expression of phosphoenolpyruvate carboxykinase, (PEPCK), pyruvate dehydrogenase kinase (PDK1), acetyl-CoA carboxylase (ACC) and acetyl-CoA oxidase (ACO); downregulated the hepatic gene expression of carnitine palmitoyl transferase 1 (CPT1); and unchanged the expression of hepatic genes in glycolysis and autophagy. 3) In response to hypoxia-inducible factors (HIFs), the hepatic HIF-2α gene was activated in the hypoxia group, but HIF-1α gene expression remained unchanged. Thus, during acute hypoxic stress, triploid rainbow trout were in a defensive state, with an enhanced immune response and altered antioxidant status. Additionally, the hepatic mitochondrial oxidation of glucose- and lipid-derived carbon in trout was suppressed, and hepatic gluconeogenesis and lipid synthesis were activated, which might be regulated by the HIF-2α pathway.