Cod vs salmon
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Cod vs Salmon: A Comparative Analysis
Gut Microbiota Modulation by Cod and Salmon Intake
High intake of both cod and salmon has been shown to modulate the gut microbiota profile in overweight adults. A study found that participants consuming 750g/week of either fish exhibited distinct changes in their gut microbiota compared to a control group that avoided fish intake. Specifically, the salmon group showed lower counts of bacteria in the Bacteroidetes phylum and the Clostridiales order of the Firmicutes phylum, while having higher counts of bacteria in the Selenomonadales order of the Firmicutes phylum. The cod group displayed a similar but less pronounced effect.
Serum Neopterin and Antioxidant Levels
Cod and salmon intake also have different impacts on serum neopterin concentrations, a marker of cellular immune activation. High intake of cod significantly reduced serum total neopterin concentration, whereas salmon intake did not show a similar effect. Additionally, cod intake increased serum selenium levels, an essential element for antioxidant enzyme activity, while salmon did not have this effect.
Liquid-Holding Capacity and Post-Mortem Changes
The liquid-holding capacity of fish muscle is crucial for texture and quality. Salmon muscle has been found to possess better liquid-holding properties compared to cod. This is attributed to species-specific structural features and better stability of muscle proteins in salmon. Cod, especially fed cod, undergoes more severe structural alterations post-mortem, leading to greater liquid loss.
Biomarkers of Fish Intake
Biomarkers such as trimethylamine N-oxide (TMAO), creatine, and 1-methylhistidine (1-MeHis) can indicate compliance in dietary studies involving fish intake. Cod intake significantly increases serum and urine concentrations of TMAO, creatine, and 1-MeHis, whereas salmon intake primarily increases 1-MeHis and creatine levels. These biomarkers can effectively differentiate between cod and salmon intake.
Salting and Preservation
Salting is a traditional method for preserving fish, and the mass transfer kinetics during brine salting differ between cod and salmon. The fat content in salmon acts as a barrier to water and NaCl transport, resulting in different salting behaviors. When adjusted for fat content, the kinetic parameters for salmon become similar to those of cod.
Mercury Levels in Farmed vs. Wild Fish
Mercury concentrations vary between farmed and wild fish. Farmed salmon have significantly lower mercury levels compared to wild salmon, and both have lower levels than farmed cod. However, none of the mercury concentrations in farmed or wild salmon exceed federal consumption guidelines, making them safer options in terms of mercury exposure.
Nutrient Utilization and Growth
Cod and salmon differ in their nutrient utilization and growth efficiency. Cod retains more digested nitrogen compared to salmon, but salmon shows higher retention of digested energy. Both species exhibit efficient nutrient utilization, although cod's feed efficiency ratio is better than that of salmon.
Gelatine Extraction and Properties
Gelatine extracted from cod and salmon skins shows different properties. Cod gelatine has a higher yield and gel strength compared to salmon gelatine. However, salmon gelatine has a higher gelling temperature and initial gel strength. These differences are important for their potential applications in food products.
Protein Isolate Functional Properties
Protein isolates from cod and salmon by-products have high nutritional value and functional properties. Cod protein isolate shows better emulsion and foaming capacity compared to salmon, which is beneficial for food applications. However, sensory attributes such as lipid oxidation need to be considered, as cod protein scores lower in these aspects.
Textural Changes During Storage
During iced storage, the textural properties of cod and salmon fillets change differently. Salmon fillets become softer and less elastic compared to cod. The activity of collagenolytic enzymes, which affect texture, is higher in cod than in salmon throughout the storage period.
Conclusion
Cod and salmon offer distinct benefits and challenges in terms of gut microbiota modulation, serum biomarkers, liquid-holding capacity, nutrient utilization, and textural properties. Understanding these differences can help in making informed dietary choices and optimizing the use of these fish in various food applications.
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