Implementing fermentation technology for comprehensive valorisation of seafood processing by-products: A critical review on recovering valuable nutrients and enhancing utilisation.

Fermentation technology is a biorefining tool that has been used in various industrial processes to recover valuable nutrients from different side streams. One promising application of this technique is in the reclamation of nutritional components from seafood side streams. Seafood processing generates significant amounts of waste, including heads, shells, and other side streams. These side streams contain high quantities of valued nutritional components that can be extracted using fermentation technology. The fermentation technology engages the application of microorganisms to convert the side stream into valuable products like biofuels, enzymes, and animal feed. Natural polymers such as chitin and chitosan have various purposes in the food, medicinal, and agricultural industry. Another example is the fish protein hydrolysates (FPH) from seafood side streams. FPHs are protein-rich powders which could be used in animal nutrition and nutraceutical industry. The resulting hydrolysate is further filtered and dried resulting in a FPH powder. Fermentation technology holds great possibility in the recovery of valuable nutrients from seafood side streams. The process can help reduce waste and generate new value-added products from what would otherwise be considered a waste product. With further research and development, fermentation technology can become a key tool in the biorefining industry.

Dietary coriander (Coriandrum sativum L) oil improves antioxidant and anti-inflammatory activity, innate immune responses and resistance to Aeromonas hydrophila in Nile tilapia (Oreochromis niloticus).

The use of essential oils (EOs) as a natural alternative to antibiotics for disease prevention strategies is gaining much interest in recent decade. Coriander (Coriandrum sativum L.) essential oil is rich in bioactive compounds like linalool and geranyl acetate which have antioxidant, anti-inflammatory and antimicrobial activities. The present work was proposed to evaluate the inclusion levels of coriander oil in tilapia feed to enhance tilapia health and resistance to bacterial infection. Five iso-nitrogenous and iso-lipidic feeds were prepared with graded levels of coriander oil (0, 0.5, 1, 1.5 and 2%). The fish were then fed with the five experimental diet twice daily for a period of 60 days in triplicate. Haemoglobin, mean corpuscular volume, mean cell haemoglobin increased significantly in the coriander oil treated groups. The thrombocyte count was more in 2% inclusion level. The superoxide dismutase activity increased significantly in all the treated groups. The feeds with 1.5 and 2% coriander oil showed increased respiratory burst and myeloperoxidase activities while lysozyme and antiprotease activities were significantly higher in 1, 1.5 and 2% dietary treatments compared to control. The survival increased in dose dependent manner post challenge with an intraperitoneal injection of Aeromonas hydrophila at a LD50 dose of 5 × 106 cfu mL-1. The feed containing 1, 1.5 and 2% of coriander oil showed 89, 100 and 100% survival respectively compared to 39% in control diet. The expression level of IgM and IL-8 increased significantly post challenge with A. hydrophila in coriander oil fed groups. The expressions of TNFα, IL-1ß, TGFß and HSP 70 genes, however, decreased significantly in the treated groups compared to control. Histopathological examination of spleen showed large melano-macrophage centers in control and 0.5% coriander fed group with signs of necrosis and vacuolation post A. hydrophila infection, whereas 1, 1.5 and 2% treated groups showed normal architecture of spleen. From the above observations it can be concluded that coriander oil with 1% incorporation in feed improves tilapia health and resistance to bacterial infection.

ß-Defensin: An adroit saviour in teleosts.

ß-Defensin (BD) is an important first line innate defense molecule with potent antimicrobial and immunomodulatory activities in fish. The signatures of ß-defensins are the presence of a net cationic charge and three intramolecular disulfide bonds mediated by six conserved cysteines. It consists of three exons and two introns. The signal peptide is usually conserved and sequence divergence is mostly seen in mature peptide region. The diverse amino acid sequences of matured peptide contribute to a strong positive selection and broad-spectrum antimicrobial activity. It is constitutively expressed in both mucosal as well as systemic sites. Increased expression of ß-defensin was mostly reported in bacterial and viral infections in fish. Its role during parasitic and fungal infections is yet to be investigated. ß-Defensin isoforms such as BD-1, BD-2, BD-3, BD-4 and BD-5 can be witnessed even in early developmental days to different pathogenic exposure in fish. ß-Defensins possess adjuvant properties to enhance antigen-specific immunity promoting both cellular and humoral immune response. It significantly reduces/increases bacterial colonization or viral copy numbers when overexpressed/knockdown. Based on its chemotactic and activating potentials, it can contribute to both innate and adaptive immune responses. With mediated expression, it can also control inflammation. It is potent governing resistance in early developmental days as well. Its expression in pituitary and testis suggests its participation in reproduction and endocrine regulation in fish. Overall, ß-defensins is an important member of antimicrobial peptides (AMPs) with multifunctional role in general homeostasis and to pathogen exposure possessing tremendous therapeutic approaches.

Suitable ratio of dietary L-carnitine and α-ketoglutarate improves growth and health performance in Nile tilapia, Oreochromis niloticus.

L-carnitine (LC) and α-Ketoglutarate (AKG) are important growth promoters used in aquafeed. The study aimed to evaluate the incorporation of LC and AKG at different ratios in the diet of tilapia (initial weight 1.38 ± 0.03 g) in order to facilitate lipid utilization and protein synthesis. Fish were fed six isonitrogenous (~ 30 g/100 g CP) and isolipidic (~ 6 g/100 g CL) diets containing graded LC/AKG ratios of 0 (Control), 0.11, 0.42, 1.00, 2.33 and 9.00 in six treatments for 60 days. Fish fed with LC/AKG ratios 2.33 and 9.00 showed significantly (P < 0.05) higher percentage weight gain, specific growth rate and protein efficiency ratio. Feed conversion ratio in fish-fed diets with LC/AKG ratio 9.00 improved significantly (p < 0.05) than other treatments. The whole-body protein content of tilapia and digestive enzyme activity were significantly higher with higher weight gain. The body lipid content was significantly lower in the LC/AKG ratio 9.00. The liver antioxidant parameters and activity of the immune components were significantly higher in the LC/AKG ratio 9 group. The lower serum triglyceride and cholesterol level was also recorded in LC/AKG ratio 9 group. The histology of the intestine and liver showed increased villi area and decreased lipid droplets, respectively, in tilapia fed with higher LC/AKG ratios. It was concluded from the above results that the higher LC and lower AKG (LC/AKG ratio 9.00) combination attributed maximum lipid utilization and higher protein efficiency and thus better growth performance in tilapia. This was also reflected in activity of digestive enzymes, antioxidant enzymes and immune status in tilapia.

Nutritive value of guar and copra meal after fermentation with yeast Saccharomyces cerevisiae in the diet of Nile tilapia, Oreochromis niloticus.

Solid-state fermentation increases nutritional bioavailability of plant ingredients by reducing the antinutritional factors and complexity of the nutrients. The present experiment was conducted to replace fish meal (FM) with a mixture (3:1) of yeast fermented guar and copra meal (FGCM) in the diet of Nile tilapia. Five iso-nitrogenous (30% CP) and iso-lipidic (6% CL) diets were formulated replacing FM at 0% (FGCM0), 25% (FGCM 1), 50% (FGCM 2), 75% (FGCM 3), and 100% (FGCM 4) with FGCM mixture. Growth, nutrient utilisation, digestibility, digestive enzyme activity, haematological parameters, and antioxidant capacity were analysed in five treatments after a feeding trial of 75 days. Bioprocessing increased the protein and amino acid content and reduced the antinutritional factors in the guar and copra meal. The weight gain was significantly increased in 25% replaced diet. The feed conversion ratio of tilapia fed with FGCM 1 was similar to that of control and significantly lower (P < 0.05) among the treatments. The group fed with FGCM 1 exhibited significantly higher body protein and lipid content. The activity of digestive enzymes and digestibility of nutrients reduced significantly (P < 0.05) with the replacement of fishmeal beyond 25% with the FGCM mixture. Similarly, the antioxidant enzymes and blood parameters were also negatively affected when more than 25% FM was replaced with FGCM mixture. The cubic regression analysis found that 17.45% FM can be replaced with FGCM mixture for optimum weight gain in tilapia.

Influence of a diet containing plant ingredients at different levels on growth performance, carcass biochemical composition, and blood parameters in Indian major carps grown in polyculture earthen ponds.

The effect of feeding levels of plant ingredient-based diet on growth, body composition, and serological constituents of Indian major carps was determined in pond culture condition. Juveniles of Indian major carps (IMCs), Catla catla (catla, 65.87 ± 2.45 g), Labeo rohita (rohu, 64.67 ± 2.15 g), and Cirrhinus mrigala (mrigal, 39.58 ± 3.49 g) were fed 1%, 1.5%, 2%, and 2.5% of the body weight for a period of 150 days. At the end, the total production was significantly higher at 2.0% feeding level and did not change thereafter. The nutrient utilization parameters were significantly (P < 0.001) affected by the feeding level and decreased both linearly and quadratically with the higher level of feed. The SGR in terms of wet weight, dry weight, protein, and lipid increased up to 2% feeding level and plateaued thereafter. The whole body crude protein content of all the three species was the lowest at 1% feeding level and the whole body lipid content increased with increased feeding levels. Tissue protein gain and lipid gain of IMCs were the highest at 2% feeding level. Blood parameter did not indicate any disease or stress condition due to feeding treatments. Considering the growth and nutrition utilization and health of fish, it can be concluded that optimum feeding level of all plant ingredient-based feed of IMC could be 2% of the body weight in pond culture condition.