Marine ingredients are used in a range of products intended for animal and human consumption, food processing as well as alternative purposes such as cosmetics. The oceans contain approximately 80% of the earth’s biomass and the potential for nutritional, therapeutic and functional ingredients are endless.
Fishmeal and fish oil were traditionally considered to be one of the most important products derived from fish destined for non-food uses. However, recent innovations and developments on non-food fish and especially on the by-products from food fish production have led to a number of new marine products such as bio-active compounds, marine proteins and food processing aids. Seafood processing generates vast amounts of by-products such as trimmings, fins, frames, heads, shells, skin and viscera which can be converted and utilised as valuable products. The utilisation of by-products is essential because it eliminates waste by increasing efficiency through value addition.
Fishmeal and Fish oil
Fishmeal and fish oil provide feedstuffs for farmed fish and crustaceans. Supplementing aquaculture feed with fishmeal and fish oil effectively returns 5 millions tons of sustainable non-food product back into the human food chain. The addition of fishmeal to animal diets increases feed efficiency and growth through better food palatability, enhancement of nutrient uptake and absorption. No farmed fish species or their trimmings are used to produce aquaculture grade fishmeal and fish oil for the same species - there is no intra-species recycling.
Fishmeal of high quality provides a balanced amount of all essential amino acids, minerals, phospholipids and fatty acids (e.g. Docosahexaenoic acid or DHA and Eicosapentaenoic acid or EPA) for optimum development, growth and reproduction, especially of larvae and brood stock. The nutrients in fishmeal also aid in disease resistance by boosting and helping to maintain a healthy functional immune system. Addition of fishmeal and especially fish oil to aquaculture diets will ensure that the fish intended for human consumption is a source of the essential fatty acids EPA and DHA that is vital for human biological functions.
Incorporation of fishmeal into diets of aquatic animals helps to reduce pollution by providing greater nutrient digestibility. The incorporation of high-quality fishmeal into feed imparts a 'natural or wholesome' characteristic to the final product, such as that provided by wild fish.
Land Animal Nutrition and Health
Fishmeal is a natural ingredient of high nutritional value, and its use in livestock feeds can offer cost-effective production, optimising health or meat quality in the final product. Fishmeal and fish oil improve animal health and welfare ensuring high quality livestock especially in young and breeding animals.
Fishmeal provides a concentrated source of high quality protein and fat (5-12%) rich in omega-3 essential fatty acids EPA and DHA. These are deposited in the meat, eggs etc. of animals when they are used as supplements in their feeds. Incorporation of DHA and EPA found in fishmeal into the diets of fish and other farm animals is an efficient method to ensure a proper concentration of these important omega-3 fatty acids in the human diet.
Its high nutrient concentration gives it a special advantage as a supplement in high nutrient dense starter diets for poultry and for early weaned pigs. The lipids in fishmeal and fish oil are easily digested by all animals, especially fish, shrimp, poultry, pigs, and ruminants such as cows, sheep, and goats. In these animals the lipid digestibility is 90% or greater. The high digestibility of fish lipids means they can provide lots of usable energy.
Feeding fishmeal/fish oil has been shown to have the following advantages for animal health, welfare and productivity:
· Improved immunity greater disease resistance and reduced impact of disease (if contracted).
· Reduced mortality in younger animals, particularly lambs and piglets.
· Reduce severity of inflammatory diseases (EPA and DHA are anti-inflammatory).
· Provide a wide range of essential nutrients, many of which are not provided adequately from vegetable materials, thus improving the animal's nutritional status.
· Improved productivity through better growth and feed conversion, thereby reducing the cost of animal production (although feed cost in some cases may increase slightly, this is offset by the reduced unit cost of producing the animal).
Note: Fish oil can be used as an alternative source of EPA and DHA for all land animals in the absence of fishmeal.
Oily fish are the major source of omega-3 fatty acids EPA and DHA, which are now recognised worldwide as a key factor in human health. A major part of the oily fish caught is inedible. Thanks to fishmeal and fish oil production, EPA and DHA contained in these fish can be returned to the human food chain via fish oil supplements, as well as via farmed fish and even livestock.
EPA and DHA found in fish oil has been the subject of numerous studies showing they confer several health benefits which are well documented (see table below). Regulatory and expert scientific bodies generally recommend 250-500mg of EPA and DHA per day for primary prevention of chronic diseases although according to a study by Mozaffarian (2008) this amount is thought to be the minimum daily intake to ensure reducing the risk of fatal cardiac events.
Table 1 lists a number of health benefits that are attributed to the regular consumption of EPA and DHA along with a grading depending on the level of scientific support.
Source: Adapted from ‘What is so healthy about Seafood?’ Australian Government, Fisheries Research and Development Corporation
EPA and DHA are especially important for pregnant women because these essential fatty acids are key to foetal brain development and could help with the prevention and treatment of postpartum depression. It has also been shown to be beneficial for development of babies/infants - especially for the nervous system including brain and eyes.
Improved harvesting technology and innovation in the products derived from krill has led to significant growth in the market for krill products. The range of products derived from krill has increased with the key products focusing on pharmaceuticals, health foods and aquaculture.
Krill oil is an excellent source of EPA and DHA as well as astaxanthin and unlike most other fish oils, the major part of EPA and DHA in krill oil occurs naturally in phospholipid and not in triglyceride form. There are indications that compared to the delivery of EPA and DHA in the triglyceride form, the delivery of EPA and DHA in the phospholipid form results in higher tissue levels of EPA and DHA. Krill oil is characterized by a higher amount of EPA compared to DHA, with a ratio of 2 to 1.
Krill meal can be used as a substitute of regular ﬁsh meals in diets of various farmed species but is generally used as a high-value additive to aquaculture feeds rather than the primary ingredient.
The frames and cut-offs of fish processing contain considerable amounts of protein that can be hydrolysed to obtain highly nutritional protein hydrolysates, fish silage and biologically active peptides.
· Fish protein hydrolysates are the breakdown product of fish proteins into smaller peptides of generally between 2-20 amino acids by addition of enzymes such as papain and can be in liquid or powder form. Low end uses are as fertilizers or animal feed however research into advanced uses such as functional foods and nutraceuticals are increasing.
· Fish silage is a liquid product made from whole fish or parts of fish that are liquefied by the action of enzymes in the fish in the presence of an added acid. The enzymes break down fish proteins into smaller soluble units, and the acid helps to speed up their activity while preventing bacterial spoilage.
· Bio-active peptides are isolated from fish muscle protein after enzymatic hydrolysis. These fish-derived bioactive peptides exhibit unique structural properties, amino acid composition and sequences that have a number of potential uses under investigation such as antioxidants, antihypertensive, immunomodulatory or as antimicrobial peptides. The characteristics of the purified peptides imply that they have potential for the prevention and treatment of cancer, and that they might also be useful as molecular models in anticancer drug research.
Fish skin collagen and gelatin
Underutilised fish skin waste is a good source to isolate collagen and gelatin that can be used in food, cosmetics and biomedical industries. Collagen and gelatin are important forms of protein with unique properties and uses. Collagen is a long, fibrous structural protein with a wide range of applications from food to medical. For example, it is widely used as casings for sausages and in the medical industry for cosmetic surgery and burns surgery. Collagen is also used for unusual purposes such as in the manufacture of musical strings.
Gelatin is derived from collagen by irreversible hydrolysis and is classified as a foodstuff. Apart from its uses as a gelling agent gelatin also has biological activities as antioxidants and antihypertensive agents.
Fish bone is also a good source of collagen and gelatin but it is also an excellent source of calcium and other minerals such as phosphorus that can be used in food, feed or as a supplement. Calcium phosphates such as hydroxyapatite present in fish bone have been used for rapid bone repair after major trauma or surgery.
The internal organs of fish from processing plants often go to waste but are in fact an excellent source of enzymes. The specific characteristics of fish internal organ enzymes ensure that these fish by-products are a rich source of specialised enzymes. A range of proteolytic fish enzymes are extracted which include pepsin, trypsin, chymotrypsin and collagenases as well as lipase enzymes.
The shells of shrimps, prawns and crabs are an important category of by-products generated by marine bioprocessing plants while it is envisaged that waste from Atlantic krill will grow with the increasing popularity of krill oil. The efficient utilisation of the shells is necessary due to the volumes being generated because of increased processing as well as the slow natural degradation rate of shells.
Chitin is an important structural component of these shell wastes and is a biologically active polysaccharide that has many applications. The derivative of chitin, chitosan, has also demonstrated a number of important structural and functional properties that is desirable in a wide range of applications in the food and nutrition, biomedicine, biotechnology, agriculture and environmental protection industries. Chitin and chitosan can be further converted to oligomers that demonstrate further improved functional properties.