FEATURE
Wheat proteins
high quality proteins for aquaculture feeds by Dr Emmanuelle Apper, MSc Aurélien Feneuil, Dr Frédérique Respondek Tereos, Innovation department
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any fish feed producers now formulate low fishmeal diets. To ensure high growth performance, the use of high quality alternative protein is then required. Both Vital and Hydrolysed Wheat Gluten are high quality proteins. While they don’t exhibit the same behaviour at extrusion, they can both ensure good physical quality of pellets and high level of growth performance with high nitrogen and energy retention. Additionally, Vital and Hydrolysed Wheat Gluten may have some functional health benefits at gut level, especially by stimulating gut cell proliferation and antioxidative system without damaging gut structure.
as good water stability. Moreover, increased VWG inclusion rate in replacement of soy protein concentrate results in decreasing extruder motor load. Indeed, extrusion behaviour of 2 commercial salmon feed diets has been explored both at small scale (Application Centre, Tereos, Marckolsheim, France) and at a fish feed Technology Centre (scale-up; Nofima, Fana, Norway). One diet contained 10 percent VWG and the other 20 VWG. The two diets were extruded in the same processing conditions. This resulted in a lower motor load (i.e. torque) for 20 percent VWG compared to 10 percent VWG (36 percent versus 41 percent motor load). Higher inclusion of VWG in formulation leads to a decrease in motor load due to the lower water holding capacity of VWG compared to soy protein concentrate (Draganovic et al., 2011). The technological properties of HWG had not yet been reported in the literature while VWG and HWG have different impacts on extruder system parameters, especially on motor load and pressure at the die. Indeed, replacing 25 percent of Crude Protein (CP) of a FM diet by either VWG or HWG (Voller et al., in preparation) results in lower motor load with HWG (283 and 376 Nm with HWG and VWG respectively). The higher effect of VWG on the motor load
Intensive production of farmed fish fed with compound feeds has increased greatly, mainly due to the growth of aquaculture production, but also because it is the most efficient way of production (Olsen and Hasan, 2012). In such feeds, Fish Meal (FM) used to be the major source of proteins, especially for marine fish and salmonids (Tacon et al., 2011). Nevertheless, because of the limited amount of available FM on the market, its impact on the environment and marine diversity, and its increasing price, its utilisation has been progressively reduced in the formulation of diets. In order to achieve a low FM incorporaTable 1: Water Holding Capacity (WHC) of different vegetable proteins tion (below 10 percent in formula) without impairing growth performance, active Soy Protein Amytex® (VWG) Solpro 508® (HWG) Concentrate (Imcosoy research was conducted on plant proteins 62, Imcopa) (PP), which represent an interesting alternaWHC in g of water/g of tive to FM. In this context, many studies commercial product (Mean 1,5 +/- 0,0 0,6 +/- 0,0 3,0 +/- 0,0 were undertaken to evaluate the effects +/- Standard Deviation) of replacing FM with different types of PP, tested one by one or in mixture, on fish growth and health. Among the tested PP being considered to replace FM, Wheat Proteins (WP), including Vital can be attributed to the higher water holding capacity (table 1) of this Wheat Gluten (VWG) and Hydrolysed Wheat Gluten (HWG) are ingredient (1.5 g of water/g) compared to HWG (0.6 g of water/g). easily available PP sources that have given very promising results from The reduction in motor load can be seen as a direct process advantage allowing reduction of energy consumption during extrusion (Specific technological, nutritional and health points of view. Vital and Hydrolysed Wheat Gluten exhibit different behaviour in Mechanical Energy reduced from 65 to 50 Wh/kg). An alternative is to extrusion and both proteins allow obtaining pellets of high physical run the HWG diet at the same motor load as the VWG diet with the potential to increase the extrusion capacity. quality VWG has already been described elsewhere (Apper-Bossard et al., 2013) as an effective binder in fish feed, imparting good mechanical Wheat Proteins: Amino acid profile properties (i.e. durability and hardness) to the fish feed pellets as well Wheat proteins are a source of functional amino acids, especially 14 | INTERNATIONAL AQUAFEED | March-April 2015