July 8, 2020
Nor-Feed's dry grape extract receives EC authorization
The Dry Grape Extract (Nor-Grape® 80) developed and commercialised by Nor-Feed, is now the first botanical sensory additive authorised for animal nutrition by the European Commission.
Nor-Grape 80 is increasingly used in aquaculture, providing various benefits such as improvement of zootechnical performance and better quality of aquaculture products.
1- The benefits of active antioxidants present in grape extract
The Dry Grape Extract is rich and standardised in total polyphenols, procyanidins and anthocyanins, active molecules well known for their strong antioxidant potential. It is used worldwide to reduce oxidative stress which is the disbalance between antioxidants and free radicals. This phenomenon can be caused by many factors (water temperature, water quality, level of dissolved oxygen, stress…) and may have dramatic effects on the fish growth, health and the quality of its products. Its potential applications in aquaculture are numerous. In particular, grape polyphenols have been shown to have a protective effect on fish meat when added directly on it after slaughter (Pazos et al. 2005, Gai et al. 2015, Magsood et al. 2013).
2- A more efficient antioxidant defense and a better meat quality on fish
A trial was set up in an experimental station in the south of France (CREUFOP, Montpellier) on sea bass (Dicentrarchuslabrax) to establish if such a protective effect would be observed on the meat when orally supplementing the fish (drip loss during storage and cooking, or oxidation state) and whether it would at the same time benefit the fish by improving its antioxidant defences.
Sea bass of 120 to 170-gram were divided in two homogeneous groups: a control group ("CTL"), fed a classic grower extruded feed (43% proteins, 20% fats), and a Dry Grape Extract group ("NG"), fed the same feed supplemented with 40ppm of Nor-Grape80. The fish were fed for 66 days, until slaughter.
- Total glutathione peroxidase was measured on blood samples at slaughter.
- 16 filets were weighed before and after being cooked for 12 min at 80°C to evaluate drip loss.
3- Enhancement of the antioxidant defences and improvement of the meat quality
The measure of total glutathione peroxidase on blood samples evidenced a significantly higher level (p<0,05) in sea bass supplemented with the Dry Grape Extract (Figure 1), demonstrating a beneficial effect of the grape extract on the stimulation of endogenous antioxidant defences.
Figure 1: Blood Glutathione peroxidase levels of sea bass
Furthermore, the improvement of the oxidative stability of the filets in the NG group resulted in a significant reduction of drip loss during cooking (-25%, p<0,01, Figure 2).
Figure 2: Drip loss of sea bass filets during the cooking process®
4- Conclusion and other applications demonstrated
The supplementation of the diet with 40ppm of Nor-Grape 80 for 2 months before slaughter therefore increased the fish antioxidant defences. This resulted in an improved meat quality by improving the oxidative stability of the meat leading to a reduction of drip loss during the cooking process.
Other studies on the use of Dry Grape Extract in aquaculture have demonstrated similar improvements on the products' quality (meat, eggs) as well as growth performances improvement in several species (fish and crustaceans). This demonstrates the need for a combination of synergistic water- and fat-soluble antioxidants in aquaculture to better protect fish against oxidative stress.
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