Food or edible material: processes – compositions – and products – Treatment of live animal
Patent
1990-10-01
1992-10-27
Penland, R. B.
Food or edible material: processes, compositions, and products
Treatment of live animal
426 60, 426 62, 119 3, 119 4, A23K 100
Patent
active
051587882
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a new process for preparing a feed that may be used in aquaculture.
More particularly, the present invention relates to a process for preparing a feed highly digestible by molluscs and crustaceans, by their larvae and juveniles, as well as by the aquatic invertebrates that form their feed.
The development of aquaculture has led many teams to study the feeding of juveniles and of aquatic larvae.
The feed of these animals has two origins: micro-algae.
Micro-algae thus form the first link of the food chain in aquatic environment.
Those algae are, however, not easily available. They must be grown intensively and this contributes to a significant increase in the production costs of aquaculture products.
It would thus be particularly advantageous to be able to replace micro-algae by a substitute product.
Such substitute should have a high nutritive value, and it should not alter the water characteristics.
Moreover, it must satisfy the predator's requirements, i.e. it must have a size such that it can be swallowed in one piece without fracture (while not having a pulverulent consistency), it must be appetizing, and it must be digestible.
Recent research works have led to the development of micro-encapsulated feeds (such as CAR of Frippak-United Kingdom); however these products find a delicate and limited use because of their very high manufacturing cost and because a portion of the nutrients escape from the microcapsule.
Another micro-algae substitute consists of proteins of unicellular origin (Single Cell Protein, or SCP) and more particularly of yeasts.
These products are presently used in the formulation of some feeds, among others for cattle.
Although this type of SCP-based product has recently been relatively popular, its use encounters difficulties arising more particularly from its digestibility which is rather bad. Said bad digestibility implies that before incorporating them into feed for cattle, the cells must be burst, by grinding or thermal treatment.
Such treated product may be used to feed cattle, but it is incompatible with the feeding of animals in aquatic environment. Indeed, the use of such a product leads to an important water pollution which is hardly acceptable.
Experiments made by the assignee have allowed to develop products such as that disclosed in patent application EP-209510-A which uses unburst cells as feed for aquaculture.
Although that product represents an improvement, more particularly for feeding certain shrimp species, it is hardly digested by oyster larvae and by Artemia.
No research has up to now succeeded in the preparation of a suitable substitute of micro-algae, i.e. offering the nutritional advantages of micro-algae while being more easily obtainable.
Applicants now propose a process for preparing such a product. More particularly, applicants have now found a process allowing one to obtain a substitute of micro-algae from yeasts.
The process according to the invention allowing one to prepare from yeasts a highly digestible feed, more particularly digestible by molluscs, crustaceans and larvae thereof, is characterized in that the yeast cells are processed to hydrolyze at least partially the external layer of the cell wall without damaging the wall itself.
The process of the invention is particularly suitable for yeasts of the hemiascomyceteae type, the external layer of which contains disulfide bonds. More particularly, it is preferred to use Saccharomyces yeasts, preferably Saccharomyces cerevisiae.
Experiments made with reactants hydrolyzing at least partially the external layer of the cell wall, either enzymatically or chemically, have shown that yeast cells thus processed evidenced an improved digestibility although the processed cells retained their integrity.
In a particularly advantageous way, the process according to the invention allows one to obtain yeasts that are accessible to the digestive enzymes of their predators, but the wall of which remains sufficiently intact so that the cell contents does not flow into the water.
Such s
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Coutteau Peter
Lavens Patrick
Sorgeloos Patrick
Vandamme Erick
Abokhair John K.
Caddell Michael J.
Parkhurst Roger W.
Penland R. B.
Synfina-Oleofina, S.A.
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