Background Art

A food supplement of this invention has an advantageous and fundamental applicaticn in the f__τπ___aticn of protein αr high-protein food produces in which the protein content is not derived from animal meat. These food products, numerous and varied according to local requirements, and/or quotas of consumption, represent a new line in vegetarian dietetics.

The following amiπo-acids are a necessary part of che human diet (essential amino-acids) : isoleuciαe, leucine, methionine, phenylalanine, chreoαine, crypcophan, valine and lysine.

Iα the diet of man and of other animals, proteins are in practice che sole source of essential amino-acids, and chis is che reason for the well-known and general interest in protein pro¬ duction for human nutrition.

Ic_ is likewise known chat the autotrophic icro-orgaαisms and, among these, che algae, ^' are poceαcially che main sources of procein of noα-conveαcional origin.

With regard co che use of algae in hu aα foodscuffs, onLy racher unsatis actory resulcs have been obcained from acce pcs co add che direccly, ____re appropriate in exures -τ._n czisr food prccu s. fcr exampLe flour. Eveα wich Limited daiLy doses, there have been drawbacks, for exa pLe oedema of che face and hands, pecechiaL haemorrhages, cyanosis of che nails, general incescmaL probLe s, and chese have rapidly discouraged cheir use. Some of chese dr___£__ks had a Less nσticeaόle effect when che aLgae were subjecced co prior physico-chemical creacmencs to remove or reduce cheir colour.

In addition to che above entioned drawbacks of direct administration, there is also the problem of the casce which cannot easily be neglected. For the majority of people, its intensity and unpleasantness has been a basic reason for rejecting che use of these algae in foodscuffs. This problem could be Largely overcome, according to a technical suggestion which appeared in Chemical Abstract 91,90329, by a treatment which

removes the bitter taste: this consists mainly in boiling or cooking the fresh algae for a period of 10-15 minutes.

However, the drawback which limits the direct use of the algae in human foodstuffs is the high concentration of nucleic acids, which are known to cause dangerous levels of uric acid in the blood. It is further known that, of all the algae used for alimentary purposes, alga Spirulina is the most important," since it contains all of ^" the essential amino-acids mentioned above and since it is the one which has been most widely tested and utilised.

A great deal has been reported, in fact, on its use by the people who live on the banks of Lake Chad in Africa, where alga Spirulina has been an ingredient of their daily diet for several hundred years. This alga was also used by the Aztecs in ancient Mexico.' However, this information remains anecdotal in character, since from a strictly technical point of view, there is little information available on the quantities of alga Spirulina consumed by these people. The cnly certain fact is that this alga, which is especially rich in the basic components of human nutrition, can be administered up to a maximum of 26 g per day as a dry substance, without there being any apparent side-effects. Although alga Spirulina has been produced both in the laboratory as well as in _^ small pilot plants in France and Mexico, published results indicate that its acceptability to man is very limited.

Disclosure of the Invention

Precisely because of the high and valuable- protein content of alga Spirulina, the problem underlying the present invention is to provide a process for obtaining a .protein-vitamin food supplement which can be used in the formulation of protein or high-protein food products, or actually added as such, overcoming the abovementioned drawbacks of the prior art.

According to the present invention, this problem is resolved by a process which consists of the successive stages of:

- boiling and cooking a predetermined quantity of alga S irulina for a period of between 10 and 15 minutes,

- proteolytic enzymatic attack of the cooked Spirulina, after cooling it to about 20-45 C,

- subsequent centrifugation so as to obtain an aqueous extract containing . most of -the water-soluble molecules present in the original alga Spirulina, and a moist residue,

- alcoholic extraction of the said residue, previously heated to about 80°C, with ethyl alcohol at 95 C,

- centrifugation so as to obtain an alcoholic extract and a residue forming a protein food supplement containing up to 83% protein, up to 11% carbohydrate and up to 3% fat.

Alga Spirulina subjected to the process of this invention can be fresh or in powder form.

In the first case, having a water content of up to 85%, the alga Spirulina is cooked as such. In the second case, it will be added with an appropriate quantity of water.

The 10-15 minute cooking (boiling) stage is sufficient to change the taste of the alga Spirulina,owing to substantial steam distillation of some of the substances responsible for .the bitter after-taste, which is consequently completely absent from the protein food supplement obtained using the process of this invention.

During the same abovementioned cooking stage , coagulation of the larger proteins contained in the alga Spirulina takes place; this coagulation facilitates the predigestive task of proteolytic enzymatic attack. This hydrolytic attack has several purposes: it liberates extractable elements, it reduces the molecular complexity of certain proteins with the consequent formation of free amino-acids, and it confers an acceptable, if not pleasant, taste to the protein food supplement obtained. The two-fold attack, hydrother al and enzymatic, also ensures the breakdown of the cell wall, which, fortunately, is mucopolysaccharide and not cellulose in character.

The aqueous extract from the first stage of centrifugation, carried out after cooking the alga Spirulina, contains all the water-soluble molecules and especially the mineral salts which occur in notoriously excessive amounts in the original alga. In accordance with this invention, this extract is fractionated in order to recover the vitamins, water-soluble proteins and pol saccharides, which are eventually recycled into the protein food supplement so as to restore its original biological value.

S.till in accordance with this invention, the alcoholic extract containing fats, vitamins, styrols, cholesterol, oligopeptides, beta-carotene, chlorophyll, blue pigment and other small molecules present in the original alga Spirulina is also fractionated in order to recover valuable components as well as the ethyl alcohol itself which is recycled to the alcoholic extraction stage.

Advantageously and in accordance with a further characteristic feature of this invention, the protein food supplement obtained by the process outlined above is cooked with flours and/or tubers - such as wholemeal flour, whole millet, whole sorghum, whole manioca flour and yam and/or potato flour for example - either in the fresh state, or ground, and after being partially or totally dried.

Further characteristic features and aάvantagss of the process of this iπverrticn will becαne clearer from the following description of an exa _m pτ_ _{e 0} f i s implementation, givsi α_ly by way of e_-_rrple, and of several examples of formulations of European-type vegetarian food products containing the protein supplement obtained by the- atσvsnarticned prccεss.

Modes for Carrying Out the Invention

1500gm of alga Spirulina in dry powder form with a residual moisture content of 6% were loaded into a 10 litre batch reactor together with 10 litres of water.

The contents were brought to boiling, and this was maintained for 15 minutes in order to cook the algae adequately. This operation caused , on the one hand, coagulation of the larger proteins and, an the o-tiber hand, substantial steam distillation of the bitter-tasting substances originally present in the alga Spirulina.

After cooling the contents to 40 C, a mixture of proteolytic enzymes was added to the reaction vessel. In particular, the preferred enzymatic mixture included:

amylase - 400.5 units lipase - 45 units trypsin - 48,000 units chymotrypsin " - 36,000 units cellulose - 60 g

The enzymatic attack stage was allowed to last for 4 hours 15 minutes, and a suspension was obtained which was filtered under vacuum on a Buchner type filter.

The aqueous extract was sent for fractionation, from which the. mineral salts, vitamins and water-soluble proteins were obtained.

The filter-cake obtained from the abovementioned filtration was pressed and returned to the 10-litre batch reactor, together with 3 litres of good quality ethyl alcohol at 95°C. The total contents underwent reflux distillation for 1 hour 10 minutes. Subsequently, the contents were filtered whilst hot on a Buchner type filter under vacuum.

The filter-cake obtained from this latter filtration was pressed and washed once with 1000 cc of distilled water after removing the alcoholic eluate.

On analysis, the water-washed protein filter-cake had a residual humidity of 50%; analysis of the dried material indicated the following composition in terms of percentage weight: ash 2.45 protein 83.2 carbohydrate 11.0 fat 2.7 fibre 0.65

This protein filter-cake which constitutes the protein food supplement of this invention, was subdivided into five portions each of 800 g wet weight (approx. 260 g dry material). The portions were kept in a refrigerator from which samples were taken to be formulated into a protein foodstuff. Some examples of these formulations are given below.

EXAMPLE 1

A portion of protein supplement was loaded into a 10 litre batch reactor with 2 kg of wholemeal flour and 3 litres of water. The total contents were cooked for 20 minutes until the flour was gelatinised. After cooling, the mixture obtained was loaded into a double-Z type food-mixer with an effective volume of 5 litres. 8 eggs and 1 kilogram of flour were loaded into the same machine.

After obtaining a homogeneous mixture, the latter was rolled into a thin sheet and cut in the shape of tagliatelle.

The tagliatelle, cooked and seasoned in the normal way, left no after-taste in the mouth when sampled.

EXAMPLE 2

A portion of the abovementioned protein food supplement was loaed into a double-Z type food-mixer together with bread crumbs, parmesan cheese, meat extract, spices, natural meat flavourings and four eggs.

After obtaining a homogeneous mixture, the latter was subdivided to make rissoles with a diameter of about 5 cm. The rissoles were fried in plentiful oil, and left no after-taste in the mouth on sampling.

EXAMPLE 3

A portion of the protein food supplement obtained using the procedure of this invention was loaded into a double-Z type food- mixer together with sugar, eight eggs, milk and vanilla sugar.

After obtaining a homogeneous and slightly fluid mixture, the latter was poured into a cake tin, and the cake obtained , when sampled, had no after-taste reminiscent of the original alga Soirulina.

EXAMPLE 4

A further portion of the protein food supplement of this invention was cooked with flour as in Example 1 and subsequently dried under vacuum in the 10 litre batch reactor. The dry material was ground in order to obtain an instantaneous semolina with a pleasant flavour. No after-taste remained in the mouth when this food product was sampled.

EXAMPLE 5

A portion of the protein supplement of this invention was placed in a double-Z type food-mixer together with sugar, dextrin and a little milk. After obtaining a homogeneous mixture, the latter was loaded into a batch reactor under vacuum in order to 'reduce the moisture content to about 25%; this allowed subsequent rolling

and pressing out of biscuits by hand; these were dried in an oven. Crisp biscuits were obtained with the specific taste of so-called breakfast biscuits. No after-taste was left in the mouth reminiscent of the original alga Spirulina.