Fish-protein concentrate

The mmen is not functional at birth and milk is shunted to the abomasum. One to two weeks after birth, the neonate consumes soHd food if offered. A calf or lamb that is nursing tends to nibble the mother s feed. An alternative method of raising the neonate is to remove it from its mother at a very young age, <1 week. A common example of an early weaning situation is the dairy calf that is removed from the cow soon after birth so that the cow s milk supply might be devoted entirely to production. In this instance, the neonate requires complete dietary supplementation with milk replacer. Sources of milk replacer protein have traditionally included milk protein but may also include soybean proteins, fish protein concentrates, field bean proteins, pea protein concentrates, and yeast protein (4). Information on the digestibiUty of some of these protein sources is available (4). 

In general, nonconventional protein foods must be competitive with conventional plant and animal protein sources on the bases of cost delivered to the consumer, nutritional value to humans or animals, functional value in foods, sensory quality, and social and cultural acceptability. Also, requirements of regulatory agencies in different countries for freedom from toxins or toxic residues in single-cell protein products, toxic glycosides in leaf protein products, pathogenic microorganisms, heavy metals and toxins in fish protein concentrates, or inhibitory or toxic peptide components in synthetic peptides must be met before new nonconventional food or feed protein products can be marketed. 

Figure 3. Spectra of ethylisocyanide-ferrocytochrome P-450 complexes, rainbow trout. Conditions were as in Figure 2, except rainbow trout hepatic microsomes were used. (A) Microsomes from rainbow trout treated with (j-naphthoflavone (100 mg/kg sacrificed 4 days later). Protein concentration, 1.4 mg/mL total P-450 concentration, 0.48 fi.M. (B) Microsomes from control fish. Protein concentration, 0.93 mg/mL, total P-450 concentration, 0.22 /iM.

Solubilization of fish protein concentrates, recover oil or meat scraps from inedible parts Waste product conversion to feed, digestive aid... 

Similarly, lysine has been incorporated into gluten hydrolyzate and lysine, threonine and tryptophan have been individually incorporated into zein hydrolyzates. Lysine, methionine, and tryptophan were incorporated simultaneously into hydrolyzates of protein from photosynthetic origin. A very interesting application of this procedure involved the preparation of low-phenylalanine plasteins from a combination of fish protein concentrate and soy protein isolate by a partial hydrolysis with pepsin then pronase to liberate mainly phenylalamine, tyrosine, and tryptophan, which were then removed on sephadex G-15. Desired amounts of tyrosine and tryptophan were added back in the form of ethyl esters and a plastein suitable for feeding to infants afflicted with phenylketonuria was produced. 

Several proteolytic enzymes have been shown to enhance the solubility of fish protein concentrate (38). Product inhibition and self destruction of enzymes occurred, so that rates of hydrolysis decreased with time. 

The elimination or inactivation of enzymes used to treat proteins is a critical problem once the desired modification in functionality is achieved. In many instances, product inhibition or self destruction does not occur as noted above for fish protein concentrate. As stated by Puski (20), if heat inactivation is used, the proteins may be denatureT"and revert to insoluble forms. Washing out the enzyme at its isoelectric point would also remove a portion of the protein which is solubilized by the enzyme. Inactivation of enzymes by chemical means may also cause significant changes in the protein. Thus, while desired functional modifications of food ingredients may be obtained through enzyme treatment, the problem of latent enzyme activity in food formulations must be addressed. 

Considerable effort has been devoted to the improvement of functional properties of fish protein concentrate. Spinelli et al. (44) conducted a study to determine the feasibility of modifying myofibrillar fish proteins by partially hydrolyzing them... 

Fish caught by human beings can be turned into fish meal, and the fish meal can be used as feed to produce meat for human beings or used directly as food. The direct use of fish meal significantly increases the efficiency of the food chain. However, fish-protein concentrate, primarily for aesthetic reasons, is used as a supplementary protein food. As such, it competes with soy and other oilseed proteins. 

A plant at Canso, Nova. Scotia, makes fish-protein concentrate (FPC). It takes 6.6 kg of whole fish to make 1 kg of FPC, and therein is the problem—to make money, the plant must operate most of the year. One of the operating problems is the drying of the FPC. It dries in the fluidized dryer at a rate approximately proportional to its moisture content. If a given batch of FPV loses one-half of its initial moisture in the first 15 min, how long will it take to remove 90% of the water in the batch of FPC ... 

FPC. (1) Abbreviation for fish protein concentrate. (2) Abbreviation for Federal Power Commission. 

Much research has been devoted to working out optimum parameters of producing different protein concentrates from fish and krill (Lanier, 1994). While the products have high nutritional value and many are tasteless and odorless, some, manufactured in denaturing conditions, lack the desired functional properties. A good example is the fish protein concentrate obtained by hot azeotropic isopropanol extraction. On the other hand, a concentrate of myofibrillar proteins known as surimi, produced mainly from fish and to a lesser extent from poultry and meat, is highly functional. 

Figure 3. Modulus of rigidity during heating of fish protein concentrate as a function of temperature. Note minima at 28° and 45°C. (From Wu et al., 1985a).

Two potential pathways of actinide transfer from marine environments to human populations may cause increased intake and concommitant radiological impact. These are the consumption by humans of seaweed and fish protein concentrate. For restricted human populations, seaweed in the form of laverbread (49, 60), for example, can serve as a basic component of the diet. Seaweed has been shown to concentrate Pu by a factor of 21,000 times its surrounding medium (57). Thus, where it may be a significant dietary item, seaweed is a potentially Important vector for transfer of environmental Pu to human populations. The second potential source of Pu and other actinides to humans is from consumption of fish protein concentrate prepared by processing whole fish. Since concentrations of Pu in liver and GI tract may be 20 and 1000 times greater respectively than muscle, this food source may serve as a significant vector for Pu to human populations (16). 

Fish protein concentrate Trash fish Fish oil Buianol ... 

Grant (58), single-cell protein concentrates by McElwain et al. (59), and fish protein by Groninger and Miller (60) and Chen et al. (61). Succinylated fish myofibrillar protein had rapid rehydration and good dispersion characteristics at neutral pH (60). Succinylation of fish protein concentrate improved its emulsifying capacity and emulsion stability (61). 

The functional properties of food proteins is a subject of considerable interest and importance. For example, in the last two decades much effort has gone into the development of various nonconventional sources of protein. The vast majority of this effort, however, has been concentrated on various aspects of production of economical protein resources and not on the actual utilization of these resources. The result is that many nonconventional protein resources, while they can now be produced fairly easily, can in many cases be produced only in a form lacking desirable functional properties. The point is simply that a protein, even though it may have excellent amino acid balance and all other prerequisites for a nutritionally superior protein, will have no impact on human nutrition unless it has the functional properties necessary for its incorporation into food systems. A specific example of this problem is the case of fish protein concentrate, the utilization of which is severely restricted by its very limited solubility in water. There are, of course, many other examples, but for present purposes it is sufficient to emphasize that there is a real need for the development of chemical, physical, or enzymatic methods that increase the usefulness of proteins in food systems. 

Figure 3. Relative curd strength (Brookfield viscometer readings) of gels prepared from 3% solutions of either fish protein concentrate extracted at high pH, succinylated FPC at various pH values, or raw skim milk. (A) Succinylated protein plus corn oil. (B) Succinylated protein. (C) Succinylated protein plus Ca2+. (D) High pH FPC extract plus corn oil. (E) High pH FPC extract. (F) Raw skim milk curd prepared with rennet. (75)...

Fish Solubilization of fish protein concentrate. Recovery of oil and proteins from inedible parts. 

Of the many functions of proteolytic enzymes listed in Table I, the most extensively used commercially are chillproofing of beer, production of cheese, tenderization of meats, and production of protein hydrolysates. Two of the most active research areas at the moment include use of proteolytic enzymes for plastein formation (see Proteolytic-Induced Aggregation of Proteins, p. 99) and the solubilization of fish protein concentrate. 

Solubilization of Protein. Fish protein concentrate has high nutritional quality as determined both from its essential amino acid composition and from animal feeding experiments. Unfortunately, the concentrate is quite insoluble in water because of its denaturation by the solvent extraction method used in processing thus it contributes no functional properties to a food and must be used in bakery products primarily. A potentially useful method of solubilizing the protein is by proteolysis (9-12). As is the case with protein hydrolysates of casein and soybean protein, bitter peptides are formed during the hydrolysis. Papain and ficin produce more of these bitter peptides than does Pronase, for example (12). Pronase was found to produce a more brothy taste (13). A possible method of removing the bitter peptides is to convert the concentrated protein hydrolysate to plastein by further proteolytic enzyme action (14) to remove the bitter peptides. 

Fish protein concentrate, although a good protein source nutritionally, is very insoluble this limits its use in foods. The protein can be solubilized by proteolytic enzymes, but the hydrolysate is bitter (12). It would be useful to investigate the plastein reaction for removal of the bitter taste as well as for changing the solubility properties of the digest (14). The plastein reaction is described more fully in Chapter 6 of this monograph. 

Modification of fish proteins by proteolytic enzymes to increase their solubilities illustrates a variety of techniques and approaches. Basically, three general enzymic methods have been used to prepare fish proteins or hydrolysates with altered solubilities and other functionalities. These methods include (a) the enzymic solubilization of fish protein concentrate prepared by hot solvent extraction of fish, (b) the enzymic modification of myofibrillar proteins extracted from fish with 0.6M NaCl, and (c) the proteolysis of whole fish to prepare biological fish protein concentrate (FPC). 

One of the current approaches to the improvement of the functional properties of proteins is enzymatic hydrolysis [148], The emulsifying ability of soy protein isolate can be increased by treatment with neutral fungal protease however, this treatment decreases emulsion stability [163], Partial hydrolysis of fish protein concentrate improves both emulsification and stability [164]. On the other hand, treatment of whey protein concentrate with pepsin, pronase, and pro-lase leads to a decrease in emulsification ability, suggesting that there... 

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