Protein concentrates hydrolysates

Hermansson et al. (36) used pepsin and papain to solubilize rapeseed protein concentrate. Papain had a lower solubilizing effect than did pepsin. However, the fact that pepsin has an optimum pH for activity at about 1.6, far below the pH range of most foods, made it possible to study the effects of controlled hydrolysis. At pH 7.0, all hydrolysates were more soluble than the original rapeseed protein concentrate. 

Pepsin and papain hydrolysates of rapeseed protein concentrate increased foam volumes and decreased drainage compared to the untreated control (36). Foaming properties could be further enhanced by adding a stabilizer such as carboxymethylcellulose. 

Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Lactose and lactose derivatives Fresh cheeses and cheese-based products Functional applications, e.g. coffee creamers, meat extenders nutritional applications Whey powders, demineralized whey powders, whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Various fermented milk products, e.g. yoghurt, buttermilk, acidophilus milk, bioyoghurt... 

Enzymatic gelation of partially heat-denatured whey proteins by trypsin, papain, pronase, pepsin, and a preparation of Streptomyces griseus has been studied (Sato et al., 1995). Only peptic hydrolysate did not form a gel. The strength of the gel depended on the enzyme used and increased with increasing DH. Hydrolysis of whey protein concentrate with a glutamic acid specific protease from Bacillus licheniformis at pH 8 and 8% protein concentration has been shown to produce plastein aggregates (Budtz and Nielsen, 1992). The viscosity of the solution increased dramatically during hydrolysis and reached a maximum at 6% DH. Incubation of sodium caseinate with pepsin or papain resulted in a 55-77% reduction in the apparent viscosity (Hooker et al., 1982). 

D Alvise, N., Lesueur-Lambert, C., Fertin, B., Dhulster, P., and Guillochon, D. 2000. Hydrolysis and large scale ultrafiltration study of alfalfa protein concentrate enzymatic hydrolysate. Enzyme Microb. Technol. 27, 286-294. 

Preparation of cheeses and soy derivatives Solubilization of protein concentrates Production of protein hydrolysates Gluten modification in bread doughs Chillproofing of beer Plastein formation Tenderization of meats Quality determination of proteins... 

Most amino acids are readily available to chemists. If proteins are hydrolysed with, say, concentrated HC1, they are broken down into their amino acids. This mixture is tricky to separate, but the acidic ones are easy to extract with base while the aromatic ones crystallize out easily. 

Table 10-10 Protein Hydrolysate Products Produced from Casein and Whey Protein Concentrate (WPC)...

Aluko and Monu (2003) studied the use of enzymatic hydrolysis to improve some functional properties of QPs. They found that protein solubility of the hydrolysate was over 80%, a value higher than that of protein concentrate. The protein concentrate (obtained by an alkaline method) had minimum solubility at pH 4—6 ( 5%) and maximum solubility at alkaline pH (70%) Aluko and Monu (2003) also measured foam expansion and stability (expressed as %). Protein concentrate showed the smaller foam expansion (<20%), but protein hydrolysate presented values over 160%. Foam stability was better with protein concentrate. 

The emulsifying activity index and stability were also measured by Aluko and Monu (2003), who found high stability for the hydrolysate, but a small activity index. The hydrolyzed proteins are not as adequate for food emulsions as the protein concentrate. 

An industrial process has been developed for production of isoelectric soluble soy protein hydrolysate with no bitterness and a bland taste (13). The raw material may be acid washed soy white flakes, soy protein concentrate or soy protein isolate. The raw material is hydrolyzed by the alkaline protease ALCALASE to a specified degree of hydrolysis using the pH-stat at pH 8.0... 

A few experiments have been carried out in the laboratory scale with a one litre hydrolysis vessel, connected to a small impeller pump and a Sartorius laboratory module fitted with DDS GR6-P membranes (0.2 m ). However, the flow resistance in this module was too large, and it was soon concluded that a resonably constant flux was unattainable. Despite these difficulties, the qualitative behaviour of the reactor variables could be predicted from the model and verified experimentally. For example, with decreasing flux DH increased, but the rate of the base consumption decreased, while the protein concentration in the permeate remained quite stable as predicted. The hydrolysate was evaluated and found comparable in quality to ISSPH produced in the batch process. These results have encouraged us to continue the work in pilot plant with the DDS-35 module, where we can expect considerably more favourable flow conditions. The first experiments carried out so far indicate that a reasonable flux in the order of 50 1/m /h (approx. 1 1/m /min.) can be attained but that foaming problems necessitate the construction of pressurized air free reactor. Future studies will therefore be needed to produce a complete experimental verification of the derived model. 

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. 

Roozen and Pilnik (7) studied the preparation of acid-soluble enzymic hydrolysates of a soy protein concentrate suitable for enrichment of orange juice. Seventeen commercial proteolytic enzyme preparations were used on denatured and native 4% w/v aqueous solutions of soy protein concentrate. The degree of hydrolysis (estimated from trichloro-... 

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). 

Partial proteolysis of soybean proteins with endopeptidases has been used to remove flavor compounds and related fatty materials from soybean curd and defatted soybean flour (21). Certain soybean protein concentrates possess an undesirable beany and oxidized flavor. Treatment of soybean curd and defatted soybean flour with endopeptidases such as aspergillopeptidase A released off-flavor compounds such as 1-hexanal and 1-hexanol which could be removed from the hydrolysate by solvent extraction. The enzymically digested products had less odor, taste, and color than the starting material and were more stable to oxidative deterioration. 

There have been a limited number of studies on the effects of enzymic modification of protein concentrates on functional properties other than solubility. Studies on functional properties, as modified by enzymic treatments, emphasize foam formation and emulsifying characteristics of the hydrolysates. Treatment of chicken egg albumen alters the functional properties of the egg proteins in terms of foam volume and stability and the behavior of the proteins in angel food cakes (25). Various proteolytic enzymes were used to degrade the egg albumen partially. However, proteolytic enzyme inhibitors indigenous to the egg proteins repressed hydrolysis of the egg proteins compared with casein. 

In spite of the above limitations and the relatively small number of Studies involved, it is evident that the functionality of proteins as protein concentrates can be modified substantially by enzymes. Solubilities of proteins can be altered (generally increased) by hydrolytic reactions viscosities and gelation of protein solutions can be decreased dramatically by limited proteolysis the volume of foams of whipped hydrolysates is generally greater than that of the parent protein, but the foam stability is usually less. Emulsification properties of hydrolysates are affected in different ways depending on the protein. From the very limited number of studies on partial hydrolysis of food proteins it appears that water binding is increased as a result of proteolysis. ... 

Functional properties of some enzymatically modified and EPM-treated products of milk proteins [136] were determined as follows. An enzymatically prehydrolyzed commercial milk protein concentrate (SR) without further hydrolysis, and casein hydrolyzed by alcalase, a-chymotrypsin, and papain, respectively, were used as substrates in the EPM reaction. The concentration of the hydrolysates was 20% w/ v in the EPM reactions. A methionine methyl ester hydrochloride/ substrate ratio of 1 5 was used for incorporating this amino acid. After incubation, the products with methionine incorporation were simultaneously dialyzed for 2 days through a cellophane membrane against distilled water. The nondialyzable fractions and the EPM products without amino acid enrichment were freeze-dried. Covalent methionine incorporation in the EPM products with amino acid enrichment was verified by exopeptidase hydrolysis of the protein chains. The functional properties of the different EPM products are summarized in Table 1. An important functional property of proteins and/or peptide mixtures is their emulsifying behavior. This is highly influenced by the molecular structure, the position and ratio of hydrophobic-hydrophilic amino acids. Emulsion activity was found to be low (34.0) for casein, and the values determined for enzyme hydrolyzed and modified products were in general even lower. The papain hydrolysate, sample H3, showed here a different behavior as well this was the one of the sample series that had the highest EAI value (43.0). The emulsion stability of the enzymatically modified products displayed tendencies quite opposite to the values of emul-... 

Figure 6 Potential allergenic activity of different soy protein products. Potential allergenic activity of competitive soy proteins as percentage of maximal binding activity at the concentrations of competitive antigens of 102 /Ltg/mL. (1) Raw soybean, dehulled (2) heat-treated extrusion soy protein concentrate (3) soy protein isolate (4) proteolytic hydrolysate of soy protein isolate (5) EPM (1) product of soybean isolate without amino acid enrichment (6) EPM (2) product of soybean isolate with methionine enrichment (7) EPM (3) product of soybean isolate.

Acid coagulation Cheese whey protein concentrates, whey protein isolates, individual whey proteins, whey protein hydrolysates, neutraceuticals Lactose and lactose derivatives Fresh cheeses and cheese-based products... 

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