Enzymatic hydrolyses, production

Setlow et al.83 have studied the photolysis of poly dl poly dC (polydeoxyinosinic acid polydeoxycytidylic acid, see Glossary) and poly dA dT. The photochemical changes were estimated by following absorbance changes, by chromatographic separation of acid hydrolysates, and by chromatographic separation of products from enzymatic hydrolysates. 

FIGURE 4.1 Schematic diagram of the three-step recycling membrane reactor for production and separation of enzymatic hydrolysates. PI, pressure indicator FI, flow indicator pHIC, pH indicator controller FSEH, first hydrolysates SSEH, second hydrolysates TSEH, third hydrolysate. 

The chromatogram of free BA standard mixture is reported in Fig. 5.4.7. The Br-AMN degradation products are eluted at lower retention times than derivatised BA, close to the solvent front, so they do not impair BA separation. Free BA fraction also encloses taurine conjugates, previously enzymatically hydrolysed. The separation of glycine conjugated BA is illustrated in Fig. 5.4.8. In both chromatograms, the peaks of BA naphthacyl esters are fully resolved and separated from the reagent peaks. 

Protein hydrolysates are usually produced by limited enzymatic hydrolysis of protein molecules in foodstuff, yielding polypeptides that are smaller in molecular mass. Protein hydrolysis has several aims. The most common is to make the protein moiety of afoodstuff soluble by reducing the size of the peptides. Solubilization simplifies isolation of the protein moiety by physical means. Protein hydrolysis has also been applied to improve the functional, organoleptic, and nutritional value of a foodstuff. Advances in the technology of protein hydrolysate production has allowed the use of unconventional protein sources for animal and human food. 

Scheme 15)62. After terminating the reaction at a conversion of 38% (relative to total amount of substrate rac-78), the product (S)-43 was separated from the nonreacted substrate by column chromatography on silica gel and isolated on a preparative scale in 71% yield (relative to total amount of converted rac-78) with an enantiomeric purity of 95% ee. Recrystallization led to an improvement of the enantiomeric purity by up to >98% ee. The biotransformation product (S)-43 is the antipode of compound (/ )-43 which was obtained by enantioselective microbial reduction of the acylsilane 42 (see Scheme 8)53. The nonreacted substrate (/ )-78 was isolated in 81% yield (relative to total amount of nonconverted rac-78) with an enantiomeric purity of 57% ee. For further enantioselective enzymatic hydrolyses of racemic organosilicon esters, with the carbon atom as the center of chirality, see References 63 and 64. 

Ethanol Production in Immobilized-Cell Bioreactors from Mixed Sugar Syrups and Enzymatic Hydrolysates of Steam-Exploded Biomass... 

This research quantified the enzymatic digestibility of the solid component and the microbial inhibition of the liquid component of pretreated aspen wood and com stover hydrolysates. Products of liquid hot water and carbonic acid pretreatment were compared. Pretreatment temperatures tested ranged from 180 to 220°C/ and reaction times were varied between 4 and 64 min. Both microbial inhibition rates and enzymatic hydrolysis rates showed no difference between pretreatments containing carbonic acid and those not containing no carbonic acid. Microbial inhibition increased as the reaction severity increased, but only above a midpoint severity parameter of 200°C for 16 min. Both the rates and yields of enzymatic hydrolysis displayed an increase from the lowest tested reaction severity to the highest tested reaction severity. 

In summary, enzymatic hydrolysis presents numerous possibilities to modify the properties of proteins. Several food-grade enzymes with different specificities are now available. The selection of an enzyme is mainly dictated by its cost, while the cost of an enzyme accounts for only a small percentage of the protein hydrolysate production cost. 

This chapter consequently focuses on the application of enzymes for the selective cleavage of esters, amides and nitriles [2], Out of all the reported industrial applications of enzymes these type of hydrolyses constitute more than 40% [3], Enzymatic hydrolyses are often performed because of the enantioselectivity of enzymes, and in particular of the lipases that are used for the production of enantiopure fine chemicals. 

Vazquez, J. A. and Murado, M. M. (2008). Enzymatic hydrolysates from food wastewater as a source of peptones for lactic acid bacteria productions. Enzyme Microb. Technol. 43,66-72. 

The results of the three batches are shown in Tab. 2. The enzymatic hydrolyses went smoothly within the expected time and yielded product of high quality. In spite of the automated pH control the reaction was supervised continuously. The stirrer speed was chosen such (100 rpm) that intensive mixing was secured while the formation of foam avoided (the latter supported by a slight overpressure of 0.2 bar). After termination of the reaction the reaction mixtures were transferred from the fermenter to the extraction plant in a mobile tank and processed as described below. 

A resolved phosphonothioic acid has also been used to synthesize the optical isomers of GB via an apparently stereospecific reaction with picryl fluoride, but the product has racemized, in part, before it could be isolated. The partially racemized isomers thus obtained showed an even greater stereospecificity in their reaction with ChE than their V agent analogs. Partially resolved GD isomers have also been obtained by a similar procedure and samples of each of the four fully resolved GD isomers have been obtained by GLC methods. Recently, the two isomers of GA were obtained by enzymatic hydrolyses. 

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-... 

Many stereoselective enzymatic hydrolyses of nonnatural esters do not show a perfect selectivity, but are often in the range of 50-90% e.e., which corresponds to E values which are considered as moderate to good (E = 3-20). In order to avoid tedious and material-consuming processes to enhance the optical purity of the product, e.g., by crystalhzation techniques or via repeated kinetic resolution, several methods exist to improve the selectivity of an enzymatic transformation itself [24, 277], Most of them can be applied to other types of enzymes. 

The following protocol uses the relatively uncommon ELISA detection system of the enzyme p-galactosidase plus the substrate, 4-methylumbellifeiyl (3-galacto-side, which is enzymatically hydrolysed to the highly fluorescent product 4-methylumelliferone. This stem has several favourable features ... 

Araujo, A, and D Souza, J. 1980, Production of biomass from enzymatic hydrolysate of agricultural waste, J. Ferment. Technol., 58 399. 

Oxazolidine-2-thiones are also goitrogenic. They occur as secondary products in the enzymatic hydrolysate of glucosinolates when the initially formed mustard oils contain a hydroxy group in position 2 ... 

Free amino acids are only found in small amounts in most foods. Therefore, they only influence the flavour of foods when production is based on proteolysis (some cheeses, but also meat and fish). Enzymatic hydrolysates of proteins (such as soy sauces) or hydrolysed vegetable proteins (add hydrolysates), which contain only amino acids, are used extensively as seasonings. 

The best-known enzymatic hydrolysate is soy sauce, which originated in China around 500 BC. The Chinese priest Zen reportedly introduced its production in Japan in 1250 AD. Japanese soy sauces known as honjozo hoshiki are produced exclusively by fermentation, shinshiki hoshiki sauces contain 30 50% of enzymatic hydrolysate and 50-70% of acid hydrolysate, and aminosanekikongo hoshiki sauces are pure acid protein hydrolysates. 

Olsen HS, Adler-Nissen J. 1979. Industrial production and application of soluble enzymatic hydrolysate of soy protein. Process Biochemistry, 14 7-10. 

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