Application Lipid Hydrolysis

The most prevalent naturally occurring esters are the triacylglycerols, which were first discussed in Section 10.6. Triacylglycerols are the lipids that comprise animal fats and vegetable oils. 

Animals store energy in the form of triacylglycerols, kept in a layer of fat cells below the surface of the skin. This fat serves to insulate the organism, as well as provide energy for its metabolic needs for long periods. The first step in the metabolism of a triacylglycerol is hydrolysis of the ester bonds to form glycerol and three fatty acids. This reaction is simply ester hydrolysis. In cells, this reaction is carried out with enzymes called lipases. 

Three fatty acids containing 12-20 C s are formed as products. 

The fatty acids produced on hydrolysis are then oxidized in a stepwise fashion, ultimately yielding CO2 and H2O, as well as a great deal of energy. Oxidation of fatty acids yields twice as much energy per gram as oxidation of an equivalent weight of carbohydrate. 

Diets high in fat content lead to a large amount of stored fat, ultimately causing an individual to be overweight. One recent attempt to reduce calories in common snack foods has been to substitute fake fats such as olestra (trade name Olean) for triacylglycerols. 

This triacylglycerol has no double bonds in the three R groups (each with 11 C s) bonded to the ester carbonyls, making it a saturated fat. 

Chapter 22 Carboxylic Acids and Their Derivatives—Nucleophilic Acyl Substitution 

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For edible applications, lipids are often used intact. For such uses, the whole fats and oils are subjected to hydrogenation. For industrial uses, lipids are the feedstocks for free fatty acid production. When firmer fractions are needed for industrial applications, the free fatty acids obtained by lipid hydrolysis are subjected to... 

The many circumstances leading to the Henri equation for enzyme conversion of soluble substrates are first noted, followed by some kinetic forms for particulate and polymer hydrolysis. Effects common to immobilized enzyme systems are summarized. Illustrative applications discussed Include metabolic kinetics, lipid hydrolysis, enzymatic cell lysis, starch liquefaction, microenvironment influences, colloidal forces, and enzyme deactivation, all topics of interest to the larger themes of kinetics and thermodynamics of microbial systems. 

The application of high-sensitivity ICP-MS detectors coupled to HPLC has enabled the detection of trace arsenic compounds present in marine animals. Thus, arsenocholine has been reported as a trace constituent (<0.1% of the total arsenic) in fish, molluscs, and crustaceans (37) and was found to be present in appreciable quantities (up to 15%) in some tissues of a marine turtle (110). Earlier reports (46,47) of appreciable concentrations of arsenocholine in some marine animals appear to have been in error (32). Phosphatidylarsenocholine 45 was identified as a trace constituent of lobster digestive gland following hydrolysis of the lipids and detection of GPAC in the hydrolysate by HPLC/ICP-MS analysis (70). It might result from the substitution of choline with arsenocholine in enzyme systems for the biogenesis of phosphatidylcholine (111). 

As mentioned, hydrolysis is the other important mechanism by which some lipids (glycerides and phosphoglycerides) degrade and can lead to a reduction in pH due to liberation of free fatty acids this was discussed in Chapter 10 (Part I Parenteral Application). This phenomenon is less important for oral formulations when compared to parenteral products, since the former generally have low amounts of water in the formulation. Hydrolysis could occur on storage if water is absorbed from or through the gelatin shell. 

Applications of whole-cell biocatalytic membrane reactors, in the agro-food industry and in pharmaceutical and biomedical treatments are listed by Giorno and Drioli [3], Frazeres and Cabral [9] have reviewed the most important applications of enzyme membrane reactors such as hydrolysis of macromolecules, biotransformation of lipids, reactions with cofactors, synthesis of peptides, optical resolution of amino acids. Another widespread application of the membrane bioreactor is the wastewater treatment will be discussed in a separate section. 

Lipase (Aspergillus niger var.) Produced as an off white to tan, amorphous powder by controlled fermentation using Aspergillus niger var. Soluble in water (the solution is usually light yellow), but practically insoluble in alcohol, in chloroform, and in ether. Major active principle lipase. Typical application used in the hydrolysis of lipids (e.g., fish oil concentrates and cereal-derived lipids). 

With conventional emulsified systems, it is not possible to control the interfacial qualit/ and to easily assess the distribution of soluble versus adsorbed amphiphilic molecules. This prompted us to use the monolayer technique, based upon surface pressure decrease due to lipid-film hydrolysis [55, 56]. This technique is applicable to those cases where the lipid forms a stable monomolecular fihn at the air/ water interface and where reaction products are freely soluble and diffuse away rapidly into the aqueous phase. 

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