Food enzyme chemistry

Some basic food analytical methods such as determination of °brix, pH, titratable acidity, total proteins and total lipids are basic to food analysis and grounded in procedures which have had wide-spread acceptance for a long time. Others such as analysis of cell-wall polysaccharides, analysis of aroma volatiles, and compressive measurement of solids and semi-solids, require use of advanced chemical and physical methods and sophisticated instrumentation. In organizing the Handbook of Food Analytical Chemistry we chose to categorize on a disciplinary rather than a commodity basis. Included are chapters on water, proteins, enzymes, lipids, carbohydrates, colors, flavors texture/ rheology and bioactive food components. We have made an effort to select methods that are applicable to all commodities. However, it is impossible to address the unique and special criteria required for analysis of all commodities and all processed forms. There are several professional and trade organizations which focus on their specific commodities, e.g., cereals, wines, lipids, fisheries, and meats. Their methods manuals and professional journals should be consulted, particularly for specialized, commodity-specific analyses. 

Gregoriadis, G. 1987. Encapsulation of enzymes and other agents liposomes. In Chemical Aspects in Food Enzymes, ed. A.J. Andrews. London, U.K. Royal Society of Chemistry. 

Jakob, A., Bryjak, J., Wojtowicz, H. et al. (2010) Inactivation kinetics of food enzymes during ohmic heating. Food Chemistry, 123, 369-376. 

Enzyme preparations chemistry recommendations for food additive and GRAS affirmation petitions (http //vm.cfsan.fda.gov/ dms/opa-cg7.html)... 

High pressure has proven to be a useful tool in biochemistry for the study of a number of cell-mediated processes, the most important being the effect on gene expression. The pressure effect on the stability of enzymes and biopolymers is a topic of general interest that may generate a number of possible applications in the area of food science. Biochemistry and biophysics continue to attract many new research groups, especially in the field of protein chemistry. Pressure may be a tool to obtain unique textures and provide biochemical products with new properties. 

Brady J.F., J. Turner, and D.H. Skinner (1995). Application of a triasulfuron enzyme immunoassay to the analysis of incurred residues in soil and water samples. Journal of Agricultural and Food Chemistry 43 2542-2547. 

Various excellent reviews are available on phenolic compounds, their chemistry and analysis, content in foods and nutritional significance (Bravo, 1998 Dykes and Rooney, 2006 Manach et al., 2004 Naczk and Shahidi, 2006 Robbins, 2003). From a nutritional perspective, phenolic compoimds (especially tannins) are regarded as antinutritional factors due to their ability to form complexes with dietary proteins and minerals and digestive enzymes (Bravo, 1998). However, lately there has been increasing focus on the positive aspects of phenolics due to their ability to act as antioxidants which may offer potential health benefits such as prevention of diseases such as cancer and cardiovascular disease. 

Cantos, E., Tudela, J. A., Gil, M. I., Espin, J. C. (2002). Phenolic compounds and related enzymes are not rate-limiting in browning development of fresh-cut potatoes. Journal of Agricultural and Food Chemistry, 50, 3015-3023. 

The lipid components of food are known to be critical in the development of much of a food s flavor. Modifications to lipid modifying enzymes such as lipases have led to new products useful in the rapid preparation of other food components Chapter 13,14), Better utilization of lipid constituents in food products can be gained from a better understanding of the thermodynamic and physicochemical characteristics of emulsions. Significant advancement in emulsion chemistry and food engineering have recently appeared in the literature and are an important portion of this volume Chapter 19),... 

Esters are widespread in fruits and especially those with a relatively low molecular weight usually impart a characteristic fruity note to many foods, e.g. fermented beverages [49]. From the industrial viewpoint, esterases and lipases play an important role in synthetic chemistry, especially for stereoselective ester formations and kinetic resolutions of racemic alcohols [78]. These enzymes are very often easily available as cheap bulk reagents and usually remain active in organic reaction media. Therefore they are the preferred biocatalysts for the production of natural flavour esters, e.g. from short-chain aliphatic and terpenyl alcohols [7, 8], but also to provide enantiopure novel flavour and fragrance compounds for analytical and sensory evaluation purposes [12]. Enantioselectivity is an impor-... 

At a glance, the rapprochement between biochemistry and polymer chemistry seems to have played an important role in the methodological development of preparations for immobilized biocatalysts. A number of articles on the preparation and characterization of immobilized biocatalysts, together with their applications in a variety of fields besides synthetic chemical reactions - chemical and clinical analysis, medicine, and food processing, for example - have already been published. These results have been reviewed by many of the pioneers in this and related fields [1-20]. The technology for immobilizing enzymes and cells is believed to be relatively mature at this point. In addition, the nature of immobilized biocatalysts has become somewhat more transparent to us. The key now is to come up with new uses and new systems which can fulfill specific needs [21]. 

Pectinases These enzymes carry out the hydrolytic degradation of the D-glycosidic linkage in pectins. The latter substances, also known as pectic substances, are polymeric components of plant cell walls and. like starch, are composed of sugar residues linked by glycosidic bonds. The chemistry is the same as that shown for the amylases previously described. The main application of pectinases is in the production of fruit juices, wines, and certain other food products. 

A.L. Hart and W.A. Collier, A contribution to convenience for enzyme-based assays of pesticides in water. In S.A. Clark, K.C. Thompson, C.W. Keevil and M.S. Smith (Eds.), Rapid Detection Assays for Food and Water, Royal Society of Chemistry, Cambridge, 2001, pp. 80-83. 

During the last twenty years, biochemical reactions performed by microorganisms or catalyzed by microbial enzymes have been extensively evaluated from the viewpoint of synthetic organic chemistry, and as a consequence they have been shown to have a high potential for both theoretical and practical applications in synthetic chemistry. Many attempts to utilize biological reactions for practical synthetic processes have been made - for example, for the preparation of pharmaceuticals, fine chemicals, food additives, and commodity chemicals. Such synthetic technology is called microbial transformation, or alternatively, microbial conversion, biotransformation, bioconversion, or enzymation [1,2]. 

Specific modifications of proteins result from adding a selected reagent to the pure protein or crude protein-rich material. This may be done in the course of a fundamental study in protein chemistry or as a step in the production of a bulk protein product for practical purposes. The same chemical modification can be useful in both processes. For example, enzyme chemists use charge-changing modifications to dissociate oligomeric proteins to their monomer components, while the same modifications are proposed as a means of solubilizing yeast proteins to permit their extraction for use in foods (11). This chapter is concerned mainly with the many types of intended modifications. 

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