Isolation And Purification

The relative ease of the isolation and purification of large quantities of food-grade pectic substances account for their early discovery. Commercially, apple pomace or citrus peels (eg, orange, grapefruit, and primarily lemon or lime) are extracted with the goal of producing food-grade pectin for gels (6). Typically, pectin is acid extracted at low pH (1.5— 3) to inhibit degradation by endogenous enzymes, ester saponification, and alkaline degradation by beta-elimination reactions. Extracts are filtered or centrifuged to remove insolubles and precipitated with alcohol or polyvalent salts such as those from aluminum or copper.

To obtain pectins with maximum retention of native structure and properties for research purposes, milder techniques have been adopted at the expense of product yield and with considerable lengthening of the isolation-purification process. In these procedures, relatively intact cell walls are isolated by macerating plant tissues in aqueous alcohol, washing to remove extraneous debris and deactivate endogenous enzymes, then sequentially extracting with chelating agent and mild alkali. Attempts to reduce size heterogeneity by gel filtration chromatography and chemical heterogeneity by ion exchange chromatography have been met with limited success.

600 Chocolate Recipes

600 Chocolate Recipes

Within this in cookbook full of chocolate recipes you will find over 600 Chocolate Recipes For Chocolate Lovers.

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