Gelation, fruit juice

It is natural that pectin, a normal constituent of fruits and berries, should be used with these foods when thickening and gelation are required. Although pectin does give nearly the same caloric effect upon digestion as does sucrose, it imparts a desirable body and viscosity to fruit juices at a much lower concentration than does sucrose. Knowledge of this fact is used in many canned fruits and berries prepared especially for dietetic purposes. 

Pectic Substances 46, 77). An important group of substances commonly called pectins is found in the primary cell wall and intercellular layers of all land plants, and, in some ways, seems to correspond to the hyaluronic acid of the ground substance of much animal tissue. Because of the immense gelling power of pectic substances, they are widely used for the gelation of fruit juices to form jellies. 

The present paper demonstrates applications of combinations of cloned monocomponent enzymes, including combinations with rhamnogalacturonases, for production of cloud stable apple juice, gelation of fruits, degradation of soy cell walls, production of dietetic soy and production of carrot puree are demonstrated. 

Versteeg et al. (50) have isolated various multiple forms of pectin esterases in oranges and shown that they differ in affinity to pectins and pectates and in heat stability and therefore may play different roles in cloud loss phenomena. One form (about 5% of the total PE activity) was found to be much more heat stable than the other forms it was also active at low pH (2.5) and at low temperatures. Another form did not cause self-clarification for this enzyme a similar mode of attack was proposed as for fungal pectin esterases which produce low-ester pectins less sensitive to calcium. Multiple forms of pectin esterases are present in the fruits of all of the orange varieties and citrus species tested. The two isoenzymes known to be responsible for cloud loss and gelation in citrus products were found to occur in all of the component parts of the orange fruit (51). In the French cider industry the endogenous PE of apple is used for the self-clarification of apple juice (52). 

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