Processing of vegetables which are frozen before canning and sterilizing
AssigneeCornell Research Foundation, Inc.
InventorMalcolm C. Bourne
Life of this patent
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Abstract
The improved firmness obtained in frozen vegetables by a two-step blanch prior to freezing consisting essentially of a lower temperature blanch to activate pectin methyl esterase in the vegetable to increase firmness followed by a higher temperature blanch to inactivate enzymes thereby to prevent the development of off flavors during frozen storage is retained when the frozen vegetables are canned and heat sterilized. The firming effect is accentuated when the food grade calcium salt is added or when a food grade acid is added to reduce the pH below 4.5. The greatest firming effect is obtained when both a food grade acid and a food grade calcium salt are added.
Claims26
A process for improving the firmness of canned vegetables which are frozen before canning, said process comprising the steps of:
- (a) blanching a vegetable in a blanching step under conditions to activate pectin methyl esterase in said vegetable, thereby to firm said vegetable, which consists essentially of blanching said vegetable at a temperature in the range of 125.degree. to 155.degree. F. for two to 60 minutes and then holding the vegetable without the application of heating for about zero minutes to 120 minutes,
- (b) blanching said vegetable in a succeeding blanching step under conditions to inactivate all enzymes therein thereby to prevent the development of off flavors during step (d), which consists essentially of blanching the vegetable which has been processed in step (a) at a temperature ranging from about 190.degree. to 210.degree. F. for two to 10 minutes,
- (c) treating vegetable that has been previously processed in accordance with steps (a) and (b), to produce frozen vegetable,
- (d) storing the frozen vegetable,
- (e) removing the frozen vegetable from storage and optionally thawing it,
- (f) canning the vegetable obtained in step (e),
- (g) heat sterilizing the canned vegetable.
Dependencies are inferred from the claim text.