Effects of freezing on the organic acid content of frozen green beans and Padron peppers
1997
Gonzales-Castro, M.J. | Oruna-Concha, M.J. | Lopez-Hernandez, J. | Simal-Lozano, J.
HPLC was used to monitor the quantities of oxalic acid (Uv detection at 245 nm) and quinic, malic, citric and fumaric acids (UV detection at 215 nm) of deep frozen (-22 deg. C) green beans and Padron peppers over 12 months. Malic, oxalic and citric acid contents decreased considerably in the first month of frozen storage, then oscillated before returning to those one-month levels after 12 months. The amount of fumaric acid increased, most notably in the peppers. Quinic acid was only detected in the peppers; its content also increased. Freezing the vegetables in vacuum-sealed bags did not moderate these changes. Blanching the beans decreased the quantities of all the acids in the vegetable; then, in most cases, values varied similarly to those of the unblanched beans (notably, the citric acid content of the blanched beans doubled during the first 6-8 months of frozen storage, then fell sharply to roughly its initial, post-blanching level). Overall, blanching and than freezing green beans led to greater losses of their organic acids compared to freezing alone.
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