44C-31 |
Production and stability of trans-2,cis-6-nonadienal from pickling cucumbers |
M. YU, C. Hamilton, and R. W. Buescher. Department of Food Science, University of Arkansas, 2650 N. Young Ave., Fayetteville, AR 72704 Large quantities of oversized cucumbers are annually produced that are not used for pickle manufacturing or fresh markets. These cucumbers could possibly serve as a source of natural cucumber flavor. The major cucumber flavor volatile is trans-2, cis-6-nonadienal (NDE) that is enzymatically produced when tissues are disrupted. Currently information is lacking on factors affecting the production and stability of NDE from cucumbers. Factors affecting the production and stability of NDE were investigated. Freshly harvested pickling cucumbers were donated by Dean Pickle and Specialty Products Co. NDE was immediately extracted from tissue homogenates containing an internal standard of pentane and then measured by GC. The effects of cucumber storage, slicing, temperature, pH, ionic strength and homogenization method on NDE production were determined. NDE stability was determined in filtered homogenates and concentrates prepared by 50°C vacuum distillation. Observations included the effects of temperature, time and pH on stability. In addition, the association of NDE stability to peroxidase activity was evaluated. NDE production was adversely affected by cucumber storage and slicing prior to homogenization or pH<5.5 and >6.5 or increasing ionic strength during homogenization. Slow disruption of tissues resulted in more production of NDE than fast homogenization. Temperatures from 30°C to 50°C had no effect on NDE production; however, above 50°C it declined and none was produced at 70°C. The combination of concentrating NDE and adjusting the pH to 3 greatly improved NDE stability. Peroxidase activity was associated with NDE degradation although it may not be responsible for the degradation. Inactivating enzymes after homogenizing tissues or separation from degradative enzymes by distillation was critical for NDE stability. These results will assist with the development of procedures for utilizing unused cucumbers as a natural source of NDE.
Session 44C, Fruit & Vegetable Products: Chemistry
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