39B-16

C. L. GOODMAN, Food Science and Technology, The Ohio State University, 2121 Fyffe Rd, Columbus, OH 43210 and S. A. Barringer, Food Sciecne and Technology, The Ohio State University, 2121 Fyffe Rd, Columbus, OH 43210.

JUSTIFICATION: Two methods are used commercially to produce tomato juice: hot and cold break. "Hot" is chopped at 85-90°C to inactivate enzymes important to flavor and viscosity. Polymethylesterase and polygalacturonase break down pectin in tomato tissue. By inactivating these enzymes in the hot break process, a more viscous product is achieved. Conversely, lipoxygenase creates important flavor compounds, and when it is inactivated in the hot break, the product lacks flavor. "Cold" refers to a temperature below 70°C to increase enzyme activity. This is an advantage for flavor, but a disadvantage for viscosity.

OBJECTIVES: Compare the color, viscosity, sensory, and volatiles of hot and cold break tomato juice.

METHODS: Fifty pound batches of tomatoes were chopped and allowed to sit for various time intervals to simulate the cold break process. This allowed enzyme activity before inactivation in the tubular heat exchanger at 93°C. Zero minutes was the hot break process, and 2, 5, 7, 10, 15, and 20 minutes were the cold break process. The Hunter Colorimeter was used for color analysis, and an efflux tube was used for viscosity. The sensory evaluation was conducted with a panel of 78 consumers. Solid phase microextraction and gas chromatography were used to identify volatile flavor compounds.

RESULTS: No difference in color was found between samples. Hot break was significantly more viscous than cold break. No difference was found between cold break samples. 15 min cold break was disliked, most likely due to lipid oxidation off-flavors, while 7 min cold break was liked the most by the sensory panel. The volatiles show a higher concentration of cis-3-hexenal and trans-2-hexenal in the cold break than in the hot break juice, with concentration a function of holding time.

SIGNIFICANCE: The cold break process can be used to produce a premium flavored tomato juice.