Journal of Taiwan Agricultural Research

Author:Shwu-Jene Tsai*, Tsung-Yen Wu, King-Hsing Yang, Huey-Ing Liu and Ching-Liang Liaw

Abstract:

    The effects of cooking on the chemical composition and texture of peanut were studied. Several factors were considered: with or without shell during cooking; cooking methods; drying and rehydration. Peanut cultivars used in the research included Lih-Jr-Chai, Tainung #6, Tainan sel. #9 and Tainan #11. Compared to raw materials, the cooked peanut kernels had similar contents in proximate components; lower contents in titratable acidity, formol-N, water-soluble sugar and water-soluble protein; a higher content in water-insoluble solid. The results indicated that cooking processing caused the losses of water-soluble components as well as the partial changes of soluble components into insoluble ones. The cooked in-shell peanuts demonstrated higher contents of soluble components and insoluble solids than cooked peanut kernels. It might be concluded that the shell behaved as a barrier, preventing the leakage of peanut nutrients during cooking. Cooking time was shortened when peanuts were cooked by autoclave. Peanuts treated by autoclave steaming had a higher content of water-soluble sugar, but showed a drier and poor appearance. Overall, the autoclave boiling of peanut is recommended as the better cooking method for its cooking efficiency and quality. The rehydration of dry in-shell peanut was expeditiously improved by vacuum soaking. Dry peanut had similar composition as fresh raw one, except it was lower in titratable acidity. The rehydrated peanuts, including raw and cooked kernels, had similar contents as the fresh ones for most chemical components. However, soaking process of dry peanut kernel during rehydration caused significant losses of minerals, such as Fe, Cu and Mg.

Key words:Arachis hypogaea, In-shell peanut, Kernel peanut, Chemical composition, Cooking methods, Rehydration

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