The impact of deep-frying on the fat, protein and isoflavone content of tofu with sensory evaluation of five types of tofu

Fresh and frozen tofu (coagulated soybean milk) was deep-fried in soybean oil (SBO), peanut oil (PNO) and cottonseed oil (CSO) to compare the nutritional and sensory qualities of deep-fried verses fresh tofu. A commercial deep-fried tofu product was also analyzed for protein, isoflavones and fat content and evaluated for sensory attributes.; The fat content of samples was measured by traditional acid hydrolysis and the Smart Trac(TM) Fat Analyzer by CEM Corporation. The fat content of the tofu increased from 6% in fresh to 11% when deep-fried, and to 13% when frozen and deep-fried. The protein content of the samples, measured using the Kjeldahl method, did not change appreciably. The isoflavone content of fresh and fried samples of tofu was analyzed using HPLC. The isoflavone content decreased in the deep-fried samples however the profile of the specific isoflavones remained the same. A consumer sensory evaluation indicated that the flavor, texture and overall likeability ratings increased when the tofu was deep-fried.