Improvement of Malang Tahu Quality Using Sweet Potato Natural Dyes by Adsorption Technology

Tahu is a popular culinary product in Malang town. This product is produced from soyabean and rich of protein. Besides, tahu is also rich of water, so that surface of tahu tends to polar. Colorization of tahu by extract of yellow and sweet potatoes is interesting because both sweet potatoes contains different polarity molecular dyes, i.e. polar anthocyanin in the purple sweet potato but non-polar beta carotene in the yellow sweet potato. In this paper, changing of tahu's color after colorization by extract of both sweet potatoes was observed at different times of adsorption process (2, 4, 6 h), different compositions of the sweet potato and water (100g/1L and 300g/1L), and effect of palm oil addition (250 mL oil/1L water). Result of observation showed that the higher time of adsorption process, the higher ratio of the sweet potato weight and water volume, the darker color of the colorized tahu. Addition of the palm oil just improved extraction of β - carotene from the yellow sweet potato but did not improve the adsorption of the dyes on the tahu surface. Results of this study are used for supporting program of community service DPP SPP 2020 of Inorganic lecturers, as application of adsorption technology using tahu food as adsorbent and application of intermolecular force theory as part of Inorganic Chemistry I course.