The production of soybean products has been increasing throughout the world, and there has been a corresponding increase in the quantity of soybean curd residue (SCR) being thrown out. The dumping of SCR has become a problem to be solved due to its contamination to the environment. SCR is rich in fiber, fat, protein, vitamins, and trace elements. It has potential for value-added processing and utilization; options that simultaneously hold the promise of increased economic benefit as well as decreased pollution potential for the environment. The objective of this study is to fully investigate, review, and summarize the existing literature in order to develop a comprehensive knowledge base for the composition and reuse of SCR. It is evident from the literature survey that SCR shows good potential as a functional food material. However, there are several drawbacks to the use of SCR and corresponding solutions presented in this paper. 1. Introduction Soy milk and tofu have maintained wide popularity as food sources for thousands of years, and large quantities of their byproducts are generated during the manufacturing process [1]. In Asian countries, soybean is made into various foods such as tofu, soymilk, soymilk powder, bean sprouts, dried tofu, soy sauce, soy flour, and tempeh soybean oil. Soybean curd residue (SCR), namely, okara in Japanese, is the main surplus material of soybean products, and it is often regarded as waste. About 1.1？kg of fresh SCR is produced from every kilogram of soybeans processed into soymilk or tofu [2]. In 2010, the annual output of soybean exceeded 261 million tons. As far as Japan is concerned, imported soybean amounted to 3.5 million tons in 2009 according to FAO report [3]. About 800,000 tons of SCR is disposed of annually as byproducts of tofu production in Japan. The expense for SCR disposal costs around 16 billion yen per annum [4]. Currently, SCR is used as stock feed and fertilizer or dumped in landfill. Particularly in Japan, most of the SCR is burnt which will create carbon dioxide [5]. Meanwhile, discarding of SCR as waste is a potential environmental problem because it is highly susceptible to putrefaction [6, 7]. The environmental problems arising from the massive generation of residues have been attracting considerable attention [8]. In fact, SCR also has high moisture content (70%–80%), which makes it difficult to handle and expensive to dry by conventional means [9]. On the other hand, SCR is a relatively inexpensive source of protein that is widely recognized for its high nutritional and excellent functional
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