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Corn is a high starchy cereal crop with the highest production and provides over 85% of the starch produced worldwide. Various by-products, differentiated by technological process features such as steep liquor, corn germ, corn bran, gluten, are created largely during corn starch processing. They are inexpensive, nutrient-rich, and vary widely in chemical composition such as proteins, oils, carbohydrates, and minerals. In an increasingly resource-constrained modern world, the utilization approach of these by-products for non-starch industrial processing is attractive widely considering both nutritive value and economic aspects. In fact, at present, applications of these by-products can often be found in feed, fermentation, nutrient extraction and other industries. For example, protein-rich corn gluten can be used as a good animal feed, and corn germ can be used as a raw material for the high-quality edible oil industry. Undoubtedly, increasing utilization means that these by-products will no longer be treated as waste but will be transformed into high value-added products. In this work, the separation process and chemical composition of several main by-products of the corn starch industry is briefly described, and the application in many industrial fields of these by-products over the last ten years are discussed in particular. This review attempts to summarize all aspects of the application and research of these by-products. For the by-products of the corn starch industry, the most promising way is to be utilized in high value and used to produce high value-added products. According to the characteristics of their chemical composition, they have a better application prospect and research significance in the industries directly related to human beings, such as medicine, green food and health care products. In fact, in recent years, some researchers have recognized this and carried out the research. It is clear from these studies that the main issues to be faced now and in the future are how to produce efficiently while maintaining the quality of the product and using it effectively. The retrospective discussions also provide some ideas for other grain and oilseed crops to be fully utilized.

In this study, we analyzed the potential of using dry matter content for determining ethanol yield of sweet potatoes as one of the raw materials for bioethanol production. We tested dry matter content, total starch content, crude protein content, glucose content, fructose content, sucrose content and fermentation indicators of 29 sweet potato varieties in Henan province. Correlation analysis between main component contents of sweet potato and the fermentation indicators were carried on. The results showed that there was strong linear correlation between dry matter content and bioethanol yield (R2 = 0.935). In order to prove the conclusion, we also tested dry matter content and ethanol yield of another 24 sweet potato varieties. Based on the dry matter content and linear correlations, we predicted the ethanol yields. We performed correlation analysis between the predicted values and the measured values of bioethanol yield of the 24 sweet potato varieties, and found highly significant positive correlation between the predicted values and the measured values. These results confirmed the reliability of using dry matter content for bioethanol production prediction for sweet potatoes.