CHAPTER 15 Solid-State Fermentation for Food Applications Emilio Rosales, Marta Pazos, M a A ´ ngelesSanroma´n University of Vigo, Vigo, Spain 1. Introduction Many consumers are now demanding that the food and beverage industry have 100% natural labels or use more natural compounds derived from microorganisms, since they are thought to be healthier than the synthetic ones produced by chemical processes. Therefore, the food and beverage industry is rediscovering fermentation as a crucial step in product innovation, which can provide various benefits such as unique flavor, health and nutrition, texture, and safety [1]. One of the problems of fulfilling this demand is that natural products are more expensive to produce. In order to tackle this demand and to overcome its limitation there is a great interest in the development of processes to obtain these popular products. Therefore, cultures based on solid-state fermentation (SSF), which resemble natural microbiological processes like composting and ensiling using a wide range of solid materials that can be employed as nutrients, are presented as an attractive option. In addition, in SSF the liquid volume is low and for this reason the metabolites produced are concentrated and purification procedures are less costly [2]. Although its interest has increased in the last years, the application of SSF for the production of food has been known since ancient times. Traditional food fermentation such as koji process, tempeh, or cheese production can be considered examples of the oldest documented applications of SSF. As described in Fig. 15.1, although the initial application was applied to produce oriental food and brewed foods (such as Chinese wine, soy sauce, and vinegar) [3], new versions and potential uses of SSF have been evaluated. For example, peanut meal, which is considered limited in practical use (feed or food) due to the imbalance of amino acid profile and denaturation of protein, could be enhanced by fermentation. Results showed that the nutritional properties of fermented peanut meal (crude protein content, dry matter content, ash content, acid soluble oligopeptides content, Current Developments in Biotechnology and Bioengineering. http://dx.doi.org/10.1016/B978-0-444-63990-5.00015-3 Copyright © 2018 Elsevier B.V. All rights reserved. 319