ORIGINAL ARTICLE Hydration kinetics of cereal and pulses: New data and hypothesis evaluation Alberto Claudio Miano | Viviane Deroldo Sabadoti | J  essica da Costa Pereira | Pedro Esteves Duarte Augusto Department of Agri-food Industry, Food and Nutrition (LAN), Luiz de Queiroz College of Agriculture (ESALQ), University of S~ ao Paulo (USP), Piracicaba, SP, Brazil Correspondence Pedro Esteves Duarte Augusto, Avenida P adua Dias, 11 – Piracicaba/SP – 13418- 900, Brazil. Email: pedro.ed.augusto@usp.br Funding information S~ ao Paulo Research Foundation (FAPESP, Brazil), Grant/Award Numbers: 2014/ 16998-3, 2014/26433-3 (to Pereira), 2016/ 23908-6 (to Sabadoti); The National Council for Scientific and Technological Development (CNPq, Brazil), Grant/Award Number: 401004/2014-7; The “Consejo Nacional de Ciencia, Tecnología e Inovaci  on Tecnol  ogica” (CONCYTEC, Peru), Grant/ Award Number: 272-2015-FONDECYT Abstract This work described the hydration kinetics of several grains from the legumes and cereal families, which many of them were studied for the first time. In addition, some comparisons among the dif- ferent hydration kinetics were performed to corroborate some hypothesis about this process. By comparing the hydration kinetics of the studied grains and fitting their data to suitable equations, the idea that this process is very complex was reinforced. It is difficult to say how intrinsic proper- ties of the grains (color, size, specie, family, structure or composition) affect the hydration process. Some reported hypothesis about the hydration process were argued. For instance, it was demon- strated that some hypotheses about the grains hydration are not completely true: the grains with darker color seed coat do not always hydrate slower than the lighter color ones; the grains with sigmoidal behavior can hydrate faster than the grains with downward concave shape behavior; the bigger size grains sometimes hydrate slower than the smaller ones. It was concluded that the hydration process behavior and velocity are affected by many intrinsic properties of the grains (composition and structure, in a complex interaction) acting together to give the representative hydration kinetics behavior of each curve. Practical applications From the academic point of view, the results of this work will help to avoid misunderstandings during the study of the grains hydration process, as many hypotheses were reanalyzed and argued. Furthermore, it provides new data, in special for sigmoidal behavior grains, which is very scarce in the literature. From the industrial point of view, this work provides data about the hydration kinetics of several grains, which is very useful for the process design. 1 | INTRODUCTION Cereal and pulses are raw materials with huge importance for the human consumption and nutrition. Cereals, such as corn, wheat, barley, sorghum and others are important source of carbohydrates as starch. Pulses, as many beans, peas, lentils and others are good source of veg- etable proteins, besides its carbohydrate contribution. After their har- vest, both cereal and pulses are dried to increase their shelf life during storage. Consequently, a future hydration is necessary. In fact, the hydration process of these raw materials is very important before cooking, germination, extraction, fermentation and malting. The hydration process of cereal and pulses has been widely stud- ied, demonstrating that this is not a simple process as it seems. Their structure are very complex with different tissues and presence of pores, which involves different mechanisms of mass transfer (water transfer) (Miano, García, & Augusto, 2015). For that reason, each cereal or pulse has its own hydration kinetics behavior, which can be a down- ward concave shape (DCS) behavior or a Sigmoidal Shape behavior (Ibarz & Augusto, 2014; Miano & Augusto, 2015). The DCS behavior of hydration is characterized by a rapid hydration at the beginning of the process and a gradually decreases of the hydration rate along the time until reaching the equilibrium moisture content. Several mathematical models are used to fit the data; however, the Peleg model (Peleg, 1988) is the most used due to its simplicity and interpretation. How- ever, the sigmoidal shape behavior is characterized by an initial slow hydration rate of the grain, which accelerates until certain point (inflex- ion point). Then, the hydration rate is reduced until reaching the equi- librium moisture content. Only two mathematical models are reported J Food Process Eng. 2017;e12617. https://doi.org/10.1111/jfpe.12617 wileyonlinelibrary.com/journal/jfpe V C 2017 Wiley Periodicals, Inc. | 1 of 8 Received: 4 November 2016 | Revised: 15 June 2017 | Accepted: 3 August 2017 DOI: 10.1111/jfpe.12617