Nuts such as walnuts (Juglans nigra) and pecans are part of a nutritious diet. The separation of nutmeat from shells and the characterization of its quality are essential in nut processing and trading. This chapter introduces conventional and advanced techniques in nut processing engineering. These methods, including various sensing and imaging modalities for industrial scale characterizations, will be demonstrated. Other related potential physical-chemical characterization methods may also be reviewed. Selected examples of current industrial practices and state-of-the-art research and development are illustrated in this chapter.