Energy Usage and Quality Attributes of Dry English Walnuts in Californi

English walnuts (Juglans Regia) are the ninth most prolific agricultural commodity in California, accounting for 28% of global walnut production. For the global walnut industry, energy consumption, and walnut quality (i.e. External appearance, and color) are two important economic drivers. Therefore, the objective of this manuscript is to describe: 1) A 2016 California state-wide (20 dryers and hullers) survey that recorded energy consumption, and the effect of energy conservation strategies during walnut dehydration; and 2) The development and validation of a Color Vision System (CVS) for the grading of walnut kernels.;Previous estimates of energy consumption during dehydration indicate a total of 555-TJ of energy were employed to dehydrate walnuts in California in 2009, making dehydration one of the most energy intensive steps, during production. During this research, it was determined that the walnut industry uses energy equivalent to 1.8 MJ per kg w.b. of walnuts, which reflects a 21% increase in energy consumption per kilogram since 2009 (1.4 MJ per kg w.b.). Additionally, due to increased walnut production, estimates indicate that there is an 87% increase in overall energy consumption during walnut dehydration from 2009. It was determined that production volume and climatological factors most significantly correlated with energy consumption (p < 0.1). It was not determined if energy conservation strategies significantly impact energy consumption.;Currently, licensed inspectors of the Dried Fruit and Nut Association of California (DFA) manually and visually grade walnuts. DFA inspectors are certified to manually grade shelled walnuts using a four-color scale; however, there is inherent subjectivity in this method. To address this, a CVS was developed and validated with 1900 randomly selected seedling samples, 1238 Chandler samples and 857 Howard samples. The CVS classified up to 88.8% of samples correctly when individual models were developed for each variety. Differences in color values, standard deviation of color values, and size among varieties indicate separate models are required for increased accuracy. The CVS was found to be an objective and useful tool for walnut categorization.