Nutritional composition of almond hulls

Abstract

Objective: The aim of this research was to determine the nutritional composition of different varieties of almond hulls (AH) along with the total, pure, or non-hull material of almond hulls. Materials and Methods: Twelve samples of commercial almond hulls were used. Each sample was divided into 2 subsamples. One subsample represented the commercial almond hulls (total hulls). The other half was hand sorted to separate the hulls (pure hulls) from non-hull sticks and shells (debris). These samples were then ground for subsequent chemical analysis. Results and Discussion: Reducing the proportion of debris in AH reduced the fiber and ash content. The Nonpareil variety was superior in quality as measured by greater sugar content and lower content of ash, lignin, and NDF compared with other varieties. Crude fiber was more closely associated with aNDFom (ash-free aNDF) rather than aNDF (NDF assayed with heat-stable amylase), suggesting that any change in the fiber definition of AH should be based on fiber content that is ash free. Implications and Applications: The results from this study will help dairy nutritionists to better formulate diets including AH for lactating dairy cows. Almond huller operations can also use these findings to better understand how debris affects the composition of almond varieties to help stay below the legal concentration of crude fiber in AH being sold as feed. In addition, this information will aid the California Department of Food and Agriculture in making any changes to feed laws regulating the fiber composition of AH.