ExtractionIndustrial Agriculture produces enormous quantities of excess biomass not fit for human consumption, termed co-products. This is especially prominent in the world’s highly produced crops - such as rice, sugarcane, fruits, soybeans, peanuts, and almonds. These co-products are the components of the crop that remain after the food processing, such as leaves, stems, shells etc. Much of the agricultural co-products are thought to be high in usable sugars. For example, almond hulls have between 20 and 30 percent weight in volume of soluble sugars – of mostly glucose and fructose. Additionally, 40% of edible food produced within the United States is trashed and never consumed. Both of these resources are abundant and dramatically underutilized in respect to their inherent value. Considering the water, land, energy, and time invested, the loss arising from these agricultural resources is an indication of the economic and societal value that is not being tapped into.
The central goal of the project is to produce a conversion process of erythritol that will lessen the biological waste footprint in the agricultural industry, improve current methods of erythritol production, and reduce the cost of the product. It is essential to compare the economic viability of our method as compared to the traditional techniques. Almond shells were chosen as our starting co-product due to its position as California’s leading cash-crop, high sugar content of its hulls, and exceptional growth of almond production predicted in coming years.
In order to produce erythritol, the organism of choice must be able to successfully grow on almond co-products as its carbon source. To test for this, a series of experiments were conducted to test viability in different concentrations of media. Water was added to the dehydrated almond hulls to form a paste-like mixture. The solution was then boiled, in order to release the sugars. The particulates were filtered with two techniques – a coffee filter and a silk filter. Bacillus subtilis 3NA was added to be 1% of the solution. Multiple dilutions were made - these all had a final volume of 5 mL, with water being added as the remainder. Almond sugar solutions ranged from D1 (5 mL almond extract, 0 mL water), D2 (3.75 mL almond extract, 1.25 mL water), D3 (2.5 mL almond, 2.5 mL water), D4(1.25 mL almond extract, 3.75 mL water), and D5 (0 mL, 5 mL water). A positive control (5 mL of almond sugar solution) and a negative control (5 mL of water), both without Bacillus subtilis, were incorporated. The positive control was used as a visual basis for sedimentation build-up; the negative control tested for contamination. A LB broth culture was also incorporated to observe growth rate. The cultures were incubated at 37º overnight and plated.
In a second trial of experiments, smaller dilutions were created (1.25 mL of almond sugar solution and 3 3-fold serial dilutions). Yeast autolysate extract was added to provide various nitrogenous compounds, sulfur, vitamin B and other growth factors.