The seeds of Cannabis sativa L are used in various industries, such as food, cosmetics, feed, and pharmaceuticals. During the processing of seeds, a byproduct known as hemp bran (HPB) is produced and customarily discarded or used for livestock feed. But should seed processors be doing more with their HPB? Or is it of little value? Italian researchers with a grant from the University of Bologna found that HPB does in fact have valuable properties worth exploiting. [1]
The researchers chose three biorefinery processes to use on HPB, not only to test for the presence of valuable properties of the HPB, but to also find efficient methods of processing the bran. The processes selected were a chemical procedure, microbial liquid fermentation, and solid-state fermentation.
The chemical procedure was carried out using an alkaline protein extraction that was then followed up with hydrolysis by proteolytic enzymes including pepsin, trypsin, pancreatin, and chymotrypsin. The liquid fermentation was completed using ten types of Lactobacillus spp, and the solid-state fermentation (SSF) using Pleurotus ostreatus.
All three processes were able to recover meaningful amounts of biocompounds from the HPB. Fermentation with Lactobacillus led to the largest amounts of material (20g/100g HPB), followed by the chemical/enzymatic process (7g/100g HPB), and ranking third, the SSF process (1.7g/100g HPB). The Lactobacillus experiments were depending on the strain of bacteria used and incubation time. Within the set of experiments that evaluated the eight enzymes, hydrolysis using the pepsin produced the best results, solubilizing approximately 10% of the HPB proteins.
The antioxidant capacities of the proteins were assessed. The products obtained after enzymatic hydrolysis demonstrated an increase in antioxidant activity. The chymotrypsin hydrolysate had the best activity. Lactobacillus hydrolyzed samples showed only a modest increase in antioxidant activity after fermentation. The antioxidant activity of the SSF treatments were time-dependent.
The researchers found that the proteins exhibited highly variable anti-hypertensive properties, in some cases rivaling the IC50 values of angiotensin-converting enzyme (ACE) inhibition found in whole-seed hydrolysates. Treating the proteins with the different enzymes resulted in the varied anti-hypertensive activities as did the length of fermentation time in SSF.
This research demonstrates that HPB is more than a byproduct, and its use should not be limited to livestock feed. It most surely should not be discarded if it can be efficiently processed and valorized as a value-added product in the many industries in which whole-seed hemp is already being used.
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References:
1- Setti L, Samaei SP, Maggiore ID, Nissen L, Gianotti A, & Babini E. Comparing the effectiveness of three different biorefinery processes at recovering bioactive products from hemp (Cannabis sativa) byproduct. Food and Bioprocess Technology. 2020;13:2156-2171. [journal impact factor = 4.793; times cited = 4]
