The almond industry is poised to add value to hulls, a byproduct traditionally sold as a dairy cattle supplement. The potential for using almond hulls as a safe, healthy and sustainable food ingredient was highlighted by panelists at The Almond Conference 2024. 

Studies show almond hulls are rich in dietary fiber and phytochemicals and can be processed into functional ingredients with unlimited application potential. This almond byproduct is sustainable, and a steady supply is available. Adding 10% or more hull powder qualifies foods for certified upcycled claims. 

Outside of food ingredients, Josette Lewis, Almond Board of California’s (ABC) chief scientific officer, reports new inquiries seeking to receive almond shell and wood samples for trials with bioplastic and biofuel technologies. 

Lewis said ABC continues to partner with BEAM Circular, a bioeconomy initiative in the northern San Joaquin Valley that is ramping up activities to attract new industries, now providing seed funds to startups and welcoming six companies into their accelerator program. 

For food ingredients, Lewis added, ABC expects to complete the food safety work to position almond hull powder as a nutritious and functional food ingredient. Initial market analyses suggest the natural fiber and other properties of hulls will offer new value back to the industry. 

In his conference presentation, Michael Kelley, president and CEO of Central California Almond Growers Association, noted the decrease in California’s dairy herd size has decreased demand for hulls. 

“The price of hulls is presently trading well below the cost of production,” Kelley said. 

Hulls’ sugar and fiber content lend them to potential uses in a variety of food products. The goal of the almond industry is to find value-added alternatives for almond hulls, which make up 50% of the almond fruit. 

Kelley, who chairs ABC’s Biomass Working Group, said the committee has brought in scientists and business leaders who have offered a myriad of ideas on almond hull use in human food production. The possibility of using flour made from hulls in baking products is just one of the many new uses being explored. Kelley also noted hull use in coffee and as an ingredient in a snack bar product. 

“Clearly, such potential could enhance the revenue stream for hullers and shellers in California,” he said. 

Almond hulls are 88% to 94% dry matter after harvest and are rich in dietary fibers, sugars, phytochemicals and minerals. The almond kernels contain higher levels of protein and fat. 

Potential Largely Untapped
Guangwei Huang, ABC’s associate director of food research and technology, said the potential for hulls as a high-value ingredient in human food remains largely untapped. 

He focused on the health aspect of hulls in human food, noting the high level of phytochemicals makes almond hulls unique as health-promoting human food ingredients. The phytochemicals accumulate from long exposure to the sun during the growing season. They are extractable, and the phenolic compounds contained in hulls are anti-inflammatory, antimicrobial and antibacterial. 

Hulls can be easily processed into various ingredient forms. Studies have shown hull extracts lower LDL cholesterol and protect cells from oxidative damage. Hull powder also improves the nutrient profile in food products. 

Huang noted hull-derived powders excel in oil-holding and emulsifying qualities over commercial fiber products. Hull powder-derived drinks show stronger antioxidative capacity than many commercial antioxidant-rich beverages. Trials using hull powder to replace a portion of the flour in bread improve nutritional value. Added to coffee, hull powder modifies the sensory profile, decreasing bitterness. 

Almond hulls have also been proven safe in food uses. Huang said FDA toxicity studies have shown hulls to be safe with no adverse results at any dose level. The roadmap to commercialization of hulls as a food ingredient includes a self-assessment and filing an FDA notification, acquiring high-quality hulls for food uses and exploring milling options for hull flour. Huang said the almond industry expects to complete the FDA requirements next year. 

Speaking from the consumer viewpoint, Daniel Kurzrock, founder and CEO of food ingredients company Upcycled Foods, said consumer demand for upcycled foods is growing. Upcycling reduces the use of virgin resources, maximizing existing ones. Upcycled foods are projected to become one-fifth of the global food ingredient market by 2031. 

Kurzrock said almond upcycling has the potential to unlock new revenue streams, reduce disposal costs, align with growing consumer and industry demands and create partnerships and collaborations that drive technological advancements and market expansion. 

Hull Processing Aims at Quality
Dave Thiel, with Turlock-based Cortez Growers Association, said the co-op recognized years ago the need to find alternative uses for almond byproducts and began developing a system to produce quality hulls. This is allowing them to sell different classes of hulls, including prime hulls, and to extract more kernel pieces to be sold as a higher-value product. 

Achieving the quality levels hulls need for food ingredient use has been ongoing. Corbin Sturdivan of Wilkey Industries explained processes for removing sticks, shells and other foreign material. Traditional hull cleaning components include an aspirator to remove shells from hulls, a detwigger deck to remove sticks and screening to separate by size. More refinement can be done by adding screening and aspiration. Introducing screening allows classification of hulls and enables air aspiration to be more targeted and focused. 

An expanded hull cleaning system would entail a detwigger, then screening out the fines, leaving “scalped” hulls, Sturdivan said, meaning larger-sized hulls. Depending on the variety, he said there could also be large pieces of shell included. Aspiration can remove the lighter-weight shells, creating a premium hull product. 

An expanded hull cleaning system includes screening to sift fines. Those can be small, broken hull pieces, shell pieces and broken, split or whole kernels. Double aspiration can remove hull and shell, and a second pass can remove shell pieces from hull pieces. The recovered kernels, Sturdivan said, can represent 1.3% of the hull product weight. 

“That translates into roughly 3% of your kernel production that is actually sitting in the hull pile,” Sturdivan said. 

“By integrating screening and some additional aspiration, not only can we clean hulls as well as we practically can at the huller-sheller level, we can also reclaim those kernels and hash that have a much higher value, enabling them to be sold to a secondary processor.” 

Sean Chandler of Chandler Automation specializes in electronic sorting.

The capabilities of this type of system allow for the creation of pure hull piles. The company has made great strides in sorting in the last two years, Chandler said, but moving forward, he questions where the sorting should take place: at the huller or at the processor? 

The almond industry has taken the next step in advancing hull use in byproducts, he said, “not as a by-the-wayside product.”