Project : USDA ARS

ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Bioproducts Research » Research » Research Project #439387

Research Project: Zero Waste Agricultural Processing

Location: Bioproducts Research

2024 Annual Report

Objectives
Food processing losses can represent up to 40 percent of the initial harvest, resulting in significant environmental and economic costs. With stakeholders like the Almond Board of California committed to achieving zero waste, we aim to create viable bioproducts from agricultural byproducts, everything from field to table. The first objective is to add value to a low-value almond processing coproduct, the hulls, which are the bitter, but sugar-rich fruit of the almond tree, by: (1) creating a phenolic-rich sweetener for human consumption; (2) extracting sugar from almond hulls for use in bee diets during the winter, and (3) developing cost-effective carbon feedstock for fermentation that produces bioplastics and specialty chemicals. With a commercial partner we will optimize a novel fermentation process to convert food waste (including hulls) into a commercially-viable family of bioplastics specifically polyhydroxyalkanoates (PHA) using the latest techniques in biotechnology. Objective 1: Develop sustainable technologies toward “zero waste” production by converting food waste, byproducts and under-utilized biomass streams into marketable plastics, specialty chemicals, additives, and active agents. • Sub-objective 1A. Add value to almond hulls. • Sub-objective 1B. Convert food waste and under-valued byproduct streams into bioplastics]. • Sub-objective 1C. Convert pectin-rich citrus peel waste, sugar beet biomass, and almond hulls into aldaric acid and aldonate bioproducts. Objective 2 focuses on optimizing new uses for underutilized agricultural fibers. In collaboration with several commercial partners, we plan to scale up torrefaction (heating biomass to 200-300 'C), to convert tree nut shells and hemp residue into functional fillers that will improve commodity plastics. We also propose to convert underutilized polysaccharides like pectin, alginate, and xylan were isolated from enzyme conversion processes into industrially-relevant environmentally friendly diacids such as aldaric acid for use as solvents in homecare products. Our group has developed a wide array of enzymes to deconstruct plant cell walls. These enzymes will be used, via combinatorial enzymatic strategies and in vitro reaction schemes, to create “designer oligosaccharides” and green chemicals that meet specific marketable needs. Objective 2: Optimize end-use technology for underutilized agricultural fibers, including straw residue, bagasse, and grasses by developing commercially-viable chemicals and nanoparticles for novel applications including nanocomposites. • Sub-objective 2A. Apply thermochemical conversion technology to add value to tree nut shells and underutilized crop residues including hemp. • Sub-objective 2B. Convert biomass into designer oligosaccharides using combinatorial enzyme technology.

Approach
Objective 1: Develop sustainable technologies toward “zero waste” production by converting food waste, byproducts and under-utilized biomass streams into marketable plastics, specialty chemicals, additives, and active agents. Sub-objective 1A. Add value to almond hulls. Sub-objective 1B. Convert food waste and under-valued byproduct streams into bioplastics. Sub-objective 1C. Convert pectin-rich citrus peel waste, sugar beet biomass, and almond hulls into aldaric acid and aldonate bioproducts. Objective 2: Optimize end-use technology for underutilized agricultural fibers, including straw residue, bagasse, and grasses by developing commercially-viable chemicals and nanoparticles for novel applications including nanocomposites. Sub-objective 2A. Apply thermochemical conversion technology to add value to tree nut shells and underutilized crop residues including hemp. Sub-objective 2B. Convert biomass into designer oligosaccharides using combinatorial enzyme technology.

Progress Report
This report documents progress for project 2030-41000-068-000D, titled, “Zero Waste Agricultural Processing”, which started in November 2020. In support of Sub-objective 1A, ARS researchers in Albany, California, are examining ways to add value to almond coproducts by using extracts from almond hulls to improve the material properties of fish gelatin films. Almond hull extracts contain phenolic compounds, which can be used as a natural cross-linker for gelatin molecules. The cross-linked gelatin films showed improved mechanical properties as well as bioactive properties, such as antioxidant capacity. Also, heat treatment of the films resulted in the films being insoluble in water. The results from these studies indicated that the cross-linked films can be used in possible coating and packaging applications, and add value to almond hulls, an important byproduct of almond processing, a $7 billion agricultural market. In support of Sub-objective 1B, ARS researchers continue to optimize the production of polyhydroxyalkanoates (PHAs), a bacterially produced sustainable polymer, from undervalued carbon sources including (1) methane (with CRADA partner, Mango Materials), (2) diary waste effluent (with U.C. Davis researchers) and (3) waste glycerol from the biodiesel industry. Our society relies heavily on plastic, but most plastic is petroleum-based and non-biodegradable resulting in major negative environmental impacts. PHAs are produced from microorganisms cultured on renewable feedstocks. In their commercial collaboration with Mango Materials, ARS researchers helped Mango launch their commercial PHA-producing facility located at a California township wastewater treatment facility that converts waste methane into a commercial polymer that is now sold into home care products. To convert waste glycerol into PHA, ARS researchers optimized selection and growth conditions of genetically engineered Priestia megaterium strains. Specifically, a number of P. megaterium strains were screened from readily accessible repositories for their ability to produce PHA from glycerol, resulting in a wide range of growth and PHA production characteristics on glycerol: resulting in percent PHA yield of (4-42%), PHA titer up to 2 g/L, and carbon-conversion yield ranging from 26-303 mg/g). Resulting PHA polymers exhibited high molecular weight that could be exploited in a range of commercial products. In support of Sub-objective 1B, ARS researchers worked with CRADA partner, Hughes Energy, to convert an under-valued biomass source, banknotes from the Federal Reserve, into nanocellulose via optimal chemical and biochemical conversion processes. There are ~175 billion banknotes in circulation in the world with the majority of banknotes (89%) made almost entirely from cotton. A streamlined process for isolating nanocelluloses from shredded cotton banknotes was optimized by first steam-treating banknotes in an industrial autoclave system, coupled with carboxymethylation and mechanical blending, resulting in >95% yield of nanocelluloses in the aqueous supernatant. Culmination of this work was filing of a patent application 63/637,957 titled "Synthesis of Cellulose of Micro and Nanoparticles from Cotton Banknotes", a “first-of-its-kind” demonstration of creating cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and cellulose microfibrils/microfibrillated celluloses (MFC) from banknotes. The key advantage of the process is the creation of valuable products from something that would otherwise just be discarded, thus the agriculturally derived components of the banknotes reenter the circular economy as a high-value plastics additive versus being landfilled or incinerated, both of which would otherwise add to greenhouse gasses. In support of Sub-objective 2A, ARS researchers developed highly-porous activated carbon (AC) via thermal-conversion of almond and walnut shells and compared their performance against two commercial AC-derived water filters (Calgon Carbon Filtersorb 400 and Kuraray YP50). The ultimate goal is to develop commercial water filters from under-valued biomass resources to clean up unwanted water toxins, including per- and polyfluoroalkyl substances (PFAS), with methylene blue (MB) used as a test molecule. Activated carbons were generated from nutshell biochar using 2 levels of thermal activation to investigate the effect of activation residence time on filtration properties including pore development and MB adsorption. Raw nutshells, nutshell biochars, and nutshell ACs were characterized using a wide array of techniques, all showing that almond and walnut shells can be used to make activated carbon that has a similar or better methylene blue adsorption performance than the tested commercial carbons. Physical activation using carbon dioxide led to enhanced micropore development, and specifically, greater volume of pores with widths between 8-18 Å led to higher MB adsorption capacity. Considering that nutshell activated carbon shows comparable methylene blue adsorption to commercial carbons derived from coconut fibers, plans are underway to work with America producers to create a product that could reduce shell waste and generate new income for nut growers and processors. In support of Sub-objective 2B, ARS researchers used combinatorial enzyme chemistry to optimize the release of arabinose residues from wheat insoluble arabinoxylan. Arabinose is a non-caloric sugar used as an alternative sweetener and in probiotic nutraceuticals to reduce visceral (belly) fat, suppressing obesity. The optimization of arabinose release was realized by analyzing the activities of two families of a-L-arabinofuranosidase and two families of endo-xylanases and their synergistic interactions in enhancing the arabinose yield. It was shown that wheat arabinoxylan (the water-insoluble fraction) contains ~36% arabinose and applying the two enzymes produced twice the yield of arabinose residues from the heteroxylan compared to either single enzyme under the same reaction conditions. When the ratio of enzymes was optimized, a synergistic increase of 73.8% in arabinose yield was observed.

Accomplishments
1. Conversion of waste banknotes into nanocellulose fibrils to create stronger, more sustainable plastic composites. ARS researchers in Albany, California, in collaboration with a commercial partner, created nanocrystalline cellulose additives from an unusual under-valued biomass source, banknotes from the Federal Reserve. Worldwide, there are ~175 billion banknotes in circulation, with the majority (89%) of bills made almost entirely from cotton and all of this money must be discarded, often via processes that create greenhouse gas emissions. ARS researchers created and filed a patent on a streamlined process for isolating nanocelluloses from shredded cotton banknotes that relies on, first, steam-treating banknotes in an industrial autoclave system, coupled with carboxymethylation and mechanical blending. The optimal process resulted in >95% yield of nanocelluloses in the aqueous supernatant and has great potential for commercialization considering that it supplants the disposal costs. This “first-of-its-kind” demonstration of creating cellulose nanocrystals (CNC), cellulose nanofibrils (CNF), and cellulose microfibrils/microfibrillated celluloses (MFC) from banknotes brings forth several advantages in that it creates valuable additives that are then used in plastics to make them stronger, more flexible and more sustainable. Additionally, it ensures that the agriculturally derived components of the banknotes (cotton) reenter the circular economy as a high-value plastics additive versus being landfilled or incinerated, both of which would otherwise add to greenhouse gasses.

U.S. DEPARTMENT OF AGRICULTURE

Bioproducts Research: Albany, CA