The fascinating profusion of uses of soy: Inputs for industry

Soy is widely known as a food, both for direct human consumption and for formulating feed to feed pigs, poultry, cattle and other animals for the production of animal protein. But soy is much more than that, it is included in the composition of other commonly used products, other than food. This is the first article, in a series of four, that presents the plethora of soy-derived products that are increasingly present in our daily lives.

Soy has been used as a substitute for petroleum in a wide range of products, especially in the concept of green chemistry. The diversity of products is impressive and continues to grow. Rubbers, fibers, plastics, coatings, solvents, biodiesel, lubricants, adhesives and thousands of consumer products use soy as an ingredient.

Soybean components, including oil, protein, soy protein isolate byproducts, hulls, and soybean hull cellulose, are progressively incorporated into industrial products as researchers and manufacturers use soybeans to decrease dependence on petroleum, secure a source sustainable sourcing and making products more environmentally friendly.

Obtaining inputs from soybeans

When soybeans are crushed, around 20% oil is obtained, used to obtain products ranging from personal hygiene items to alkyd resins for paints and polyols for foam. High-oleic soybean oil is naturally more stable than conventional soybean oil, reducing the need for antioxidants and other expensive additives. It is also chemically modified to obtain synthetic lubricants, replacing cheaper polyalphaolefins and synthetic petroleum esters.

Epoxidized soybean oil is used as a plasticizer in polyvinyl chloride (PVC) for bags, food film, medical supplies such as blood bags and intravenous tubes, vinyl sheet products, sealants, coatings, paints and other applications. Soybean oil-based polymeric surfactant technology offers low cost, high biodegradability and potential for high renewable biocontent in final products.

In Brazil, biodiesel represents almost 20% of the fuel used in diesel cycle engines, with around 95% obtained from soybean oil. In addition to fuel, soy fatty acid methyl esters (biodiesel) can be used as industrial inputs, solvents in cleaning products and as co-solvents when mixed with other products, such as d-limonene. Soy-based amide substitutes and surfactant blends provide superior performance such as rich foam, flash foam and smoothness in personal care products.

Soybean meal is a mixture of approximately 50% protein (amino acids) and 50% non-digestible, high molecular weight carbohydrates. This fraction is a cheap source of sugar for fermentation and transformation into industrial inputs. An increasing percentage of soy protein is used to make products such as wood adhesives and paper coatings.

To transform soybeans or their fractions (oil and bran) into industrial inputs, processes such as epoxidation, alcoholysis, transesterification, acidulation, direct esterification, metathesis, isomerization, monomer modification and polymerization are necessary. This way, six basic industrial inputs are obtained: a) triglycerides; b) fatty acid esters; c) soybean oil epoxides (ESBO); d) fatty acid ester epoxides (SEM); e) glycerin; f) amino acids. From soybean oil can be other inputs such as resins, modified latex, reactive diluents, functional additives, diacids, diols and polyurethane dispersions.

Consumers' growing preference for renewable and sustainable raw materials is a favorable point for soy, the cost of which has been lower than that of petroleum inputs. Furthermore, soy has lower greenhouse gas (GHG) emissions than oil, which attracts companies that have sustainability goals to meet. Biological nitrogen fixation in the atmosphere requires nitrogen fertilizers, the production of which is highly GHG-emitting. With the increase in productivity, each ton of soy produced emits less GHG, as demonstrated by CESB's maximum productivity challenges (cesbrasil.org).

Décio Luiz Gazzoni, researcher at Embrapa Soja and founding member of the Soja Brasil Strategic Committee and the Sustainable Agro Scientific Council