As an important category of eco-friendly packaging, the source of raw materials for biodegradable bags has always attracted much attention. The question of "whether they consume large quantities of grain" is not only related to food security and resource allocation, but also affects the public's perception of such eco-friendly products. In fact, the grain consumption of biodegradable bags cannot be generalized; it is jointly determined by the type of raw materials, production processes, and industry development directions, and requires in-depth analysis from a scientific perspective.
From the perspective of raw material composition, biodegradable bags can be divided into two categories: "grain-dependent" and "non-grain-dependent", with significant differences in their grain consumption. In the early stage, some biodegradable bags used starch as the main raw material, mostly food-grade starch from corn, wheat, etc. The grain consumption of such products was indeed relatively high — to produce 1 ton of starch-based biodegradable bags, approximately 2-2.5 tons of corn are needed (the extraction rate of corn starch is about 60%-70%). If such products were promoted on a large scale, they might occupy grain cultivation land or consume grain reserves, posing potential risks of "competing with grain for land" and "competing with people for food". This was also the core reason for the controversy surrounding early biodegradable bags.
However, with the iteration of technology, non-grain-dependent raw materials have become mainstream in the production of biodegradable bags, fundamentally reducing grain consumption. Currently, polylactic acid (PLA), the most widely used material in the industry, has expanded its raw material sources from the initial corn starch to non-staple food crops such as cassava starch and sweet potato starch, as well as cellulose from agricultural wastes (e.g., corn cobs and straw). Crops like cassava and sweet potatoes not only do not compete with staple grains for arable land (they mostly grow on marginal land) but also have higher starch yields — to produce 1 ton of PLA using cassava starch, only 3-3.5 tons of cassava are required (the extraction rate of cassava starch is about 70%), and the planting cost of cassava is lower than that of corn, exerting minimal impact on the grain market.
A more groundbreaking development is the application of "non-starch-based" raw materials. Taking polybutylene adipate terephthalate (PBAT) as an example, its main raw materials are adipic acid and butanediol, both derived from petrochemical derivatives or biomass wastes (e.g., waste oil), and do not rely on grain at all. Additionally, some enterprises produce lactic acid through fermentation of agricultural wastes such as straw and bagasse, and then synthesize PLA. This process not only realizes "turning waste into treasure" but also completely breaks away from dependence on grain raw materials. According to industry data, in 2024, non-grain sources accounted for 78% of the raw materials for global biodegradable bags, while grain-dependent raw materials only accounted for 22%, showing a continuous downward trend.
Industry standards and policy guidance are also promoting the production of biodegradable bags to move away from grain consumption. China's 14th Five-Year Plan for Plastic Pollution Control clearly states that "the use of non-grain raw materials for biodegradable plastic products should be encouraged to avoid consuming staple grain resources". The European Union's Biobased Products Directive also requires that if the raw materials of biodegradable materials come from food crops, they must undergo a "food security impact assessment" to ensure no impact on the regional food supply. Driven by policies, leading domestic enterprises have successively laid out production lines for non-grain raw materials. For instance, a certain biomaterial company produces PLA using bagasse, with an annual production capacity of 100,000 tons, reducing corn consumption by approximately 150,000 tons per year.
Furthermore, technological progress is constantly improving the utilization rate of raw materials, indirectly reducing grain consumption. Through the optimization of enzymatic hydrolysis processes, the extraction rate of corn starch has increased from 60% in the early stage to over 75% today. The corn consumption for producing 1 ton of starch-based biodegradable bags has decreased by about 20% compared with that 10 years ago. Meanwhile, the breakthrough in cellulase technology has significantly improved the conversion efficiency of cellulose in wastes such as straw and sawdust, further reducing the dependence of biodegradable bags on grain raw materials.
Objectively speaking, some early biodegradable bag production did consume grain, but the industry has now achieved a transformation from "grain dependence" to "non-grain dominance" through adjustments in raw material structure, technological innovation, and policy guidance. In the future, with the application of more new raw materials such as agricultural wastes and marine biomass, the production of biodegradable bags will further break away from dependence on grain, realizing environmental value while avoiding impacts on food security. When choosing biodegradable bags, the public can pay attention to the product's raw material labels and prioritize products made from non-grain raw materials such as cassava starch and straw fiber, jointly promoting the industry towards a more sustainable direction.
