Yogurt manufacturer Stonyfield Farms announced yesterday that it is now using NatureWorks’ Ingeo polylactic acid (PLA) resin for its multi-pack yogurt cups under the brands YoBaby, YoToddler and YoKids as well as B-Healthy, B-Well, Probiotic & O’Soy.
The new cups replace petroleum-based polystyrene (PS#6) and will be stamped with “Made From Plants” on the bottom. The cup is 93% made from corn-based PLA compounded by Clear Lam Packaging in Illinois, where the Ingeo resin is mixed with colorings and other additives before being sent to Stonyfield Farms. The rest of the cup materials are composed of 4% colorant made with titanium dioxide (hmmmm, I wonder if there’s a slight grumble with this tidbit of information from health advocates…) and 3% additives.
Stonyfield noted that the entire multipack, including the paper label and PET lidding, is 81% bio-based material.
“By comparison, Coca-Cola®’s “plant bottle” is 30% bio-based and The SunChips® bag is 90% bio-based,” the company said.
An interesting information regarding this new product is that Stonyfield presented a lifecycle assessment study of the yogurt cups based on the use of polystyrene (PS) vs PLA. While Ingeo production uses 22% less total energy and 8% less greenhouse gas (GHG) emissions compared to PS production, PLA production still needs improvement in electricity use and wastewater emissions (during corn production).
Fertilizer use for corn was also considered in the study.
Toxicity impacts of Ingeo were many times lower compared to PS although noxious air emissions are said to be larger for PLA. Other areas of comparison still being studied include water use and environmental assessment of PLA and PS recycling, neither of which is currently practiced, according to the study. PLA, of course, has the upper hand when it comes to composting because of its degradability.
Still, Stonyfield does not recommend the cups to be composted as they are said to be too thick to be considered compostable under American Society for Testing and Materials (ASTM) international standards.
“The independent review of PLA’s environmental impact found that composting is also not the best option for disposing of the cups because composting would release the carbon dioxide (CO2) in the plant-based plastic (CO2 absorbed by the corn when it was growing) back into the atmosphere where it would contribute to global warming.” – Stonyfield Farms
So when it comes to end-of-life comparison, both PLA and PS are currently the same since the cups are not recommended for composting and there is no recycling system available for both materials for yogurt cups. Stonyfield, however, pointed out that the PLA cups can be converted back into lactic acid and then reformed into PLA packaging material, creating a continuous closed-loop system. That will be in the future when some companies can collect the cups for PLA recycling.
Back to the LCA study, both PS and PLA are said to have equal impacts when it comes to cup manufacturing, post-polymer transportation, and end of life via landfill.
Lastly, the company pointed out that they are working with the Institute for Agriculture and Trade Policy (IATP) and their Working Landscapes Certificate (WLC) program where Stonyfield pays farmers who agree to grow the corn they need according to very strict sustainable production standards. The program also ensures the use of non-GMO corn.
Stonyfield said they cannot use organic corn as it would add more than 30% to the price of the plastic cup, which they can’t pass on to consumers.