Reese's Peanut Butter Cups don't meet the federal definition of peanut butter. Hershey has pledged to fix that by 2027
Federal rules require peanut butter to be at least 90% peanuts with no chemical preservatives. Reese's filling has TBHQ - and after a viral backlash, Hershey has pledged to fix it by 2027.
Emily Harper
There is nothing inside a Reese's Peanut Butter Cup that the FDA would let anyone sell in a jar as "peanut butter." That's not a taste complaint - it's what happens when you check the filling's ingredient list against the actual federal rule, and it's the same rule a candy heir's grandson pointed at in a viral post that forced Hershey to respond within six weeks.
What the federal standard actually requires
Under 21 CFR 164.150, a product can only be labeled "peanut butter" if it's at least 90% peanuts by weight, with salt, sweeteners and stabilizers capped at the remaining 10%. The rule is explicit that artificial flavorings, artificial sweeteners, color additives, and chemical preservatives are not permitted at all. Reese's peanut butter filling is peanuts, sugar, dextrose, salt, TBHQ and citric acid. TBHQ is a chemical preservative, full stop - which means the filling doesn't clear the bar no matter what percentage of it is peanuts. According to Ingredient Inspector's side-by-side, the original Reese's cup ran 9 ingredients with no TBHQ, PGPR or citric acid; today's version has 14.
The preservative doing the work
TBHQ (tert-butylhydroquinone) is a synthetic antioxidant manufactured from petroleum-derived butane, used to keep oils and fats from going rancid. It's been FDA-approved since 1972, capped at 0.02% of a food's oil content. It's also been studied specifically for immune effects: Michigan State University researchers fed mice low-dose dietary tBHQ and then infected them with influenza. The tBHQ-fed mice showed slower initial T-cell activation, weaker CD4/CD8 response, and let the virus spread further before the immune system caught up. When researchers re-exposed the same mice to a related flu strain later, the impaired response carried over - the additive had blunted the mice's immune memory, not just their reaction to the first infection. It's a mouse study on dietary exposure, not proof of the same effect at human dosing, but it's a specific, published reason "chemical preservative" is a category the peanut butter standard excludes rather than a technicality.
The chocolate side isn't cleaner
The coating has its own shortcut. Reese's chocolate lists sugar first, and includes PGPR (E476), an emulsifier derived from castor oil that lets a manufacturer thin the chocolate enough to use less cocoa butter - cocoa butter being the expensive ingredient PGPR is standing in for. Hershey removed PGPR from its plain Hershey's Milk Chocolate Bar back in 2015; it stayed in the Reese's cup formulation.
The sugar has its own loophole, and a court just narrowed it
Sugar beet is on USDA's official Bioengineered Food list, but refined beet sugar has been exempt from "bioengineered" disclosure because USDA decided that refining destroys enough of the modified DNA to make it undetectable in the final product - so the label doesn't have to say anything, even though the crop it came from is genetically engineered. That exemption is no longer settled law: on October 31, 2025, the Ninth Circuit ruled USDA's "undetectable" carve-out for highly refined ingredients was adopted unlawfully and sent the disclosure standard back to the agency for revision. The refined-sugar loophole hasn't been closed yet - USDA still has to rewrite the rule - but a federal appeals court has now said the loophole's legal basis doesn't hold up.
Hershey's own fix, forced by its own family
None of this stayed quiet. Brad Reese, grandson of H.B. Reese, posted on LinkedIn criticizing the company for selling "chocolate candy" and "peanut butter creme" instead of the genuine chocolate and peanut butter his grandfather's name is on - a post that drew millions of views and real pressure inside six weeks. On April 1, 2026, Hershey announced it would restore classic milk and dark chocolate recipes across the affected products, with the change rolling out through 2027 - notably with no accelerated timeline for Halloween 2026, so this season's cups are still the reformulated version. Reese's is not a niche brand riding this out quietly: it did $3.17 billion in US candy sales in 2024, an 8.2% share of the entire domestic candy market.
What this actually tells you
- A federal "peanut butter" standard exists and current Reese's filling doesn't meet it - not on a technicality, but because it contains an ingredient category (chemical preservatives) the rule excludes outright.
- The company that owns the brand has already admitted the formula changed for the worse. Hershey's own April 2026 announcement is effectively a concession that the 14-ingredient version is worse than the 9-ingredient one it's promising to bring back.
- A regulatory exemption being "settled" can change under you. The refined-sugar bioengineered exemption looked permanent for years; a single 2025 appellate ruling put it back in play.
If you want a cleaner cup before 2027, look for a peanut butter with one or two ingredients, chocolate that lists cacao before sugar, and no PGPR or TBHQ on the label. Scan it on Tallow before you buy - it shows the score and full ingredients on the shelf, not after you've already opened the wrapper.
Figures and facts in this post are sourced from FDA and USDA regulations, court filings, published research and the press coverage linked above, current as of the time of writing. This is not medical advice.