For agricultural professionals, the enduring mystery of which potato variety fuels In-N-Out Burger’s iconic fries is more than a culinary curiosity—it’s a case study in the precise alignment of agronomic traits with stringent commercial specifications. While the company maintains a well-documented silence, the public debate centers on two powerhouse cultivars: Russet Burbank and Kennebec.
The case for Russet Burbank is rooted in its industrial dominance. It remains the most widely grown potato in the United States, accounting for a significant portion of the processed potato market. According to the USDA National Agricultural Statistics Service (NASS), Russet varieties occupied over 50% of the total U.S. fall potato acreage in recent years. Its key attributes—high specific gravity (leading to a fluffy, mealy texture), long shape ideal for cutting long fries, and reliable storage characteristics—make it the undisputed choice for giants like McDonald’s. A 2022 research review in the American Journal of Potato Research reaffirmed that Russet Burbank’s processing quality, particularly for frying, is the benchmark against which new varieties are measured, despite its well-known challenges like susceptibility to hollow heart and high input requirements.
Conversely, the Kennebec variety, while less dominant in overall acreage, is a legendary dual-purpose chipstock and fresh-market potato prized for its versatility. Industry data from state potato commissions, such as those in Oregon and Washington, highlight Kennebec’s reliable performance and superior flavor profile. Its slightly lower specific gravity compared to Russet Burbank can yield a crisper exterior with a creamy interior—a texture highly sought after in artisanal and fresh-cut fry applications. Crucially, Kennebec is known for consistent yields and better resistance to certain foliar diseases, offering a potentially more stable input profile for growers. The mention by a California supplier, Specialty Produce, aligns with Kennebec’s reputation as a preferred variety in food service for its “clean potato taste” and consistent frying performance straight from storage.
The most plausible explanation for In-N-Out’s secrecy, supported by supply chain experts, is strategic sourcing flexibility. Large chains often use proprietary blends or allow regional co-packers to source from a pre-approved list of varieties that meet strict quality parameters (dry matter content, sugar levels, defect tolerances). This mitigates risk against regional crop failures, price volatility, and seasonal quality fluctuations. The 2023 Potato Outlook report from Agri-Food Analytics underscores that climate volatility is pushing processors and food service giants toward more adaptable and resilient sourcing agreements, often involving multiple approved varieties with similar functional characteristics.
The “In-N-Out potato debate” underscores a fundamental truth for the agricultural sector: the end-use specification is the ultimate driver of variety selection. For growers and agronomists, it highlights the market value of cultivars that deliver not just high yield, but exceptional and consistent functional quality—specific gravity, sugar profile, and storage longevity. The future points toward an integrated approach where breeding programs, informed by precise food service needs, develop varieties that marry the processing excellence of Russet Burbank with the agronomic resilience and flavor of Kennebec. The real lesson is that in a competitive market, the most successful potato is the one that reliably disappears into a brand’s iconic product, bite after identical bite.
