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Forward contracts shielded rich-world farmers from the first shock. Now those contracts are expiring — and cooking oil is being pulled in two directions at once.

This is Part 2 of a three-part series on how the Iran conflict will reprice the global grocery store. Part 1 covered why the produce aisle spikes first and how forward contracts create a deceptive calm in staple prices through 2026. Part 3 covers the retail tactics, global welfare fallout, and what to watch.

By the time the produce aisle peaked in autumn 2026, most shoppers assumed the worst was behind them. Bread prices were flat. Meat was unchanged. The grocery bill was up — but only in the fresh section, and only uncomfortably, not catastrophically.

That perception is structurally wrong. The commodity disruption that drove produce prices in summer 2026 is the same one now working its way through a second, slower layer of the food system. Wave Two lands in Q2–Q4 2027. And it won't arrive alone — a second force, entirely separate from fertilizer, is bearing down on the same commodities at the same time.

The Biofuel Amplifier: When Your Cooking Oil Competes with a Diesel Tank

The fertilizer story is a supply-side shock — less nitrogen means smaller harvests. But the Hormuz disruption also triggers a demand-side pull on the exact same commodities through the biofuel channel. These two forces hit corn and cooking oils simultaneously, from opposite ends of the supply-demand equation.

The Strait of Hormuz carries roughly 20% of global crude oil supply. A sustained blockade drives oil prices higher — and when oil is expensive, biofuel production becomes more profitable. That creates a direct bidding war between food processors and fuel producers for the same agricultural commodities.

Corn and the Renewable Fuel Standard. The US Renewable Fuel Standard requires that roughly 40% of the domestic corn crop be diverted to ethanol each year. This proportion responds to the crude oil price: when oil rises, ethanol blending becomes more profitable and refiners bid more for corn — pushing up prices for feed mills, food processors, and importers alike. Research by the International Council on Clean Transportation estimates the RFS raised corn prices 12–30% even under normal conditions; during an oil price spike, the amplification is larger. A PNAS study found the RFS expanded US corn cultivation by 8.7% and increased nationwide fertilizer use by 3–8%, illustrating how deeply the fuel and food markets are coupled. During the 2007–08 food crisis, economists attributed roughly 20–30% of the corn price spike to biofuel demand — running in parallel with, not instead of, supply disruptions.

Cooking oils and the biodiesel floor. Soybean oil, palm oil, rapeseed/canola, and sunflower oil are the primary feedstocks for biodiesel and hydrotreated vegetable oil (HVO). EU renewable fuel directives (RED II and RED III) require a rising share of transport fuel from these sources. When diesel prices rise, biodiesel processors can pay more for oil feedstock and still clear a margin — effectively setting an energy-parity price floor under food-use prices. A supermarket cooking oil buyer now competes not just against other food buyers globally, but against fuel blenders whose cost tolerance is indexed to crude oil. This is why cooking oil is the most volatile food category in energy shocks: it sits at the intersection of two vast markets, and the energy market is orders of magnitude larger.

Sugar and Brazil's flex-fuel mills. Brazil's sugarcane mills can swing between sugar and ethanol depending on relative prices. A sustained oil price spike pulls production toward ethanol, tightening global sugar supply and adding to the fertilizer-driven cost pressures already building in the cane sector.

Wave Two: The Staples Shock

Q2–Q4 2027 — basket CPI peaks at +22%

Wave Two is the one that changes the feel of the weekly shop. Bread, pasta, rice, cereal, and cooking oil all move within a compressed window — because they all trace back to the same upstream event: the 2026–27 planting season that went in without adequate nitrogen, by farmers facing contract expiry and full spot prices.

Wheat and corn yields from that season are projected down 20–50% on nitrogen-deficient fields, according to IFPRI's modelling of the Iran war's agricultural impact. Processors burn through existing inventory first — then reprice. By Q2 2027 the mill-gate price moves. By Q3, it has passed through to retail:

• Bread, pasta, buns: +15–25% (Q3 2027)
• Breakfast cereal: +20–35% (Q3–Q4 2027)
• Cooking oil (soy, palm, sunflower): +42% base / +56% biofuel-amplified (Q2 2027)
• Rice: +20–30% in most markets; +40–70% in Asian staple markets (Q2–Q3 2027)
• Flour, sugar: +15–25% (Q3 2027)
• Packaged carbs (tortillas, crackers): +10–20% (Q4 2027)

The USDA ERS Food Price Outlook — revised monthly, broken out across 15 food-at-home categories — is the clearest US retail signal of when this wave completes. The FAO Food Price Index cereals sub-index leads retail by 3 to 6 months and is the global advance read.

Cooking oil is the sharpest single move in the entire grocery store across this period. It is the category where the fertilizer shock and the biofuel amplifier converge most directly. Both forces are pulling simultaneously: supply is down because oilseed crops were under-fertilized; demand is up because biodiesel processors are bidding against food buyers. The result is not a simple price increase — it is a sustained dislocation.

By mid-2027 the shopper experience has fundamentally shifted. The complaint is no longer about the produce aisle. It is about basics — the items that were always assumed to be affordable. Shrinkflation becomes obvious: the 400g pasta bag is now 350g at the same price, an effective 12.5% increase that doesn't show up in any CPI headline.

Wave Three: The Animal-Protein Lag

Q4 2027 through H1 2028 — the final crest

Animal protein is the last category to move because it sits behind the most time. Feed grain — corn and soy — makes up roughly 60–70% of the cost of producing eggs and chicken. When grain costs double, protein costs follow, with a lag built into every step of the supply chain.

Eggs are the fastest: feed constitutes ~70% of egg production cost, cycles are short, and there are no meaningful inventory buffers. Eggs peak at +28% in Q3 2027. Chicken follows in Q4 2027 at +15–25%. Pork arrives in Q1 2028 (+20–30%), driven by the 6 to 9 month hog cycle. Beef is last, cresting in Q2 2028 (+15–25%) — herd cycles run 18 months or longer. Dairy moves in Q4 2027 through Q1 2028 (+15–25%), as feed costs for dairy herds pass through at roughly 50%.

Restaurants absorb cost for as long as possible before repricing — menu increases are visible and jarring in a way that a 2% shelf-tag move is not. When menus do move, in Q1–Q3 2028, they move 15–30%.

Federal Reserve research on grocery inflation dynamics shows that household-level inflation rates diverge sharply during animal-protein spikes, with lower-income households bearing disproportionate welfare losses — foreshadowing the distributional picture covered in Part 3.

Part 3 covers how retailers tactically manage the price wave, who bears the greatest welfare burden globally, how consumers adapt over 18 to 30 months, and which leading indicators to track.

Sources

• IFPRI — The Iran war's impacts on global fertilizer markets and food production
• EPA — Overview of the Renewable Fuel Standard Program
• ICCT — The impact of the US Renewable Fuel Standard on food and feed prices
• PNAS — Environmental outcomes of the US Renewable Fuel Standard
• USDA ERS — Food Price Outlook
• USDA ERS — Food Markets and Prices
• FAO Food Price Index
• Federal Reserve — Measuring and Interpreting Grocery Inflation Heterogeneity
• S&P Global — Middle East war impacts global food security over fertilizer, fuel and freight