Poblano peppers are a popular variety of chili pepper that originates from the state of Puebla, Mexico. They are large, heart-shaped peppers that start out dark green in color and eventually turn bright red as they ripen.
One common question about poblano peppers is whether they get hotter as they change from green to red. There are a few factors that contribute to a pepper’s heat level, so let’s take a closer look at how color affects a poblano’s spiciness.
What determines a pepper’s heat level?
The spiciness of any chili pepper depends on the amount of capsaicin it contains. Capsaicin is an alkaloid compound that acts as an irritant for mammals, causing a burning sensation when contacted. It is produced in the ribs and placenta of the pepper fruit.
Some factors that influence capsaicin levels include:
- Genetics – Some pepper varieties naturally produce more capsaicin than others.
- Environmental conditions – Stressors like sunlight, temperature changes, and soil moisture can impact capsaicin production.
- Maturity – Capsaicin levels often increase as the pepper ripens.
The reason maturity affects heat is that capsaicin production ramps up toward the later stages of fruit growth. More seeds need protection as the pepper nears full ripeness.
Do poblanos get hotter as they turn red?
Since capsaicin levels tend to increase as peppers mature, it’s reasonable to assume red poblano peppers are hotter than green ones. However, the reality is more nuanced.
Several factors influence whether red poblanos actually contain more heat:
Time of harvest
Poblano peppers are edible at any point during their maturation process. Green poblanos are typically harvested early before they reach their maximum heat potential. Red poblanos left longer on the plant will continue accumulating capsaicin.
If picked at the same stage of development, red vs green poblanos will not have a significant difference in spiciness. But allowing the red peppers additional ripening time gives them a heat advantage.
Individual pepper genetics
Some poblano plants naturally produce peppers with higher capsaicin content. Selective breeding can also develop spicier pepper lineages.
Within a given variety, individual pepper heat can vary based on genetic factors. So a red poblano could potentially be milder than a green one, depending on natural variation.
Environmental factors impact how much capsaicin accumulates as the pepper matures. Stressors like drought, high temperatures, and nutrient deficiencies can trigger increased production.
If red poblanos are grown under optimal conditions with minimal stress, they may not develop significantly higher heat levels compared to green peppers from the same plant. But stressful growing environments would likely heighten the difference.
How much hotter are red poblanos?
While individual peppers can defy expectations, most evidence indicates red poblano peppers are moderately hotter than green ones on average:
- Scoville ratings – A commonly used scale to measure chili pepper heat – generally range from 1,000-2,000 for green poblanos and 2,000-5,000 for ripe red ones.
- In taste tests, red poblanos frequently rank as spicier than green by a noticeable margin.
- Lab tests of capsaicin content show increases ranging from 50% to 150% more for red poblanos compared to green.
However, the difference is typically described as subtle rather than dramatic. Both green and red poblanos fall on the milder end of the chili pepper spectrum.
Poblano pepper Scoville scale
The Scoville Organoleptic Test measures chili pepper heat by dilution. The number refers to how much the pepper extract must be diluted before heat becomes undetectable.
Here are typical Scoville units for poblano peppers:
- Green poblanos – 1,000 to 2,000 SHU
- Red poblanos – 2,000 to 5,000 SHU
- Jalapeño – 3,500 to 10,000 SHU
- Habanero – 150,000 to 350,000 SHU
- Carolina Reaper – 1,500,000 to 2,200,000 SHU
Poblanos register at the lower end of the pepper heat spectrum, though red ones range nearer to jalapeño territory.
Subjective heat levels
General descriptions of poblano heat levels compared to other peppers:
- Green poblano: Mild spice.
- Red poblano: Moderate spice.
- Jalapeño: Medium heat.
- Habanero: Very hot.
The difference between green and red poblanos is noticeable but not extreme. Both are significantly milder than hotter pepper varieties.
How does capsaicin increase as poblanos ripen?
To produce hotter red peppers, capsaicin biosynthesis must ramp up during the maturation process. Here’s what’s happening inside the pepper:
Transport of capsaicin precursors
Capsaicin originates from compounds called capsaicinoid precursors that are produced in the pepper plant leaves. These precursors are transported to the pepper fruit through vascular bundles called phloem.
As the pepper matures, more vascular bundles form to deliver larger quantities of precursors. This provides the raw materials for increased capsaicin production.
Activation of capsaicin synthase enzyme
The capsaicinoid precursors convert into capsaicin inside the pepper fruit cells, facilitated by the enzyme capsaicin synthase. The activity level of this enzyme determines capsaicin accumulation rates.
During ripening, increased expression of the genes that code for capsaicin synthase boosts enzyme activity. This enables faster biosynthesis and paves the way for higher capsaicin content.
Evolution of capsaicin glands
Capsaicin is synthesized and stored in discreet structures called glands that develop in the pepper fruit. More glands form as the pepper grows, resulting in additional capsaicin production capacity.
As chloroplasts convert to chromoplasts when chlorophyll breaks down, they become the sites where capsaicin glands emerge. This transformation facilitates greater capsaicin accumulation in red ripe peppers.
How to control poblano pepper heat
While allowing poblanos to fully ripen tends to increase their spiciness, there are ways to moderate the heat:
Picking poblano peppers early when they are dark green results in milder heat levels. Time your harvest based on desired spiciness.
Leaving harvested poblanos at room temperature allows them to continue ripening and boosts capsaicin levels. Refrigeration slows the process for maintained low heat.
Some poblano pepper cultivars have been bred to maximize flavor while limiting spiciness. ‘El Rey’ is a good low-heat option.
Limiting water or applying fertilizer stress can trigger increased capsaicin production as a defense response. Keep plants healthy to minimize environmental impact on heat.
Remove seeds and veins
Capsaicin content is highest in the inner ribs and seeds. Removing these before eating reduces heat.
How to tell if a poblano is hot
It can be difficult to judge a pepper’s spiciness just by looking. But some signs can indicate higher heat levels:
- Darker red color – Fully ripe poblanos are darker red than younger ones.
- Shiny skin – Glossy skin results from greater capsaicin oil accumulation.
- Pointed tip – Sharp-tipped poblanos tend to be hotter.
- Smaller size – Compact peppers pack more heat.
- Dried appearance – Extreme wrinkling indicates advanced maturity.
Cutting open the pepper also reveals clues. Signs of higher capsaicin content:
- White ribbing – Paler ribs signal more capsaicin glands.
- Seeds adhered to ribs – Sticky ribs and seeds correlate with spiciness.
- Water inside – Hot peppers tend to have thinner, hotter flesh.
When in doubt, tasting a tiny piece of the peppers is the best way to gauge their bite. Just be sure to start small!
Reasons why red and green poblanos can taste different
Beyond just heat, ripe red poblano peppers can differ in flavor from younger green ones. Here’s why their taste profiles sometimes vary:
As chlorophyll breaks down during ripening, sugars concentrate making red poblanos taste sweeter than green ones. The sweetness balances out their added spiciness.
Higher acidic tang
Organic acids accumulate more as the peppers age, lending a bright, acidic component to red poblano taste. Their tanginess contrasts with the richer sweetness.
Ripening causes flavors to become more complex. Red poblanos develop fruitier floral and berry undertones complementing the stronger chili taste.
Thinner flesh and thinner cell walls give red poblanos a softer, smoother mouthfeel compared to crunchier green peppers.
Varying volatile aromas
Different volatile compounds build up during maturation, altering the peppers’ perceived aromas. Red poblanos give off richer, more robust smells.
Differing cholesterol-lowering agents
As poblano peppers age, they produce increased amounts of vitamin C and carotenoids. These antioxidants can affect flavor while also boosting health benefits.
While a given red or green poblano pepper’s spiciness depends on individual growing conditions and genetics, most evidence supports red poblanos being moderately hotter on average.
This increase results from more capsaicin precursors transported to the fruit, ramped up enzyme activity, and extra capsaicin glands forming as the peppers ripen from green to red.
However, the difference is generally not radical, with both green and red poblanos rating relatively low on the chili pepper heat scale. Taste and aroma profiles evolve as well during maturation, adding sweet, fruity, and acidic notes to balance out the additional heat.
Careful harvesting, storage, and preparation can moderate pepper spiciness. So enjoy poblano peppers at your desired spice level whether they are fully ripe red or still green!