Arugula, also known as rocket, is a popular leafy green prized for its distinctive peppery flavor. When considering this plant, many people ask about its acidity. Understanding the difference between its measured pH and its metabolic effect is key to understanding its place in nutrition. This article will break down the science behind arugula's pH and explore the benefits that make it a nutritional powerhouse.
The Measured pH of Fresh Arugula
On the standard pH scale, where 7 is neutral, fresh arugula typically falls in the slightly acidic to neutral range. According to some measurements, the estimated pH of raw arugula is around 6.9, placing it very close to neutral. Other data, particularly for hydroponic growing, suggests a range of 5.5 to 6.8, which is slightly more acidic.
Unlike fruits with a clear acidic taste, arugula's peppery bite comes from compounds called glucosinolates, not a low pH. This explains why it tastes sharp but isn't highly acidic in its natural state. The specific pH can vary based on growing conditions, variety, and maturity.
Arugula vs. Spinach: A pH Perspective
When comparing arugula to other leafy greens like spinach, their pH characteristics and metabolic effects differ. The key difference lies not in their raw acidity but in their Potential Renal Acid Load (PRAL), which indicates their acid-forming or alkaline-forming effect in the body.
| Feature | Arugula | Spinach |
|---|---|---|
| Measured Raw pH | Around 6.9 (Slightly acidic to neutral) | 5.38 to 7.18 |
| Metabolic Effect (PRAL Value) | Alkaline-forming (-7.9) | Strongly alkaline-forming (-11.8) |
| Oxalate Content | Very low | High |
| Calcium Absorption | Higher bioavailability | Lower bioavailability due to oxalates |
How Arugula Becomes Alkaline-Forming in the Body
While a food's raw pH is what is measured on a scale, its effect on the body is determined by its PRAL value. The PRAL score measures the amount of acid or base a food produces in the body after it is metabolized. A negative PRAL score, like arugula's -7.9, means the food is alkaline-forming.
Arugula's wealth of alkalizing minerals, such as potassium, calcium, and magnesium, contributes to this effect. After digestion, these minerals produce alkaline byproducts, which help neutralize acids and promote a more alkaline internal environment. This is why arugula is often promoted as a staple for alkaline diets, despite its raw, neutral pH.
Optimal pH for Growing Arugula
For gardeners, the crucial pH is that of the soil, not the leaf. Arugula grows best in a slightly acidic to neutral soil pH, typically in the range of 6.0 to 7.0. If the soil is too acidic (pH below 6.0) or too alkaline (pH above 7.0), the plant can struggle to absorb essential nutrients, leading to stunted growth and other problems.
To ensure a healthy crop, gardeners can perform a soil test and amend the soil as needed. For overly acidic soil, adding agricultural lime can help raise the pH. For alkaline soil, incorporating sulfur or organic matter like compost can help lower the pH over time.
Best Practices for Growing Arugula
- Soil Preparation: Ensure well-drained soil rich in organic matter. Work compost into the soil before planting.
- Watering: Keep the soil consistently moist, but not waterlogged, as arugula needs regular watering, especially during hot weather.
- Sunlight: Plant in a location with full sun to partial shade. Afternoon shade can help prevent bolting (going to seed) in warmer climates.
- Harvesting: Begin harvesting the outer leaves when they are a few inches long, allowing the inner leaves to continue growing.
Beyond pH: The Significant Health Benefits of Arugula
Arugula's mild, peppery flavor belies its potent nutritional profile, which extends well beyond its pH properties. It is packed with vitamins and minerals that support overall health.
- Boosts Cardiovascular Health: Arugula is rich in nitrates, which convert into nitric oxide in the body. This helps lower blood pressure and improve blood flow, supporting heart health.
- Protects Vision: High in carotenoids like lutein and zeaxanthin, arugula filters high-energy blue light to protect the eyes from cellular damage and reduce the risk of age-related macular degeneration.
- Strengthens Bones: A great source of Vitamin K, calcium, and magnesium, arugula supports strong and healthy bones and aids in the body's absorption of calcium.
- Supports Detoxification: The glucosinolates in arugula, which are broken down into isothiocyanates, aid the liver's detoxification processes, helping neutralize toxins.
- May Fight Cancer: Isothiocyanates, particularly erucin, have been studied for their ability to inhibit the proliferation of cancer cells.
Conclusion
Understanding what is the pH of arugula reveals a fascinating distinction: its measured acidity is mild and close to neutral, while its metabolic effect is alkaline-forming due to its rich mineral content. This makes it a great choice for those following an alkaline diet. For gardeners, maintaining a soil pH between 6.0 and 7.0 is key for a healthy harvest. With its rich array of vitamins, minerals, and compounds like nitrates and isothiocyanates, arugula's health benefits are significant, making it a valuable and versatile addition to any diet.
For more in-depth information on growing arugula and other crops, you can explore resources from agricultural universities, like Oregon State University's horticulture guides.
Note: This is not medical advice. Consult a healthcare professional regarding diet-related health concerns.
