The Science Behind Purple Pigmentation
While traditional red tomatoes produce anthocyanins in their leaves and stems, most commercial varieties lack the genetic "on switch" to produce significant amounts in the fruit itself. The purple hue in modern varieties comes from activating or introducing the genes responsible for anthocyanin production into the fruit. There are two primary methods used to achieve this:
- Conventional Breeding: Varieties like 'Indigo Rose,' developed by Oregon State University, were created by crossing conventional tomatoes with wild relatives that naturally produce anthocyanins in their fruit. For more details on this method, refer to {Link: The Purple Tomato FAQ | College of Agricultural Sciences horticulture.oregonstate.edu}.
- Genetic Engineering: The Norfolk Purple tomato was developed by inserting two genes from the edible snapdragon flower into a tomato plant. This activates the anthocyanin pathway throughout the fruit, resulting in a dark purple color in both the skin and flesh. This method significantly increases the overall anthocyanin concentration compared to conventionally bred varieties.
Anthocyanins vs. Other Tomato Pigments
The inclusion of anthocyanins adds a powerful antioxidant dimension to the nutritional profile of the fruit. {Link: The Purple Tomato FAQ | College of Agricultural Sciences horticulture.oregonstate.edu}
Comparison of Purple vs. Red Tomatoes
| Feature | Purple Tomatoes (e.g., Norfolk Purple, Indigo Rose) | Red Tomatoes (Conventional) |
|---|---|---|
| Primary Pigment Source | Anthocyanins, from either genetic engineering or conventional breeding | Lycopene, a carotenoid |
| Color | Deep purple to black, sometimes with colored flesh | Classic red color |
| Antioxidant Type | Anthocyanins (hydrophilic) and carotenoids (lipophilic) | Primarily lycopene (lipophilic) |
| Antioxidant Potency | Higher overall antioxidant capacity due to both anthocyanins and lycopene | Robust antioxidant capacity, but lacks the specific benefits of anthocyanins |
| Health Benefits | Cardio-protective, anti-inflammatory, anti-cancer, and neuroprotective properties | Strong link to reduced risk of certain cancers and cardiovascular diseases |
Potential Health Benefits of Purple Tomatoes
The increased anthocyanin content in purple tomatoes offers a range of health benefits that complement the existing nutrients in traditional tomatoes. Research has identified several potential advantages of consuming these antioxidant-rich fruits:
- Powerful Antioxidant Effects: Anthocyanins are potent antioxidants that help neutralize harmful free radicals in the body, which can damage cells and contribute to aging and disease. The combination of anthocyanins and lycopene in purple tomatoes creates a more robust antioxidant profile.
- Anti-Inflammatory Properties: Studies show that anthocyanins exhibit anti-inflammatory effects by inhibiting key signaling pathways involved in inflammation. This can help prevent chronic diseases associated with long-term inflammation.
- Cardiovascular Health: The flavonoids and anthocyanins in these tomatoes have been linked to improved cardiovascular function and a lower risk of heart disease.
- Anti-Cancer Effects: Preliminary studies, including a trial with cancer-prone mice, showed that a diet supplemented with purple tomatoes significantly extended their lifespan. These results are promising, though human studies are still needed.
- Improved Shelf-Life and Disease Resistance: The elevated anthocyanin levels also provide a benefit to the plant itself, enhancing its resistance to certain fungi like Botrytis cinerea. This improved resistance translates to a longer shelf-life for the fruit.
Key Purple Tomato Varieties
Several types of purple tomatoes are now available for home gardeners and consumers, each with its own story and characteristics:
- Indigo Rose: Developed through conventional breeding at Oregon State University, this was one of the first antioxidant-rich purple tomatoes available. Its purple pigment is most prominent on the sun-exposed parts of the skin.
- Norfolk Purple Tomato: A genetically engineered cherry tomato variety created by Norfolk Plant Sciences. {Link: The Purple Tomato FAQ | College of Agricultural Sciences horticulture.oregonstate.edu}
- Indigo Varieties: The initial 'Indigo Rose' led to a new "Indigo market class" of conventionally bred purple tomatoes, including varieties like 'Indigo Cherry Drops' and 'Midnight Roma'.
- Other Bred Varieties: Other conventionally bred options like 'Sun Black' and various "black" tomato heirlooms also contain anthocyanins, though the concentrations and distribution may vary.
Other Anthocyanin-Rich Foods
While purple tomatoes are a new and exciting source, many other fruits and vegetables are excellent sources of this beneficial antioxidant. A list of common sources includes:
- Blueberries and blackberries
- Cherries and red grapes
- Red cabbage and red onions
- Eggplant and black carrots
- Purple potatoes
Conclusion
In conclusion, yes, purple tomatoes have anthocyanins, and it is this potent antioxidant that gives them their distinctive coloration and enhanced nutritional value. Whether developed through traditional breeding or genetic engineering, these tomatoes offer consumers a powerful new source of health-promoting compounds to complement the lycopene already found in red tomatoes. The availability of varieties like Norfolk Purple and Indigo Rose offers an easy way to increase your intake of these valuable phytonutrients, either by growing them yourself or finding them at specialty markets. {Link: The Purple Tomato FAQ | College of Agricultural Sciences horticulture.oregonstate.edu}
