Understanding Glutamate, Umami, and MSG
Before delving into tomatoes and cheese, it's essential to understand the key players. Glutamate is an amino acid, one of the building blocks of protein, and it is abundant in most protein-containing foods. When proteins are broken down through processes like ripening, aging, or fermentation, free glutamate is released. This free glutamate activates specific taste receptors on our tongues, resulting in the fifth basic taste: umami.
MSG, or monosodium glutamate, is the sodium salt of glutamic acid. It was first isolated from seaweed broth in 1908 and is now produced commercially through the fermentation of starches or sugar. The key takeaway is that the glutamate molecule itself is chemically identical, whether it comes from a ripe tomato or a packet of powdered MSG. The distinction lies in how the glutamate becomes 'free' and its concentration.
The Umami Powerhouse of Tomatoes
Tomatoes are famously rich in umami, and this flavor deepens as they ripen. The concentration of free glutamate increases significantly as the fruit matures, which is why a sun-ripened tomato tastes so much richer and more savory than an unripe one. This is also why tomato paste, which is concentrated and cooked, is a powerful umami booster in so many dishes. A single, ripe tomato contains naturally occurring free glutamate, a form of what is present in MSG, but it is not added monosodium glutamate.
The Aging Process and Glutamates in Cheese
Cheese is another excellent example of a food that develops its umami flavor through aging and fermentation. During the cheese-making process, bacterial cultures break down milk proteins into their constituent amino acids, including glutamate. The older the cheese, the more protein has been broken down, and the higher the free glutamate content. This is why aged cheeses like Parmesan have such an intense, savory flavor. The high concentration of free glutamate in Parmesan has even led some to jokingly call it 'basically MSG'.
The Difference: Natural Free Glutamates vs. Added MSG
The core confusion often lies in the chemical distinction and concentration. While the body metabolizes glutamate from either source identically, the source and context are different. Natural free glutamates in foods like tomatoes and cheese are part of a complex food matrix, bundled with other nutrients and compounds. Added MSG is a purified, isolated salt added as a food additive.
Comparison Table: Natural Glutamate vs. Added MSG
| Feature | Natural Glutamate (in Tomatoes & Cheese) | Added MSG (as an additive) |
|---|---|---|
| Source | Produced naturally through aging, ripening, or fermentation of proteins in whole foods. | Manufactured via fermentation of plant-based ingredients like starch or molasses. |
| Form | Occurs as a 'free' amino acid within the complex structure of the food. | Purified, crystalline powder (monosodium glutamate) that dissolves into free glutamate. |
| Concentration | Varies widely based on factors like ripeness and aging; part of the food's overall composition. | Added in controlled, smaller amounts to enhance flavor; standardized ingredient. |
| Labeling | Not required to be listed as MSG on ingredient panels. | Required to be explicitly listed as 'monosodium glutamate'. |
| Context | Ingested along with the food's natural fiber, protein, and water content. | A specific additive mixed into processed foods or used as a seasoning. |
Common Foods with Naturally High Free Glutamates
- Aged Cheeses: Parmesan, Roquefort, and aged Cheddar have particularly high levels.
- Tomatoes: Ripe, juicy, and cooked tomatoes contain significantly more free glutamate than unripe ones.
- Mushrooms: Especially dried mushrooms like shiitake, which have very high concentrations.
- Fermented Sauces: Products like soy sauce, fish sauce, and oyster sauce are rich in glutamates from fermentation.
- Cured Meats: Ham, bacon, and other cured meats undergo processes that release free glutamates.
Safety and Sensitivities
Major health and safety organizations, including the U.S. Food and Drug Administration (FDA), classify MSG as “generally recognized as safe” (GRAS). While some individuals report symptoms such as headaches or flushing, large-scale, double-blind studies have not consistently been able to trigger reactions in people who believe they are sensitive. The so-called 'Chinese Restaurant Syndrome' has been largely debunked and attributed to racist and xenophobic biases, as highlighted in a Smithsonian article. The dose required to produce mild symptoms in a small, sensitive population is typically much higher than what is found in a typical serving of food. For most people, consuming glutamate, whether from tomatoes, cheese, or added MSG, is perfectly safe and poses no risk.
Conclusion
In conclusion, tomatoes and cheese do not contain added MSG, but they are naturally abundant in free glutamate, the component responsible for MSG's savory flavor. The body does not differentiate between the glutamate found naturally in these beloved foods and the glutamate added as a flavor enhancer. The flavor-enhancing properties of dishes like pizza or tomato soup are a testament to the powerful umami taste delivered by their natural ingredients. Rather than avoiding these flavorful foods, embracing the rich, savory taste of natural glutamates can enhance your culinary experience. For further information, the FDA provides a comprehensive Q&A on monosodium glutamate.
Frequently Asked Questions
Question: Is the glutamate in tomatoes and cheese the same as in MSG? Answer: The glutamate molecule is chemically identical whether it comes from natural sources like tomatoes and cheese or from manufactured MSG. The body metabolizes both in the same way, but the natural source contains it as part of a complex food matrix.
Question: Why do tomatoes and aged cheeses taste so savory? Answer: The intense savory flavor, known as umami, comes from high concentrations of naturally occurring free glutamates that are released as the tomatoes ripen or the cheese ages and ferments.
Question: Do foods with natural glutamate have to be labeled as containing MSG? Answer: No. Food manufacturers are only required to list 'monosodium glutamate' on the label if it has been added as a food additive. They are not required to specify that ingredients like tomatoes or cheese naturally contain glutamate.
Question: Does cooking tomatoes increase their glutamate content? Answer: Yes, cooking tomatoes, such as in a sauce, concentrates their ingredients and helps to release more free glutamate, which intensifies their natural umami flavor.
Question: Is it healthier to get glutamate from natural foods instead of added MSG? Answer: The glutamate molecule itself is handled identically by the body. However, natural foods like tomatoes and cheese provide additional nutrients like vitamins, minerals, and protein, which are not present in the isolated additive.
Question: What is the real difference between natural glutamate and manufactured MSG? Answer: The primary difference is the source and concentration. Natural glutamate is part of a complex food, while manufactured MSG is a highly pure salt added to achieve a specific flavor enhancement.
Question: Can I be sensitive to the glutamate in tomatoes or cheese? Answer: The vast majority of people can consume foods containing natural glutamate without any issue. While a very small percentage may have sensitivity, major health authorities have found no consistent evidence linking common symptoms to glutamate in the amounts typically consumed.
