Is yellow garlic safe to eat? (Effects of garlic color)

In this brief article, we are going to answer the question “Is yellow garlic safe to eat?”. We will discuss what factors affect garlic color and the health benefits of garlic

Is yellow garlic safe to eat?

Yes, yellow garlic is safe to eat. Despite consumers typically favoring creamy-white garlic, a yellow hue is not a sign of spoilage but it means that the garlic is not as fresh anymore. During distribution and sale, unfavorable changes in color can be linked to a decline in the quality of processed garlic.

When pre-peeled and chopped, garlic becomes susceptible to enzymatic browning. This browning can be attributed to the oxidation of polyphenols, such as pyrogallol and gallic acid, transforming into quinonic compounds due to the activity of polyphenol oxidase. This enzymatic process leads to a shift in color from creamy white to dark yellow or brown.  (1)

How does color change affect garlic?

Garlic color can include raw, yellow, red, and black garlic. By controlling the degree of ripening and temperature, the desired color of processed garlic can be obtained.

Depending on the degree of processing, there are differences not only in color but also in physical properties, flavor, and physiological activity, and there are also differences in economic feasibility such as processing time and production costs. 

The production process for yellow garlic is simpler compared to that of red and black garlic, resulting in a color that leans more toward yellow. The Alliin content of yellow garlic has no difference compared with fresh garlic, whereas the S-allyl cysteine content of yellow garlic was higher than that of fresh garlic.

Red garlic also requires a shorter processing time than black garlic, showing intermediate activity levels between raw and black garlic. Black and red garlic varieties have higher antioxidant levels than raw garlic, red garlic water extract has superior anti-inflammatory properties in comparison to both raw and black garlic water extract. (2)

How to prevent undesirable changes in garlic?

Undesirable color changes can be mitigated using methods such as heat treatment and adjustments to pH levels. Garlic discoloration is attributed to polyphenol oxidase, which is responsible for the formation of brown compounds through oxidative polymerization of quinones.

Peeling the cloves exposes them to the environment, which can lead to unwanted alterations in quality. These changes include a rapid browning that can progress from yellow to brown. 

Heat inactivation of these enzymes is crucial for preserving the natural color of the raw garlic material before any further processing. Nonetheless, it’s worth noting that prolonged hot water blanching can introduce a range of unfavorable modifications to the garlic, including the loss of color, flavor, and texture. (3)

What are the health benefits of garlic?

Garlic species and their active constituents are known to reduce the risk of diabetes and cardiovascular ailments, enhance immunity against infections, and exhibit antimicrobial, antifungal, anti-aging, and potential anti-cancer properties.

Garlic, in particular, offers therapeutic benefits, including the management of lung disorders, whooping cough, stomach ailments, colds, and earaches, and the prevention of cardiovascular diseases.

Many of garlic’s health-promoting properties are linked to its organosulfur compounds, with thiosulfates being particularly noteworthy.

Diallyl thiosulfate, also known as allicin, stands out as one of the most potent compounds in garlic. It is recognized for its antimicrobial, anti-inflammatory, antithrombotic, and antiatherosclerotic attributes. Furthermore, allicin is associated with the ability to lower serum lipid levels and blood pressure. (4, 5)

How to store garlic?

Garlic bulbs intended for consumption are traditionally stored at temperatures between 25-30°C with a relative humidity (RH) of 70-80%. This method typically results in a weight loss of approximately 21-25% over a 3-month storage period. Lowering the storage temperature effectively slows down the metabolic processes and extends the garlic’s shelf life.

Additionally, it serves as a deterrent to the growth of unwanted microbes. Storing garlic at temperatures of -1 to 0°C, with an RH of 60-70%, can significantly prolong its shelf life to over 9 months. Garlic is customarily subjected to a curing process, which involves drying the neck and outer skin layer of the bulbs.

Curing serves several purposes, including the healing of bulb skin injuries incurred during harvesting, reducing moisture loss, and safeguarding against microbial infestations during storage. A well-executed curing process helps preserve the quality, flavor, and bioactive components of garlic while extending its overall shelf life. (6)

Conclusion

In this brief article, we answered the question “Is yellow garlic safe to eat?”. We also discussed what factors affect garlic color and the health benefits of garlic. Through my studies on this topic, I was able to conclude that the yellow color is the product of oxidative activity in the garlic and that, the yellow color may indicate a loss in quality, but it doesn’t make garlic unsafe to eat.

References