Learn what happens to the tangy flavor of your curd as it sits in the fridge for a long time. Discover how the culture changes over time.
1 Answer
Curd loses its tang over time due to the continued activity of lactic acid bacteria, which convert lactic acid (the source of the tang) into other, less acidic compounds. This process gradually reduces the overall acidity and diminishes the sour taste.
Detailed Explanation:
The characteristic tangy flavor of curd, also known as yogurt, comes from lactic acid produced by lactic acid bacteria during fermentation. These bacteria, such as *Lactobacillus* and *Streptococcus* species, consume lactose (milk sugar) and convert it into lactic acid. This acid lowers the pH of the milk, causing the milk proteins to coagulate and form the thick, creamy texture of curd.
However, even after the curd is set and refrigerated, the lactic acid bacteria remain active, albeit at a slower rate due to the lower temperature. Over time, these bacteria continue to metabolize lactic acid. Some bacteria may convert lactic acid into other compounds, such as acetoin and diacetyl, which have a less acidic or even buttery flavor. Additionally, some lactic acid may be further broken down into other, less tangy substances. This gradual reduction in lactic acid concentration leads to a decrease in the overall acidity and a corresponding loss of the characteristic tangy flavor. The longer the curd is stored, the more pronounced this effect becomes.
Pro Tip:
To preserve the tangy flavor of curd for longer, store it in an airtight container in the coldest part of your refrigerator. This helps to slow down the metabolic activity of the lactic acid bacteria and minimize the conversion of lactic acid.