Learn what causes curd to sometimes develop a sweet smell right before it spoils. Discover the chemical changes happening during fermentation.
1 Answer
Curd smells sweet before spoiling due to the lactose (milk sugar) being broken down into simpler sugars like glucose and galactose by bacteria. These simpler sugars have a sweeter aroma.
Detailed Explanation:
The process of curd formation involves bacteria, primarily lactic acid bacteria, fermenting lactose. Initially, as the bacteria multiply, they actively break down lactose into lactic acid, which gives curd its characteristic sour taste. However, before the curd completely spoils, the bacteria also produce enzymes that further break down lactose into simpler sugars like glucose and galactose. These simpler sugars are naturally sweeter than lactose, leading to a temporary sweet smell. This sweet smell is a sign that the lactose is being converted, but it also indicates that the bacterial activity is increasing, and the curd is nearing its spoilage point. As spoilage progresses, other bacteria and molds may take over, leading to the production of undesirable compounds that cause foul odors.
Pro Tip:
While a slightly sweet smell might be present initially, always check for other signs of spoilage like mold growth, discoloration, or a drastically changed texture before consuming curd. Trust your senses and err on the side of caution!