Why do many spices lose their characteristic flavour and aroma when they are subjected to prolonged boiling during cooking?

Introduction:
Spices are widely used in cooking to enhance flavour and aroma. However, experienced cooks know that if spices are boiled for too long, much of their characteristic smell and taste is lost. This question tests your understanding of the underlying reason for this loss of flavour and asks you to distinguish the correct explanation from distractor statements related to pickles and colouring.

Given Data / Assumptions:
- The observation is that spices deteriorate or lose flavour after prolonged boiling. - Options mention evaporation of essential oils, use of spices in pickles and combinations of these statements. - We assume typical culinary practices where spices are added to hot dishes. - The term essential oils refers to volatile aromatic compounds in spices.

Concept / Approach:
The strong aroma and taste of spices such as cloves, cardamom, cumin and others are due to volatile essential oils present in them. These oils are sensitive to heat and can evaporate easily when exposed to high temperatures for extended periods. When spices are boiled for too long, a large portion of these essential oils vaporises and escapes into the air, leaving the food with a much weaker flavour. The statement about spices being put in pickles simply to add flavour is true in a general sense but does not explain why flavour deteriorates with boiling. Therefore, the correct option focuses on the evaporation of essential oils.

Step-by-Step Solution:
Step 1: Identify the key property of spices that gives them their characteristic aroma and taste, which is the presence of essential oils. Step 2: Recall that essential oils are volatile compounds, meaning they vaporise at relatively low temperatures compared with many other food components. Step 3: Understand that prolonged boiling involves continuous heating and exposure to steam, which encourages these volatile oils to evaporate. Step 4: Once the oils evaporate, they are no longer present in sufficient amounts in the food, leading to a noticeable loss of flavour and aroma. Step 5: Compare the options and see that only the statement about evaporation of essential oils directly explains the deterioration of spices during prolonged boiling.

Verification / Alternative check:
Cookery science references and food technology texts explain that delicate herbs and spices are often added near the end of the cooking process to preserve their volatile aroma compounds. They also note that strong boiling or frying can cause essential oils to break down or evaporate. In contrast, the role of spices in pickles is to provide flavour, aroma and sometimes preservative effects, but this is not the reason for flavour loss during boiling. Therefore, option A correctly describes the mechanism, while the other options either mix unrelated facts or add no explanatory value.

Why Other Options Are Wrong:
Because spices are always put into pickles only to add colour and not for flavour: Incorrect and incomplete. Spices are used for flavour, aroma and sometimes preservation, and this statement does not address boiling at all. Both statements A and B are correct: Only statement A directly explains the deterioration of spices due to heat; statement B is not an accurate or sufficient explanation. None of the above statements is correct: This is wrong because statement A accurately describes the role of volatile essential oils.

Common Pitfalls:
A common misunderstanding is to think that flavour is lost because spices dissolve completely or because boiling destroys all their chemical components. While some chemical breakdown can occur, the main issue for many spices is evaporation of volatile oils. Another pitfall is choosing a combined statement like both A and B without checking whether both parts are logically connected to the question. Always focus on the option that directly explains the observed change in flavour under the given conditions.

Final Answer:
Spices lose much of their flavour after prolonged boiling mainly because The essential oils responsible for flavour and aroma evaporate easily on prolonged heating.