Final answer:
The artificial sweetener composed of two amino acids that is not heat stable is aspartame. Aspartame is suitable for cold foods and drinks but not for baking or cooking due to its instability when heated. Other sweeteners like sucralose, saccharin, and acesulfame K do not have this issue and are heat stable.
Step-by-step explanation:
The artificial sweetener composed of two amino acids that is not heat stable is aspartame. Aspartame is a methyl ester of the dipeptide of the amino acids aspartic acid and phenylalanine. It is approximately 180 times sweeter than sucrose and is often used as a sugar substitute in various foods. However, aspartame is not used in baked goods or exposed to high temperatures because it is not heat stable. In comparison, other sweeteners such as sucralose, saccharin, and acesulfame K are heat stable. Sucralose is especially known for maintaining its sweetness even when used in baking.
It is important to note that aspartame can be metabolized into methanol and eventually formaldehyde, which has been a subject of controversy concerning safety. The risks associated with aspartame consumption are most pronounced in individuals with the genetic disorder phenylketonuria (PKU), who cannot properly metabolize phenylalanine.