Fresh pineapple contains the enzyme bromelain that hydrolyzes peptide bonds in proteins.
<IMAGE>
a. The directions for a gelatin (protein) dessert say not to add fresh pineapple. However, canned pineapple where pineapple is heated to high temperatures can be added. Why?

Verified step by step guidance

1. Understand the problem: The question is asking why fresh pineapple cannot be added to a gelatin dessert, but canned pineapple can. This involves understanding the role of the enzyme bromelain and how it interacts with proteins in gelatin.
2. Step 1: Recall that bromelain is an enzyme found in fresh pineapple. Enzymes are biological catalysts that speed up chemical reactions, and bromelain specifically hydrolyzes (breaks down) peptide bonds in proteins.
3. Step 2: Gelatin is a protein derived from collagen. When gelatin is dissolved in water and cooled, it forms a gel-like structure due to the interaction of its protein molecules. If bromelain is present, it will hydrolyze the peptide bonds in gelatin, breaking down the protein structure and preventing the gel from forming.
4. Step 3: Canned pineapple is heated during the canning process. High temperatures denature enzymes, which means the bromelain in canned pineapple is inactivated. Denaturation alters the enzyme's structure, rendering it unable to catalyze the hydrolysis of peptide bonds.
5. Step 4: Since the bromelain in canned pineapple is denatured, it cannot break down the proteins in gelatin. This is why canned pineapple can be added to a gelatin dessert without affecting its ability to set, while fresh pineapple cannot.

Key Concepts

Bromelain

Bromelain is a proteolytic enzyme found in fresh pineapple that breaks down protein molecules by hydrolyzing peptide bonds. This enzymatic activity can prevent gelatin from setting properly, as it disrupts the protein structure necessary for the gelatin to solidify.

Gelatin

Gelatin is a protein derived from collagen, commonly used as a gelling agent in food products. It requires a specific temperature and pH to form a stable gel. The presence of bromelain in fresh pineapple can interfere with this process, leading to a failure in achieving the desired texture in gelatin desserts.

Heat Treatment

Canned pineapple undergoes heat treatment during processing, which denatures the bromelain enzyme, rendering it inactive. This means that when canned pineapple is added to gelatin, it does not affect the gelling process, allowing the dessert to set properly without the interference of the enzyme.