Question

The bloom strength is directly proportional to:

• A. Measure of the strength and stiffness of the gelatin
• B. Density
• C. Molecular weight
• D. Viscosity

Answer 1

The Correct Option is C

The correct option is (C): Molecular weight.

Answer 2

Bloom strength is a standard measure used to grade gelatin, and the question asks what physical property of the gelatin actually drives that strength upward or downward. Let's weigh each option.

1. Measure of the strength and stiffness of the gelatin: This phrase describes what bloom strength itself is, the gel's resistance to deformation under a fixed load, rather than a separate property it is proportional to. It restates the definition instead of answering what causes it, so it cannot be the answer to a "directly proportional to" question.
2. Density: The bulk density of dry gelatin granules is mostly a manufacturing and packing characteristic and has no established direct relationship with the strength of the gel network the gelatin forms once hydrated.
3. Molecular weight: Gelatin gels form through partial reassembly of collagen-like triple helices between polypeptide chains. Longer chains, meaning higher average molecular weight, create more cross-linking points and a tighter three-dimensional network, which raises the bloom strength. Manufacturers control gelatin's molecular weight distribution specifically because it is the main lever for tuning bloom value.
4. Viscosity: Viscosity of a gelatin solution is influenced by molecular weight too, but it measures resistance to flow in the liquid sol state, not the strength of the set gel. The two properties often move together but bloom strength is defined and standardized independently of solution viscosity.

Because longer gelatin chains build a denser gel network capable of resisting more load before deforming, bloom strength rises directly with molecular weight.

The correct answer is Molecular weight.