Questão de Natural Sciences and their Technologies #019e354b
Uma agricultora, com a intenção de comercializar o milho recém-colhido, testou uma forma de preservar o sabor adocicado do seu produto. O melhor resultado foi obtido quando ela imergiu as espigas em água fervente durante alguns minutos e, em seguida, em água gelada. Com esse procedimento, parte da glicose do milho não foi transformada em amido, mantendo o seu sabor adocicado.
Using this procedure, the flavor was preserved because there was
Enzymatic denaturation by high temperature.
nutrient conversion through temperature reduction.
Degradation of nutrient reserves due to thermal shock.
Preventing oxygen from entering through boiling water.
Dehydration of the grains due to temperature changes.
Explicação Oficial / Explicações da Comunidade
Analysis of Sweet Corn Conservation
The correct answer is option A. A) Enzymatic denaturation by high temperature.
1. The Biochemical Process in Corn
After harvesting, sweet corn begins to lose its characteristic flavor rapidly. This occurs due to a natural biochemical process:
- Sugars (Glucose): They are responsible for the sweet taste. * Starch: It is a storage polysaccharide, without a sweet taste, into which sugars are converted. * Enzymes: This conversion of sugar (glucose) into starch is a chemical reaction catalyzed by enzymes Enzymes are proteins that accelerate biological reactions, present within the corn kernel itself.
For an enzyme to function, it needs to maintain its specific three-dimensional structure, known as its native form.
2. The Effect of the Farmer's Procedure
The method used by the farmer directly interferes with the activity of these enzymes:
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Immersion in Boiling Water (High Temperature): This is the crucial step. The high temperature of the boiling water causes... denaturation of enzymes. Denaturation is the process by which proteins lose their complex three-dimensional structure due to heat, extreme pH, or other factors. A denatured enzyme loses its shape and, consequently, its function. It becomes permanently inactiveBy denaturing the enzymes responsible for converting sugar into starch, the reaction is interrupted, and glucose is preserved.
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Immersion in Ice Water (Thermal Shock): This step serves to quickly interrupt the cooking process. If the ears of corn remained hot, the heat would continue to cook the kernels, altering their texture and flavor in other ways. Rapid cooling ensures that only enzymatic inactivation occurs, preserving the desired texture.
3. Evaluation of Other Alternatives
- B) Conversion of nutrients by reducing the temperature: Incorrect. Lowering the temperature (ice water) slows down the chemical reactions, but it doesn't cause the "nutrient conversion" that would preserve the sugar. Preservation occurred in the previous step, with the heat. * C) Degradation of nutrient reserves due to thermal shock: Incorrect. The objective and the result of the process are the preservation of glucose, not its breakdown. * D) Preventing oxygen from entering by boiling the water: Incorrect. Although boiling reduces the amount of dissolved oxygen in the water, the conversion of glucose to starch is an internal anabolic process of the grain that does not directly depend on external oxygen. The main factor that prevents the reaction is the inactivation of the enzyme by heat. * E) Dehydration of the grains due to temperature changes: Incorrect. The process involves immersing the ears of corn in water, which causes hydration, not dehydration.
4. Conclusion
The success of the procedure lies in the use of high temperature (boiling water) to cause the enzymatic denaturationBy permanently inactivating the enzymes that convert sugar into starch, the sweet taste of corn is effectively preserved.