RD Exam Food Science Practice Questions
Food Science makes up 3 of every 50 questions on a Tigertest RD Exam practice test. Here are 10 of the 12 questions on it, each with the answer and the reason.
Updated by the Tigertest team. Based on the CDR Registration Examination for Dietitians test specifications. Original questions; 50 per test, weighted like the real exam. Not affiliated with the Commission on Dietetic Registration.
1. Starch granules swell and thicken a sauce as it is heated in liquid. What is this process called?
- A.Denaturation
- B.Gelatinization
- C.Retrogradation
- D.Caramelization
Answer: B. Gelatinization is the swelling of starch granules with water and heat, which thickens the liquid. Retrogradation is the later re-forming of starch crystals that causes staling and weeping.
2. A seared steak browns because amino acids react with reducing sugars. What is this reaction?
- A.Enzymatic browning
- B.Hydrogenation
- C.Caramelization
- D.Maillard reaction
Answer: D. The Maillard reaction between amino groups and reducing sugars creates the browned color and flavor of seared meat and baked crusts. Caramelization involves sugar alone at higher heat.
3. Sliced apples turn brown on standing. What prevents this best?
- A.Dipping in lemon juice
- B.Cutting them with a dull knife
- C.Storing them at room heat
- D.Sprinkling them with salt water
Answer: A. Browning is caused by polyphenol oxidase. Acid and ascorbic acid in lemon juice lower the pH and slow the enzyme; cutting with a dull knife damages more cells and speeds browning.
4. Which ingredient in mayonnaise acts as the emulsifier?
- A.Sodium in the salt
- B.Water in the lemon juice
- C.Lecithin in the egg yolk
- D.Acetic acid in vinegar
Answer: C. Egg yolk lecithin has water-loving and fat-loving ends that hold oil droplets in the water phase. Vinegar adds flavor and acidity but does not emulsify.
5. Why does bread flour make a chewier product than cake flour?
- A.Less protein, more sugar
- B.A higher fat content
- C.More protein for gluten
- D.More starch for softness
Answer: C. Bread flour is higher in the proteins glutenin and gliadin, which form a strong, elastic gluten network when kneaded. Cake flour is low in protein for a tender crumb.
6. A muffin recipe using baking soda turns out bitter and soapy. What is the likely cause?
- A.Too little acid in the batter
- B.Oven heat set much too low
- C.Too little salt added
- D.Too much flour stirred in
Answer: A. Baking soda needs an acid (buttermilk, yogurt, brown sugar) to react. Without enough acid, excess soda leaves a soapy, bitter taste and a yellow color.
7. Adding a pinch of cream of tartar to egg whites before whipping does what?
- A.Lowers the volume
- B.Speeds up the yolk setting
- C.Adds sweetness
- D.Stabilizes the foam
Answer: D. The acid in cream of tartar strengthens the protein film so the foam is more stable and less likely to weep. Even a trace of fat from yolk prevents a good foam.
8. Green beans cooked a long time with a lid on turn olive-drab. Why?
- A.Salt turns beans brown
- B.Acids turn chlorophyll drab
- C.Heat turns chlorophyll red
- D.Steam adds more green color
Answer: B. Plant acids released during cooking collect under a lid and convert chlorophyll to olive-brown pheophytin. Short cooking, uncovered at first, keeps the bright green.
9. Which cooking method best keeps water-soluble vitamins in vegetables?
- A.Soaking cut pieces overnight
- B.Steaming for a short time
- C.Boiling in plenty of water
- D.Long simmering in soup
Answer: B. Water-soluble vitamins such as vitamin C and folate leach into cooking water and break down with heat. Short cooking in little or no water, as with steaming, keeps more of them.
10. Panelists are given three samples, two alike and one different, and asked to pick the odd one. Which sensory test is this?
- A.Paired preference
- B.Ranking test
- C.Hedonic scale
- D.Triangle test
Answer: D. The triangle test is a difference test showing whether people can tell two products apart. A hedonic scale measures how much people like a product.
Practice all 12 food science questions, and the rest of the 200-question bank, in the free RD Exam training sets. Questions you miss come back until you have mastered them.
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