flushes each yields.
603. Upon what does the quality and grade of tea depend? 604. Give
differences in the preparation and composition of green and black teas.
605. The characteristic flavor of tea is imparted by what compound? 606.
To what compound are its peculiar physiological properties due? 607.
What can you say of the protein in tea as to amount and food value? 608.
Why should tea--especially green tea--be infused for a very short time,
never boiled? 609. What effect has tannin upon the digestion of
proteids? 610. What three points are considered in judging a tea? 611.
What is the most common form of tea adulteration? 612. Describe the
coffee plant and fruit, and its method of preparation for market. 613.
What is the difference in the chemical composition of tea and coffee?
614. Name the characteristic alkaloid of coffee. How does it compare
with theme? 615. Why may coffee not be considered a food? 616. Tell
different ways in which coffee may be adulterated. 617. Which is more
commonly practiced, tea or coffee adulteration? Why? 618. How may real
coffee be distinguished from chicory? Why? 619. Name the three kinds of
coffee in general use. Give distinguishing features of each. Which is
usually considered best? 620. From what are cocoa and chocolate
obtained? 621. Give the two methods of preparing cocoa. 622. What
alkaloid similar to the theme and caffeine of tea and coffee is present
in cocoa and chocolate? 623. What is the difference in preparation of
cocoa and chocolate? 624. What are cereal coffee-substitutes? 625. What
nutritive value have they? 626. How do they differ in composition from
coffee? 627. To what extent does cocoa add to the nutritive value of a
ration? 628. What is plain chocolate? 629. Why do chocolate preparations
vary so widely in composition? 630. What treatment is given to the cocoa
bean in its preparation for commerce? 631. What treatment is sometimes
given to prevent separation of the cocoa fat? 632. In what ways may
cocoa and chocolate preparations be adulterated?

CHAPTER XV

DIGESTIBILITY OF FOODS

633. Define the term nutrient. 634. Do all the nutrients of food have
the same degree of digestibility? 635. What is a digestion coefficient?
636. How is the digestibility of a food determined? 637. What volatile
products are formed during the digestion of food? 638. Define digestible
protein; digestible carbohydrates, digestible fat. 639. What is the
available energy of a ration? 640. H