8 MASS. EXPERIMENT STATION BULLETIN 440 



Table 4. — Uronic Acid Value of Some Apple Varieties and Other Fruits 



(Manville, 1936b) 



Uronic Acid 

 Variety per Gram of Fruit 



milligrams 



Arkansas Black 10.6 



Baldwin 9.8 



Delicious 11.8 



Gravenstein 7.3 



Jonathan 8.5 



Rome Beauty 13.3 



Spitzenberg 12.1 



\\inesap 13.9 



Winesap juice 5.4 



Yellow Newtown. 16.5 



Lemon juice filtered 2.0 



Orange juice filtered 4.0 



Tomato juice filtered _ 2.0 



Kobren, Fellers, and Esselen (1939) investigated the effect of adding pectin to 

 the diet of vitamin A-deficient rats in order to observe its vitamin A-sparing 

 action. It is generally recognized that xerophthalmia and the keratinization of 

 the mucous epithelium of the body are due in part to a deficient synthesis of 

 mucin, occurring as a result of dehydration of the mucous membranes. From 

 this investigation, pectin appeared to be a beneficial supplement to a diet de- 

 ficient in vitamin A only insofar as pathological changes due to avitaminosis A in 

 the vagina, nares, and eyelids are concerned. 



The effectiveness of raw apples in the treatment of diarrhea is attributed largely 

 to their pectin content, as will be discussed more fully later. 



Minerals 



The apple contains approximately 0.25 to 0.36 percent of ash. The approximate 

 composition of the ash of the edible portion of the apple as compared with other 

 fruits is shown in Table 5. Although apples cannot be considered an important 

 source of minerals, they are comparable to other fruits in this respect, and their 

 liberal use in the diet does contribute definite amounts of these specific nutrients. 



The iron, phosphorus, and calcium in the apple have been reported to be highly 

 available and fully utilized by the human body. Moreover, the preponderance 

 of base-forming elements makes the apple an efficient agent in reducing the acid 

 output. The principal base-forming elements in apples are potassium, sodium, 

 calcium, and magnesium, of which potassium occurs in the greatest quantity'. 



In addition, it is of interest to note that apples contain traces of iodine.^ The 



2 The estimated daily requirement of humans for iodine is about 0.002 to 0.004 milligram a day 

 for each kilogram of body weight- This amounts to about 0.15 to 0.30 milligram daily for the 

 adult. Iodine is especially important in adolescence and pregnancy. (U.S. National Research 

 Council, 1945.) 



