SOME FRUITS OF HAWAII 



57 



like manner yielded a value of 0.015 per cent calcium. The juice for 

 analysis was passed through a copper sieve of 10 mesh to the inch, a 

 size comparable to household orange juice strainers on the market. 



A personal communication from C. Chatfield of the food composition 

 section of the Bureau of Home Economics, U.S.D.A., states that reports 

 filed in their office indicate that the calcium content of oranges and 

 orange juice varies greatly. 



It is highly probable that the calcium content of oranges and orange 

 juice may be affected by a number of factors such as variety, soil and 

 fertilizer. Our analyses would indicate that the quantity of membran- 

 ous material included in the juice is also an important factor. 



Oranges are a fair source of vitamins A, B, and G and an excellent 

 source of vitamin C. Hawaiian oranges have not been tested for their 

 vitamin A, B, and G content ; but results of experiments summarized in 

 Tables 10 and 14 show that they are excellent sources of vitamin C. 



Our tests were made over a short period when the local oranges 

 were available so that we found no differences in the vitamin C values. 

 However, Nelson and Mottern (41) have reported variations in the 

 vitamin C content of fresh oranges and we have some evidence of varia- 

 tions in the vitamin C content of guavas. 



Juice made from Hawaiian oranges, like that made from oranges 

 grown elsewhere, develops a bitter flavor on standing a few hours. The 

 cause of this bitter taste has been investigated by Traub and co-workers 

 (67) in Florida. As the result of extended experiments, they con- 

 cluded that the bitter taste which develops in prepared citrus juices is 

 due to the glucosides contained in certain portions of the fruit, espec- 

 ially the white inner peel and the membranes surrounding the sections. 

 They also concluded that enzymes of the fruit were not concerned in 

 the development of the bitter flavor. Their experiments showed that 

 the bitter flavor of the juices tended to decrease with the maturity of 

 the fruit used, which they state is in harmony with the fact that the 

 glucoside content of citrus fruits decreases with maturity. 



Hawaiian oranges are commonly used with little or no previous stor- 

 age, a practice which accounts in part for the fact that juice from some 

 Hawaiian oranges seems to develop more bitter flavor than oranges from 

 the mainland. We have also found that the juice from some varieties of 

 oranges grown in Hawaii develops a bitter taste much more quickly than 

 others. Juice from some Hawaiian seedlings had a slightly bitter taste 

 half an hour after extraction by the usual household methods and a 

 decidedly bitter taste after 1 hour. On the other hand, juice from 

 Navel oranges grown at the Station showed no bitter flavor after almost 

 2 hours. 



Supply: The oranges, grown principally in the Kona region on 

 Hawaii, have not previously been in great demand because of the 

 quality and appearance, very little grading being done for market. Plans 

 are being perfected (1935) to improve the marketing of Hawaiian 

 oranges by sorting them to conform to standard sizes and grades, and 

 by ripening with ethylene gas, a practice used on the mainland for many 

 years. The supply of first quality oranges is less than the demand. They 

 are in season during October, November and December. 



