Studies on the Usage of Tropical Fruits in Okinawa (Part 1)

Characteristics and Chemical Composition of Guava

Abstract

A comparison was carried out of the physical characteristics of chemical components among four varieties of ripened guava fruit, and of the effects of heat processing on the ascorbic acid content of one variety of fruit.
The hardness of the fruit varied from 0.67 (Taiwan round white) to 1.60 kg/cm² (Taiwan pearshaped white). Both Taiwan varieties yielded more purée per unit weight than the other varieties, namely 83.33 (round) and 84.34% (pearshaped). Hawaiian pink showed the highest acidity, 1.01% as citric acid, and the lowest Brix/acidity ratio, 10.89. Taiwan round white contained the largest amount of ascorbic acid, 270.32 mg%.
The total ascorbic acid contents in the peel, flesh and core were determined for Okinawan pink, the peel showing a high of 125.54 mg%, followed by the flesh (61.25 mg%) and core (59.03 mg%). The highest acidity was found in the peel, and the Brix/acidity ratio was the highest in the core.
The effect of heat treating the purées on the ascorbic acid content was determined at 104°C. Ascorbic acid in the heat treated puree was retained as 42.24% of the original total ascorbic acid content. This high heat resistance indicates that guava jam offers more advantage as a source of ascorbic acid than strawberry jam (1.7 times higher value).