Development of Vitamin A During Ripening of Tomatoes.

Abstract

In the progress of an inquiry into the conditions under which vitamin A is developed in plants a comparison was made of the vitamin A content of tomatoes ripened under various conditions. The tomatoes were of the variety called San Jose Canner and were supplied us by J. T. Rosa of the University Farm, Davis, California. They were plucked from the vines when green but completely matured, and were divided into 6 lots. One lot, designated lot 1, was ground at once, placed in small air tight glass jars fitted with outlet and inlet glass tubes, the air from which was evacuated and released with carbon dioxide 4 or 5 times. The jars were then stored at 17 degrees below zero centigrade. This process of preparation and storage was used to ensure as much freedom from oxidation as possible during the testing period. The other lots of tomatoes were similarly treated after being ripened as follows: lot 2, ripened in diffused light; lot 3, ripened in the dark; lot 4, ripened in ethylene, 1:2000 parts for 1 week 1 ; lot 5, ripened in the dark except for 3 periods of ultra-violet irradiation of 30 minutes each at 12 inches distance from the arc. Temperature, ventilation and humidity were kept constant during ripening for all lots, a precaution indicated by the work of Duggar. 2 In addition lot 6 was later taken from the vines in the ripened condition. An attempt was made to allow all specimens of the fruit to ripen to a uniform color by comparison with Tallquist hemoglobin standards, but the results were not satisfactory since all the tomatoes with the exception of lot 4, showed varied degrees of redness in different parts of the same fruit. The ethyleneripened specimens, lot 4, were uniformly colored a deep red, the tint of the deepest colored portions of the other fruits. The ripening period occupied 10 days in diffused light, 19 days in the dark, 7 days in ethylene, and 27 days for the ultra-violet treated lot. The oxidase contents of all specimens were determined but these were found to exhibit no significant differences.