Light and processing effects on proteins, lipids, carbohydrates, carotenoids, vitamin C, and on plastid ultrastructure of Phaseolus aureus Roxb. (mung bean) seedlings

Abstract

1. EM and Nutrient Studies of Light-Treated Etiolated Mung Bean Seedlings. The prolamellar bodies of leaf plastids of 4-day-old dark-grown mung bean seedlings were gradually being converted to grana membranes, and after 8 h of a 24 h illumination period this conversion was complete. In parallel studies, an increase in nutrients was observed mostly after 6 h illumination. By the end of 24 h, total lipids, total available carbohydrates and total proteins showed a marked increase compared to those of dark-grown seedlings. Carotenoids, on the other hand, started to increase after 1 h illumination, and chlorophylls, which were absent from etiolated seedlings, showed an immediate increase on exposure to light. The vitamin C content of seedlings did not change significantly with light. Twenty simple and complex lipids, three free sugars, seventeen amino acids and seven carotenoids were identified in etiolated and greened seedlings. 2. Nutrient Studies of Processed Mung Bean Seedlings Stored at Three Temperatures. Blanching of dark-grown mung bean seedlings prior to packing them into jars and cans had a marked effect on vitamin C, on total available carbohydrates, on free sugars and on starches and dextrins, whereas total proteins and amino acids were not severely affected by the blanching process; lipids and carotenoids were only slightly affected. The blanched seedlings were packed in jars and in cans. Bottled (jars) seedlings were stored for six months under three temperatures: 10°C, room temperature (RT) and 35°C, while canned seedlings were stored for the same period at RT only. Generally speaking, the seedlings packed in jars and kept at 35°C sustained the most losses in nutrients, while the seedlings kept at 10°C retained the most. There were no marked differences in nutrients of bottled and canned seedlings stored at RT.