Retinol and beta carotene content of indigenous raw and home-prepared foods in Northeast Thailand

Abstract

Retinol and β-carotene contents of raw and home-prepared indigenous foods in Northeast Thailand were studied. The criteria used to select the vitamin A-rich foods were high retinol or β-carotene contents of the individual food items, the amount and frequency of consumption, preference of consumption and food availability. Items selected were chicken liver, chicken egg, ivy gourd, amaranth, swamp cabbage (Chinese), Chinese cabbage, pumpkin, yellow sweet potato and two traditional menu items, kang-nho-mai and om-kruang-nai-kai. Raw food items were purchased from the local market; the traditional cooking procedures of the community were duplicated in the laboratory. Retinol and β-carotene contents were determined prior to and following cooking using HPLC methodology. The results indicated that boiling intact chicken liver resulted in 5% loss of retinol; boiling with cutting into small pieces and grilling resulted in losses of 8 and 16%, respectively. Greater losses (43%) were observed for egg omelet compared to hard-boiled egg (11%). For vegetables, blanching resulted in 7-11% loss of β-carotene, while steaming, frying and boiling showed losses of 15, 18 and 43%, respectively. Traditional foods such as bambooshoot soup (Kang-nho-mai) and chicken organ soup (Om-kruang-nai-kai) exhibited β-carotene losses ranging from 6-21%. Copyright (C) 1998 Elsevier Science Ltd.