Modelling beta-carotene Retention in three Nigerian palm oil soups

Background: Pre-heating of crude palm oil during the preparation of soups is a common practice in Nigeria, used to enhance flavour and taste. However, it leads to degradation and loss of pro-vitamin A carotenoids.Objective: The study modelled the effect of pre-heating and cooking on beta-carotene retention in commonly consumed palm oil soups in Ibadan North LGA in Nigeria.Methods: Seventy-five people participated in a quantitative dietary recall, and 60 participants were selected based on their frequent consumption of palm oil soups. Three most-frequently consumed palm oil soups – egusi (melon soup), efo-riro (vegetable soup) and obe ata (palm oil stew) were selected from 15 palm oil dishes recalled by participants. Retention of beta-carotene in the composite soups was calculated using an exponential decay model (model I) at 190°C for the pre-heating phase of palm oil and a polynomial model (model II) for the cooking phase of the soups. Beta-carotene retention in palm oil was calculated experimentally by simulating the pre-heating process and measuring beta-carotene concentrations at 5 minutes, 15 minutes and 30 minutes. Beta-carotene content of soup ingredients was calculated using nutrient values from the West African Food Composition Database, while considering the yield factors for each soup.Results: Seventy-eight percent, 82%, and 91% of carotenoid loss was estimated for egusi, efo-riro, and palm oil stew respectively, corresponding to 13,822 μg/100g, 12,297 μg/100g and 5,880 μg/100g of betacarotene retained in the soups respectively.Conclusion: Pre-heating of palm oil contributed mostly to carotenoid loss. Caution should be taken when preheating of palm oil to minimize nutrient loss.