A Study of Beta-Carotene Stability in Processed Vitamin A-Rich Foods
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Date
1995-12
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University of Ghana
Abstract
Vitamin A deficiency (VAD) is a public health problem in Ghana, leading to blindness. Year-round access to Vitamin A rich foods will curb its incidence. This study sought to identify appropriate processing, preservation and fortification methods to enhance E-carotene retention in foods towards VA alleviation. Carrots were steamed, blanched in water, NaHS03, NaCl or alkali rock salt (Kanwa) solutions. Amaranthus and Xanthosoma leaves were blanched in a range of kanwa solutions (0-0.1%) at varied temperatures (85-100°C) and time (4-10 min). The effect of the treatment and storage time (0-90 days) of the samples was studied by determining the S-carotene using HPLC. Ecarotene degradation in palm oil was evaluated at 100-200°C for0-240 min. Carrots and palm oil were incorporated into gari at0-20% by co-fermenting or fermenting before addition. Ecarotene stability was predicted with mathematical models during processing and storage. Highest E-carotene retention occurred in oven-dried NaCl, NaHS03 and kanwa treated carrots (22.9-65.6%) after storage. Kanwa blanching improved carotene retention during dehydration and storage of Amaranthus and Xanthosoma. Solar dried products had longer E-carotene half-lives (T1/2) than oven dried. High heating temperatures caused complete loss of E-carotene and color. Thermal degradation rates of 3.9-99.7 x 10"3 min'1 and an activation energy (EJ of 4.8 Kcal/mole in palm oil were calculated. Gari products fortified with carrots and palm oil had 13-28 and 11-20 mg/lOOg E-carotene respectively. Ecarotene losses occurred during fermentation (5-57%) and roasting (30-60%).The rate of E-carotene loss was slower in co-fermented products during storage. NaCl and kanwa could be used in the preservation of carotene in carrots. Carrot and palm oil fortification of gari improved its vitamin A and organoleptic properties. The use of palm oil in deep-fat frying is not recommended. Degradation kinetics and response surface plots generated from predictive models could establish the relationships between processing factors and E-carotene retention.