A Study Of Beta-Carotene Stability In Processed Vitamin A-Rich Foods

ABSTRACT

Vitamin A deficiency (VAD) is a public health problem in

Ghana, leading to blindness. Year-round access to Vitamin Arich

foods will curb its incidence. This study sought to

identify appropriate processing, preservation and fortification

methods to enhance E-carotene retention in foods towards VAD

alleviation.

Carrots were steamed, blanched in water, NaHS03, NaCl or

alkali rocksalt (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 for

0-240 min. Carrots and palm oil were incorporated into gari at

0-20% 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

colour. 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.