Influence of baking temperature and time on beta-carotene contents of baked sweet potatoes

Abstract

The influence of baking temperatures and time on carotene contents of baked TNG66 sweet potatoes were successfully evaluated. Because TNG66 sweet potatoes had orange flesh, they are a good food source of carotenes. The goal of this study was to evaluate the influence of baking process on the degradation of beta-carotenes. An UV analytical method was designed to measure the total beta-carotene content of baked sweet potatoes, while a HPLC method was used to measure the all-trans-beta-carotene. When baking temperatures were lower than 100 degrees C, the total carotene content was not significantly affected by increasing the baking temperature. With 30 min of baking, the total carotene content reached the highest level at 150 degrees C of baking. However, the all-trans-beta-carotene content was not significantly increased with increasing the baking temperature. When the baking temperature was 200 degrees C, the carotene content initially increased with increasing baking time. After 30 min of baking, the carotene content decreased. Higher baking temperatures and longer baking time caused the degradation of beta-carotenes. Two carotene isomers, including 9-cis-beta-carotene and 13-cis-beta-carotene, were formed during the thermal process of making baked sweet potatoes. The baked TNG66 sweet potatoes mainly contained all-trans-beta-carotene which reached the highest level of 29.82 mg/g with 50 min of baking. The UV analytical method was originally designed to measure the total beta-carotene content of baked sweet potatoes. Based on the correlation study. UV analytical results were positively correlated (n = 33, r = 0.401) to HPLC results which represented the amount of all-trans-beta-carotenes. Results of this study will benefit manufacturers to make baked sweet potatoes with better bio-activity.