Abstract

This study is aimed at comparing swell drying versus conventional shade drying and optimizing the texturing by instant controlled pressure drop (DIC) of green okra pods. Differences in quality attributes such as content of flavonoids, carotenoids, and chlorophyll pigments, functional characteristics such as the antioxidant activity (AOA), microstructure and relative expansion ratio of dried okra pods were considered. The DIC processing parameters were the saturated steam pressure (0.2-0.6 MPa) and duration (40-60 s). A 2-parameter, 5-level central composite rotatable design was selected for establishing the experimental trials. They represent 8 factorial and star trials, and five repetitions of central/middle point of the square edges. Significant variations in total phenolic and flavonoid contents, carotenoids, antioxidant activity, and chlorophyll pigments were observed between swell-dried and conventional shadow dried okra pods. An increase of 25% and 99% was respectively observed for the relative expansion ratio and flavonoid content in swell dried okra pods compared with conventional shadow dried ones. The microstructure observations showed a significantly more porous open solid matrix of swell-dried okra pods compared to the compact/dense solid matrix of the conventional shadow dried okra pods. The optimum conditions of DIC-texturing were found to be 0.4 MPa for 50 s exhibiting the highest values of total phenolic content, flavonoids, antioxidant activity, and chlorophyll pigments with good preservation of the carotenoid content.

摘要

本研究旨在比较膨胀干燥与传统遮荫干燥，并通过绿色秋葵豆荚的即时控制压降 (DIC) 优化纹理。考虑了黄酮类化合物、类胡萝卜素和叶绿素色素含量等品质属性的差异，以及干秋葵荚的抗氧化活性（AOA）、微观结构和相对膨胀率等功能特性的差异。DIC 工艺参数是饱和蒸汽压力 (0.2-0.6 MPa) 和持续时间 (40-60 s)。选择 2 参数、5 级中央复合可旋转设计来建立实验试验。它们代表 8 次阶乘和星型试验，以及方形边缘中心点/中点的 5 次重复。总酚和类黄酮含量、类胡萝卜素、抗氧化活性、在膨胀干燥和常规阴影干燥的秋葵豆荚之间观察到叶绿素色素。膨胀干燥的秋葵豆荚的相对膨胀率和黄酮类含量与常规阴影干燥的豆荚相比分别增加了 25% 和 99%。微观结构观察表明，与常规阴影干燥秋葵荚的致密/致密固体基质相比，膨胀干燥的秋葵荚具有明显更多孔的开放固体基质。发现 DIC 制绒的最佳条件为 0.4 MPa，持续 50 秒，显示总酚含量、黄酮类化合物、抗氧化活性和叶绿素色素的最高值，并能很好地保留类胡萝卜素含量。膨胀干燥的秋葵豆荚的相对膨胀率和黄酮类含量与常规阴影干燥的豆荚相比分别增加了 25% 和 99%。微观结构观察表明，与传统阴影干燥秋葵荚的致密/致密固体基质相比，膨胀干燥的秋葵荚具有明显更多孔的开放固体基质。发现 DIC 制绒的最佳条件为 0.4 MPa，持续 50 秒，显示总酚含量、黄酮类化合物、抗氧化活性和叶绿素色素的最高值，并能很好地保留类胡萝卜素含量。膨胀干燥的秋葵豆荚的相对膨胀率和黄酮类含量与常规阴影干燥的豆荚相比分别增加了 25% 和 99%。微观结构观察表明，与传统阴影干燥秋葵荚的致密/致密固体基质相比，膨胀干燥的秋葵荚具有明显更多孔的开放固体基质。发现 DIC 制绒的最佳条件为 0.4 MPa，持续 50 秒，显示总酚含量、黄酮类化合物、抗氧化活性和叶绿素色素的最高值，并能很好地保留类胡萝卜素含量。微观结构观察表明，与常规阴影干燥秋葵荚的致密/致密固体基质相比，膨胀干燥的秋葵荚具有明显更多孔的开放固体基质。发现 DIC 制绒的最佳条件为 0.4 MPa，持续 50 秒，显示总酚含量、黄酮类化合物、抗氧化活性和叶绿素色素的最高值，并能很好地保留类胡萝卜素含量。微观结构观察表明，与常规阴影干燥秋葵荚的致密/致密固体基质相比，膨胀干燥的秋葵荚具有明显更多孔的开放固体基质。发现 DIC 制绒的最佳条件为 0.4 MPa，持续 50 秒，显示总酚含量、黄酮类化合物、抗氧化活性和叶绿素色素的最高值，并能很好地保留类胡萝卜素含量。