Effect of Combined Osmotic Dehydration and Hot-air Drying on the Quality of Dried Apple Products

삼투건조와 열풍건조의 조합이 사과 건조제품의 품질에 미치는 영향

  • Published : 2008.02.28

Abstract

This study was conducted to investigate the effects of combined osmotic dehydration and hot-air drying on the quality of dried apple products. Apple cylinders were steeped in 30% and 50% sucrose solutions at different steeping times. During the osmotic dehydration, as the concentration of the sucrose solution and steeping time increased, weight reduction and water loss increased, and the solid gain showed similar results. Osmotic dehydration in the sucrose solutions was followed by hot-air drying at 50 and $70^{\circ}C$. The experimental data were fitted successfully using the modified Page model. At the drying temperature of $50^{\circ}C$, the drying time increased from 4.15 hr for the control to 5.78 hr and 6.42 hr for the 30 and 50% sucrose solution treatments, respectively. Similar results were shown at the $70^{\circ}C$ drying temperature. The k and n values of the apple cylinders decreased by osmotic dehydration, and the k and n of the apple cylinders steeped in the 50% sucrose solution were lower than those of the samples steeped in the 30% sucrose solution. The qualities of the dried apple products were compared to samples that did not undergo osmotic dehydration. The shrinkage and rehydration capacity of the apple products decreased via osmotic dehydration, and decreased as the concentration of the sucrose solution increased. The compressibility ratios of the apple products to raw apple cylinders increased by osmotic dehydration, and increased as the concentration of sucrose solution increased. The sensory evaluation results for the apple products rehydrated in yoghurt indicate that osmotic dehydration greatly enhances the palatability of apple products in terms of appearance, taste, and texture.

삼투건조와 열풍건조의 조합이 사과 건조제품의 품질에 미치는 영향을 알아보기 위하여 삼투건조시 물질이동 특성과 열풍건조시 건조특성, 그리고 사과 건조제품의 품질을 조사하였다. 삼투건조시 침지용액의 농도와 침지시간이 증가함에 따라 중량감소와 수분손실이 증가하였으며 고형분 증가도 같은 경향을 나타내었다. 열풍건조시 건조시간에 따른 사과 실린더의 수분함량 변화를 Page model에 적용하여 지수 n, k 및 건조시간을 산출하였다. 건조온도 $50^{\circ}C$에서 건조시간이 대조구의 4.15시간에서 30%와 50% sucrose 용액 처리시 각각 5.78시간과 6.42시간으로 증가하였으며, 건조온도 $70^{\circ}C$에서도 유사한 경향인 것으로 나타났다. 삼투건조에 의해 k와 n 값이 감소하였고 삼투용액의 농도가 높을수록 더욱 감소하는 것으로 나타났다. 삼투건조한 사과 건조제품의 품질을 삼투건조하지 않은 사과 건조제품과 비교하였다. 삼투건조에 의해 건조제품의 수축도와 복원력이 감소하였고 침지용액의 농도가 높을수록 감소하는 것으로 나타났다. 압착력은 삼투건조에 의해 증가하였고 침지용액의 농도가 높을수록 증가하는 것으로 나타났다. 복원한 사과 건조제품에 대한 관능적 기호도 측정 결과 외관, 조직감, 종합적인 기호도 등의 모든 관능검사 항목에서 삼투건조한 사과 건조제품이 삼투건조하지 않은 대조구에 비해 유의적으로 높은 기호도를 나타내었다.

Keywords

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