Two fractions (permeate and retentate) from fiber free Aloe vera gel were prepared using an ultra-filtration (UF) system with a tubular ceramic membrane (MWCO of 50 kDa), and their dilute solution properties were investigated. The intrinsic viscosities of fiber free Aloe vera gel and the retentate and permeate fractions that were prepared by ultra-filtration were 18.48, 37.74, and 2.01 dL/g, respectively. UF aloe retentate as a polysaccharide rich fraction exhibited polyelectrolyte behavior showing a sharp decrease of intrinsic viscosity by the addition of NaCl. However, as its NaCl concentration increasing to 1 M, its intrinsic viscosity slightly increased due to conformational change caused by the high concentration of NaCl. On the one hand, the intrinsic viscosities of the dilute UF-retentate solution were exponentially decreased with increasing temperature, and the temperature dependency of its intrinsic viscosity showed a sharp discontinuity at 30oC instead of a linear Arrhenius behaviour, indicating a variation of flow mechanism or network rearrangement of a molecular chain. The chain stiffness of polysaccharide rich fraction at bellow and above 0.5 M of NaCl addition was 0.048 and 0.515, respectively, showing different stiffenings and significant conformational change. The coil overlap parameter and critical concentration of UF-retentate were 3.0 and 0.08 g/dL, respectively.

알로에의 최소공정개발 연구의 일환으로 DIS(dewatering & impregnation soaking) 공정에 미치는 온도의 효과를 조사하였다. 삼투탈수는 분자량 4000의 PEG을 삼투제로 하여 이의 40%(w/v) 용액에 두께 0.5 cm의 알로에 잎 슬라이스를 넣고 간헐적으로 교반하면서 2시간 동안 수행하였다. 서로 다른 침지온도(25-55oC)가 DIS의 성능(수분소실 및 고형분 획득)에 미치는 영향을 현미경관찰에 의한 세포조직 구조의 경시변화를 모니터링하면서 조사, 비교되었고, 동역학적으로 분석하였다. 고온(55oC) 처리에서는 저온(25 and 35oC)에서보다 더 높은 수분소실을 보였으나 세포조직의 파괴를 동반하였다. 또, 품질지표값으로서의 glucomannan 함량은 세포조직구조를 잘 유지하였던 침지온도 35oC에서 얻어졌다. 얻어진 시료의 실온건조제품을 재수화시켜 조사하고 동역학적으로 해석한 결과, 재수화 동역학은 Peleg 및 Weibull 모델로 잘 설명할 수 있었다. DIS 제품은 DIS 처리하지 않은 제품에 비해 세포구조 및 재수화성질의 향상을 주어 적정온도하에서 DIS 처리함으로써 최소공정의 알로에 제품을 얻을 수 있음을 확인하였다.

Two fractions (permeate and retentate) from fiber-free Aloe vera gel were separated using ultra-filtration (UF) system with tubular ceramic membrane (MWCO of 50 kDa), and their molecular properties were investigated. The retentate of UF Aloe gel was a polysaccharide-rich fraction containing about 2.3-fold higher polysaccharide content than fiber-free gel. The FT-IR and 1H NMR spectra of this fraction showed the characteristic patterns of β-binding polysaccharide and a higher degree of acetylation indicating a higher level of bioactive polysaccharide content. The molecular weight and polydispersity of polysaccharide fraction from GPC (gel permeation chromatography) were determined to be 36.8-43.9 kDa and 1.24, respectively, indicating a kind of undispersed polysaccharide. From the SEM observation, the surface structure of polysaccharide fraction had a gel cluster-like structure with a convoluted rough surface. The molecular conformation by Congo red assay exhibited a property of helix structure confirming the existence of a higher-ordered structure as a biological activity conformation.

The optimization of dewatering and impregnation soaking (DIS) process for a concentrated Aloe vera product was investigated using Taguchi method in combination with desirability function analysis. Polyethylene glycol (PEG) as osmotic agent was adopted, and soaking temperature (T), immersion time (t), PEG concentration (C), PEG molecular weight (MW), and thickness of Aloe vera leaf slice (x) were selected as affecting variables. L16 (45) orthogonal array was designed by Taguchi method with four parameters such as water loss, solid gain, glucomannan, and anthraquinone contents as objective functions. An overall quality index was transformed from individual objective functions, and was optimized finally. The optimal setting for maximum overall desirability was obtained at 55oC (T), 2 hr (t), 40% w/v (C), 0.5 cm (x), and 4,000 Da. (MW). The obtained overall desirability was 0.7842. The order of affecting factors was T>C>x>MW≈x>t and the experimental results under optimum condition were similar to the prediction of an overall desirability of 0.8384. Also, it was found that the optimized DIS condition could be reproduced for a minimally processed Aloe vera product with high quality.