This study intented to standardize the method for total polysaccharide, which is a functional marker for aloe vera gel in Korea. We used four lyophilized raw materials and commercial aloe gel products, certified as Health Functional Food by Korea Food and Drug Administration, including powder, solution, jelly, tablet and capsule, to optimize the analytical condition of dialysis and phenol-sulfuric acid reaction in polysaccharide analysis. The optimal conditions for polysaccharide analysis included 1 L water for dialysis and change 3 times for 24hr against 25 mL prepared sample solution. Validation test showed lower than 5% of coefficient of variation(CV) in intra-, interday validation in lyophilized raw materials and 4 types of commercial products. In inter-person and inter-laboratory validation with 4 persons from 4 different laboratories, CV(%) were 5.50 and 6.64 respectively. The linearity of polysaccharide analysis was assessed using 5 serial concentration of lyophilized raw materials(0.1, 0.2, 0.3, 0.4, 0.5%(w/v)). The results showed R2 ≥ 0.995 of high linearity. In the commercial aloe vera gel products, the results of reproductivity showed lower than 7.08% and revealed that the standardized method from this study ensured high precision for polysaccharide analysis.

This study was aimed to develop a novel qualitative multiplex polymerase chain reaction (PCR) for simultaneous detection of genetically modified (GM) soy and maize within a single reaction. The specific primers designed to detect four respective GM events (A2704-12, MON88017, Bt11, and MON863) were included in the tetraplex PCR system. Each of PCR products for four GM events could be distinguished by agarose gel based on their different lengths. The specificity and reproducibility of this multiplex PCR were evaluated. This multiplex PCR consistently amplified only a fragment corresponding to a specific inserted gene in each of the four GM events and also amplified all four of the PCR products in the simulated GM mixture. These results indicate that this multiplex PCR method could be an effective qualitative detection method for screening GM soy and maize in a single reaction.

Recently, studies on natural source antioxidants have become increasingly active in various fields. Among analytical methods for assessment of antioxidant activity, the DPPH, ABTS, and TBA assays have become quite popular in natural antioxidant studies. One of the reasons is that these methods are simple to use and highly sensitive. In particular, DPPH and ABTS assays are based on the theory that a hydrogen donor is an antioxidant. The antioxidant effect can be easily evaluated by following the decrease of specific UV absorption and the results are usually expressed in terms of Trolox equivalent antioxidant capacity (TEAC). The TBA assay has been commonly used for measurement of lipid oxidation in some foods and biological systems. Because the colored complex is formed by the TBA-malonaldehyde interaction, the TBA value can be evaluated using a UV spectrophotometer or HPLC. However, the TBA-malonaldehyde complex is very unstable and often is either not detected in many oxidized lipids or is a minor product of secondary oxidation. As a result of these defects, numerous studies are ongoing.