Preparation, Analysis And Characteristics Evaluation Of Natural Sweetener Mogrosides

Mogrosides were proved to be the main active components of fruits of Siraitia grosvenori, a traditional Chinese medicinal plant, which was a kind of low-calorie, high-sweet, healthy and natural sweetener. On the basis of the study of our laboratory, in this paper, the preparation, identification and analysis of different mogrosides were studied, at the same time, the evaluating the sweetness and flavor of mogrosides, and the influences of mogroside extract on physical characteristics of corn starch and soy protein were also discussed.1. Preparation and identification of MogrosidesThe HPLC method for the preparation of 11-oxo-MogrosideV, MogrosideIV, and Siamenoside I was studied. The chromatogram condition was: column, Shim-PackPREP-ODS (25mmx20.0mm I.D) ; mobile solvent, acetonitrile:water=23:77(v/v);flowrate, 8mL/min; sensitivity setting, 2.56 AUFS; wavelength of UV detection, 210nm. The white crystal powers were obtained by collecting, concentrating and freeze-drying eluting solution according to the chromatogram peaks. And the 11-oxo-Mogroside V, Mogroside IV and Siamenoside I were identificated by MP, UV-VIS, IR, ESI/MS/MS ,~1H NMR and ~13C NMR.2. The analysis of Mogrosides by HPLCAn HPLC analysis method of determination 11-oxo-MogrosideV, Mogroside V, MogrosidelV, and Siamenoside I had been established. The chromatogram condition was: column, C18ODS (250mmx4.6mm I.D, 5μm); eluting solvent, acetonitrile-water, 23:77 (v/v); flowrate, 1.0 mL/min; temperature, 25℃; sensitivity setting, 0.04AUFS; wavelength of UV detection, 210nm. The results showed that this analysis method was simple, accurate and had a good linear relationship between the peak areas and the content of mogrosides, high recoveries and better relative standard deviation.The contents of mogrosides were different in different varieties and parts. In the fruits of Bai-Mao, except 11 -oxo-Mogroside V, the contents of Mogroside V, Mogroside IV and Siamenoside I were lower than that of Qin-pi fruits. Furthmore, the contents of 11-oxo-Mogroside V, Mogroside V, Mogroside IV and all mogrosides in pulp were higher than that in peel, but the contents of Siamenoside I in pulp were lower.The influences of different dry methods on the contents of mogrosides were obvious. For these two varieties, the best drying method was that the fresh fruits were dried by heating after insolation. In addition, mogrosides were stable, and the variation of pH value, heating temperature, heating time and keeping time had few influences on their contents.3. Evaluating the sweetness of MogrosidesUsing comparison evaluation tests, the equisweet sucrose concentration (ES) and the relative sweetness (RS) of Mogrosides had been determinded. The more contents of mogrosides, the higher RS. When the different sweeteners were at lower concentration, an appropriate product can be obtained with a higher sweetness, good taste and flavor. The RS and the flavor of mogroside V were better than that of 11-oxo-Mogroside V, because there is difference of their structure. The synergisms between Mogroside extract and other sweeteners had been measured, a great of synergisms was found in mixtures of sample and acesulfame K with a synergistic rate of 24.5%, and a few synergisms with aspartame, but a negative synergism with combined sweetening and cyclomate.4. Influences of Mogroside extract on physical characteristics of cornstarch and soy protein.Using rotating viscometer, rapid visco-analyzer and texture analyzer, the influences of Mogroside extract on the apparent viscosity, gelatinization, and the gel texture of corn starch were determined. Because Mogrosides could dissolve in water easily, starch was gelatinized in little water. So, the gelatinization temperature, peak viscosity, breakdown value, and gel value of corn starch increased slightly.The influences of Mogroside extract on the viscosity, foaming property and gel characteristic of soy protein were analysed with rotating viscometer, high speed tissue triturator, and texture analyzer. Because the foam stability of mogroside extract was bad while its foaming strong, and at the same time it can dissolve in water easily, the results showed that the viscosity, foaming property, hardness, brittleness, chesion of soy protein gel increased slightly, and the foam stability of it decreased slightly.