Stevioside

Stevioside is one of the naturally occurring sweeteners,belonging to the diterpene glycoside family, which can be widelyapplied in food, drinks, medicine and consumer chemicals. It is agood dietary supplement, being non-calorific, thermally stable,non-toxic, with a sugar-like taste profile, and suitable fordiabetics, phenylketonuria patients and the obese. It is alsonon-fermentable, and exhibits anti-carcinogenic, antioxidant andanti-hyperglycemic properties. Stevioside tastes about 300 timessweeter than 0.4% sucrose solution. Thus, it offers a reasonablyrare combination of health benefits and taste benefits, making theextraction of stevioside is an area of active research for the foodindustry as well as academic food scientists.With the rapidincrease in the popularity of stevioside as a sugar substitute,particularly with regard to its associated health benefits, thereis a need for more efficient and feasible extraction processes forstevioside in the near future.This book offers an in-depth look at perhaps the major"sugar alternative of the future", up-to-date and inline with the latest global legislation regarding its suitabilityfor consumption and its scope for application.

Authors' Biographies viiPreface ixAcknowledgements xiList of figures xiiiList of tables xvii1 Introduction to stevioside 11.1 History of Stevia 31.2 Composition of Stevia 61.3 Source of stevioside 101.4 Physicochemical and biological properties of steviol glycosides 131.5 Analysis of stevioside (steviol glycosides) and Stevia extract 182 Health benefits and pharmacological effects of steviol glycosides 272.1 Effect of stevioside in absorption, distribution, metabolism and excretion 272.2 Antihyperglycaemic effect 292.3 Antihypertensive effect 312.4 Anti-inflammatory effect 322.5 Anticarcinogenic antitumour effects 332.6 Antioxidant activity 342.7 Antimicrobial and antidiarrhoeal effects 342.8 Effect on renal function 353 Applications of stevioside 454 Conventional extraction processes of stevioside 514.1 Ion exchange 514.2 Solvent extraction 534.3 Extraction by chelating agents 544.4 Adsorption and chromatographic separation 564.5 Ultrasonic extraction 594.6 Microwave-assisted extraction 594.7 Supercritical fluid extraction 605 Brief introduction to pressure-driven membrane-based processes 655.1 Advantages of the membrane-based process 665.2 Classification of the processes 665.3 Characterisation of membranes 675.4 Membrane modules 705.5 Limitations 735.6 Quantification of concentration polarisation 745.7 Applications of membrane-based processes 796 State of the art of stevioside processing using membrane-based filtration 916.1 Clarification and purification 926.2 Concentration by nanofiltration 956.3 Limitations 977 Detailed membrane-based technologies for extraction of stevioside 997.1 Outline of processing 997.2 Optimisation of water extraction process 997.3 Optimisation of primary clarification (centrifuge or microfiltration) 1097.4 Selection of membrane 1227.5 Optimisation of operating conditions 1247.6 Mechanism of flux decline 1307.7 Ultrafiltration of primary clarified Stevia extract 1417.8 Concentration by nanofiltration 1558 Performance modelling of stevioside separation using membrane processing 1618.1 Modelling of stirred ultrafiltration 1628.2 Modelling of cross-flow ultrafiltration 1748.3 Steady state 1808.4 Transient state 1809 Enhancement of stevioside recovery by diafiltration 1959.1 Multiple stage diafiltration 19710 Economics of the process 209Index 215A colour plate section falls between pages 12 and 13