ISSN 1330-9862 review (FTB-2388) Fructose Syrup: A Biotechnology Asset Danyo Maia Lima 1 , Pedro Fernandes 2 , Diego Sampaio Nascimento 1 , Rita de Cássia L. Figueiredo Ribeiro 3 and Sandra Aparecida de Assis 1 * 1 Laboratory of Enzymology and Fermentation Technology, Department of Health, State University of Feira de Santana – UEFS, University Campus, Km 03, BR 116, Feira de Santana, 44031460 Bahia, Brazil 2 IBB, Institute for Biotechnology and Bioengineering, Centre for Biological and Chemical Engineering, Higher Technical Institute, Av. Rovisco Pais, 1049-001 Lisboa, Portugal 3 Institute of Botany, PO Box 68041, CEP 04045-972 São Paulo, SP, Brazil Received: November 28, 2009 Accepted: April 19, 2010 Summary In response to the growing demand for the consumption of natural, healthy and low- -calorie food, a large number of so-called alternative sugars has emerged since the early 80s, among them fructose. This sugar is a ketohexose, known as D-fructose or levulose, and is considered the sweetest sugar found in nature. Currently, fructose is mostly pro- duced through the acid hydrolysis of sucrose, or through the multi-enzymatic hydrolysis of starch. Processes involving specific enzymes like inulinases, acting on widely available fructose polysaccharides such as inulin, have been studied as alternatives to the current approaches, in order to reduce time, complexity and costs involved in this process. Fruc- tose syrup is used worldwide, mainly because of its sweetening power and functional prop- erties. The present work aims to provide an overview of the properties of fructose and of the present and envisaged production processes, within the scope of a biotechnological ap- proach. Key words: fructose, syrup, fructooligosaccharides, microorganisms Introduction In the last decades particular care has been given to the impact of nutritional habits on public health. Concom- itantly with such growing concern, developed countries have put considerable efforts in order to understand the links between diet and health. Policies and guidelines have been adopted to provide suitable information to the consumer and also to adequately influence food product composition and technological approaches for food processing (1). Given the widespread presence of sweeteners in common diet, particular consideration has been given to these compounds (2). The industrial use of sugars, particularly in the liquid form, is also of rele- vance, since food manufacturers often prefer to use sugar in the form of syrup, mostly due to the ease and effi- ciency of manipulation of liquids, and to the favoured 424 D.M. LIMA et al.: Fructose Syrup, Food Technol. Biotechnol. 49 (4) 424–434 (2011) *Corresponding author; Phone: ++55 75 3161 8341; E-mail: sandrinhaassis@yahoo.com.br, sandraassis@uefs.br process economics. Sugar syrups consist mostly of su- crose syrup; of invert sugar syrup; of blends of more or less complex carbohydrates, including oligosaccharide syrups (and particularly fructooligosaccharides); and of fructose-rich syrup (3–5). Oligosaccharides are mostly used due to their functional properties, namely their prebiotic nature, rather than their sweetness, which is relatively low (6,7). Sweeteners produce pleasant flavour, and oc- casionally cooling sensations, enhance shelf-life proper- ties, and may simultaneously provide energy, in which case they are termed nutritive. If they do not provide energy, they are termed nonnutritive. Nutritive sweet- eners encompass several natural sugars, such as sucrose or fructose, which are considered GRAS (Generally Rec- ognized As Safe) by the FDA (Food and Drug Adminis- tration, USA) (8). Among nutritive sweeteners, fructose