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Consumers are conscientiously changing their eating preferences toward healthier options, such as functional foods enriched with pre- and probiotics. Prebiotics are attractive bioactive compounds with multidimensional beneficial action on both human and animal health, namely on the gastrointestinal tract, cardiometabolism, bones or mental health. Conventionally, prebiotics are non-digestible carbohydrates which generally present favorable organoleptic properties, temperature and acidic stability, and are considered interesting food ingredients. However, according to the current definition of prebiotics, application categories other than food are accepted, as well as non-carbohydrate substrates and bioactivity at extra-intestinal sites. Regulatory issues are considered a major concern for prebiotics since a clear understanding and application of these compounds among the consumers, regulators, scientists, suppliers or manufacturers, health-care providers and standards or recommendation-setting organizations are of utmost importance. Prebiotics can be divided in several categories according to their development and regulatory status. Inulin, galactooligosaccharides, fructooligosaccharides and lactulose are generally classified as well established prebiotics. Xylooligosaccharides, isomaltooligosaccharides, chitooligosaccharides and lactosucrose are classified as "emerging" prebiotics, while raffinose, neoagaro-oligosaccharides and epilactose are "under development." Other substances, such as human milk oligosaccharides, polyphenols, polyunsaturated fatty acids, proteins, protein hydrolysates and peptides are considered "new candidates." This chapter will encompass actual information about the non-established prebiotics, mainly their physicochemical properties, market, legislation, biological activity and possible applications. Generally, there is a lack of clear demonstrations about the effective health benefits associated with all the non-established prebiotics. Overcoming this limitation will undoubtedly increase the demand for these compounds and their market size will follow the consumer's trend.

Health benefits associated with the consumption of nondigestible oligosaccharides (NDOs) are well documented, and being also functional food components, they are now in a privileged position within the functional food business. Lactose-derived NDOs have some salient features for being derived from industrial outputs and have some unique properties, like their similar functionality to human milk oligosaccharides. This chapter reviews the available technologies for their production (chemical or enzymatic), identifying the more relevant products derived from lactose (galacto-oligosaccharides, lactulose, lactosucrose, lactitol, lactobionic acid, tagatose, epilactose, and fructosyl-galacto-oligosaccharides). Applications for each of them are reviewed, analyzing its present status and technological perspectives. An updated market outlook is presented for each of them, being a central issue in this chapter. Galacto-oligosaccharides and lactulose, as well-documented prebiotics, outstand; the case of tagatose as a noncaloric sweetener with health-promoting attributes is gaining a salient position in the functional food business.

Strong base catalysts, prepared by substituting a part of the Mg2+ located at the borders of the channels of sepiolite with alkaline ions (Li+, Na+, K+ and Cs+), were investigated as catalysts for the isomerization of lactose to lactulose and epilactose. The activities exhibited by alkaline-exchanged sepiolites were significantly higher than that of natural sepiolite. The influence of temperature, time of the reaction and catalyst loading were also evaluated. A 20% conversion was obtained at 90°C at a catalyst loading of 15 g litre-1. Copyright (C) 1999 Elsevier Science Ltd.

The kinetics of formation of lactulose, galactose and epilactose during heating of milk were examined over a wide temperature/time range (). Formation of the studied carbohydrates was best described with apparent first order reactions. The Arrhenius plot of the logarithm of the rate constant as a function of the reciprocal of the temperature (°K) enabled calculation of the activation energies (125 kJ/mol for lactulose, 131 kJ/mol for epilactose and 139 kJ/mol for galactose). By using the kinetics parameters for calculating lines of equal degrees of formation in a plot of log-time versus reciprocal of absolute temperature it was possible to predict the effect of different heat-treatments on the formation of individual carbohydrates., The authors wish to acknowledge financial support for the research project No. 158/88 provided by the Comisi6n Interministerial de Ciencia y Tecnologia.

Carbohydrate composition of commercial pasteurized, UHT, sterilized and dried milk samples, and laboratory heat-treated milks was determined by gas-liquid chromatography. Glucose, galactose and lactulose were present in all types of commercial milk samples. The concentrations of galactose and lactulose increase with the severity of the heating process. The amount of glucose present in commercial milks was similar to that found in unheated milk. Epilactose was only detected in sterilized milk samples. UHT and sterilized milks can be differentiated by their lactulose, galactose or epilactose content.