Development of a functional prebiotic strawberry preparation by in situ enzymatic conversion of sucrose into fructo-oligosaccharides

[Display omitted] •In situ enzyme treatments can be exploited to generate low-sugar functional foods.•Fructo-oligosaccharides (FOS) were enzymatically synthesized at 60 ℃ and pH 5.0.•A strawberry preparation with 50 % (w/w) FOS and less 80 % sucrose was obtained.•The caloric value of the prebiotic-treated preparations was lowered in 26–31 %.•More than 90 % of the FOS resisted to the in vitro digestion. Food industry has been pressed to develop products with reduced sugar and low caloric value, while maintaining unchanged their rheological and physicochemical properties. The development of a strawberry preparation for the dairy industry, with prebiotic functionality, was herein investigated by in situ conversion of its intrinsic sucrose content into prebiotic fructo-oligosaccharides (FOS). Two commercial enzymatic complexes, Viscozyme® L and Pectinex® Ultra SP-L, were evaluated for the synthesis of FOS. Operational parameters such as temperature, pH, and enzyme:substrate ratio (E:S) were optimized to maximize FOS yield. The rheological and physicochemical properties of the obtained strawberry preparation were evaluated. For functional analysis, the resistance of FOS to the harsh conditions of the gastro-intestinal digestion was evaluated by applying the standardized INFOGEST static protocol. At optimal conditions (60 ℃, pH 5.0), Pectinex® produced 265 ± 3 g·L−1 FOS, yielding 0.57 ± 0.01 gFOS·ginitial sucrose−1 after 7 h reaction (E:S:1:40); and Viscozyme® produced 295 ± 1 g·L−1 FOS, yielding 0.66 ± 0.00 gFOS·ginitial sucrose−1 after 5 h (E:S:1:30). The obtained strawberry preparations contained more than 50 %(w/w) prebiotic FOS incorporated (DP 3–5), with 80 % reduction of its sucrose content. The caloric value was therefore reduced by 26–31 %. FOS showed resistance to gastrointestinal digestion being only slightly hydrolysed (