Processing effects on four prebiotic carbohydrates supplemented in an extruded cereal and a low pH drink

Prebiotic carbohydrates are added as functional ingredients to a variety of processed foods. Data on the stability of prebiotics during food processing in complex matrices remain limited. The objective of this project was to determine the stability of fructooligosaccharides (FOS), inulin, galactooligosaccharides (GOS), and resistant starch (RS₂), when added as ingredients (1% w/w) to an extruded cereal and a low pH drink. The cereal was prepared using different screw speeds and barrel temperatures. GOS was not affected by any of the extrusion conditions, whereas inulin decreased significantly at 140 and 170°C. FOS levels decreased in all extrusion conditions, while resistant starch (RS) unexpectedly increased for each of the parameters. The low pH drink was prepared with different sucrose to corn syrup solids (S:CSS) ratios (1:2, 1:1, 2:1) at pH 3.0, 3.5, and 4.0. The 1:1 S:CSS drink at pH 3.0, negatively impacted FOS and inulin. Moreover, FOS levels decreased when exposed to 1:2 S:CSS (pH 3.5 and 4.0) and 1:1 S:CSS (pH 3.0). GOS and RS were unaffected by any drink formulations. As different conditions impact the stability of prebiotics differently, this study addresses the importance of developing product specific processes for each prebiotic when supplemented into a processed food.