Fermentability of Novel Type-4 Resistant Starches in In Vitro System

Abstract

Resistant starches are non-digestible starches that are fermented in the colon by microbiota. These carbohydrates are prebiotic and can be beneficial to consumer health. Many types of resistant starch exist with varying physical properties that may result in differences in fermentability. The objective of this research project was to compare potential prebiotic effects and fermentability of four novel resistant starches using an in vitro fermentation system and measuring changes in total gas production, pH, and formation of SCFAs (short chain fatty acids). Fecal donations were collected from seven healthy volunteers. Four novel resistant starches, modified potato starch (MPS), modified tapioca starch (MTS), and modified maize starches (MMS-1 and MMS-2), were analyzed and compared to polydextrose and short chain fructooligosaccharides (FOS) as controls. After twenty-four hours of fermentation, MPS and MTS responded similarly in gas production (74 mL; 70.6 mL respectively), pH (5.93; 5.93 respectively), and SCFA production (Acetate: 115; 124, Propionate: 21; 26, Butyrate: 29; 31 μmol/mL respectively). While MMS-1 had similar gas production and individual SCFA production, the pH was significantly higher (6.06). The fermentation of MMS-2 produced the least amount of gas (22 mL), with a higher pH (6.34), and lower acetate production (78.4 μmol/mL). All analyzed compounds were fermentable and promoted the formation of beneficial SCFAs.

Keywords: dietary fiber; prebiotics; resistant starch.

Figure 1

Mean total gas production following the in vitro fermentation of various carbohydrate sources at between 4 and 24 h post exposure to fecal microbiota of five different donors. Error bars indicate standard error. Columns with different letters are significantly different from one another within each time measurement. n = 15 (5 donors × 3 replicates), FOS: fructooligosaccharides.

Figure 2

Total gas production after 24 h of fermentation of various carbohydrate sources in an in vitro system for each individual donor. Blank spaces above a donor number indicate a sample that did not produce gas during the in vitro fermentation.

Figure 3

Mean pH of various carbohydrate sources following in vitro fermentation between 4 and 24 h post exposure to fecal microbiota of seven different donors. Error bars indicate standard error. Columns with different letters are significantly different from one another within each time measurement. n = 21 (7 donors × 3 replicates).

Figure 4

Mean acetate production at 12 and 24 h of fermentation in an in vitro system with various carbohydrate sources. Error bars indicate standard error. Columns with different letters are significantly different from one another within each time measurement. n = 21 (7 donors × 3 replicates).

Figure 5

Mean propionate production at 12 and 24 h of fermentation in an in vitro system with various carbohydrate sources. Error bars indicate standard error. Columns with different letters are significantly different from one another within each time measurement. n = 21 (7 donors × 3 replicates).

Figure 6

Mean butyrate production at 12 and 24 h of fermentation in an in vitro system with various carbohydrate sources (n = 7). Error bars indicate standard error. Columns with different letters are significantly different from one another within each time measurement. n = 21 (7 donors × 3 replicates).

Figure 7

Mean total SCFA production at 12 and 24 h of fermentation in an in vitro system with various carbohydrate sources (n = 7). Error bars indicate standard error. Columns with different letters are significantly different from one another within each time measurement. n = 21 (7 donors × 3 replicates).

Figure 8

Total SCFA production after 24 h of fermentation of various carbohydrate sources in an in vitro system for each individual donor.