In vitro evaluation of fermentation characteristics of type 3 resistant starch

Four different resistant starch (RS) type 3 (RS3; retrograded starch) and a RS type 2 (RS2; native high amylose maize starch) were in vitro digested and fermented by faecal inoculum. Total and individual short chain fatty acid (SCFA) production and associated kinetic parameters were assessed up to 20 h of in vitro fermentation. Total SCFA production was different (p < 0.05) among RS-rich ingredients, ranging from 7.43 to 8.72 mmol/g dry starch incubated. Differences (p < 0.05) were recorded for propionate and butyrate productions. Different (p < 0.05) half-time of total SCFA fermentation (T_1/2), maximum rate of production (R_max) and the time of occurrence (T_max) values were measured among RS-rich ingredients, ranging from 3.3 to 5.6 h, from 1.06 to 1.85 mmol/g dry starch incubated per hour and from 2.6 to 4.9 h, respectively. Similar trends were measured considering the fermentative kinetics of individual SCFA. Present preliminary in vitro findings indicated that quantitative and qualitative production of SCFA, and inherent fermentation kinetics, were influenced by the type of RS. These findings are based on an in vitro approach, thus requiring in vivo trials.