PREBIOTIC POTENTIAL OF MICRONIZED OLIVE POMACE: METABOLIZATION OF PHENOLIC COMPOUNDS AND PRODUCTION OF SHORT-CHAIN FATTY ACIDS

Olive pomace (OP) is a residue rich in phenolic compounds (PC) and dietary fiber (lignin). Micronization is an alternative to modify the fibrous matrix and PC functionality during the gastrointestinal tract. Thus, we evaluated the effect of micronization on the biotransformation of OP in an in vitro colonic fermentation model. In vitro digestion was simulated according to INFOGEST 2.0 and colonic fermentation was simulated with human feces from 18 volunteers during 0, 2, 8, 24, and 48 hours at 37 °C. Biotransformation of PC in fermentation was monitored by HPLC-MS-MS and SCFA by GC-FID. The unfractionated OP (NF) was subjected to granulometric fractionation with a 2 mm sieve (F2) and subsequently micronized (F2M) in a planetary ball mill. At 0h, F2M had a higher concentration of PC, in which micronization favored the release of hydroxytyrosol in F2M compared to F2NM at 2h and 8h (p<0.05). Tyrosol only increased to F2M in 2h. Oleuropein significantly increased for F2M in relation to the other samples and was degraded up to 2h and oleuropein aglycone in F2 and F2M increased the release in up to 2h. The presence of this PC in up to 8 hours contributed to the production of SFCA, mainly acetate, propionate, and butyrate. In 24h, F2M had higher SFCA production (6394.5 µmol/100 mL of broth) compared to F2, NF, control, and inulin (p<0.05). For F2M, F2 and NF produced more propionate (1065.5, 1058.7, 1117.0 µmol/100 mL of broth, respectively) than control and inulin (659.9 and 741.2 µmol/100 mL of broth) (p<0.05). In 8h, F2 had a higher production of butyrate than inulin (469.8 vs 367.9 µmol/100 mL of broth) (p<0.05). OP particle reduction can increase the availability of PC in the colon and have a prebiotic effect for the intestinal microbiota since it contributed to the production of SFCA.