Extrusion cooking combined with Lacticaseibacillus paracasei fermentation improves the physicochemical properties and estimated in vitro glycemic index of Pleurotus citrinopileatus-cereal meal replacement powder

This study investigated the effects of extrusion cooking, Lacticaseibacillus paracasei fermentation, and pasteurization on the quality characteristics of Pleurotus citrinopileatus- cereal meal replacement powders (MRPs). Twin-screw extrusion at 65–150 °C (zone 1–5/die) and 120 rpm significantly increased the viscoelastic moduli and decreased the average particle size from 56 to 17 μm. Fermentation at 37 °C for 24 h significantly increased the total phenolic and flavonoid contents as well as the antioxidant activities. Additionally, it further reduced the particle size to 13.6 μm. The two sequential processing treatments progressively increased the resistant starch content from 28.49% to 36.81%, and further to 45.23%, with a corresponding decrease in estimated in vitro glycemic index (eGI) values from 64.51 to 58.69, and further to 51.37. The combined X-ray diffraction, Fourier transform infrared spectroscopy, and differential scanning calorimetry results suggested that changes in starch ordering and the possible formation of amylose-lipid complexes contributed to the reduction in eGI values. Pasteurization had no significant effect on the antioxidant activity, sensory attributes, or eGI value of the fermented MRPs. These findings provide preliminary scientific support for the further development of fermented, extrusion-processed MRPs with potentially lower in vitro starch digestibility.