Effects of fermentation residues on the melt processability and thermomechanical degradation of PHBV produced from cheese whey using mixed microbial cultures

"Available online 28 March 2016"

Two polyhydroxy(butyrate-co-valerate) (PHBV) produced from mixed microbial cultures (MMC) fed with fermented cheese whey (CW) and recovered with different down streaming routes, were processed into filaments by plasticating extrusion. The thermorheological characteristics were improved when fermentation residues were recovered together with the MMC PHBV polymer. Thermogravimetric analysis of the extruded filaments showed that MMC PHBV with 11% residues was less degraded than pure PHBV after the thermomechanical processing. Infrared spectroscopy indicated that residues rich in OH groups were volatilized during extrusion, thereby originating filaments that were less degraded than those produced with purified MMC PHBV. Residues had no impact on the semi crystalline properties of the filaments, but were responsible for their depressed mechanical properties, significant color deterioration upon processing and narrowed the processing operating window of MMC PHBV.

The authors would like to acknowledge the financial support given by the FEDER Funds through the COMPETE 2020 Programme, by the National funds from the Portuguese Foundation for Science and Technology (FCT) in the scope of Project PTDC/AGR-ALI/ 122741/2010, Project PEst-C/CTM/LA0025/2011 (Strategic ProjectdLA 25-2011-2012) and Project UID/CTM/50025/2013, and Grants SFRH/BPD/88817/2012 and SFRH/BPD/88705/2012. Additional funding by Programa Operacional Regional do Norte (ON.2) through the project “Matepro e Optimizing Materials and Processes”, with reference NORTE-07-0124-FEDER-000037 FEDER COMPETE, is also acknowledged.