Impact of fermentation residues on the thermal, structural, and rheological properties of polyhydroxy(butyrate‐co‐valerate) produced from cheese whey and olive oil mill wastewater

Abstract

On the use of tris(nonylphenyl) phosphite as a chain extender in melt-blended poly(hydroxybutyrate-co-hydroxyvalerate)/ clay nanocomposites: Morphology, thermal stability, and mechanical properties Interaction and quantification of thymol in active PLA-based materials containing natural fibers I. S. M. A. Tawakkal, M.ABSTRACT: The effects of recovered residues on the characteristics of polyhydroxy(butyrate-co-valerate) (PHBV) produced from mixed microbial cultures (MMCs) fed with cheese whey, olive oil mill wastewater, or a synthetic mixture of acetic and propionic acid were investigated. The different types of MMC PHBVs were extracted and purified with different downstream routes; this enabled the recovery of polymers with different hydroxyvalerate contents and different residue types and levels, ranging from 0 to 11%. The results indicate overall that the recovery of residues together with the biopolymer brought benefits to the melt processability of these MMC PHBVs. Impurities triggered thermal degradation at smaller temperatures, promoted melting at lower temperatures, acted as thermal stabilizers, improved the melt viscosity, and enhanced the shear thinning. The degree of crystallinity of the aged samples was not affected by the impurities, but the crystallites size increased. MMC PHBVs recovered with residues containing more proteins showed better thermal stability, whereas MMC PHBVs containing more inorganic residues showed better melt viscoelastic properties. The results of this study show that impurities recovered together with the MMC PHBVs introduced changes to their thermal, semicrystalline, and rheological properties; these changes, in some cases, were detrimental, but they were also potentially advantageous to the processing and conversion of these materials into products such as packages.

Polyhydroxyalkanoate (PHA) purification through dilute aqueous ammonia digestion at elevated temperatures

“…The thermal transition observed in the first heating curve at 60 °C (Fig. (A)) – hereafter T g2 – has previously been reported for samples stored at room temperature, and has been attributed to the glass transition temperature of the rigid amorphous fraction (RAF) . The RAF is formed even after very short periods (< 24 h) of storage at temperatures above the glass transition temperature of the mobile amorphous fraction .…”

“…Several studies have led to similar observations in regards to the effect of the biomass residues and the purification methods on the thermal stability. 11,13,28,37,38 In addition, it has been reported that some impurities can behave as plasticisers, enhancing the mechanical properties of PHA, 28,38 which emphasize the importance of testing other properties besides the PHA purity when evaluating purification methods. The presence of impurities should only be considered detrimental when affecting negatively the PHA properties and applicability.…”

The Next Generation of Sustainable Food Packaging to Preserve Our Environment in a Circular Economy Context

“…The FP7 EcoBioCAP project 6 demonstrated the feasibility, using food industry by-products as feedstock (olive wastewater or cheese whey) and mixed natural microbial cultures (MMC), of lab scale production of a P(HB-co-HV) with a HV fraction (in the range of 10–25%) higher than the current commercial grade (39–41). This higher HV fraction induces some polymer structural changes that can be advantageous to its processing and conversion into packaging (42, 43). Higher HV contents could be achieved using Volatile Fatty Acids (VFAs precursors) with a high propionic acid content.…”

Carbon recovery from wastewater through bioconversion into biodegradable polymers

“…The extent to 781 which a product of consistent quality can be delivered with wastewater as feedstock has not been 782 proven or refuted even if there is speculation that methods to achieve consistency of product quality 783 will be a challenge in real world implementations. The thermal, structural and rheological properties 784 of PHA produced by MMC have been studied in PHA produced from cheese whey permeate [101] 785 and PHA produced from cheese whey and olive oil mill wastewaters [102]. In addition, Hilliou et 786 al.…”

“…In addition, Hilliou et 786 al. (2016) [102] assessed the effects of the recovered PHA residues on properties that were relevant 787 for the conversion of polymers into packages. It has been suggested that lipids that are co-recovered 788 with PHA from biomass can be used to advantage as compounded agents [103].…”