Thermal and Mechanical Properties of Biocomposites Made of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and Potato Pulp Powder.

The thermal and mechanical properties of biocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) containing 5 wt % of valerate units, with 20 wt % of potato pulp powder were investigated in order (i) to obtain information on possible miscibility/compatibility between the biopolymers and the potato pulp, and (ii) to quantify how the addition of this filler modifies the properties of the polymeric material. The potato pulp powder utilized is a residue of processing for the production and extraction of starch. The final aim of this study is the preparation of PHBV based materials with reduced cost, thanks to biomass valorization, in agreement with the circular economy policy, as result of the incorporation of agricultural organic waste. The results showed that the potato pulp powder does not act as reinforcement, but rather as filler for the PHBV polymeric matrix. A moderate loss in mechanical properties is detected (decrease in elastic modulus, tensile strength and elongation at break), which regardless still meets the technical requirements indicated for rigid packaging production. In order to improve the mechanical response of the PHBV/potato pulp powder biocomposites, surface treatment of the potato pulp powder with bio-based and petroleum-based waxes was investigated. Good enhancement of the mechanical properties was achieved with the natural carnauba and bee waxes.

Thermal, Mechanical, and Rheological Properties of Biocomposites Made of Poly(lactic acid) and Potato Pulp Powder.

The thermal, mechanical, and rheological properties of biocomposites of poly(lactic acid) (PLA) with potato pulp powder were investigated in order to (1) quantify how the addition of this filler modifies the structure of the polymeric material and (2) to obtain information on the possible miscibility and compatibility between PLA and the potato pulp. The potato pulp powder utilized is a residue of the processing for the production and extraction of starch. The study was conducted by analyzing the effect of the potato pulp concentration on the thermal, mechanical, and rheological properties of the biocomposites. The results showed that the potato pulp powder does not act as reinforcement but as filler for the PLA polymeric matrix. A progressive decrease in elastic modulus, tensile strength, and elongation at break was observed with increasing the potato pulp percentage. This moderate loss of mechanical properties, however, still meets the technical requirements indicated for the production of rigid packaging items. The incorporation of potato pulp powder to PLA offers the possibility to reduce the cost of the final products and promotes a circular economy approach for the valorization of agro-food waste biomass.

Effect of Sodium Sulfite, Sodium Dodecyl Sulfate, and Urea on the Molecular Interactions and Properties of Whey Protein Isolate-Based Films.

Whey protein coatings and cast films are promising for use as food packaging materials. Ongoing research is endeavoring to reduce their permeability. The intention of this study was to evaluate the effect of the reactive additives sodium sulfite, sodium dodecyl sulfate (SDS), and urea on the oxygen barrier, water vapor barrier, and protein solubility of whey protein cast films. The concentration of the reactive additives was 1 to 20 wt.-%. Dried whey protein cast films were used as substrate materials. The water vapor transmission rate, the oxygen permeability, and the protein solubility were measured. Effective diffusion coefficients and effective sorption coefficients were calculated from the results of the water vapor sorption experiments. The presence of sodium sulfite resulted in an increased number of hydrophobic interactions and hydrogen bonds and a slightly decreased number of disulfide bonds. The oxygen permeability decreased from 68 to 46 cm3 (STP/standard temperature and pressure) 100 µm (m2 d bar)-1 for 1 wt.-% SDS in the whey protein cast film. The water vapor transmission rate decreased from 165 to 44 g 100 µm (m2 d)-1 measured at 50 to 0% r. h. for 20 wt.-% SDS in the whey protein cast film. The reduction in the water vapor transmission rate correlated with the lower effective diffusion coefficient.

Enzyme-assisted process for DAG synthesis in edible oils.

This study deals with the enzymatic synthesis of diacylglycerols in rapeseed oil by the esterification of free fatty acids and monoacylglycerols. As enzymatic reactions are influenced by many factors, a statistical design of experiments was conducted to investigate the enrichment of diacylglycerols, systematically. Simultaneously, the investigated method contributes to the refining process, as the amount of free fatty acids could be reduced significantly from 2% to 0.3%. Utilizing an immobilized lipase from Rhizomucormiehei, a maximum diacylglycerol content of 23% was obtained, after optimization. By washing with iso-propanol and hexane the immobilised lipase could be reused in 14 consecutive batches. In addition, glycerol was proven to be an alternative to MAG as acyl-group acceptor. However, the diacylglycerol enrichment was not accomplished in the same yields as for monoacylglycerols. Summarizing, the present study revealed the potential of an enzymatic diacylglycerol synthesis in edible oils as a suitable alternative to conventional processes also enabling the reduction of free fatty acids in crude oils.

Enzymatic esterification of free fatty acids in vegetable oils utilizing different immobilized lipases.

Different immobilized lipases were screened for their ability to esterify free fatty acids (FFA) with monoacylglycerol (MAG) as acyl-group acceptor. A lipase from Rhizomucor miehei (Lipozyme RMIM) was the most suitable for lipase-catalyzed de-acidification-a promising alternative to conventional neutralization. A reduction of the FFA content to 0.6 % (w/w) was achieved by applying a substrate with an initial FFA-content of 6 % (w/w), the reaction at 50 °C for 22 h as well as the stepwise addition of a quadruple stoichiometric amount of MAG.