Closing the loop, adding value

This article describes an innovation which uses waste blood from meat processing to create a valuable bio-based plasti

Single screw extruder performance characteristics during processing of corn protein blends

During the last decade, the global biofuels industry has experienced exponential growth. By-products such as distillers dried grains with solubles (DDGS) have grown in parallel. DDGS is primarily an animal feed, but it has also been shown to be suitable as a biopolymer. In this study, the extrusion processing behaviour of DDGS was evaluated. Prior to processing, water was added to DDGS at a level of 3 kg DDGS to 1.5 kg water (water at 50 parts per hundred (pph)). Additionally, a DDGS/water blend with 50 pph CaCO₃ was used as a tracer to determine residence time during processing. The blends were processed in a single screw autogenous extruder, which relied solely upon friction for dissipative heating. Two die plates were used: one consisted of 6 orifices equally spaced, 2 mm diameter each, with a total opening area of 18.85 mm²; the other consisted of multiple orifices (960 in total) arranged concentrically around the plate, with a diameter of 2.30 mm each, for a total opening area of 3988.45 mm². Processing began with DDGS blends without tracer; after reaching steady state, the tracer blend was introduced. Samples were collected every 5 sec during processing to determine extrudate changes over time. Extruder power consumption, mass flow rate, and temperature profile were determined during processing. Extrudates were analysed for Hunter colour (L-a-b) changes over time. Extrusion processing characteristics were highly influenced by the die opening area. Die exit temperatures ranged from room temperature (25°C) to more than 100°C, purely due to increased friction for the smaller die opening. Future work should characterize the mechanical properties of these extrudates to assess their suitability as either bioplastic feedstocks or pelletized animal feeds

Processibility of corn protein blends and resulting properties of the extrudates

During the last decade, the global biofuels industry has experienced exponential growth. By-products such as high protein corn gluten meal (CGM) and high fibre distillers dried grains with solubles (DDGS) have grown in parallel. CGM has been shown to be suitable as a biopolymer; the high fibre content of DDGS reduces its effectiveness, although it is considerably cheaper. In this study, the processing behaviour of CGM and DDGS blends were evaluated and resulting extrudate properties were determined. Prior to processing, urea was used as a denaturant. DDGS:CGM ratios of 0, 33, 50, 66 and 100% were processed in a single screw extruder, which solely used dissipative heating, with a 2 mm circular die. Resulting screw speeds ranged from 216 to 228 rpm, and die exit temperatures ranged from 96 to 150oC. Blends containing DDGS were less uniformly consolidated and resulted in more dissipative heating. Blends showed multiple glass transitions, which is characteristic of mechanically compatible blends. Transmission electron microscopy revealed phase separation on a micro-scale, although distinct CGM or DDGS phases could not be identified. On a macro-scale, optical microscopy suggested that CGM-rich blends were better consolidated, supported by visual observations of a more continuous extrudate formed during extrusion. As with all biological materials, the extruded blends exhibited sorption behaviour over time, the magnitude of which varied according to blend ratio. EMC values ranged from approximately 0% to nearly 50%, depending upon the humidity level and blend ratio. Nonlinear regression was successfully used to model the effects of relative humidity and blend ratio on the equilibrium moisture contents, with a coefficient of determination of 99%. Future work should aim to also characterize the mechanical properties of these blends to assess their suitability as either bioplastic feedstock or pelletized livestock feed

Blends of linear-low-density polyethylene and thermoplastic bloodmeal using maleic anhydride grafted polyethylene as compatibilizer

Linear Low-Density Polyethylene (LLDPE) was blended with Novatein Thermoplastic from bloodmeal (NTP.) The compatibilizing effect of maleic anhydride grafted polyethylene (PE-g-MAH) on mechanical, morphology thermal properties and water absorption were studied and compared with blends without compatibilizer .The amount of polyethylene added was varied between 20% to 70% with 10% of compatibilizer. An improvement in compatibility between NTP and LLDPE was evident across the entire composition range only when using compatibilizer. The tensile strength of blends decreased over that pure LLDPE, but never dropped below that of pure NTP. Results showed that blending NTP with LLDPE decreased water absorption significantly, even more so using a compatibilizer. The result is a more water stable material

Biofibre production from chicken feather

The global poultry industry generates at least 2 million tonnes of chicken feather every year. Feather fibre has potential as reinforcement for polymer composites with light-weight, thermal insulation and acoustic dampening properties. This study aimed to develop a process to produce clean fibre recovered from chicken feather. Raw feather was decontaminated by 0.15% sodium hypochlorite in 25 L water at pH 10.0 for two 30 min stages and cleaned by 0.15% hydrogen peroxide in 25 L water for three 30 min stages. Cleaned feather was comminuted in 300 L water using a centrifugal pump at 30 Hz impeller speed on full recycle for 4 h. Rachis and partially cut feather were removed using a 5 mm filter and fibre was recovered using a 1 mm filter. Wet fibre was dried in an air-forced oven at 70°C. Morphological studies revealed fibre surface remained intact after the treatment process

Development of blood meal protein thermoplastic

Polymers are blended with other polymers to combine their properties or improve physical characteristics and blending turns to be the most reliable techniques compare to synthesis of chemically new polymers. In the research of sustainable materials from non-potential food sources, bloodmeal is one of the best candidates for bioplastic manufacture. It is one of the highest non-synthetic sources of nitrogen coming from meat processing and approximately 80000 tonnes of raw blood is collected annually in New Zealand. Natural polymers often present processing difficulties as well as maintaining product quality over extended periods because of their hydrophilic nature. Blending bloodmeal with other polymers may offer a solution to this problem. However, most blends are immiscible, and the processing are challenging because of dissimilar nature of natural and synthetic polymer, thus requiring compatibilization to achieve good blends performance. The process to solve incompatibility is the compatibilizer should migrate to the interface, reducing the interfacial tension, stabilizing the blend morphology and improving the adhesion between phases in solid state, hence improving the mechanical properties. True thermodynamic term of miscibility of polymer blends is a mixture containing two or more components that form one phase system but this determination of miscibility may be rather ambiguous. In practice, polymer blend compositions is said compatible if they exhibit two phases on a microscopic level but the interactions between polymer groups might be reasonable in a manner that provides useful properties of the multicoponent system. In many instances, it is desirable to have two phases present, as long as we can control the multicomponent systems which depend on their structure, polymer interactions and phase sizes. We have identified several strategies in order to improve miscibility; 1. Addition of a small quantity of a third component that is miscible with both phases 2. Addition of a copolymer whose one part is miscible with one phase and another with another phase 3. Compounding blends in the presence of chemical reactants that lead to modification of at least one macromolecular species (reactive compatibilization), resulting in generation of an in-situ desired quantity of compatibilizer. The propose of this paper is to explore the potential of blending bloodmeal with other thermoplastic by taking account the type of polymer, type of compatibilization and processing condition in order to improve processability and mechanical properties

Processing peracetic acid treated bloodmeal into bioplastic

Renewable and biodegradable bioplastics can be produced from biopolymers such as proteins. Animal blood is a by-product from meat processing and is rich in protein. It is dried into low value bloodmeal and is used as animal feed or fertiliser. Previous work has shown that bloodmeal can be converted into a thermoplastic using water, urea, sodium dodecyl sulphate (SDS), sodium sulphite and triethylene glycol (TEG). To increase its range of applications and acceptance from consumers, the colour and odour was removed from bloodmeal using peracetic acid (PAA). The aim of this study was to investigate the bioplastic processing of 3-5% (w/w) PAA treated bloodmeal. 3-5% PAA treated bloodmeal powder was compression moulded using different combinations of water, TEG, glycerol, SDS, sodium sulphite, urea, borax, salt and sodium silicate at concentrations up to 60 parts per hundred bloodmeal (pphBM). Partially consolidated extrudates and fully consolidated compression moulded sheets were obtained using a combination of water, TEG and SDS. 4% PAA treated bloodmeal produced the best compression moulded sheets and extrudates and was chosen for investigating the effects of water, TEG and SDS concentration on consolidation, specific mechanical energy input (SME) and product colour during extrusion. Analysis of variance (ANOVA) showed SDS was the most important factor influencing its ability to be extruded because it detangled protein chains and allowed them to form new stabilising interactions required for consolidation. The best extruded sample, which was 98% consolidated and 49% white, contained 40 pphBM water, 10 pphBM TEG and 6 pphBM SDS

Settling of bentonite in gelatine solutions

New Zealand has a sizeable meat by-products processing industry, associated with significant aqueous effluent called stickwater. Stickwater has a biological oxygen demand of 50-150 g O₂/l and has to be treated prior to disposal. Currently, stickwater is dried and added to meat and bone meal in some inedible meat rendering plants. In edible rendering plants, the gelatin can be removed and the remaining broth is concentrated as a flavor enhancer. Where no further unit operations are carried out on stickwater, the stickwater must be treated to reduce the BOD. A medium size meat rendering plant in NZ can produce up to 30,000 L of stickwater at 2-5% solids per day¹. In Hamilton, waste water treatment costs NZ$0.90 per kg solids or approximately NZ$1350 per day. In comparison, abattoir waste treatment costs NZ$ 0.23/kg in the US.

Rheology of the gel formed in the California Mastitis Test

The California Mastitis Test has previously been adapted for use in an inline, cow-side sensor and relies on the fact that the viscosity of the gel formed during the test is proportional to the somatic cell concentration. In this paper, the use of capillary and rotational viscometry was compared in light of the expected rheology of the gel formed during the test. It was found that the gel is non-Newtonian, but the initial phase of viscosity increase was not due to shear dependence, but rather due to the gelation reaction. The maximum apparent viscosity of the gel was shear dependent while the time it took to reach the maximum was not truly shear dependent, but was rather dependent on the degree of mixing during gelation. This was confirmed by introducing a delay time prior to viscosity measurement, in both capillary and rotational viscometry. It was found that by mixing the reagent and infected milk, then delaying viscosity measurement for 30 s, shortened the time it took to reach maximum viscosity by more than 60 s. The maximum apparent viscosity, however, was unaffected. It was found that capillary viscometry worked well to correlate relative viscosity with somatic cell count, but that it was sensitive to the reagent concentration. It can therefore be deduced that the rheology of the gel is complicated not only by it being non-Newtonian, but also by the strong dependence on test conditions. These make designing a successful sensor much more challenging

Plasticization of Bloodmeal-based Thermoplastics

Water is the most common plasticizer for proteinbased thermoplastics, lowering the softening point to a allow processing without excessive degradation. The biggest drawback of using water a plasticizer is that water easily evaporates from the material during use or storage. This leads to embrittlement and loss of functionality over time. In this study a series of high molecular mass plasticizers were evaluated for their efficiency in plasticizing bloodmeal-based thermoplastics. It was found that propylene glycol, di and tri-ethylene glycol were most efficient in increasing the material’s ductility, as measured by elongation at break. Using 10 parts plasticizer per hundred bloodmeal (pphBM) in combination with 10 pphBM urea gave optimal results in terms of Young’s modulus, tensile strength and processability. The mechanical properties of plasticized samples showed a stronger dependency on moisture content, compared to unplasticized samples and reached higher equilibrium moisture content in a shorter time. Using 10 pphBM TEG as plasticizer in resulted in a plastic material with a Young’s modulus of 869 MPa, tensile strength of 14.7 MPa and an elongation at break of 46%