title: Extraction of amaranth starch from an aqueous medium using microfiltration

authors: Middlewood, Paul Gregory

subjects: Microfiltration

abstract: Amaranth starch granules are very small, which makes them suitable for a range of specialty applications. This starch is difficult to extract by wet milling due to the strong association between the starch and protein, the high protein content of the seed, and the small granule size. At the time of this research, no commercial amaranth starch extraction methods existed. The recently developed Al-Hakkak process has been successfully used to extract amaranth starch on a laboratory-scale. The work reported here forms part of the Al-Hakkak process scale-up investigations being performed by AgResearch Ltd, for the Biopolymer Network Ltd. During the Al-Hakkak process, an aqueous stream (known as starch-milk) containing insoluble starch granules, soluble carbohydrates, soluble proteins, and lipids, is produced. On the laboratory-scale the starch is recovered from the starch-milk using a high-speed centrifuge. However, at pilot and industrial scales density-based processes, such as centrifuges, settling tables, or hydrocyclones, may not be practical due to the small size, and low mass, of the amaranth starch granules. The research reported here investigated microfiltration as an alternative to density-based processes for separating the amaranth starch-milk into (i) a starch-rich concentrate and (ii) an aqueous stream containing the soluble proteins and carbohydrates. A Millipore ProFlux M12 Tangential Filtration System, fitted with a 1000 kDa regenerated cellulose membrane, was used as the experimental apparatus. It was shown that microfiltration has the potential to recover amaranth starch from the starch-milk produced during the pilot-scale Al-Hakkak process. The selected membrane retained all the starch granules, but also retained more protein than desired (protein retention was 67 % and the starch-rich concentrate had a dry-basis protein content of 12 %). Diafiltration was used to decrease the protein content of the starch-rich concentrate and after six washes the protein content had stabilised at 4 %, which was significantly higher than the 0.1 % previously reported for the laboratory-scale Al-Hakkak process. Analysis of the feed liquor, and diafiltered concentrate, revealed the presence of some non-starch insoluble material. This material, which may have been protein-based, was present in the starch-milk produced using the pilot-scale method but not the laboratory-scale method, and its presence determined the final protein content of the diafiltered concentrate. During processing to reach steady-state conditions membrane flux declined from 60 to 15 L m-2 h-1 over the first 45 minutes. This decrease was predominantly caused by the soluble components of the feed stream, and to a lesser extent by the starch granules. During concentration, flux had a three stage relationship with volumetric concentration (VCF). During the first stage flux decreased almost linearly with increasing VCF, in the second stage flux increased with increasing VCF, and in the third stage flux was independent of VCF. The second stage (flux increase) is unusual, and could form the subject of a separate study. The optimal transmembrane pressure was approximately 100 – 150 kPa, above which flux increased non-linearly with pressure. However, the flux-pressure relationship was weak, suggesting that higher operating pressures may be sustainable. The membrane proved very difficult to clean. A multi-step cleaning cycle was developed which adequately cleaned the membrane between runs. Key cleaning steps were: a cold water rinse to remove loosely bound material, a protease wash to remove protein, a sodium hydroxide wash to “pre-treat” any remaining starch granules, an amylase wash to degrade the starch granules, and a final sodium hydroxide wash to remove residues from the previous step. Additional research is needed to determine why the starch-milk from the pilot-scale process contains insoluble non-starch material, and to improve the process to prevent its inclusion, or remove it. Microfiltration should then be re-evaluated as a potential starch recovery process. An alternative membrane material, and larger pore size, should be trialled with the aim of decreasing protein retention and improving cleanability.

text: Extraction of amaranth starch from an aqueous medium using microfiltration Amaranth starch granules are very small, which makes them suitable for a range of specialty applications. This starch is difficult to extract by wet milling due to the strong association between the starch and protein, the high protein content of the seed, and the small granule size. At the time of this research, no commercial amaranth starch extraction methods existed. The recently developed Al-Hakkak process has been successfully used to extract amaranth starch on a laboratory-scale. The work reported here forms part of the Al-Hakkak process scale-up investigations being performed by AgResearch Ltd, for the Biopolymer Network Ltd. During the Al-Hakkak process, an aqueous stream (known as starch-milk) containing insoluble starch granules, soluble carbohydrates, soluble proteins, and lipids, is produced. On the laboratory-scale the starch is recovered from the starch-milk using a high-speed centrifuge. However, at pilot and industrial scales density-based processes, such as centrifuges, settling tables, or hydrocyclones, may not be practical due to the small size, and low mass, of the amaranth starch granules. The research reported here investigated microfiltration as an alternative to density-based processes for separating the amaranth starch-milk into (i) a starch-rich concentrate and (ii) an aqueous stream containing the soluble proteins and carbohydrates. A Millipore ProFlux M12 Tangential Filtration System, fitted with a 1000 kDa regenerated cellulose membrane, was used as the experimental apparatus. It was shown that microfiltration has the potential to recover amaranth starch from the starch-milk produced during the pilot-scale Al-Hakkak process. The selected membrane retained all the starch granules, but also retained more protein than desired (protein retention was 67 % and the starch-rich concentrate had a dry-basis protein content of 12 %). Diafiltration was used to decrease the protein content of the starch-rich concentrate and after six washes the protein content had stabilised at 4 %, which was significantly higher than the 0.1 % previously reported for the laboratory-scale Al-Hakkak process. Analysis of the feed liquor, and diafiltered concentrate, revealed the presence of some non-starch insoluble material. This material, which may have been protein-based, was present in the starch-milk produced using the pilot-scale method but not the laboratory-scale method, and its presence determined the final protein content of the diafiltered concentrate. During processing to reach steady-state conditions membrane flux declined from 60 to 15 L m-2 h-1 over the first 45 minutes. This decrease was predominantly caused by the soluble components of the feed stream, and to a lesser extent by the starch granules. During concentration, flux had a three stage relationship with volumetric concentration (VCF). During the first stage flux decreased almost linearly with increasing VCF, in the second stage flux increased with increasing VCF, and in the third stage flux was independent of VCF. The second stage (flux increase) is unusual, and could form the subject of a separate study. The optimal transmembrane pressure was approximately 100 – 150 kPa, above which flux increased non-linearly with pressure. However, the flux-pressure relationship was weak, suggesting that higher operating pressures may be sustainable. The membrane proved very difficult to clean. A multi-step cleaning cycle was developed which adequately cleaned the membrane between runs. Key cleaning steps were: a cold water rinse to remove loosely bound material, a protease wash to remove protein, a sodium hydroxide wash to “pre-treat” any remaining starch granules, an amylase wash to degrade the starch granules, and a final sodium hydroxide wash to remove residues from the previous step. Additional research is needed to determine why the starch-milk from the pilot-scale process contains insoluble non-starch material, and to improve the process to prevent its inclusion, or remove it. Microfiltration should then be re-evaluated as a potential starch recovery process. An alternative membrane material, and larger pore size, should be trialled with the aim of decreasing protein retention and improving cleanability.

year: 2011

title: Constraints on the thermal and tectonic evolution of Greymouth coalfield

authors: Kamp, Peter J.J.

subjects: Greymouth Coalfield

abstract: The southern end of the Paparoa Range in Westland, South Island, New Zealand, comprises an asymmetrical, southward plunging, faulted (Brunner-Mt Davy) anticline, the eastern limb of which is common with the western limb of an asymmetrical (Grey Valley) syncline forming a Neogene foreland basin (Grey Valley Trough). The faulted anticline is a classic inversion structure: compression during the Neogene, associated with the development of the modern Australia-Pacific plate boundary, caused a pre-existing normal fault zone, about which a late Cretaceous-Oligocene extensional half graben had formed (Paparoa Trough), to change its sense of displacement. The resulting basement loading formed the foreland basin, containing up to 3 km of mainly marine sedimentary section. 
Fission track results for apatite concentrates from 41 shallow drillhole and outcrop samples from the Greymouth Coalfield part of the Brunner-Mt Davy Anticline are reported and interpreted, to better establish the timing and amount of inversion, and hence the mechanism of inversion. The fission track results integrated with modelling of vitrinite reflectance data, show that the maximum paleotemperatures experienced during burial of the Late Cretaceous and mid-Eocene coal-bearing succession everywhere exceeded 85deg.C, and reached a peak of 180deg.C along the axis of the former basin. Cooling from maximum temperatures occurred during three discrete phases: 20-15 Ma, 12-7 Ma, and c. 2 Ma to the present. The amount of denudation has been variable across the inverted basin, decreasing westward from a maximum of c. 2.5 km during the first deformation phase, c. 1.2 km during the second phase, and 1.4 km during the third phase. It appears that exhumation over the coalfield continued for about 2 m.y. beyond the biostratigraphically determined time ranges of each of two synorogenic unconformities along the western limb of the Grey Valley Syncline. Stick-slip behaviour on the range front fault that localised the inversion is inferred. The tectonic evolution of the anticline-syncline pair at the southern end of the Paparoa Range, is therefore identical in style, and similar in timing, to the development of the Papahaua Range-Westport Trough across the Kongahu Fault Zone, in the vicinity of Buller Coalfield.

text: Constraints on the thermal and tectonic evolution of Greymouth coalfield The southern end of the Paparoa Range in Westland, South Island, New Zealand, comprises an asymmetrical, southward plunging, faulted (Brunner-Mt Davy) anticline, the eastern limb of which is common with the western limb of an asymmetrical (Grey Valley) syncline forming a Neogene foreland basin (Grey Valley Trough). The faulted anticline is a classic inversion structure: compression during the Neogene, associated with the development of the modern Australia-Pacific plate boundary, caused a pre-existing normal fault zone, about which a late Cretaceous-Oligocene extensional half graben had formed (Paparoa Trough), to change its sense of displacement. The resulting basement loading formed the foreland basin, containing up to 3 km of mainly marine sedimentary section. 
Fission track results for apatite concentrates from 41 shallow drillhole and outcrop samples from the Greymouth Coalfield part of the Brunner-Mt Davy Anticline are reported and interpreted, to better establish the timing and amount of inversion, and hence the mechanism of inversion. The fission track results integrated with modelling of vitrinite reflectance data, show that the maximum paleotemperatures experienced during burial of the Late Cretaceous and mid-Eocene coal-bearing succession everywhere exceeded 85deg.C, and reached a peak of 180deg.C along the axis of the former basin. Cooling from maximum temperatures occurred during three discrete phases: 20-15 Ma, 12-7 Ma, and c. 2 Ma to the present. The amount of denudation has been variable across the inverted basin, decreasing westward from a maximum of c. 2.5 km during the first deformation phase, c. 1.2 km during the second phase, and 1.4 km during the third phase. It appears that exhumation over the coalfield continued for about 2 m.y. beyond the biostratigraphically determined time ranges of each of two synorogenic unconformities along the western limb of the Grey Valley Syncline. Stick-slip behaviour on the range front fault that localised the inversion is inferred. The tectonic evolution of the anticline-syncline pair at the southern end of the Paparoa Range, is therefore identical in style, and similar in timing, to the development of the Papahaua Range-Westport Trough across the Kongahu Fault Zone, in the vicinity of Buller Coalfield.

year: 1999

title: Pūtahitanga: The intersection of western science and mātauranga Māori in the context of Aotearoa New Zealand’s physical oceanography

authors: Stevens, Craig L.

subjects: Mātauranga Māori

abstract: Aotearoa New Zealand is a land and cultures surrounded by one of the planet’s larger marine exclusive economic zones per capita. Understanding, living within and utilising this domain requires a well-developed knowledge of the physical oceanography–fate, provenance and transfer of ocean-water, material and energy. In the Aotearoa New Zealand context, understanding and utilising the environment through science also requires that Māori have a stake in the science and a pathway to connecting with their mātauranga. The pūtahitanga (intersection) of mātauranga Māori and western science perspectives brings challenges for implementation of the Vision Mātauranga framework for physical oceanographic science. Here we discuss the drivers and key themes for the pūtahitanga and propose a mahere kaupapa/plan bound by: (i) climate, (ii) decolonisation, (iii) shared language, (iv) data sovereignty, and (v) developing a cohort who can lead the field in the coming decades.

text: Pūtahitanga: The intersection of western science and mātauranga Māori in the context of Aotearoa New Zealand’s physical oceanography Aotearoa New Zealand is a land and cultures surrounded by one of the planet’s larger marine exclusive economic zones per capita. Understanding, living within and utilising this domain requires a well-developed knowledge of the physical oceanography–fate, provenance and transfer of ocean-water, material and energy. In the Aotearoa New Zealand context, understanding and utilising the environment through science also requires that Māori have a stake in the science and a pathway to connecting with their mātauranga. The pūtahitanga (intersection) of mātauranga Māori and western science perspectives brings challenges for implementation of the Vision Mātauranga framework for physical oceanographic science. Here we discuss the drivers and key themes for the pūtahitanga and propose a mahere kaupapa/plan bound by: (i) climate, (ii) decolonisation, (iii) shared language, (iv) data sovereignty, and (v) developing a cohort who can lead the field in the coming decades.

year: 2021