title: Carbon balance of an intensively grazed temperate pasture in two climatically contrasting years

authors: Mudge, Paul Lawrence

subjects: eddy covariance

abstract: Grazed grasslands occupy 26% of the earth's ice free land surface and are therefore an important component of the global C balance. In New Zealand, pastoral agriculture is the dominant land use and recent research has shown that soils under intensive dairy pastures have lost large amounts of carbon (∼1000 kg C ha⁻¹ y⁻¹) during the past few decades. The objective of this research was to determine the net ecosystem carbon balance (NECB) of an intensively grazed dairy pasture in New Zealand. Net ecosystem CO₂ exchange (NEE) was measured using an eddy covariance (EC) system from 1 January 2008 to 31 December 2009. Other C imports (feed) and exports (milk, methane, leaching, and harvested biomass) were calculated from farm production data and literature values. During 2008 there was a one in 100 year drought during summer/autumn, which was followed by a very wet winter. There were no prolonged periods of above or below average rainfall or soil moisture in 2009, but temperatures were consistently lower than 2008. The severe summer/autumn drought during 2008 caused a loss of CO₂ to the atmosphere, but annual NEE remained negative (a CO₂ sink, −1610 ± 500 kg C ha⁻¹), because CO₂ lost during the drought was regained during the winter and spring. The site was also a net CO₂ sink during 2009 despite the colder than usual conditions (−2290 ± 500 kg C ha⁻¹). Including C imports and exports in addition to CO₂ exchange revealed that the site was a C sink in both years, with a NECB of 590 ± 560 kg C ha⁻¹ in 2008, and 900 ± 560 kg C ha⁻¹ in 2009. The C sequestration found in this study is in agreement with most other Northern Hemisphere EC studies of grazed pastures on mineral soils, but is not consistent with the large C losses reported for soils under dairy pastures throughout New Zealand. In the current study (like many other EC studies) the influence of climatic conditions and management practices on the annual C balance was only semi-quantitatively assessed. An extended period of EC measurements combined with modelling is required to more accurately quantify the effect of different climatic conditions on the annual C balance, and the influence of different management practices needs to be quantified using specifically designed studies (such as paired EC towers), so that practices which minimise C losses and maximise C sequestration can be identified.

text: Carbon balance of an intensively grazed temperate pasture in two climatically contrasting years Grazed grasslands occupy 26% of the earth's ice free land surface and are therefore an important component of the global C balance. In New Zealand, pastoral agriculture is the dominant land use and recent research has shown that soils under intensive dairy pastures have lost large amounts of carbon (∼1000 kg C ha⁻¹ y⁻¹) during the past few decades. The objective of this research was to determine the net ecosystem carbon balance (NECB) of an intensively grazed dairy pasture in New Zealand. Net ecosystem CO₂ exchange (NEE) was measured using an eddy covariance (EC) system from 1 January 2008 to 31 December 2009. Other C imports (feed) and exports (milk, methane, leaching, and harvested biomass) were calculated from farm production data and literature values. During 2008 there was a one in 100 year drought during summer/autumn, which was followed by a very wet winter. There were no prolonged periods of above or below average rainfall or soil moisture in 2009, but temperatures were consistently lower than 2008. The severe summer/autumn drought during 2008 caused a loss of CO₂ to the atmosphere, but annual NEE remained negative (a CO₂ sink, −1610 ± 500 kg C ha⁻¹), because CO₂ lost during the drought was regained during the winter and spring. The site was also a net CO₂ sink during 2009 despite the colder than usual conditions (−2290 ± 500 kg C ha⁻¹). Including C imports and exports in addition to CO₂ exchange revealed that the site was a C sink in both years, with a NECB of 590 ± 560 kg C ha⁻¹ in 2008, and 900 ± 560 kg C ha⁻¹ in 2009. The C sequestration found in this study is in agreement with most other Northern Hemisphere EC studies of grazed pastures on mineral soils, but is not consistent with the large C losses reported for soils under dairy pastures throughout New Zealand. In the current study (like many other EC studies) the influence of climatic conditions and management practices on the annual C balance was only semi-quantitatively assessed. An extended period of EC measurements combined with modelling is required to more accurately quantify the effect of different climatic conditions on the annual C balance, and the influence of different management practices needs to be quantified using specifically designed studies (such as paired EC towers), so that practices which minimise C losses and maximise C sequestration can be identified.

year: 2011

title: Thermophilic enzymes and their impact on milk powder during storage

authors: Chen, Lin

abstract: Milk powder quality and storage life can be compromised by functionality and flavour defects. These defects can be the result of chemical or biochemical reactions, such as the Maillard (browning) reaction, proteolysis and lipolysis. The New Zealand dairy industry has set specifications for thermophile numbers in milk powders that have been used for many years as an indicator of microbial quality. However, any correlation between the numbers of these bacteria and product quality is anecdotal, and there is little supportive scientific evidence. 

This research has set out to: (1) survey the cause of the problem for off-flavours in milk powder storage, mainly whole milk powders (WMPs) because they are the largest powder-product, and most likely to have problems associated with flavour; (2) develop assay methods for detecting possibly very low levels of protease and lipase in the WMPs; and finally (3) determine enzymatic effects in the WMPs during storage. 

The study has focused on the detection of protease and lipase activities. Several sensitive and commonly used assay methods were applied in reconstituted milk made from different batches of commercial WMPs. Both protease and lipase activities were detected, and the lipase activity was quantified at 0.7-1.1 U/g powder (pNP caproate unit), but the level of protease activity is yet to be accurately determined. 

A lipase was semi-purified from a WMP using Phenyl Sepharose hydrophobic chromatography. The enzyme is most active at 60°C under the conditions used, and has similar substrate specificity to the lipases produced by seven Bacilli isolated from a milk powder production stream. Although the source of the powder lipase is yet to be identified, data suggest that it is most likely from a thermophilic bacterium. 

Preliminary studies on the characteristics of the proteases and the lipases produced by the seven Bacilli showed that the proteases differ between isolates in term of pH optima and heat-stabilities, so do the lipases. The lipases are more heat-stable than the proteases in a buffer system. Under the protection of milk proteins, these enzymes can survive the heat-treatments applied in the milk powder manufacture process, and retain activities in the powder. 

Further studies on WMPs spiked with thermophilic proteases and lipases, or taken directly from the commercial process have confirmed that the proteases and the lipases are active in the powder (at moisture < 5%) during storage. Proteolysis was observed as the increase of 1% trifluoroacetic acid (TFA) soluble protein fragments and the decrease of solubility, and lipolysis was shown as the release of free fatty acids (FFA). The lipases showed the same specificities in a buffer system and in the powder. The levels of enzymatic products increase with increasing storage temperatures and time. Proteolysis resulted in poor solubility of WMP within one week of storage at 37°C. Lipolysis resulted in the levels of FFA, especially short chain butyric and caproic acids, exceeding the organoleptic threshold values under the same storage conditions. 

Nevertheless, none of the defects observed showed any correlation with thermophile numbers - one of the current specifications for quality control of WMP. Therefore, it is not thermophiles per se that affect milk powder quality during storage, it is the heat-stable enzymes, from whatever source.

text: Thermophilic enzymes and their impact on milk powder during storage Milk powder quality and storage life can be compromised by functionality and flavour defects. These defects can be the result of chemical or biochemical reactions, such as the Maillard (browning) reaction, proteolysis and lipolysis. The New Zealand dairy industry has set specifications for thermophile numbers in milk powders that have been used for many years as an indicator of microbial quality. However, any correlation between the numbers of these bacteria and product quality is anecdotal, and there is little supportive scientific evidence. 

This research has set out to: (1) survey the cause of the problem for off-flavours in milk powder storage, mainly whole milk powders (WMPs) because they are the largest powder-product, and most likely to have problems associated with flavour; (2) develop assay methods for detecting possibly very low levels of protease and lipase in the WMPs; and finally (3) determine enzymatic effects in the WMPs during storage. 

The study has focused on the detection of protease and lipase activities. Several sensitive and commonly used assay methods were applied in reconstituted milk made from different batches of commercial WMPs. Both protease and lipase activities were detected, and the lipase activity was quantified at 0.7-1.1 U/g powder (pNP caproate unit), but the level of protease activity is yet to be accurately determined. 

A lipase was semi-purified from a WMP using Phenyl Sepharose hydrophobic chromatography. The enzyme is most active at 60°C under the conditions used, and has similar substrate specificity to the lipases produced by seven Bacilli isolated from a milk powder production stream. Although the source of the powder lipase is yet to be identified, data suggest that it is most likely from a thermophilic bacterium. 

Preliminary studies on the characteristics of the proteases and the lipases produced by the seven Bacilli showed that the proteases differ between isolates in term of pH optima and heat-stabilities, so do the lipases. The lipases are more heat-stable than the proteases in a buffer system. Under the protection of milk proteins, these enzymes can survive the heat-treatments applied in the milk powder manufacture process, and retain activities in the powder. 

Further studies on WMPs spiked with thermophilic proteases and lipases, or taken directly from the commercial process have confirmed that the proteases and the lipases are active in the powder (at moisture < 5%) during storage. Proteolysis was observed as the increase of 1% trifluoroacetic acid (TFA) soluble protein fragments and the decrease of solubility, and lipolysis was shown as the release of free fatty acids (FFA). The lipases showed the same specificities in a buffer system and in the powder. The levels of enzymatic products increase with increasing storage temperatures and time. Proteolysis resulted in poor solubility of WMP within one week of storage at 37°C. Lipolysis resulted in the levels of FFA, especially short chain butyric and caproic acids, exceeding the organoleptic threshold values under the same storage conditions. 

Nevertheless, none of the defects observed showed any correlation with thermophile numbers - one of the current specifications for quality control of WMP. Therefore, it is not thermophiles per se that affect milk powder quality during storage, it is the heat-stable enzymes, from whatever source.

year: 2000

title: 'No-body' is my friend: Cultural considerations of young children's 'imaginary companions'

authors: Hayes (Bluett), Shilo Jane

subjects: imaginary companions

abstract: The variegated relationships young children may have during their early childhood education (ECE) years have long been of interest to theorists and teachers alike.  Relationships, and understandings of companionship, can take multiple forms. Our understandings of what these relationships may look like are frequently informed by complex social and cultural constructs; therefore, seeking to apply a one-size-fits-all interpretation is theoretically and culturally problematic, especially when the companions young children may spend time with may be unseen or unnoticed by surrounding adults.
A common Euro-western notion is that unseen companions are not real; hence they are generally referred to in the literature as being imaginary.  In an extensive literature review, this thesis explores whether companionship with the unseen are one of many possible forms of relationships.  Dominant Euro-western claims that such relationships are imaginary are considered critically before the analysis widens in theoretical scope to draw on various alternative cultural accounts.  The analysis draws on the theoretical work of Jacques Derrida, Michel Foucault and Karen Barad, in particular.  An additional exploration considers the author’s own situated experiences of parenting a child who during her childhood years had companions that were unseen to the author.  The final analysis, based on a small selection of carefully chosen autoethnographic accounts, draws on the significance of ancestral inheritance. Within this specific research context that inheritance comprises my daughter’s Māori ancestry and our shared Celtic ancestry. 
Ancestral inheritance provides reflexive companionship for the entire thesis.  Examining inheritance sheds light on ways that traditional Euro-western claims of the imagined worlds of children, and consequently childhood, have produced a legacy of ideas which have subsequently held the term imaginary in place.  These dominant worldviews are shown to fall short in their capacity to cover the diversity of lived realities of children and their unseen (to others) companion(s).  Inheritance also denotes the culturally mediated birthright that may travel alongside a young child and how this birthright may provide insight and alternative cultural knowledge and understandings of various multiform relationship companions.
As a result of analysing several possible perspectives on the relationships under study, this thesis proposes the new term culturally compatible travelling companions (CCTC): companions who travel alongside children as ordinary, expected features of their lifespan.  This shift in term acknowledges that diverse notions of companionship, and the forms this may take, are integral and salient constructions of each culture’s historical and narrative accounts.  
This is timely research, as currently nearly 64% of young children aged between birth and four years of age attend some type of Early Childhood Education (ECE) service in Aotearoa New Zealand (Ministry of Education [MoE], 2019).  The national ECE curriculum document Te Whāriki (MoE, 2017) recognises the significance of young children’s relationships and understands those relationships within the rich and complex cultural knowledge patterning that travels alongside a young child.  
The aim of this research is to add to the theoretical understandings of the forms, functions and features of the multiple, complex relationship companions who may share the lives of young children, whether or not these companions are seen or discernible to those around the children.  It suggests an alternative perspective to the dominant view and offers provocations for those who work alongside young children to think differently about whether these relationship companions are indeed only imaginary.

text: 'No-body' is my friend: Cultural considerations of young children's 'imaginary companions' The variegated relationships young children may have during their early childhood education (ECE) years have long been of interest to theorists and teachers alike.  Relationships, and understandings of companionship, can take multiple forms. Our understandings of what these relationships may look like are frequently informed by complex social and cultural constructs; therefore, seeking to apply a one-size-fits-all interpretation is theoretically and culturally problematic, especially when the companions young children may spend time with may be unseen or unnoticed by surrounding adults.
A common Euro-western notion is that unseen companions are not real; hence they are generally referred to in the literature as being imaginary.  In an extensive literature review, this thesis explores whether companionship with the unseen are one of many possible forms of relationships.  Dominant Euro-western claims that such relationships are imaginary are considered critically before the analysis widens in theoretical scope to draw on various alternative cultural accounts.  The analysis draws on the theoretical work of Jacques Derrida, Michel Foucault and Karen Barad, in particular.  An additional exploration considers the author’s own situated experiences of parenting a child who during her childhood years had companions that were unseen to the author.  The final analysis, based on a small selection of carefully chosen autoethnographic accounts, draws on the significance of ancestral inheritance. Within this specific research context that inheritance comprises my daughter’s Māori ancestry and our shared Celtic ancestry. 
Ancestral inheritance provides reflexive companionship for the entire thesis.  Examining inheritance sheds light on ways that traditional Euro-western claims of the imagined worlds of children, and consequently childhood, have produced a legacy of ideas which have subsequently held the term imaginary in place.  These dominant worldviews are shown to fall short in their capacity to cover the diversity of lived realities of children and their unseen (to others) companion(s).  Inheritance also denotes the culturally mediated birthright that may travel alongside a young child and how this birthright may provide insight and alternative cultural knowledge and understandings of various multiform relationship companions.
As a result of analysing several possible perspectives on the relationships under study, this thesis proposes the new term culturally compatible travelling companions (CCTC): companions who travel alongside children as ordinary, expected features of their lifespan.  This shift in term acknowledges that diverse notions of companionship, and the forms this may take, are integral and salient constructions of each culture’s historical and narrative accounts.  
This is timely research, as currently nearly 64% of young children aged between birth and four years of age attend some type of Early Childhood Education (ECE) service in Aotearoa New Zealand (Ministry of Education [MoE], 2019).  The national ECE curriculum document Te Whāriki (MoE, 2017) recognises the significance of young children’s relationships and understands those relationships within the rich and complex cultural knowledge patterning that travels alongside a young child.  
The aim of this research is to add to the theoretical understandings of the forms, functions and features of the multiple, complex relationship companions who may share the lives of young children, whether or not these companions are seen or discernible to those around the children.  It suggests an alternative perspective to the dominant view and offers provocations for those who work alongside young children to think differently about whether these relationship companions are indeed only imaginary.

year: 2020