title: Ultimate pH and storage related changes to sheepmeat odour and flavour

authors: Braggins, Terence John

abstract: Gas chromatography/mass spectrometry (GC/MS), gas chromatography/olfactometry and a trained sensory panel were used to study the effects of meat ultimate pH on the odour and flavour of cooked sheepmeat. As part of methods development, supercritical carbon dioxide elution was evaluated as an alternative to thermal desorption of volatile compounds from Tenax-T A traps, but this technique did not offer any significant advantage. In a separate study, the sensory panel and an emerging technology, an electronic nose, were used to investigate the changes in cooked meat odour and flavour arising from long term storage of chilled lamb legs in a carbon dioxide atmosphere.

Pre-slaughter injection of adrenalin was used to produce sheepmeats of normal (5.66), moderate (6.26) and high (6.81) ultimate pH. Meat with a moderate or high ultimate pH had a significantly lower overall cooking odour and flavour intensity, as assessed by the sensory pane, than sheepmeat of a more acceptable pH (5.66). Panellists also found that desirable odour and flavour notes decreased and undesirable ones increased as ultimate pH increased. Purge-and-trap GC/MS of fat rendered during cooking identified 57 (out of a total of 325) volatile compounds that significantly decreased in concentration with increasing meat pH. The most common of these compounds were aldehydes. GC/olfactometry identified 54 odour-active compounds, 10 of which were also found to be responsive to changes in meat ultimate pH. Most of these compounds were again aldehydes.

High ultimate pH raw meat which was titrated with hydrochloric acid to pH levels close to that of low ultimate pH had odour and flavour intensities comparable to those of normal (low) ultimate pH meat. Most of the volatile compounds found by GC/MS analysis to decrease in concentration with increasing ultimate pH did not have a reduced concentration after this downward pH adjustment. These results and parallel analyses of soluble protein, free amino acids and free fatty acids led to the conclusion that pH-related changes in the odour and flavour of cooked sheepmeat are probably mediated by direct pH effects during the cooking process, rather than by a pH-related development of odour and flavour precursors in raw meat before cooking begins.

Meat pH values of lamb legs increased significantly between 4 and 14 weeks storage in the CO₂ aging. Sensory panellist found there were significant storage time effects in “overall”, “sheepmeat”, and “sweet” odours of cooked meat. Panellists also detected a significant decrease in “sweet” and “roasty” flavours in the CO₂-packed lamb legs stored at -1.5°C compared with vacuum packed controls stored frozen (-35°C). Of particular concern, after 14 weeks chilled storage in CO₂, the intensity of a “livery/offaly” flavour was significantly higher than for the frozen-stored control.

The electronic nose could detect differences in headspace volatiles of both raw and cooked minces from meat subjected to the different storage treatments. The results suggest that, under these experimental conditions, the electronic nose was more discerning and possibly gave more reproducible results than sensory panellists. What relationship the electronic nose’s measurements have to human perception of odour has yet to be determined.

The multidisciplinary approach used in this thesis has helped to explain some of the variations in meat flavour quality important to the New Zealand meat industry.

text: Ultimate pH and storage related changes to sheepmeat odour and flavour Gas chromatography/mass spectrometry (GC/MS), gas chromatography/olfactometry and a trained sensory panel were used to study the effects of meat ultimate pH on the odour and flavour of cooked sheepmeat. As part of methods development, supercritical carbon dioxide elution was evaluated as an alternative to thermal desorption of volatile compounds from Tenax-T A traps, but this technique did not offer any significant advantage. In a separate study, the sensory panel and an emerging technology, an electronic nose, were used to investigate the changes in cooked meat odour and flavour arising from long term storage of chilled lamb legs in a carbon dioxide atmosphere.

Pre-slaughter injection of adrenalin was used to produce sheepmeats of normal (5.66), moderate (6.26) and high (6.81) ultimate pH. Meat with a moderate or high ultimate pH had a significantly lower overall cooking odour and flavour intensity, as assessed by the sensory pane, than sheepmeat of a more acceptable pH (5.66). Panellists also found that desirable odour and flavour notes decreased and undesirable ones increased as ultimate pH increased. Purge-and-trap GC/MS of fat rendered during cooking identified 57 (out of a total of 325) volatile compounds that significantly decreased in concentration with increasing meat pH. The most common of these compounds were aldehydes. GC/olfactometry identified 54 odour-active compounds, 10 of which were also found to be responsive to changes in meat ultimate pH. Most of these compounds were again aldehydes.

High ultimate pH raw meat which was titrated with hydrochloric acid to pH levels close to that of low ultimate pH had odour and flavour intensities comparable to those of normal (low) ultimate pH meat. Most of the volatile compounds found by GC/MS analysis to decrease in concentration with increasing ultimate pH did not have a reduced concentration after this downward pH adjustment. These results and parallel analyses of soluble protein, free amino acids and free fatty acids led to the conclusion that pH-related changes in the odour and flavour of cooked sheepmeat are probably mediated by direct pH effects during the cooking process, rather than by a pH-related development of odour and flavour precursors in raw meat before cooking begins.

Meat pH values of lamb legs increased significantly between 4 and 14 weeks storage in the CO₂ aging. Sensory panellist found there were significant storage time effects in “overall”, “sheepmeat”, and “sweet” odours of cooked meat. Panellists also detected a significant decrease in “sweet” and “roasty” flavours in the CO₂-packed lamb legs stored at -1.5°C compared with vacuum packed controls stored frozen (-35°C). Of particular concern, after 14 weeks chilled storage in CO₂, the intensity of a “livery/offaly” flavour was significantly higher than for the frozen-stored control.

The electronic nose could detect differences in headspace volatiles of both raw and cooked minces from meat subjected to the different storage treatments. The results suggest that, under these experimental conditions, the electronic nose was more discerning and possibly gave more reproducible results than sensory panellists. What relationship the electronic nose’s measurements have to human perception of odour has yet to be determined.

The multidisciplinary approach used in this thesis has helped to explain some of the variations in meat flavour quality important to the New Zealand meat industry.

year: 1996

title: Parkins v Parkins

authors: Chevalier-Watts, Juliet

abstract: This case came about by appeal from the District Court, which dismissed the appellant’s claim.  The appellant, Grant Parkins (Grant) declared 25% interest by way of institutional constructive trust over a property in the Marlborough Sounds (the property), which is opposed by his brothers, Steven Parkins (Steven) and Reece Parkins (Reece).   Grant states that his interest arises because of his substantial contributions to the property after it was bought by his late father, Morris Parkins (Morris).  The property was substantively developed after its purchase.  The property had been left in equal shares to the three brothers by Morris in his will. Of note is that the terms of Morris’ will were not challenged in any way by any of the brothers. Whilst this case does not challenge the law of institutional constructive trusts, it provides a useful and instructive summary of the established law and thus adds to the institutional constructive trust narrative.  Prior to considering the law, we will first provide an overview of the facts.

text: Parkins v Parkins This case came about by appeal from the District Court, which dismissed the appellant’s claim.  The appellant, Grant Parkins (Grant) declared 25% interest by way of institutional constructive trust over a property in the Marlborough Sounds (the property), which is opposed by his brothers, Steven Parkins (Steven) and Reece Parkins (Reece).   Grant states that his interest arises because of his substantial contributions to the property after it was bought by his late father, Morris Parkins (Morris).  The property was substantively developed after its purchase.  The property had been left in equal shares to the three brothers by Morris in his will. Of note is that the terms of Morris’ will were not challenged in any way by any of the brothers. Whilst this case does not challenge the law of institutional constructive trusts, it provides a useful and instructive summary of the established law and thus adds to the institutional constructive trust narrative.  Prior to considering the law, we will first provide an overview of the facts.

year: 2022-06-01

title: The contested shift to a bicultural understanding of place heritage in Aotearoa New Zealand

authors: Passey, Emma

abstract: This article explores contemporary threads in the heritage history of Aotearoa New Zealand, as we witness in real-time the emergence of alternative narratives of Indigenous heritage, in contrast to those of Western dominated modernity and colonial hegemony. Moves to actively decolonise heritage studies is creating shifts in the bicultural understanding of culture and heritage to overtly include place heritage. As this new framing emerges, wider acknowledgement of the significance of Māori heritage landscapes is growing. This is explored here in a series of four case-studies. Each account illustrates how Indigenous Māori voices have gained momentum, and reinforces how Aotearoa New Zealand is transitioning to greater bicultural appreciation through inclusion, changes in social and cultural conventions, and new interpretations of dominant narratives using tools like critical heritage studies and existing legal conventions. This evolution of heritage values is not without repeated contestation, however. Positively, increasing numbers of settler-Pākehā (non-Māori) as well as those colonised, no longer believe or accept the histories previously told. Much needed, robust, and sometimes difficult discussions are taking place, enabling New Zealanders to reconsider the significance of what heritage means to all its people.

text: The contested shift to a bicultural understanding of place heritage in Aotearoa New Zealand This article explores contemporary threads in the heritage history of Aotearoa New Zealand, as we witness in real-time the emergence of alternative narratives of Indigenous heritage, in contrast to those of Western dominated modernity and colonial hegemony. Moves to actively decolonise heritage studies is creating shifts in the bicultural understanding of culture and heritage to overtly include place heritage. As this new framing emerges, wider acknowledgement of the significance of Māori heritage landscapes is growing. This is explored here in a series of four case-studies. Each account illustrates how Indigenous Māori voices have gained momentum, and reinforces how Aotearoa New Zealand is transitioning to greater bicultural appreciation through inclusion, changes in social and cultural conventions, and new interpretations of dominant narratives using tools like critical heritage studies and existing legal conventions. This evolution of heritage values is not without repeated contestation, however. Positively, increasing numbers of settler-Pākehā (non-Māori) as well as those colonised, no longer believe or accept the histories previously told. Much needed, robust, and sometimes difficult discussions are taking place, enabling New Zealanders to reconsider the significance of what heritage means to all its people.

year: 2023-01-01