Some New Zealand indigenous plants may offer unique qualities that can be used to secure an exclusive niche in the alcoholic drinks market in the same way that Scotch whisky and tequila are strongly identified with the country of origin, Scotland and Mexico. Tequila is a spirit distilled from a fermented agave, dry adapted lily. Agave is in the family Agavaceae, a notable New Zealand member of which is the common cabbage tree or ti kōuka (Cordyline australis). Similarly, to the agave having a fermentable core, ti kōuka has carbohydrate (inulin) content in its young stems and roots that can be hydrolysed in acidic suspensions or by enzyme hydrolysis to yield fructose. The main objective of this thesis was to systematically research the feasibility of the production of a tequila-like spirit from ti kōuka stem, profiling the chemical properties of the spirit with a view of future commercial production of an iconic New Zealand spirit. The initial stage of the thesis focused on extracting inulin from the ti kōuka stem and hydrolysing (by both acid and enzyme) it to yield reducing sugar. The sugar concentration yielded was too low (~ 10 to 15%) to be fermented and distilled economically. Rather, the ti kōuka extract was evaporated to produce flavoured products by the Maillard reaction, a reaction between amino acids and sugars. The flavoured compounds were then infused with potable ethanol. In outline, the dried stem was hydrolysed with an inulinase at 60°C for 1 hour. The pH was adjusted to 10 with sodium hydroxide and evaporated at 60°C for 65 hours. The dried extract was reconstituted with water, centrifuged and the supernatant infused with portable ethanol to yield final different concentrations of 80, 67, 57 and 50%. The ethanol treatments simultaneously extracted flavour and colour to varying degrees. Next, sugars and amino acids were analysed in the ti kōuka stems by liquid chromatography. The most abundant sugar present in the ti kōuka after inulinase hydrolysis was fructose and the dominant amino acids were arginine, leucine, lysine, and aspartic acid/aspargine and glutamic acid/glutamine. Amino acids and reducing sugar were also analysed at different stages of the spirit production. The reducing sugar content decreased during each step of the process. The relative concentrations of arginine, leucine and lysine decreased while that of aspartic and glutamic acids increased during the whole process of making the spirit. Model systems were then used to simulate the reactions taking place between the amino acids and reducing sugar present in the ti kōuka extract. The colour of the models became darker as a function of time, accumulating more brown pigment containing the flavoured compounds. Increasing the pH and concentration of the amino acids in the reaction mixture also increased the browning pigment formation. Dichloromethane and n-pentane and diethyl ether solvent extraction of the spirits and analysis of volatiles by gas chromatography- mass spectrometry revealed that the chemical profiles of the spirits were different from those of the commercial spirits, gin, tequila and whisky. Sensory evaluation was performed on four variations of the spirit, and demonstrated that the creations were consumer-acceptable. The costs and other issues involved in producing and marketing such a spirit were identified, the major selling point being geographical exclusivity.

Some New Zealand indigenous plants may offer unique qualities that can be used to secure an exclusive niche in the alcoholic drinks market in the same way that Scotch whisky and tequila are strongly identified with the country of origin, Scotland and Mexico. Tequila is a spirit distilled from a fermented agave, dry adapted lily. Agave is in the family Agavaceae, a notable New Zealand member of which is the common cabbage tree or ti kōuka (Cordyline australis). Similarly, to the agave having a fermentable core, ti kōuka has carbohydrate (inulin) content in its young stems and roots that can be hydrolysed in acidic suspensions or by enzyme hydrolysis to yield fructose. The main objective of this thesis was to systematically research the feasibility of the production of a tequila-like spirit from ti kōuka stem, profiling the chemical properties of the spirit with a view of future commercial production of an iconic New Zealand spirit. The initial stage of the thesis focused on extracting inulin from the ti kōuka stem and hydrolysing (by both acid and enzyme) it to yield reducing sugar. The sugar concentration yielded was too low (~ 10 to 15%) to be fermented and distilled economically. Rather, the ti kōuka extract was evaporated to produce flavoured products by the Maillard reaction, a reaction between amino acids and sugars. The flavoured compounds were then infused with potable ethanol. In outline, the dried stem was hydrolysed with an inulinase at 60°C for 1 hour. The pH was adjusted to 10 with sodium hydroxide and evaporated at 60°C for 65 hours. The dried extract was reconstituted with water, centrifuged and the supernatant infused with portable ethanol to yield final different concentrations of 80, 67, 57 and 50%. The ethanol treatments simultaneously extracted flavour and colour to varying degrees. Next, sugars and amino acids were analysed in the ti kōuka stems by liquid chromatography. The most abundant sugar present in the ti kōuka after inulinase hydrolysis was fructose and the dominant amino acids were arginine, leucine, lysine, and aspartic acid/aspargine and glutamic acid/glutamine. Amino acids and reducing sugar were also analysed at different stages of the spirit production. The reducing sugar content decreased during each step of the process. The relative concentrations of arginine, leucine and lysine decreased while that of aspartic and glutamic acids increased during the whole process of making the spirit. Model systems were then used to simulate the reactions taking place between the amino acids and reducing sugar present in the ti kōuka extract. The colour of the models became darker as a function of time, accumulating more brown pigment containing the flavoured compounds. Increasing the pH and concentration of the amino acids in the reaction mixture also increased the browning pigment formation. Dichloromethane and n-pentane and diethyl ether solvent extraction of the spirits and analysis of volatiles by gas chromatography- mass spectrometry revealed that the chemical profiles of the spirits were different from those of the commercial spirits, gin, tequila and whisky. Sensory evaluation was performed on four variations of the spirit, and demonstrated that the creations were consumer-acceptable. The costs and other issues involved in producing and marketing such a spirit were identified, the major selling point being geographical exclusivity.

The n-butanol extract of aerial parts of Cordyline australis demonstrated antifungal activity. n-Butanol and chloroform extracts of dried or fresh leaves of C. australis afforded a steroidal glycoside, which was identified as 5α-spirost-25(27)-en-3β-ol 3-O{O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside}, saponin 1. This spirostanol glycoside showed strong antifungal activity towards Trichophyton mentagrophytes and some aspecific activity and cytotoxicity against MRC5 cell. The chloroform extract of fresh leaves of C. australis yielded a second new spirostanol glycoside which was identified as 5α-spirost-25(27)-ene-1β,3β-diol 1-{O-α-L-rhamnopyranosyl-(1→2)-β-D-fucopyranoside}, saponin 2. The n-butanol extracts of senescent leaves of C. australis afforded a third new spirostanol glycoside that was identified as 5α-spirost-25(27)-ene-1β,3β-diol 1-{O-β-D- fucopyranoside, saponin 3. A mixture of two isomeric flavonoid glycosides was isolated from dried leaves of C. australis and shown to be a ca 1:1 mixture of isorhamnetin-3-O-{O-α-L-rhamnopyranosyl-(1→6)-β-D-glucopyranoside}, 4 and isorhamnetin-3-O-{O-α-L-rhamnopyranosyl-(1→6)-β-D-galactopyranoside}, 5. Three other known steroidal glycosides, β-sitosterol glucoside, 6, prosapogenin A of dioscin, 7, and trillin, 8 were also isolated from the leaves of C. australis. The n-butanol extract of dried stems of C. australis afforded (25S)-5α-spirostane-1β,3α-diol 1-{O-β-D-glucopyranoside}, 9. This spirostanol glycoside showed moderate cytotoxicity against Herpes simplex type I virus (ATCC VR733) and Polio Virus Type I (Pfiser vaccine strain).

Thesis (Ph. D.) -- Lincoln University, 2008. / Also available via the World Wide Web.

Thesis (M.Phil. Chemistry)--University of Waikato, 2006. / Author held a Georgetti scholarship. Includes bibliographical references (leaves 89-99). Also available via the World Wide Web.

Fragmentation of forest habitat by urban and rural development has had profound effects on the distribution and abundance of many native species; however, little is known about the ecological processes driving patterns in community structure (species richness and composition) of host-specialised herbivores in modified habitats. I examined patterns in community structure of 9 specialist and 19 generalist invertebrate herbivores of cabbage trees (Cordyline australis Laxmanniaceae) across a highly-modified landscape. I found that, although species richness of specialists was highest in forest sites, the majority of host-specialised species were not restricted to forest habitats and were as widespread as many generalists. In terms of site occupancy, only two specialist and four generalist species were rare. I show that patterns of species occupancy and abundance reflect differing susceptibility to habitat modification, with landscape-level variation an important predictor of abundance for nearly all species. When species occurrences and life history traits were considered I did not find strong evidence for the importance of dispersal ability, which suggests that habitat variability had a stronger organising effect on the community. In a replicated common garden experiment, I found distinct regional patterns in the community structure of the specialist invertebrates occurring on different phylogenetic groups of C. australis. In contrast, community structure of generalist herbivores did not differ significantly among host genotypes. I speculate these patterns are due to historical changes in the distribution of cabbage trees in the Southern phylogenetic region that caused specialised herbivores to become locally adapted on populations of low genetic diversity following expansion after the last glacial maximum. However, this consistent selection pressure did not occur in the Northern region where C. australis habitat has been more consistently available over the past tens of thousands of years, reflected in higher host genetic diversity. This study has advanced our understanding of the patterns in community structure of an indigenous, host-specialised fauna in a highly modified and fragmented urban and rural landscapes.