The ability of Pyrolysis-GC/MS analytical system---developed earlier to study the mechanism of Maillard reaction---was further enhanced to include chemical ionization, tandem mass spectrometry and a sample pre-concentration trap essential to detect minor components. Furthermore, the sample delivery during Py-GC/MS analysis was optimized and its relevance to the study of aqueous Maillard model systems was also characterized. The results of these investigations have indicated that the use of higher values of carrier gas flow rates or high constant pressures, during Py-GC/MS analysis can increase the total number of peaks and total area counts of the pyrograms. The influence of the reaction phase on the mechanism of formation of Maillard products was studied by comparison of 13C-label incorporation patterns of the common products formed in model systems consisting of labeled glycine and D-glucoses subjected to both pyrolysis and heating in aqueous solutions. Although pyrolysis reaction produced higher number of products, however, the major pathways of formation of variety of important Maillard products followed the same mechanism under both pyrolytic and aqueous systems. Furthermore, the advantages of the optimized system, were demonstrated both in the investigation of the mechanism of Maillard reaction, using L-serine and L-threonine as model systems and in the study of formation of Maillard generated carcinogens and chemical markers. Analyses of the pyrolysis products of [13C-1], [13C-2] and [13C-3] labeled L-serines and L-threonines have indicated the presence of three initial degradation pathways. Decarboxylation followed by deamination; a retro-aldol reaction and dehydration followed by isomerization, deamination and hydrolysis leading to the formation of pyruvic and 2-ketobutanoic acids. Interestingly, the amino carbonyl interaction between the resulting pyruvic acid and the aminoethanol can lead to the formation of an Amadori product i

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.

Thesis (Ph. D.)--University of Rhode Island, 2003. / Typescript. Includes bibliographical references (leaves 170-182).

Simplex optimization was used to maximize the production of Maillard reaction compounds which inhibit the growth of Staphylococcus aureus. The simultaneous factor shift and mapping procedures of the optimization program enabled the optimization to be completed with a minimum number of experiments. The reaction conditions likely to have the greatest effect on the production of these compounds were chosen as: (1) molar ratio of amino acid to sugar, (2) total concentration of reactants, (3) pH, (4) temperature and (5) time of heating. Inhibition of the test organism was quantified as the radius of no growth, by the concurrent use of the variable and uniform cams of the spiral plating system. Twenty nine experiments were required to reach the optimum of model system A, glucose + lysine, while model system B, xylose + lysine, was optimized after 28 experiments. The minimum inhibitory concentration (MIC) of the optimum glucose + lysine reaction mixture was 5.78 x 10⁻⁴ μg/cfu, while that of the xylose + lysine reaction mixture was 8.94 x 10⁻⁴ μg/cfu. Multiple regression analysis of the data indicated that pH and total concentration were the two most significant factors in determining the inhibitory compounds produced by the glucose + lysine mixture. Molar ratio, temperature and time were not significant for this combination of reactants. The most significant factors for the xylose + lysine combination were pH and temperature, whereas molar ratio and total concentration were not significant. Calculation of the contributing proportion (Pⅰ) of each variable to the response, supported the results of the regression analysis. Separation of the optimized Maillard reaction mixtures according to molecular weight, using ultrafiltration, failed to provide any information about the molecular weight range of the inhibitory compounds. / Land and Food Systems, Faculty of / Graduate

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