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Item Characterization and solubility properties of pumpkin seed flour for functional beverage development : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Palmerston North, New Zealand(Massey University, 2025) Mathew, MibalThe rise in demand for plant-based protein beverages has given opportunities to explore various alternatives protein rich sources like pumpkin seed flour (PSF). This research mainly focuses on the functional and structural properties of PSF which originated from hull less pumpkin seeds. The aim of the study was to check the suitability of pumpkin seed flour in beverage applications. The initial proximate on the pumpkin seed flour, determined high crude protein (53%) and crude fat (15.9). In addition to this, PSF also contains notable ash and carbohydrate levels which making PSF a strong potential nutritional source. By eye it was evident that the commercial pumpkin seed flour studied was comprised of heterogenous particles – some dark green and others light green. The functional impact of this visual variation was evaluated via a sieving experiment performed across standard mesh sizes. The darker green particles concentrated in the larger mesh size while the lighter green particles tended to be smaller. The ash and the protein content in the various particle sizes however showed minimal variation, which justifies the usage of whole flour for solubility studies. Water solubility was conducted at different pHs (3, 6.6 and 8) and temperatures (30ºC, 60ºC and 80ºC). The result showed that the solubility of PSF improved with rising temperatures and with alkaline conditions. The proximate analysis of the solubility sediments, resulted in lower amounts protein and fats, when comparing with the supernatants. The colour analysis of the sediments showed significant variations in L*, a* and b* values which mostly depend on the application of heat and pH. It also shows potential colour degradation and Maillard reaction during varying conditions. SDS – PAGE analysis confirms the solubilization of certain protein bands mostly on higher temperatures and under alkaline conditions. The notable soluble bands are Cucurbitin, 11S basic subunits and 7S globulins. Confocal laser studies gave evidence of protein and fat interactions in varying conditions. The fat and proteins were more dispersed and mixed structures in supernatant during high solubility conditions meanwhile, dense protein aggregates were visible in the sediment fractions. Generally, this study indicate that alkaline conditions are necessary to manufacture a beverage. However, the properties are highly depended on varying processing conditions, mainly certain temperature and pH. These findings help to give an idea for developing a high protein content plant-based drink with the use of pumpkin seed flour as a sustainable and functional ingredient.Item Caffeine-milk protein interactions in coffee brews : effects on the in vitro bioaccessibility of caffeine : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Food Technology, Massey University, Palmerston North, New Zealand(Massey University, 2025) Antony, TreesaCoffee is one of the most consumed beverages around the world and is known for a myriad of health benefits. Black coffee is a rich source of bioactive compounds and has high antioxidant activity. Coffee has been consumed in various forms with and without the addition of milk. The impact of milk addition on the phenolic properties, antioxidant activity, and functionality of bioactive components has been an interesting topic among researchers for the past few decades. But to the best of our knowledge, the effect of milk addition to coffee brew on caffeine bioaccessibility has not yet been addressed in the literature. Accordingly, this study aimed to investigate the interactions between caffeine and milk proteins in coffee and the effect on in vitro bioaccessibility of caffeine, as well as the antioxidant properties. A range of analytical techniques was employed to assess these interactions. Ultraviolet (UV) spectroscopy and high-performance liquid chromatography (HPLC) were used to quantify caffeine content in black coffee and milk-based coffee samples at various stages of digestion. Fourier transform infrared (FTIR) spectroscopy was applied to examine the molecular interactions between caffeine and milk proteins, focusing on non-covalent binding mechanisms such as hydrogen bonding and Van der Waals forces. Total phenolic content (TPC) and antioxidant capacity were measured using the Folin-Ciocâlteu assay and DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, respectively. Additionally, particle size distribution and ζ-potential analysis were performed to determine the stability and colloidal properties of the coffee samples. In vitro digestion was conducted to simulate gastrointestinal conditions, including the gastric and intestinal phases, to evaluate changes in caffeine bioaccessibility over digestion. The results demonstrate a significant reduction in caffeine content upon milk addition at all digestion stages, indicating strong interactions between caffeine and milk proteins. UV spectroscopy and HPLC analyses revealed that in black coffee, the initial free caffeine content before digestion was 173.1 µg/mL, which decreased to 90.7 µg/mL post-gastric digestion but increased to 147.9 µg/mL after the intestinal phase, suggesting increased free caffeine concentration at the end of digestion. The free caffeine concentration obtained for milk-based coffee was 142 µg/mL before digestion, and at the end of digestion, it was 108 µg/mL, which indicates that milk addition reduced caffeine recovery. Similarly, the addition of milk reduced the TPC and DPPH radical scavenging activity of pure caffeine and coffee brews. The TPC values for black coffee and milk-based coffee were 133.4 and 94.7 μg gallic acid equivalent (GAE)/mL, respectively, at the end of digestion. The DPPH antioxidant activity values were 27.42 and 3.54 µg/mL, respectively, for black coffee and milk-based coffee after intestinal digestion. The data from FTIR analysis suggest that non-covalent interactions, such as hydrogen bonding and Van der Waals forces, exist between milk proteins and caffeine, which may affect the functionality of caffeine. Shifts at the major caffeine peak regions (2950-2930 cm-¹) indicate the C-H stretching vibrations, suggesting a possibility for hydrogen bonding and Van der Waals interactions. The results from the particle size data are inconclusive in determining the extent of caffeine interactions or bioaccessibility, necessitating further molecular-level and bioavailability studies. Data from ζ-potential measurement reveals that milk-based coffee has a more stable system compared to black coffee after intestinal digestion. This complements other results as higher stability for a colloidal system could be an indication of less availability for further interactions or release of free caffeine. The in vitro digestion studies reveal that the overall bioaccessibility of caffeine decreases when milk is added to coffee brew. The percentage bioaccessibility of caffeine in black coffee and milk-based coffee was 85.8 and 77%, respectively. The findings of this research contribute to the understanding of coffee as a functional beverage and provide insights into how the addition of milk to the coffee brew may affect the functionality.Item Understanding the effect of processing and species on milk proteins during digestion : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Biochemistry at Massey University, Manawatū, New Zealand(Massey University, 2025-02-28) Maidment, Catherine AnnMilk is an important source of protein in a balanced human diet. Milk proteins not only have high nutritive value but also have biological properties. Milk composition and structure vary based on factors such as species, processing methods, and lactation stage. These differences are believed to affect digestion by influencing the breakdown of milk proteins, fats, and carbohydrates, as well as the rate and efficiency at which nutrients are absorbed in the gastrointestinal tract. The overall objective of this PhD thesis was to investigate how milk proteins from different species (cow, sheep, goat, and deer) are affected by digestibility under varying processing treatments (heating and homogenisation). Digestibility was assessed by the amount and types of bioaccessible peptides generated during gastrointestinal digestion. A dynamic in vitro digestion model (human gastric simulator (HGS)) was used for this study. Size exclusion chromatography was employed to measure the amount of peptides generated throughout digestion, with significant differences determined by a p-value threshold of 0.05. Mass spectrometry was used to analyse the types of peptides, requiring peptides to be present in at least two-thirds of the samples for inclusion. To assess the validity of the results obtained using the HGS model, comparisons were made with the peptide profiles generated using an in vivo (pig) digestion model. In addition, further work was undertaken looking into the protein composition of deer milk throughout the different lactation stages. This study investigating digestibility found differences in the amount and types of bioaccessible peptides generated throughout gastric digestion in milk from different species. Overall, deer milk produced the most peptides, while goat and sheep milk produced the least. Ruminant species also affected which regions of the parent protein were resistant to digestion as well as their bioactive properties. In contrast, processing treatment did not have as significant an effect on the amount and types of bioaccessible peptides but did affect the digestion kinetics. Differences were only observed during early digestion and appeared to be species dependent. Similarities were found in the peptides released throughout gastric digestion between the HGS model and the in vivo pig model, which suggests that the HGS model is suitable for the study of gastric digestion of protein-rich food. However, the peptide profiles differed during the intestinal stage indicating that the intestinal step attached to the in vitro model needs improving to fully mimic the dynamic nature of in vivo digestion. The study investigating deer milk proteins found that proteins related to transport e.g. apolipoprotein E and vitamin D-binding protein and immunity e.g. osteopontin, immunoglobulin J and lactotransferrin were found to change throughout lactation. This is thought to reflect the changing needs of the newborn as well as the development and protection of the mammary gland over lactation. Proteins were investigated using mass spectrometry, and significant differences throughout lactation were determined using simple linear regression calculations and log fold change calculations, comparing protein levels between week 3 and week 16 of lactation. The results from this thesis will contribute to the knowledge of how milk composition and structure impact protein digestibility throughout gastrointestinal digestion. The information gained from this study may have important consequences for developing dairy products that deliver superior digestive and nutritional outcomes to targeted consumer groups.Item Chemometric and sensory characterisation of New Zealand craft ciders : a preliminary study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Manawatu Campus, Palmerston North, New Zealand(Massey University, 2024) Gong, WeiThe New Zealand craft cider industry is growing, but its unique sensory characteristics and chemical components are not yet fully scientifically understood. This study aimed to understand the key components and sensory attributes that define selected New Zealand craft ciders through the integration of chemometrics and sensory characterisation. Seventeen craft cider samples were collected from New Zealand cider regions and characterized for their chemical parameters, including pH, titratable acidity, tannin content and colour. Volatile components were identified and quantified using headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS). One focus group (n=5) was organised to generate consumer-oriented descriptors for ciders. This was followed by quantitative sensory evaluation using a 9-point hedonic scale for liking of sensory attributes and Check-All-That-Apply (CATA) to characterise the samples. The results of the data analysis showed that there were significant differences (p<0.05) in chemical parameters and volatile components among the samples. Principal component analysis (PCA) revealed that tannin, pH and colour (a* and b* values) were the chemical parameters that contributed to high variability among the samples. The key volatile compounds identified in the samples were ethyl octanoate, isoamyl octanoate, and 1-octanol. According to sensory assessments, ciders from the North Island were mainly described as "fruity," whereas those from the South Island were primarily described as "bitter" and "dry." Additionally, the study showed that while bitterness and astringency were negative drivers, fruitiness and sweetness were positive drivers of acceptance for the samples. Moreover, the North Island's ciders displayed higher levels of similarity, whilst the South Island's ciders displayed higher levels of chemical variety. This finding implies that production techniques and apple varieties may be significant variables in determining the sensory and chemical profiles of the samples. This has implications for the importance of understanding the impact of geographical factors on the chemical and sensory characteristics of craft ciders. This study not only revealed differences in chemical and sensory characteristics of New Zealand craft cider but also provided valuable insights for producers. Future research could further explore the effects of apple variety, production methods and regional characteristics on cider quality, thereby contributing to the sustainable development of the New Zealand craft cider industry.Item Effect of beverage modification with molecularly imprinted polymers (MIPs), carbon granules and an adsorbent resin on the organoleptic properties of apple, orange and cranberry juice : a dissertation presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Manawatū, New Zealand(Massey University, 2024) O'Connor, Samantha Li-QianAroma and flavour volatile compounds contribute significantly to overall consumer acceptability in many food-related products. Molecularly imprinted polymers (MIPs) have been known to absorb specific volatile odour compounds (VOCs) from alcoholic beverages like red wines but minimal studies have been done to establish how MIPs could modify the overall organoleptic properties (especially the taste) of other beverages. In the present work, apple, orange and cranberry juices were subjected to various treatments with polymers SV7, GV1, CV6, resin Purosorb PAD 600 and activated carbon granules. From, gas chromatography mass spectroscopy (GCMS) analysis a significant decrease in VOCs in all cases was prevalent but was dependent on the contact time (dose and flow rate) between MIPs and the beverage. All samples treated with carbon granules were excluded from further sensory analysis as participants detected a highly unpleasant ashy aftertaste and prominent egg-like odour after informal sensory evaluation. The prominence of these attributes therefore would have hindered this investigation. Formal sensory analysis of the six selected MIPs and resin treated juices by untrained individuals resulted in differences of each sample based on mainly the colour, aroma and flavour in both apple and cranberry juice. Although, participants ratings were similar, the molecularly imprinted polymers SV7 and GV1 maintained more sensory attributes than the resin Purosorb PAD 600. This is reflected in the hedonic ratings of colour in apple juice with GV1 producing a scoring of 6.4 ± 1.7 verses 4.3 ± 1.9 whilst the aroma intensity values in cranberry juice via treatment with SV7 was rated 5.6 ± 2.3 verses 3.5 ± 2.3. Molecularly imprinted polymer CV6 also performed better than the commercial resin, but, lower contact times are needed in order for participants to have a more holistic sensory experience. Panellists could not discern any significant differences in all six orange juice samples, however, overall trends within the sensory data generated showed that polymer SV7 had a comparatively higher number of beneficial volatiles that were retained. The positive reception that the polymers SV7 and GV1 were able to achieve indicates that there is more scope for modification within the industry utilising these MIPs.Item Development of foxtail millet (Setaria italica) milk : a novel beverage : a thesis submitted in partial fulfilment of the requirement for the degree of Master of Food Technology, Massey University, Albany, New Zealand(Massey University, 2024) Cao, ChengjinGrowing environmental and health concerns related to animal-based food production has led to environmental and health concerns recently, which has resulted in plant-based foods increase in popularity. Plant-based milk alternatives, made from sources like legumes and seeds, are becoming more popular. In this study, foxtail millet is explored as a gluten-free nutritious and sustainable plant-based milk alternative. Phase I of the study focused on investigating the extraction of foxtail millet extracts (FME) by analysing three key parameters: colour, pH, and total soluble solids. Dry milling with a higher millet-to-water ratio (millet percentage) produced FME with colour similar to cow's milk. The pH of dry-milled FME ranged from 6.38 to 6.67, slightly higher with wet milling. The total soluble solids (ºBrix) were found higher processed with dry milling, extracted with higher percentage of amylase rate and millet percentage. Focus group sensory evaluation was conducted and determined parameters including dry milling, 0.20% amylase, and 10% and 12% millet grain were decided for further investigation. In Phase II, FMEs underwent emulsification with varying millet grain rates, added oil, and lecithin. Physicochemical properties including whiteness, pH, total soluble solids, particle size, viscosity, and gravitational separation rate were measured to screen 12 formulations. Higher millet grain percentage increased whiteness and soluble solids, while more added oil raised whiteness and viscosity. Particle size decreased with homogenisation but was not significantly affected by other factors. Sensory evaluation favoured formulations with 12% millet grain and 0.8% oil. The optimal formulation for further study was identified as having 12% millet grain, 0.8% oil, and 5% lecithin. Phase III investigated the physicochemical properties of the selected foxtail millet milk formulation and its shelf-life during storage at 4℃ for 4 weeks. Analysis of foxtail millet milk suggested improved microbial stability and while maintaining a similar moisture content to cow skim milk but with lower ash content. It contained 0.5% protein, 1.3% unsaturated fats, 7.6% carbohydrates, and 0.4% dietary fibre which is absent in cow's milk. It offers a healthier profile than saturated fat-rich or high-sodium alternatives. In conclusion, the foxtail millet milk developed in this study demonstrated good appearance, sensory acceptance, microbial stability, and served as a good source for carbohydrates.Item Optimising the extraction of plant milk from oats : a research report presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Palmerston North, New Zealand(Massey University, 2024) Zhou, YuanhangIn recent years, due to the various benefits of plant milk, it has become an ideal substitute for cow’s milk, among which oat milk contains many beneficial substances for the human body such as β- Glucan, phytic acid, avenanthramides and phenolic compounds. However, the cost of oat milk production is relatively high. Therefore, this study aims to improve the yield of oat milk by determining the best enzymatic hydrolysis conditions of oat milk. The study shows that the optimal production condition of oat milk is: the enzyme concentration is 16ul/500ml oat slurry, the incubation temperature is 76℃, and the slurry concentration is 8%, the hydrolysis time was 20 minutes and pH was not controlled. Oat milk produced by the optimum process was UHT treated and tested for stability and rheology. Sedimentation occurred within 3 days at both 4°C and 25°C. The power law model explains the rheological behavior of oat milk at 25 ° C, 35 ° C, 45 ° C, 55 ° C, and 65 ° C. Further recommendations to the process include addition of additives to improve stability and testing of sensory properties. The optimal process can be scaled for further testing.Item Ancient beer production : a thesis presented in partial fulfillment of the requirements for the degree of Masters in Food Technology, Massey University, Auckland, New Zealand(Massey University, 2022) Sathyanarayanan, Barath KumarBackground: Beer is considered to be one of the major historical achievements of mankind over the past several centuries in the area of fermented beverages. Beer has the ability to unite people under various cultural traditions and has geographically spread out throughout the world. It varies from nation to nation under the basis of its ingredients, production processes, sensory properties etc. However, the exploration of ancient beer research has been increasing only in the past few decades given the availability of modern analytical tools. Various civilisations adapted the concept of beer into their own cultures in a unique aspect as a safe-to-drink beverage, as opposed to drinking untreated water. Based on an archaeology study of a 5000-year-old beer recipe, one such civilisation named Yangshao (in Shaanxi, Northern China) was considered for this project. Objective: To recreate the ancient beer recipe that has been obtained from the above-mentioned Shaanxi district and adopt its ingredients into contemporary beer brewing methods. In this project, the physicochemical properties were analyzed and a focus group was conducted to understand consumer opinions and attitudes about the sensory characteristics of this beer. Methods: Initially, the ancient ingredients were identified and prepared to suit the modern brewing process. Processes such as milling, mashing, fermentation, conditioning were fine-tuned in order to suit them for the ancient beer reproduction. Physicochemical properties such as brix, colour, pH, specific gravity, alcohol content etc. using methods such as spectrophotometry, gas chromatography, refractometry etc., were investigated. A focus group was used collect qualitative information on the opinions of modern-day consumers on the ancient beer samples. Results: The beer was recreated by identifying the ingredients and their proportions, adjusting various production process parameters such as milling (15mm roller gap for barley & 10mm roller gap for adjuncts), mashing (double temperature mashing with 60 minutes), fermentation (primary and secondary fermentation), conditioning (at 4℃ for 1 week) etc. Recreated beer had similar physicochemical properties to certain commercial beers such as ales, lagers, Weiss beers etc. The similarities identified included alcohol content to modern-day beers (4.1% ABV), similar pH as ales (4.2) however focus group discussions revealed some uniqueness of this beer compared to modern beers. The unique factors included its pale colour, lack of bitterness, and increased sourness in its taste to its high malty aroma. Conclusion: The optimisations made on the physical processes resulted in a mash which yielded maximum amount of sugar extraction from the grains and a well carbonated final beer. The physicochemical analysis revealed that certain attributes of the ancient beer like pH, alcohol content were similar to some modern-day beers but overall the final beer product was unique and contrasting. The recreated ancient beer was well received by the focus group participants and most of them indicated their preference for the sample that incorporated hops. Also, the results proved that an additional carbonation process can be recommended in order to enhance the fizziness of the beer. Overall, the ancient beer proved to be feasible in modern-day brew society considering certain changes in ingredients (hops) and production processes (carbonation, filtration) are implemented in future.Item Evaluating temporal multiple sip approaches to characterise product experience : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North Campus, New Zealand(Massey University, 2021) Weerawarna N. R. P., MaheekaAs consumers become ever more demanding, methods that capture detailed insights into consumer product experiences are much needed. Adapting temporal sensory and affective measures to cater this demand beyond single time points and small sample sizes is one such approach, and of a recent interest in the sensory and consumer science research area. Firstly, this research compared single and multiple sip sensory approaches using static and time-dependent sensory methodologies with an expert panel. Multiple sip evaluations were designed to represent the consumption of a whole product serving, in this case vanilla milkshakes. Generalised linear models with Analysis of Deviance were employed as a novel approach to analyse naturally correlated temporal data. Additionally, the impact of milkshake sipping method and panel type on multiple sip temporal profiles of the milkshakes was investigated. In addition, temporal methods were adapted to investigate consumer affective responses, both hedonic and emotional response, over multiple sips. Temporal drivers of product acceptance and rejection were identified in analyses combining sensory and affective data. Finally, the impact of individual differences in sweet liker and PROP (6-n-propylthiouracil) taste phenotypes across multiple sip temporal emotion profiles of the milkshakes was investigated. Multiple sip evaluation of both static and temporal methods (Temporal check all that apply (TCATA) and Temporal dominance of sensation (TDS)) provided further discrimination of products than on a single sip of milkshakes. The use of static and temporal methods as complementary approaches, rather than as alternatives, was valuable in obtaining holistic temporal profiles of products. Specifically, the use of generalised linear models and Analysis of Deviance allowed to investigate the dynamics of within-sip and between sip which was a novel addition to the knowledge of temporal data analysis. However, temporal sensory product profiles varied depending by sipping method and emphasised the importance of adapting product evaluation protocols based on intended consumption methods of the beverages. Moreover, temporal sensory profiles were affected by panel type, i.e. experts or consumers, and the insights obtained from the two panel types were not interchangeable. Using expert panels, even on multiple sip evaluations did not provide closer insights into actual consumer product experience. The research highlighted that choice of panel type needs to be aligned with any respective project objectives. Temporal sensory responses of consumers were associated with temporal liking and emotions over multiple sips. Furthermore, dominant emotions reported depended on sweet liker status and PROP taster status. The research findings highlighted the importance of investigating temporal affective responses, i.e. both liking and emotions, and individual differences alongside temporal sensory responses in consumer research to obtain closer insight into actual product experience. Generally, findings were attribute and product specific and hence wider research using additional products and different food matrices are required to validate the findings. Overall, the research outcomes emphasised the importance of multiple sip sensory evaluations to represent the consumption of whole product servings, using appropriate sipping methods, and panels. Investigating the affective responses and individual differences were important to capture different insights according to respective project objectives.Item Development and characteristics of green tea kombucha : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Albany, New Zealand(Massey University, 2018) Wang, XiaoleiFermentation by microorganisms plays an important role in the development of manufactured food due to its ability to extend the shelf-life of the products as well as improving the nutritional value and sensory properties. Demand and interest in the consumption of fermented products, such as yoghurt, cheese, buttermilk and meat has continued to increase in the past few decades, due to their beneficial health effects which include prevention of chronic disease and enhancement of the immune system. However, because of the health challenges of these products such as lactose intolerance, high cholesterol and fat content, as well as protein allergies, consumer interest in the consumption of non-dairy and plant-based fermented products such as water kefir and kombucha is growing. Kombucha is a traditional refreshing home-made beverage with a slightly acidic, sweet and alcoholic taste, which is thought to have originated in Germany, China and Russia, but is now consumed worldwide. Kombucha is usually produced by the fermentation of tea and sugar with a symbiotic consortium of acetic acid bacteria and yeasts, commonly known as the kombucha starter culture. The physico-chemical characteristics, microbial profiles and sensory properties of kombucha are significantly affected by fermentation conditions including sugar concentration, fermentation time and temperature. The majority of previous studies have focused on the comparison of different substrates for kombucha preparation and their effects on the final composition of kombucha. Therefore, there is scanty information in the development and characteristics of kombucha under different production conditions. The present study investigated the effects of sugar concentration, fermentation time and temperature on the fermentation of green tea kombucha aimed at optimising the process to develop a consistent high quality beverage. The development and characteristics of green tea kombucha were investigated in four- integrated experimental phases. Phase 1 enumerated the microflora in the kombucha starter culture (acetic acid bacteria, lactic acid bacteria and yeasts). The effect of fermentation time (7, 10 and 14 days) on the development of kombucha was studied in Phase 2 in order to select the optimum fermentation time. In Phase 3, the effects of two sugar concentrations (7% and 10%) and two fermentation temperatures (22℃, 24℃) on the physico-chemical, microbial and sensory characteristics of green tea kombucha were studied, with the aim of selecting the optimum sugar concentration and fermentation temperature for the development of green tea kombucha. The antibacterial activity of the final optimised green tea kombucha were investigated and the stability of the beverage was monitored during storage (4℃) for 4 weeks in Phase 4. Various analyses of green tea kombucha samples were conducted during fermentation and storage in order to investigate the physico-chemical, microbial and sensory characteristics of the beverage: sugars, organic acids, ethanol, antioxidant, titratable acidity (TA) and viable cell counts (VCC) of kombucha microorganisms were analysed, pH, total soluble solids (TTS) and colour were also measured. Acetic acid bacteria (6.08±0.06 log cfu/ml) and yeasts (7.13±0.07 log cfu/ml) were present in the kombucha starter culture used in this study, while no lactic acid bacteria were found. Results from Phase 2 showed that fermentation time contributed to the physico-chemical, microbial and sensory properties of green tea kombucha. In Phase 2, TA increased steadily from Day 7 (0.36±0.02 - 0.42±0.04) to Day 14 (0.88±0.04 - 1.01±0.06) (p<0.05), while pH, total soluble solids, VCC and overall consumer acceptability decreased (p<0.05). In Phase 3, kombucha samples containing 7% or 10% sugar and fermented at 24℃ for 7 days were characterised by higher levels (p<0.05) of organic acids with lower pH, TSS and VCC than kombucha fermented at 22℃. No significant differences (p<0.05) in colour, VCC and levels fermentation. Based on the physico-chemical, microbial and sensory characteristics of green tea kombucha beverage in Phases 2 and 3, the optimum fermentation conditions were kombucha containing 7% sugar and fermented at 22℃ for 7 days. The results of the disc diffusion studies showed that the final optimised green tea kombucha had antibacterial activities against Escherichia coli 111, Listeria monocytogenes 15E03-1, Salmonella typhimurium ESR3479, Staphylococcus aureus MU-A57 and Pseudomonas aeruginosa MU-A26. High quantities of antioxidants (gallic acid = 5.7±0.04 µg/ml, EGC = 130.89±6.86 µg/ml, EGCG = 152.26±39.70 µg/ml and ECG = 41.11±16.23 µg/ml) were also present in this beverage. These observations suggested that consumption of green tea kombucha may exert beneficial health effects. During storage (4℃) for 4 weeks, the colour of the optimised green tea kombucha was stable and the consumer acceptability of green tea kombucha beverage remained high. Green tea kombucha containing 7% sugar and fermented at 22℃ for 7 days was well-liked by consumer panellists (n=60) and this beverage contained 0.35±0.03% (w/v) gluconic acid, 0.31±0.00% (w/v) acetic acid and high levels of certain antioxidants which may confer beneficial effects on human health.