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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 Evaluating consumer affective thresholds in high protein beverages using different approaches : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology at Massey University, Manawatū, New Zealand. EMBARGOED until 27 September 2028.(Massey University, 2025) Waddell, EliseUnderstanding how sensory attributes influence consumer rejection is critical for guiding the development of functional foods, such as high-protein dairy beverages. This study compared three consumer affective threshold methodologies: paired preference, liking, and binary rejection to determine thresholds for three sensory attributes in protein beverages. Consumers (N=142) performed 2-AFC preference tests and evaluated four sample series: a control and four samples with decreasing sweetness (sucralose at 0–5% sugar equivalence), four with increasing thickness (50– 350 cP), and four with increasing powdery mouthfeel from added whey protein (0–10%). Seven additional samples completed a central composite rotational design to examine sweetness and thickness thresholds simultaneously. Sensory panel descriptive analysis, instrumental characterisation, and ingredient composition were used as stimulus intensity measures. Thresholds varied significantly by methodology, with sweetness thresholds ranging from 1.7% to 4.2% sugar equivalence, thickness thresholds from 245 cP to beyond the tested range, and powderiness thresholds from 3.6% to 8.7% WPC. Consumer segmentation greatly influenced threshold positioning, highlighting individual differences. Sweetness was the strongest driver of rejection, both individually and in combination with thickness. Methodological comparisons demonstrated distinct strengths and limitations, reinforcing the need to tailor threshold methodology selection to research objectives. Paired preference was effective for detecting small changes relative to a control, whereas liking and binary rejection provided greater flexibility in assessing broader acceptability. Integrating consumer reasoning behind acceptability added insights; sensory properties were the primary drivers of acceptability, but factors such as ease of drinking, expected purchase satisfaction, and product expectations also influenced consumer decisions.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 Optimisation of sugar concentration and fermentation temperature to produce a low sugar green tea-flavoured water kefir beverage : a thesis submitted in partial fulfilment of the requirement for the degree of Master of Food Technology, Massey University, Albany, New Zealand. EMBARGOED until 16th April 2026.(Massey University, 2024) Kour, VishaldeepWater kefir is a refreshing, self-carbonated, slightly sweet, low-alcoholic beverage characterised by a mildly acidic taste and yeasty aroma. Water kefir is prepared on a household scale or semi industrial scale by inoculating sugar substrate with starter culture i.e., water kefir grains, consisting of a multispecies consortium of symbiotic lactic acid bacteria and yeast embedded in a polysaccharide matrix. Some of the microorganisms found in the kefir grains are recognized as probiotics. The improved health awareness of consumers and popular trends such as healthy hydration, low added sugar, lactose intolerance and natural products are driving the research and development ofnon-dairy beverages which has created a niche market for fermented beverages such as water kefir. Previous research on water kefir was mainly focused on the identification and role of microorganisms present in the kefir grains. In recent years, growing interest in fermented lactose free water kefir have led to the exploration of various sugar substrates (raw sugar, white sugar, brown sugar, molasses and honey), plant based substrates, dried fruits (apricot, dates, figs and raisin) and fermentation factors such as sugar concentration, temperature, kefir grain concentration and fermentation time. The aim of this study was to optimise the fermentation conditions (temperature and sugar concentration) to produce a novel, diary-free low added sugar water kefir beverage using green tea. -- Shortened abstract.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 Characteristisation of acetic acid bacteria and yeast isolated from kombucha produced in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Auckland, New Zealand. EMBARGOED until 21 August 2026.(Massey University, 2024-08-13) Wang, BoyingBackground: Kombucha is a popular functional tea beverage commonly fermented by a complex symbiotic culture of acetic acid bacteria (AAB) and yeast (SCOBY) in a base of sugared tea infusion at ambient temperature for 7-14 days. Regular consumption of Kombucha confers potential health benefits due to the presence of live cultures and high concentrations of bioactive components such as vitamins, polyphenols, and organic acids. However, industrial production of Kombucha faces challenges due to the limited information on the dynamic changes in its microbial community composition and the lack of knowledge regarding their health-promoting characteristics. The impact of fermentation conditions and added substrates on starter cultures, physicochemical characteristics and functional activities is also not well understood. Objectives: This study aimed to determine the microbiological characteristics of New Zealand Kombucha starter cultures and evaluate the probiotic potential of AAB and yeast isolated from commercial Kombucha products. The bioactive components, antioxidant activity, and antimicrobial activities of Kombucha fermented using a New Zealand starter culture under different fermentation conditions were also determined.--Shortened abstract
