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    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, Elise
    Understanding 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.
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    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, Vishaldeep
    Water 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.
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    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, Boying
    Background: 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