Browsing by Author "Gong, Wei"

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    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, Wei
    The 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.
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    Ecosystem services provided by North Island brown kiwi (Apteryx Mantelli) in two horticulture settings : vineyards and kiwifruit orchards : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Conservation Biology, Massey University, Palmerston North, New Zealand
    (Massey University, 2025) Gong, Wei
    Ecosystem services provide essential benefits to humans from natural ecosystems. Recognising and valuing these services is crucial. By implementing sustainable management practices that balance human needs with biodiversity preservation, we can ensure the long-term health of both ecosystems and people. North Island brown kiwi (Apteryx mantelli), an endemic New Zealand bird are nocturnal ground insectivores whose numbers are increasing following conservation management practices. They are now being reported more frequently from human-modified landscapes. This study explores the possible role of the brown kiwi as pest controllers in vineyards and kiwifruit orchards, focusing on its foraging behaviour and habitat use. I collected data using acoustic recorders only in one study site, and camera traps, pitfall traps, and kiwi faeces analysis across four study sites. These methods aimed to investigate their activity pattern, habitat use, diet composition, and the invertebrates’ composition in this specific area. Acoustic recorders provide kiwi vocal behaviour, estimate population density, and at the same time, camera traps monitor their movement and habitat preference between orchard and bush areas. Pitfall traps and faecal analysis help to identify available and consumed invertebrate prey for them. I used capture rate calculations, Non-Metric Multidimensional Scaling (NMDS), and Spatial Capture-Recapture (SCR) modelling for statistical analyses. That is to assess kiwi activity, diet overlap between seasons and study sites and estimate population density. I found that they were more active in bush areas, but also used orchards, especially those with dense canopy cover, like Puriri Park. Seasonal changes affected invertebrate availability and their behaviour. Kiwi were most active in summer and less active in winter. Kiwi faeces contained potential orchard pest species, suggesting they may be a potential pest controller. Using predator heat maps made with camera trap data, I found different levels of threat at different locations, with higher numbers of predators closer to the bush area. The spatial capture-recapture model estimated a low kiwi density, which may be due to detection limitations and small sample sizes. It may be necessary to increase the sample size in future studies to reflect the most realistic results. Overall, the findings suggest that habitat characteristics such as canopy cover, soil conditions and surrounding vegetation influence their behaviour and that horticultural landscapes can support kiwi if managed properly. Additionally, my findings show that kiwi use modified landscapes and can inform orchardists on how to make horticultural settings more kiwi-friendly through improved habitat and pest management. Future research should increase the number of orchards used and include more diverse horticultural settings to test the replicability of these findings and their extent. Research could also assess the effectiveness of different orchard management practices on their behaviour. These efforts will support better conservation strategies and promote eco-friendly orchard management in New Zealand.