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    The multimodality of creaminess perception : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Manawatū Campus, Palmerston North, New Zealand. EMBARGOED until 21 August 2026.
    (Massey University, 2024-02-28) Fisher, Emily Claire
    Creaminess is a complex sensory sensation that drives consumer acceptability of milk. To date, creaminess research has focused on instrumental and compositional measures overlooking the critical consumer perspective. This research took a consumer-led approach to unlock new insights into the underlying sensory attributes driving consumer creaminess perception using perceptual modelling. Robust sensory data, from a trained panel, was combined with consumer approaches for accurate modelling. Initially, attributes and modalities perceived to drive milk creaminess were identified through discussion with consumers representative of two key dairy markets, China and New Zealand (NZ). Subsequently, a milk sample set (n=32) was developed, and an expert panel trained to profile the samples based on attributes identified by consumers. A novel methodological investigation, on the impact of panel training with Polarised Sensory Positioning (PSP) of the sample set, was also explored. Focusing on NZ consumers, participants (n=117) evaluated creaminess and liking perception of the milk samples. Critically, regression modelling was employed to identify key attributes driving creaminess perception based on expert panel data. Several novel findings were discovered. Drivers of creaminess differed to some degree between NZ and Chinese consumers indicating cultural differences across markets. Trained panel sensory data revealed multicollinearity between attributes measured to describe the sample set. Modelling approaches were able to identify key attributes required to predict creaminess. New findings that training has little impact on PSP outcomes was also ascertained. Pertinently combining four attributes, across different modalities, in an Elastic net regression model (‘yellow’, ‘watery’ flavour, ‘in-mouth thickness’ and ‘astringency’) successfully predicted creaminess (R2=0.9514), however these attributes were highly correlated with others retained in a PLS model. Each model had its relative merits. Of further note, consumer creaminess response was highly variable and cluster analysis revealed two different consumer segments with perception impacted by sensitivity to certain attributes: ‘green tinge’, ‘cardboard’, ‘salty’, ‘cooked’, ‘fat separation’, ‘grassy’, ‘buttery’, ‘melting’, ‘cream’ aroma, ‘smoothness’, and ‘astringent’. This research revealed new understanding concerning perceptual attributes contributing to consumer creaminess perception and provided clearer targets for the dairy industry to ensure milk creaminess levels align to consumer expectations and related commercial gain.
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    High temperature-shear processing of plant and dairy proteins for the development of structured meat analogues : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand. EMBARGOED until further notice.
    (Massey University, 2023) Beniwal, Akashdeep Singh
    Structural and techno-functional properties of some plant proteins can be transformed into fibrous structures while undergoing high-temperature shear processing (HTSP). However, plant-based substitutes are generally considered to be nutritionally and sensorially inferior to muscle food. Blending dairy protein with plant protein during the restructuring process could improve the functional and nutritional characteristics of the hybrid blend. This study aims to create nutritionally enhanced hybrid meat analogues (HMAs) from plant and dairy protein combinations using an innovative HTSP technique, and investigate the effect on structural, sensorial and nutritional properties of these combinations. The role of protein–protein interactions responsible for fiber formation in concentrated binary protein mixtures undergoing HTSP was also studied. Results indicated that the temperature range of 120°C–140°C, a processing time of 10 min–30 min and a shear rate of 25%–75% (i.e., 806-2314 RPM) create anisotropic structures in soy protein isolate (SPI) and wheat starch (WS) (at a 90:10 ratio) dispersions. Moisture content, shear rate and processing time significantly affected the textural responses (p < 0.05). Interestingly, in the absence of mixing (shear rate ~ 0), no network was formed in protein mixture, suggesting that combined thermal and shear forces were essential to introduce physicochemical changes in protein dispersions. Consequently, the HTSP of SPI, pea protein concentrate (PPC) and plant–dairy protein combinations (using sodium caseinate [NaCas], calcium caseinate [CaCas], whey protein concentrate [WPC] and milk protein concentrate [MPC]) result in various structural morphologies such as gels, layered gels, layered fibrous or fibrous structures. Further, incorporation of 10 % WS in hybrid protein mixtures undergoing the HTSP, enhanced the fiber formation. Restructured mixtures containing 20% MPC and 10% starches (i.e., wheat starch [WS]) combined with plant proteins (35% soy and 35% pea protein mixtures) generated anisotropic structures with textural attributes very similar to “chicken breast”. Therefore, this combination was considered the best formulation for further experimentation and product testing. The effects of material composition and processing conditions on mechanism of fiber formation in novel meat analogues during HTSP and its impact on texture, macrostructure, protein interactions and protein conformations were analysed. We find that the evolution of fibers depends upon the interrelations between shear work input and processing conditions during HTSP. Processing time, moisture content, shear rate and raw material formulation significantly affect HMA energy input, texture and colour (p < 0.05). Both non-covalent (hydrogen, hydrophobic) and covalent (disulphide) interactions during HTSP were responsible for sample structure. However, processing conditions had an insignificant influence on protein–protein interactions. A significant correlation between processing parameters, texture attributes, protein solubility and secondary protein structures of meat analogues was observed. Therefore, a subtle balance of processing conditions and material properties could achieve a fibrous structure with controllable textural and structural functionality in novel meat analogues. The impact of dairy protein (0%, 10%, 20%, 30% and 40% MPC) integrated with plant proteins on physicochemical, sensory and nutritional properties of HMAs were also investigated. The results showed that plant and dairy protein ratios significantly influence HMAs’ textural properties. Meat analogues with 20% MPC are closest in terms of both textural and microstructural properties to boiled chicken. Hybrid samples with 20% and 40% MPC yield acceptable sensorial scores, although overall palatability decreases with increasing MPC concentration. The tenderness and juiciness scores were higher for the hybrid samples than for the plant-only and commercial samples. Nutritional studies showed that essential amino acid (EAA) content in hybrid mixes was higher than in the plant-only meat analogue, indicating enhanced dietary properties.
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    Assessment of process variables on the structural, material, and physical properties of acid milk gels : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand. EMBARGOED until 9 June 2026.
    (Massey University, 2023) Kim, Ji Uk
    The aim of this study was to investigate the effect of process and formulation variables on cream cheese microstructure, properties, and their interactions. A systematic approach toward assessing these effects was conducted with a model cream cheese that was developed as part of the study design. Preliminary analysis compared the structural and material properties of commercial cream cheeses against the model composition to determine the extent of formulation variations on the performance of the cream cheese. In terms of compositional variables, both the ratios of fat to moisture and protein to moisture were found to positively correlate with large deformation material properties cream cheeses. These ratios were accordingly fixed in the model cream cheese formulation used within the study. The impact of coagulation kinetics on the structural and material properties of the model cream cheese was then investigated. Milk coagulation was conducted using either glucono delta-lactone (GDL) or lactic acid starter. Acid milk gels formed using GDL showed faster pH decrease during the early stage of acidification, causing earlier gelation at higher gelation pH when compared to gels using culture as acidulant. Amongst other observations, it was seen that the application of GDL as acidulant produced greater acid gel firmness (i.e., storage modulus (G′)) and higher rigidity in the corresponding cream cheeses when compared to acid gels and cream cheeses prepared using starter cultures as the acidulant. The role of additional processing and formulation variables (homogenisation pressure, coagulation pH, coagulation temperature, and stabiliser level) on cream cheese physical, material, and microstructural properties was also determined. Protein-protein and protein-fat interactions were hypothesised as the primary structural contributors to the physical properties of cream cheese, and thus variables that impacted on these interactions were considered as most actively influencing cream cheese properties. Findings were able to show that cream cheese microstructure and its associated properties demonstrated well-defined correlations to specific and controllable processing elements within the manufacturing process, showing significance in interactions between parameters in multivariable linear regression analysis (P < 0.05). Finally, the role of mineral balance of the properties of creams cheese was investigated. Here, different concentrations of the calcium chelating agent, ethylenediaminetetraacetic acid (EDTA), were added to the milk prior to coagulation. Progressive addition of EDTA was seen to reduce levels of insoluble calcium, which in turn led to weakened structural and material properties of both acid milk gels and corresponding cream cheeses. Findings here indicated the particular contribution of ionic content and equilibrium on cream cheese properties during manufacture.
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    An empirical analysis of the cost of rearing dairy heifers from birth to first calving and the time taken to repay these costs
    (Cambridge University Press, 8/02/2017) Boulton AC; Rushton J; Wathes DC
    Rearing quality dairy heifers is essential to maintain herds by replacing culled cows. Information on the key factors influencing the cost of rearing under different management systems is, however, limited and many farmers are unaware of their true costs. This study determined the cost of rearing heifers from birth to first calving in Great Britain including the cost of mortality, investigated the main factors influencing these costs across differing farming systems and estimated how long it took heifers to repay the cost of rearing on individual farms. Primary data on heifer management from birth to calving was collected through a survey of 101 dairy farms during 2013. Univariate followed by multivariable linear regression was used to analyse the influence of farm factors and key rearing events on costs. An Excel spreadsheet model was developed to determine the time it took for heifers to repay the rearing cost. The mean±SD ages at weaning, conception and calving were 62±13, 509±60 and 784±60 days. The mean total cost of rearing was £1819±387/heifer with a mean daily cost of £2.31±0.41. This included the opportunity cost of the heifer and the mean cost of mortality, which ranged from £103.49 to £146.19/surviving heifer. The multivariable model predicted an increase in mean cost of rearing of £2.87 for each extra day of age at first calving and a decrease in mean cost of £6.06 for each percentile increase in time spent at grass. The model also predicted a decrease in the mean cost of rearing in autumn and spring calving herds of £273.20 and £288.56, respectively, compared with that in all-year-round calving herds. Farms with herd sizes⩾100 had lower mean costs of between £301.75 and £407.83 compared with farms with <100 milking cows. The mean gross margin per heifer was £441.66±304.56 (range £367.63 to £1120.08), with 11 farms experiencing negative gross margins. Most farms repaid the cost of heifer rearing in the first two lactations (range 1 to 6 lactations) with a mean time from first calving until breaking even of 530±293 days. The results of the economic analysis suggest that management decisions on key reproduction events and grazing policy significantly influence the cost of rearing and the time it takes for heifers to start making a profit for the farm.