Browsing by Author "Ellis A"
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- ItemIdentifying temporal drivers of product acceptance and rejection across sips during whole product consumption(John Wiley & Sons, Inc, 2023-10) Weerawarna N. R. P. M; Godfrey AJR; Ellis A; Hort JMeasuring emotional response gives insights into consumer product experiences beyond liking. However, existing research rarely considers that emotional and hedonic responses can change during consumption of a whole portion. This research considered how well a combined multiple-sip temporal check-all-that-apply approach captured temporal drivers of product acceptance and rejection. Consumers (n = 104) profiled temporal sensory, liking and emotional responses to three milkshakes. Associations in temporal sensory, liking and emotional response citation pattern across multiple sips were investigated using generalized linear models, analysis of deviance and Pearson's chi-square test. Differences in the temporal dynamics of sensory, liking and emotional responses and associations between temporal sensory and affective responses were identified highlighting liking and emotional experience were related to the evolution of sensory attributes over time. Notably, sensory associations with emotional responses, including “bored,” “relaxed,” and “satisfied,” were better at identifying temporal drivers of acceptance/rejection more than associations to level of liking. Practical Applications: The research demonstrated that a combined multiple-sip temporal check-all-that-apply (TCATA) approach, representing whole product consumption, is an effective approach to gain deeper insights into the sensory drivers of consumer affective response. However, the applicability of analyzing within-sip variations in perception, and potential to use check all that apply by sip as opposed to TCATA needs to be considered on a product category basis.
- ItemImpact of protectant uptake on the shelf-life of dried Lacticaseibacillus rhamnosus(Elsevier, 2022-01) Priour S; Welman A; Singh H; Ellis ATo improve the survival of dried probiotics, it is advised to expose the bacteria to protectants prior to processing, allowing equilibration of internal solutes. However, optimal conditions for this exposure remain unclear. This study examined solute uptake by Lacticaseibacillus rhamnosus HN001 (formally known as Lactobacillus rhamnosus HN001) at 4 °C and 20 °C, over exposure times of 0–240 min. The cells were exposed to hyperosmotic solutions of glucose and sucrose, two potential protective sugars, which are metabolisable and have different molecular weights. Sugar uptake was analysed through HPLC, while the impact on cell viability after freeze-drying was examined at 30 °C and 40 °C. The interactions between cell biomolecules and sugars were examined using Nano DSC. Results showed that the sugars were rapidly taken up by the cells, independent of temperature. At 20 °C, glucose was readily metabolised, eventually resulting in loss of cell viability during storage. Conversely, the Nano DSC study revealed interactions between the cells and sucrose, potentially providing some explanation as to the stability of the cells. In conclusion, sugar type and exposure temperature were shown to exert a significant effect on the viability of Lacticaseibacillus rhamnosus. Nano DSC is a promising technique to understand the protectant and cells’ interactions.
- ItemIntragastric restructuring dictates the digestive kinetics of heat-set milk protein gels of contrasting textures(Elsevier, 2024-11) Li S; Mungure T; Ye A; Loveday SM; Ellis A; Weeks M; Singh HThe gelation of milk proteins can be achieved by various means, enabling the development of diverse products. In this study, heat-set milk protein gels (15 % protein) of diverse textures were made by pH modulation and two gels were selected for dynamic in vitro gastric digestion: a spoonable soft gel (SG, pH 6.55' G' of ∼100 Pa) and a sliceable firm gel (FG, pH 5.65; G' of ∼7000 Pa). The two gels displayed markedly different structural changes and digestion kinetics during gastric digestion. The SG underwent substantial structural compaction during the first 120 min of gastric digestion into a denser and firmer gastric chyme (26.3 % crude protein, G* of ∼8500 Pa) than the chyme of the FG (15.7 % crude protein, G* of ∼3000 Pa). These contrasting intragastric structural changes of the gels reversed their original textural differences, which led to slower digestion and gastric emptying of proteins from the SG compared with the FG. The different intragastric pH profiles during the digestion of the two gels likely played a key role by modulating the proteolytic activity and specificity (to κ-casein) of pepsin. Preferential early cleavage of κ-casein in SG stimulated coagulation and compaction of solid chyme, whereas rapid hydrolysis of αS- and β-caseins in the FG weakened coagulation. This study provided new insights into controlling the structural development of dairy-based foods during gastric digestion and modulating digestion kinetics.
- ItemModelling Lactation Curves for Dairy Sheep in a New Zealand Flock(MDPI (Basel, Switzerland), 2023-01-19) Marshall AC; Lopez-Villalobos N; Loveday SM; Ellis A; McNabb WLactation curves were modelled for dairy sheep in a New Zealand flock, providing information on the lactation yields of milk, fat, protein, and lactose, corrected for 130 days of milking. From 169 ewes, a total of 622 test-day records were obtained during the milk production season of 2021-2022 (from October to January). The flock produced an average of 86.1 kg of milk, 5.1 kg of fat, 4.5 kg of protein, and 4.1 kg of lactose, and moderate to large coefficients of variation were observed (27-31%) for these traits. The lactation persistency of milk, fat, protein, and lactose yields ranged from 52.3 to 72.7%. Analyses of variance for total yield and persistency were performed with an animal model that included the fixed effects of age (parity number), litter size, coat colour, and milking frequency (days in twice-a-day milking) and random residuals. Age and milking frequency were the only factors that significantly affected the yields of milk, fat, protein, and lactose. Age significantly affected the lactation persistency of milk and lactose yields, whereas litter size affected the persistency of protein, and milking frequency affected the persistency of fat. This study on this single flock provides valuable experience for a larger-scale animal breeding programme in New Zealand.
- ItemThe Protein Composition of Bovine Milk from Once-a-Day and Twice-a-Day Milking Production Systems in New Zealand(MDPI (Basel, Switzerland), 2023-12) van der Zeijden M; Ellis A; Lopez-Villalobos N; Li S; Roy NC; McNabb W; Antanaitis RAn increasing number of dairy farmers in New Zealand (NZ) have adopted a once-a-day (OAD) milking production system, and little is known about the impact of this production system on milk protein composition. The objective of this study was to evaluate the effect of OAD milking on the protein composition in milk from individual cows. Milk was sampled in early, mid-, and late lactation from cows kept at Massey University farms Dairy No. 1 (OAD milking) and Dairy No. 4 (TAD milking) in Palmerston North, NZ. The yields of total milk and milk solids, the proximate composition, and the protein composition were determined. Results showed that OAD milking yielded less milk and milk solids than TAD milking. However, no significant differences in protein, fat, and lactose contents were found. While the proportions of total casein (CN), total whey proteins, αs1-CN, β-CN, and β-lactoglobulin were not affected by the milking frequency, milk from a OAD milking system contained higher proportions of αs2-CN and κ-CN and lower proportions of α-lactalbumin. These proteins also changed differently throughout the milking season in a OAD milking system than in a TAD milking system. These changes in the protein composition of the milk observed in a OAD milking system could have implications for its processing properties and product quality.
