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Incorporation of whey protein isolate (WPI) into paneer : impact on yield, texture and microstructure : 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) Murali Krishna
Paneer is a traditional Indian dairy product rich in protein, fat, calcium, phosphorous, and vitamins though relatively low in whey protein content due to the conventional heat and acid coagulation processes, highlighting the innovative approach for increasing the nutritional content in paneer. This study investigates the incorporation of Whey Protein Isolate (WPI) into paneer to increase the protein content and nutritional value, while evaluating the effects on yield, texture and microstructure of the paneer. Different formulation methods were tried, including the addition of WPI with and without oil incorporation, also by varying the sequence of mixing with skim milk. A 3% WPI concentration was selected based on preliminary study, as increase in concentration led to premature gelation of whey protein while heating and due to processing difficulties. The effect of WPI addition on the yield of the paneer and whey protein retention was studied. A significant improvement in yield of paneer was observed for WPI fortified samples with an increase of 12 to 26% compared to the control. A significant increase in weight from 100 grams to 350 grams was also observed in the paneer samples while fortified with WPI. SDS-Page was used to confirm the incorporation of whey protein into the paneer system. To understand the structure and other functional changes occurred during WPI incorporation, particle size distribution analysis was conducted before and after the heat treatment to the milk. Confocal laser scanning microscopy (CLSM) was employed to understand the protein network and to confirm the incorporation of oil into the system. Texture profile analysis (TPA) helped in further understanding the hardness, cohesiveness, springiness and chewiness of the fortified sample and compare it with the control. TPA was also used for the pressing of the curd into paneer and the rheological behavior during the pressing was studied. Modelling of the TPA data demonstrated that the curd compression profile was primarily influenced by the total curd mass rather than the formulation method of the paneer. Overall, the study proves that WPI can be successfully incorporated in the paneer to improve its overall protein content and yield with notable effects on its microstructure and texture. The texture of the samples with oil emulsions (SOH-WP, WOH-SP, SWOH-P) showed an increase in hardness compared to the control and SWP showing that the texture of the paneer is highly dependent on method of whey addition. Further studies can be done on improving the texture, sensory properties and formulation of the paneer. The impact of different coagulating agents and detailed nutritional analysis, like in vitro digestibility studies could be studied to assess the nutritional quality and protein bioavailability.
A study on physicochemical properties of protein gels and patties made from faba bean protein isolate and New Zealand Perna canaliculus concentrate : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Auckland, New Zealand
(Massey University, 2024) Muhammad, Nur Aina Sofea binti
This study examines the physicochemical, textural, and microstructural characteristics of protein gels and patties made from faba bean protein isolate (FBPI) and New Zealand Perna canaliculus in the form of defatted mussel powder (DMP). The initial investigation explored the influence of different proportions of FBPI and DMP proteins (100:0, 75:25, 50:50, 25:75, and 0:100 by weight) at a total protein concentration of 12.5% on the gelation process, water-holding capacity (WHC), texture, color, and microstructure of protein gels. Various methods such as rheology, confocal laser scanning microscopy (CLSM), particle size distribution analysis, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) were employed. The gelation temperature ranged from 20 °C to 90 °C, with the strength of the gel significantly affected by the FBPI to DMP ratio. The 50:50 protein mixture of FBPI and DMP proteins exhibited an increase in gel strength compared to gels made from either protein individually. The water-holding capacity (WHC) of the gels decreased as the amount of DMP increased, with the 50:50 protein ratio showing a slight improvement in WHC, suggesting better water retention. Textural analysis showed that the hardness of the gels decreased with higher DMP content, indicating a reduction in structural rigidity. Particle size distribution analysis indicated that smaller particles were associated with a denser gel network and higher storage modulus (G') values. Color analysis showed that the lightness of the gels decreased after heating, and the addition of DMP increased redness and yellowness. CLSM images revealed that FBPI formed a more continuous and denser gel structure than DMP, with the latter forming a weaker gel network. SDS-PAGE analysis offered insights into the protein composition and the effects of heat treatment on protein solubility and aggregation, showing that the solubility of proteins in the mixtures was influenced by intermolecular interactions, with different levels of solubility observed across various extraction solvents and protein ratios. When not mixed together, FBPI and DMP exhibited distinct differences in their gelation properties. FBPI gels (100:0) demonstrated a higher gel strength and better water-holding capacity compared to DMP gels (0:100). FBPI gels also showed a denser and more continuous network structure, as observed through CLSM, while DMP gels formed a weaker and less cohesive network. Additionally, FBPI gels had higher hardness values, indicating greater structural rigidity, whereas DMP gels were softer and more pliable. The second study examined the development of plant and seafood blended patties by investigating the effects of varying FBPI and DMP protein ratios (100:0, 75:25, 50:50, and 0:100 w/w%) on texture, color, and physicochemical properties. The previous study found that a 50:50 protein blend of FBPI and DMP proteins was the best for maximizing gel strength and water-holding capacity. To further improve the processing attributes of the patties, the total protein content was increased to 15% by weight, and polysaccharides were added. The study focused on blended protein mixtures (75:25 and 50:50 w/w%) combined with polysaccharides to enhance the textural attributes and stability of the analogue patties. The research aims to assess how varying protein proportions and the inclusion of polysaccharides affect the texture, color, and physicochemical attributes of the patties. Adding polysaccharides, such as methylcellulose (MC) at concentration 2 ,3, 4 w/w% and konjac glucomannan (KGM) 3, 4, 5 w/w%, significantly influenced the texture, color, and physicochemical characteristics of the analogue patties. The study utilized various analytical methods, including texture profile analysis, color measurement, cooking loss analysis, and microstructure analysis, to assess the effects of different protein ratios and polysaccharide additions. The findings indicated that the inclusion of polysaccharides can improve the patties texture, reduced cooking loss, and enhanced shape retention and structural integrity after cooking. Additionally, the color analysis revealed changes in color attributes before and after cooking, with higher DMP content leading to increased redness and yellowness. The microstructure analysis demonstrated that polysaccharides can create a denser and more uniform matrix within the patties, enhancing their overall quality. The research offered significant findings for the food sector, guiding the development of sustainable and nutritionally rich protein substitutes that align with consumer preferences for nutritional content, texture, and appearance. It highlighted the promise of integrating FBPI and DMP, along with polysaccharides, to produce blended patties with favorable characteristics. Notably, the 50:50 protein blend performed exceptionally well in the patties, demonstrating improved gel strength, water-holding capacity, and overall textural quality, making it a promising candidate for further development and commercialization.
Individual variation in taste perception : investigating sensory perception in thermal tasters and its impact on food choice behaviour : thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North Campus, New Zealand
(Massey University, 2024) Botha, Janita Jossie
Thermal taste is a phenomenon whereby some people experience taste from thermal stimulation in the absence of a chemosensory stimulus. Thermal tasters (TT) differ from thermal non-tasters (TnT) in orosensory sensitivity but are also thought to differ from TT in behavioural aspects, including food choice. In addition, TT are hypothesised to differ as a group in their thermal taste experiences. However, traditional phenotyping methods have failed to establish differences in food choice due to their inefficiency (a large proportion of participants are unclassified). In addition, traditional methods are incapable of collecting detailed data on the thermal taste response, as responses are recorded after thermal exposure. This study developed a new phenotyping method, RapCoTT, which comprises a singular thermal exposure protocol, combined with TCATA data collection. When validated compared to existing methods, this approach was found to be superior in effectiveness and efficiency, and to agree with existing approaches. From data collected through RapCoTT, TT clusters were established, each reporting different thermal tastes and reporting tastes at different temperatures. When modelling thermal taste response data, further evidence was found for the proposed link between TRPM5 and sweet thermal taste. In addition, several novel mechanistic links were discovered, including several potential pathways involving TRPA1. A group of participants with known thermal taste response groupings were profiled for a range of demographic, food behavioural, personality and orosensory responsiveness variables. Initially, links were explored between TT Status and TT Cluster and these variables, and a machine-learning approach was used to establish the relative importance of predictors. Overall, links between TT Status and TT Cluster and dimensions of the Big Five Inventory (personality) were established, and TT and TnT were found to differ in their salt and spice addition behaviours. Evidence was also found for several other factors impacting TT Status, including food neophobia, Private Body Consciousness, oral processing behaviour, and aspects of spicy food liking. TT Clusters differed in their hedonic response patterns to sucrose (Sweet liker status clusters). The Set & Disposal subscale of the Food Involvement Scale discriminated TT Clusters. Finally, food choice behaviour in the form of food frequency data was modelled from thermal taste, demographic, food behavioural, personality and orosensory responsiveness variables. Overall, TT Cluster was the most important variable set related to thermal taste in determining food choice, indicating that not only TT Status, but also the temperature and nature of thermal taste perceived affects food consumption. TT Cluster also affected the specific consumption frequencies of the most items. When clustering food items based on the impact of TT Cluster, items did not group according to predetermined categories, but some textural patterns were apparent. Overall, this work sets the scene for a paradigm shift around thermal taste, its interaction with other factors and its influence on food behaviour as a whole.
Consumer emotional engagement with plant-based meat alternatives : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Manawatū, New Zealand
(Massey University, 2024) Orr, Rebekah Eleanor
Plant-based meat alternatives (PBMAs) can support consumers in reducing meat consumption without having to drastically change the way they eat. However, consumer uptake of PBMAs is low highlighting the need for a better understanding of the drivers of PBMA acceptance. The research presented in this thesis aimed to do this by leveraging two innovative techniques in sensory consumer research: measuring emotional response and using digital immersive environments (digital-IEs). As no emotion lexicon had been published for plant-based patties (PB-patties) or PBMAs in general before this work, an emotional lexicon specific to comparing meat and PB-patties was created. Taking a unique approach, participants were immersed (using digital-IEs) in two relevant burger-eating scenarios to evoke key emotions associated with plant-based patty (PB-patty) consumption in realistic scenarios. Different age and diet groups were included in the lexicon development process to ensure it was inclusive of the range of emotions that could potentially be experienced by end-users. The lexicon included emotions not found in generic lexicons, highlighting the value of a product-specific lexicon for gaining deeper insights. Many emotions were negatively classified, such as ‘deceived’, ‘disappointed’, and ‘anxious’, while others were positively classified, including ‘amazed’ and ‘hopeful’. The lexicon was applied with meat-eating consumers to emotionally profile a variety of commercially available meat and plant-based patties, alongside measures of liking, sensory attributes, and perceived similarity to a beef patty. Findings revealed that PB-patties closely resembling beef were the most appealing to meat eaters, receiving high liking scores and evoking positive emotional responses, sometimes comparable to those elicited by the beef patty. In contrast, patties that did not mimic meat characteristics were generally disliked and evoked negative emotional responses. These results indicate that PB-patties lacking meat-like characteristics require significant product development to gain acceptance among meat-eating consumers. The lexicon was also applied to investigate the impact of eating scenarios created using digital-IEs, and accompanying foods, on emotional response, as well as liking, towards plant-based meatball alternatives (PB-meatballs). Serving two PB-meatballs with a well-liked sauce significantly increased both liking and positive emotional response. Additionally, consuming PB-meatballs in an appropriate home environment improved liking for one product and enhanced positive emotional responses toward both. These findings emphasised the importance of considering contextual factors in future research on PBMAs to better understand how they would perform in real-life eating situations. This research provided an emotion lexicon that researchers and food manufacturers can apply to better understand consumer emotional responses to PBMAs. It identified sensory attributes driving liking and positive emotional responses such as a strong beef flavour and juicy texture, as well as those that drive disliking and negative emotional responses including a beany flavour and pasty/doughy texture, providing a guide for improved PBMA product development. Furthermore, the research demonstrated that consumer acceptance of PBMAs can be improved when served with other meal components and consumed in a contextually appropriate environment, which has implications for how PBMAs are evaluated in the field. Notably, this research showcased the potential of digital-IEs as a tool for gaining insights into consumer responses in settings that are more representative of ‘real-life’ eating scenarios than traditional sensory testing facilities (i.e. sensory booths).
Development of a novel ice cream with hemp milk based on chia seed mucilage as a stabiliser : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology, Massey University, Manawatu, New Zealand
(Massey University, 2024) Zhang, Weilun
The majority of commercial ice cream products are made from dairy, which can lead to health issues for consumers with lactose intolerance and casein allergies. Commercial stabilisers are used in ice cream formulas to provide maximum performance in meeting several requirements, including consumer demands, transport, and cost-effectiveness. As a result, there is a significant need for consumers to discover substitute products that offer comparable health benefits to dairy products and products with clean labels. If there is an ice cream that uses natural sources of stabilisers that can make the ice cream label look simpler and cleaner while having health benefits, it will probably be competitive in the marketplace. Hemp seeds are rich in essential elements needed by the human body. Consequently, food manufacturers have taken an interest in hemp milk because of its exceptional nutritional content. Currently, the food industry has not made any progress in creating ice creams that contain hemp milk to improve their nutritional content. Hemp milk, on the other hand, has a specific flavour, and the direct use of hemp milk in ice cream production may have a negative impact on the product's flavour and aroma. The differences in the type and content of proteins and fats between hemp milk and cow milk may also have an unknown effect on the physical and chemical properties of the ice cream (e.g., texture, overrun, and ice crystal content). This study substituted five levels of hemp milk (0%, 25%, 50%, 75%, and 100%) for cow milk using chia seed mucilage (CSM) as stabiliser. The aim was to determine the impact of the added hemp milk on the ice cream's properties and its storage stability after 21 days to determine the most suitable hemp milk content. This study was conducted in four phases. In the first phase, chia seeds were soaked, stirred, and centrifuged to separate CSM. The extracted CSM was dried and stored after measuring its water activity and moisture content. Then, hemp milk was extracted from hemp seeds using a high-shear blender, homogenised, and filtered. Its total solid content, dissolved sugar content, dietary fibre content, and nutritional properties were measured and stored under refrigeration. In the second phase, five ice cream samples containing different amounts of hemp milk were prepared. The formulation containing 25% hemp milk was selected as the best-performing formulation based on the summary of the opinions of the focus groups (n = 6), pH, overrun, colour, and melting properties. In the third phase, the physicochemical and nutritional characteristics of the ice cream were analysed and discussed. In addition to this, a consumer sensory panel (n = 35) assessed the overall acceptability and Just-About-Right (JAR) of the best formulation ice cream sample. The average acceptability score of the ice cream containing 25% hemp milk was 6.75, and the JAR results showed that the JAR percentage was above 70% for all the attributes except for taste and aroma. The indicators of taste were found to fall within the noteworthy range by penalty analysis, but not in the high impact (>0.5) range. The results revealed that the ice cream formulation containing 25% hemp milk has ideal sensory and physicochemical properties. In the fourth phase, the stability of the best formulation ice cream during storage (-19 °C) for a period of 21 days was evaluated by measuring the pH, colour, and hardness and by consumer sensory evaluation of the best formulation ice cream. Although the L* a* values in colour and hardness of the ice cream showed statistically significant changes (p<0.05) during storage, the b* values in the colour and pH of the ice cream remained stable (p > 0.05). Meanwhile, the consumer sensory evaluation results showed that the product was still considered acceptable after 21 days of storage.
Development and characterisation of plant-based (faba bean) yoghurt : 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, 2024) Rankothge, Rohitha Somarathne
Increasing awareness of health, environmental, and ethical issues has recently increased the demand for plant-based alternatives to traditional dairy products. Plant-based milk might be a suitable choice for people looking for a healthier option because it often contains less fat, particularly saturated fat, and allergens. In recent years, the faba bean has gradually become popular as a plant protein due to its nutritional and health benefits to consumers. This master's thesis investigates the possibility of producing yoghurt using faba bean milk analogue (FBM), faba bean protein isolates (FPI) and faba bean-dairy hybrid as alternatives to traditional dairy yoghurt. Also, the effects of varying ratios of dairy and faba bean proteins on the texture, rheology, microstructure, nutritional makeup, protein digestibility, and sensory characteristics of yoghurt were investigated. This study aimed to optimize the formulation of faba bean yoghurt to develop a sustainable and nutrient-rich plant-based alternative to dairy yoghurt through a series of analytical procedures. The study's objectives include examining the interactions between faba bean milk analogue, faba bean protein isolates, and dairy milk (DM) in yoghurt production using five different formulations. These formulations include 50% dairy + 50% faba bean milk analogue (SM#2), 50% dairy + 50% faba bean protein isolates, 50% faba bean milk analogue + 50% faba bean protein isolates (SM#3), 100% faba bean milk analogue (SM#4), 50% faba bean milk analogue + 50% faba bean protein isolates (SM#5) and 100% faba bean protein isolates (SM#6). Further, assessing how these interactions affect the final product's texture, rheology, microstructure, and digestibility. The nutritional composition of various faba bean yoghurt formulations was analyzed, focusing on protein, fat, total solids, fibre, and starch content, and compared with traditional dairy yoghurt. The sensory survey was done using an internal untrained panel to evaluate the consumer preferences for different formulations based on attributes such as taste, aroma, texture, colour, and overall acceptability. Additionally, it investigated the influence of varying ratios of FBM, FPI and DM on the rate and extent of protein digestion using a static digestion (INFOGEST) model. Results indicated that yoghurts made with FPI exhibited higher storage (G’) and loss modulus (G”) values, indicating a stronger gel structure compared to those made with DM alone (reference). The product made with DM and FPI (SM#3) showed the lowest G’ and G”. Similar behaviour was observed for apparent viscosity as well. The product made with DM and FBM (SM#2), showed comparatively similar rheological properties. All yoghurt samples' loss tangent (tan δ) values were consistently less than one, indicating a mostly solid character. Texture profile analysis results of the samples showed a significant difference in textural properties like hardness, cohesiveness, springiness, gumminess, and adhesiveness between samples (p<0.05). SM#2 and SM#5 showed the least deviation from the reference (100% dairy yoghurt). Faba bean yoghurt also demonstrated better water-holding capacity and lower syneresis, particularly in formulations with higher FPI (50% and 100%) content (SM#5 & SM#6). Sensory evaluations showed that consumers preferred the formulations that closely matched the texture and flavour of traditional dairy yoghurt. The hybrid formulations of DM and FBM (SM#2) showed the least deviation from the reference (100% DM). In-vitro gastrointestinal digestion was conducted following the INFOGEST method to assess the protein digestibility of the yoghurt samples. Protein hydrolysis expressed as free amino N of all yoghurt samples by pepsin during the gastric phase (0 to 120 min) was relatively lower than in the small intestinal phase. However, all samples including 100% dairy reference showed a significant increase (p<0.05) in the release of free amino N upon the addition of pancreatin and bile salt during the simulated small intestine phase (130-240 min) compared to the gastric phase. The free amino N release (%) was significantly lower (p<0.05) in 100% plant-based yoghurts (SM#4, SM#5 & SM#6) compared to dairy and plant-based hybrid samples (SM#2 & SM#3). In conclusion, the findings suggested that faba bean yoghurt, particularly when blended with DM, can potentially meet consumer preferences and textural properties while providing a nutritious and sustainable alternative to dairy yoghurt. In addition, there is a high potential of producing 100% vegan yoghurt from faba bean proteins, but further studies on improving textural and sensory properties are needed. The study contributes to exploring the options available in the plant-based food market, addressing both environmental and nutritional needs.
The gross composition, fatty acid composition, and processability of milk from cows milked once and twice a day under New Zealand grazing conditions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science, Massey University, Palmerston North, New Zealand
(Massey University, 2023) Sanjayaranj, Inthujaa
In New Zealand, milking once a day (OAD) is practised by some farmers, with the majority of farmers milking twice a day (TAD). Once-a-day milking provides several benefits such as reduced labour cost, improved labour efficiency, improved health and reproductive performance of cows, and additional employment opportunities for farmers. Once-a-day milking causes a reduction in milk yield and modifies milk composition by increasing the fat and protein percentages. The main aim of this thesis was to study the effect of OAD milking on the gross composition, fatty acids composition, and processability of milk. To achieve this, the milk from 232 cows from a OAD herd and 182 cows from a TAD herd were collected in a full season in early, mid-, and late lactation. The samples were analysed for milk composition and fatty acid composition using Fourier-transform mid-infrared (FT-MIR) spectroscopy. Calibration equations for individual and grouped fatty acids were developed using FT-MIR calibrator software. Milk coagulation properties (rennet coagulation time, curd ﬁrming rate, and curd ﬁrmness) were analysed using a Formagraph. In addition, a SNP (rs109421300) in the diacylglycerol acyltransferase 1 (DGAT1) region on bovine chromosome 14, which is associated with a higher fat percentage in milk, was selected to study its association with fatty acid composition. Solid fat content at 10°C (SFC₁₀), a parameter that predicts butter hardness, was calculated using an equation developed from the proportions of fatty acids. The proportions of de novo synthesised fatty acids (C8:0-C14:0) were significantly higher, and the proportions of preformed, long-chain fatty acids (mainly C16:0 and C18:0) were lower in milk from cows milked OAD compared with cows milked TAD. Milk coagulation properties were superior for Jersey cows compared with Holstein-Friesian and Holstein-Friesian × Jersey cows milked OAD and TAD. The CC genotype of SNP rs109421300 was associated with higher fat yield, fat percentage, protein percentage, and SFC₁₀. Milk from OAD cows had lower proportions of C16:0 suggesting it would produce more easily spreadable butter. Selecting cows with the CC genotype would be suitable for the New Zealand dairy industry with the current payment system, however, the CC genotype was less suitable for making more easily spreadable butter. Overall, there were some significant differences noted between milk from cows milked OAD and TAD in terms of fatty acid composition and processability.
Motivations and barriers for flexitarianism of New Zealand consumers to eating plant-based products : a thesis presented in partial fulfilment of the requirements for the degree of Masters in Food Technology at Massey University, Manawatū, New Zealand
(Massey University, 2022) Coetzee, Petra
Plant-based products (PBPs) are increasingly used by consumers to replace meat in their diet. Different motivators and barriers drive consumers to eat PBPs and ultimately determine whether consumers engage with these foods. Flexitarians, people actively trying to reduce their meat intake, are of particular study interest as they encompass an increasingly larger part of the population than vegetarians and vegans. This study aimed to identify factors that motivate flexitarians in New Zealand to reduce meat intake, and to determine whether age, identified gender and meat consumption frequency play a role. An online questionnaire (n=584) gathered data concerning drivers and barriers to eating meat and PBPs together with demographic information, which was used to further segments flexitarians. Drivers and barriers included demographics, consumption behaviour, ideal sensory characteristics of PBPs, food safety, industry and authority responsibilities, nutrition, health, social status, animal welfare and environment factors associated with consumption of meat and PBPs. Flexitarians with higher meat consumption preferred meat-like properties in ideal PBPs. Generation X (born 1966-80) scored significantly higher than Millennials (born 1981-96) for food safety concerns for pesticides, antibiotics, genetically modified ingredients, and disease. Females scored significantly lower than males for wanting ideal PBPs to bleed-like-meat, be dry and bitter and significantly higher for umami. K-means clustering applied to the motivators and barriers responses identified four flexitarian clusters. Cluster 2 (n = 192) had most motivators for meat reduction whereas cluster 4 (n = 149) had most barriers. Cluster 1 (n = 90) had the lowest food neophobia. Cluster 1 was satisfied with appearance whereas cluster 2 was satisfied with the texture of currently available PBPs. The ideal PBP of clusters 1 and 3 (n = 153) was juicy, savoury, and flavourful. Cluster 2 preferred products to taste like meat. Cluster 3 was similar to cluster 2 in terms of food safety concerns but had higher meat consumption and more barriers to PBP consumption. Flexitarian segments differed in the drivers and barriers to eating meat and PBPs, suggesting they engage differently with PBPs. Future studies should investigate this difference including sensory evaluation of PBPs. These results can aid industry in developing and promoting products that meet clusters’ needs.
Protein and lipid gastro-small intestinal digestibility in vitro of pasture-fed beef, grain-finished beef, and meat alternative : a comparative study : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Food Technology at Massey University, Palmerston North, New Zealand
(Massey University, 2022) Elamurugan, Amrutha
This study addresses the protein and lipid digestibility of meat and a plant-based meat alternative using a static model in vitro digestion system. Three commercially relevant beef cuts (tenderloin, striploin and topside) from five carcasses of two different production system namely, pasture-feeding and grain-finishing along with a plant-based meat alternative (Beyond Burger® from Beyond Meat™) were chosen for this study. Breakdown of proteins and the release of peptides during digestion were analysed using tricine SDS-PAGE. The free amino nitrogen released during in vitro digestion was determined using ninhydrin assay. The results showed that there were no significant differences (p<0.05) between the pasture-fed and grain-finished meat digests in terms of in vitro protein digestibility. Both striploin and tenderloin gave good in vitro protein digestibility, but the topside did not perform well, mainly due to the longer cooking time and higher cook loss. The plant-based meat alternative performed relatively poorly in in vitro protein digestion experiments, possibly due to the formation of digestion-resistant protein aggregates formed during the manufacturing process. In terms of in vitro lipid digestibility, this study concludes that pasture-fed beef showed higher amounts of total long chain (LCn-3) polyunsaturated fatty acids (PUFAs) and lower amounts of many free individual saturated fatty acids (SFAs) than those from grain-finished animals. However, grain-finished meat digests were high in total monounsaturated fatty acids (MUFAs) when compared to pasture-fed meat digests. The plant-based meat alternative digests had the highest amount of total SFAs, mostly contributed by lauric acid (C12:0), myristic acid (C14:0), palmitic acid (C16:0) and stearic acid (C18:0). The MUFAs were also significantly higher (p< 0.05) in the Beyond Burger® owing mainly to high amounts of individual free oleic acid (C18:1c9) and vaccenic acid (C18:1c11). In Beyond Burger® there was an abundance of n-6 PUFAs in the form of the individual free linoleic acid (C18:2). However, no LCn-3 PUFAs were detected in the plant-based meat alternative.
Peptide fingerprinting and predictive modelling of fermented milk : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North Campus, New Zealand
(Massey University, 2021) Murphy, Fionnuala
Fermented milk products are valued by consumers and the food industry for their nutritional properties, pleasant taste, and texture. Consumer demands and expectations for such products are constantly changing. Understanding how consumers perceive the sensory characteristics of food and the relationship these characteristics have with the chemical components of food can provide insight that can enable food researchers and manufacturers to develop food products that are tailored to provide enhanced sensory qualities. Establishing techniques that allow for in-silico prediction or correlation of sensory qualities can enable a more rapid approach that would aim to enable researchers to meet the demands of consumers. This research firstly explored mass spectrometric techniques for the rapid fingerprinting of milk and fermented milk products, using Matrix-Assisted Laser Desorption Ionisation - Time-of-Flight Mass Spectrometry (MALDI-TOF MS) and Rapid Evaporative Ionisation Mass Spectrometry (REIMS), two technologies that require minimal sample preparation and can rapidly generate a fingerprint of a food’s chemical components. Peptide fingerprints obtained by MALDI-TOF MS and analysed by principal component analysis were effective at discriminating the two fermented milk and milk samples. Supervised discrimination of low molecular weight fingerprints obtained via REIMS and MALDI-TOF MS proved less effective but demonstrated some potential and could be used alongside other analyses in future studies. These techniques were explored with a view to establishing a technique that could provide rapid insights into a food’s chemical composition, and which could also effectively discriminate the chemical components of the product. Such techniques could be used for rapid screening of products and can provide insight into the chemical components that are driving the variation in different products, which may be reflective of the differences in sensory characteristics. Next, peptide fingerprinting and predictive modelling were investigated in milk fermented with various bacterial combinations, including probiotic cultures. Fingerprinting was performed on samples collected at each hour of fermentation. Predictive modelling techniques, using both regression and classification approaches, were trialled in order to predict the change in signal intensity throughout fermentation. This aimed to understand if peptides could be predicted throughout fermentation, with a view to enable the targeted prediction of desirable peptides, or other relevant components, which may impart favourable sensory qualities in the final product. Regression techniques were somewhat effective for predicting the signal intensity of individual m/z ions throughout fermentation. Most of the ions did not follow a linear relationship, and, as such, a multiple linear regression model was unable to model most of the ions. Using a generalised additive model, a non-linear approach, improved the performance in most cases and could predict the signal intensity of individual ions throughout fermentation. However, the model was unable to correctly predict all cases. Classification techniques were effective for predicting the general direction of the signal intensity between start and end fermentation times. Five classification techniques were trialled, with each model providing accurate predictions for the increase or decrease of signal intensity between early and late fermentation times. Lastly, consumer panellists were recruited to evaluate the change in important sensory characteristics throughout the fermentation of milk prepared using two different starter cultures. This aimed to understand if consumer responses to such products could be correlated with instrumental analysis, in order to predict the consumer responses from instrumental data. Consumers perceived significant differences in bitterness and flavour intensity between fermented milk samples at different fermentation time points. There were significant correlations between peptide fingerprints and the consumer rankings for the sensory attributes in each fermented milk product. XGBoost regression could predict consumer responses with reasonable accuracy. This thesis explored the fermentation of milk using specific bacteria and fermentation processes. To validate this work, further products could be explored, in addition to different processing parameters. Furthermore, a more in-depth analysis of the chemical components of the products could be investigated and analysed with additional sensory evaluation to further explore and confirm the findings.

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