Food and Nutritional Sciences - Doctoral Theses

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    The role of plant-based foods in the diets of adults (18-90y) in Ireland
    (University College Cork, 2022-07) Kent, Gráinne; Walton, Janette; Kehoe, Laura; Flynn, Albert; Cashman, Kevin; Sleator, Roy; Department of Agriculture, Food and the Marine, Ireland
    Plant-based (PB) diets are generally associated with good health and environmental sustainability but there is a wide range of PB diet definitions in the literature. PB foods, including ‘fruit & vegetables’ and ‘cereals, grains & potatoes’ provide important nutrients in the diets of adults and are promoted within food-based dietary guidelines (FBDG). The aims of this thesis were to first develop a systematic methodology to identify the PB component of an omnivorous diet using two extremes of PB diet definitions, i.e., plant-based (all) (PB-A): ‘all plant-based foods’ regardless of dietary quality and plant-based (healthful) (PB-H): ‘healthful plant-based foods’ only and then to use this systematic methodology to examine the nutritional quality of the PB component of the diet using the two definitions (PB-A and PB-H) compared to the baseline diet in adults in Ireland. Additionally, this thesis aimed to estimate the current intake of ‘fruit & vegetables’ and ‘cereals, grains & potatoes’ in adults in Ireland, to assess compliance with recommendations and to determine their contribution to overall energy and nutrient intakes. The analyses for this thesis were based on data from the National Adult Nutrition Survey (NANS), a nationally representative cross-sectional study that collected food and beverage consumption data from 1500 adults aged 18-90 years in the Republic of Ireland, between 2008 and 2010. Dietary data were collected using semi-weighed food diaries and nutrient intakes were estimated using UK and Irish food composition data. Mean daily intakes (MDI) of food groups and nutrients were estimated using SPSS©. The nutritional quality of the PB diet components and baseline diet was assessed by estimating energy-adjusted intakes of nutrients. Differences in the MDI of food groups and nutrients between PB diet components were assessed using independent sample t-tests. The percent contribution of food groups to energy and nutrient intakes were calculated by the mean proportion method. A novel 23-step protocol was developed which outlined the exclusion and inclusion criteria for the PB-A and PB-H components of the diet. This methodology was then used to examine the nutritional quality of the PB diet components using the two definitions (PB-A and PB-H) compared to the baseline diet (the overall diet consumed by the NANS population). Compared to the baseline diet, both PB diet components were of better nutritional quality in terms of many nutrients, including total and saturated fat, carbohydrate, dietary fibre, vitamin C, thiamin, folate, sodium, potassium, iron, but of poorer nutritional quality in terms of protein, MUFA, PUFA, total sugars, vitamin D, vitamin B12, calcium and iodine (PB-A only). Compared to the PB-A component, the PB-H component of the diet was of better nutritional quality with regards to total and saturated fat, PUFA, protein, carbohydrate, dietary fibre, free sugars, B-vitamins, vitamin C, potassium and iron but was of poorer quality for vitamin D and vitamin B12. The MDI of ‘fruit & vegetables’ (285g/d; approximately 3.6 servings) was below the World Health Organisation recommendation of ≥400g/d and the Irish FBDG of 5-7 servings/d (≤ 150ml/d from unsweetened fruit juice). Despite low intakes, ‘fruit & vegetables’ made important contributions to intakes of PUFA, carbohydrate, dietary fibre, vitamin C, vitamin A, potassium, folate, vitamin E, magnesium and thiamin, while also contributing to intakes of total sugars and free sugars. The MDI of ‘cereals, grains & potatoes’ was approximately 4.5 servings, however, only 2.1 servings were from ‘wholemeal cereals and breads, potatoes, pasta and rice’, which was below the Irish FBDG recommendation of 3-5 servings/d. ‘Cereals, grains & potatoes’ made significant contributions to intakes of energy, carbohydrate, dietary fibre, protein, folate, thiamin, niacin, vitamin B6, iron, magnesium, calcium, potassium and zinc but also contributed to intakes of sodium and made smaller contributions to the intake of saturated fat and free sugars. The data presented in this study may benefit the scientific community, health professionals, policymakers and the food industry in understanding how intakes of high-quality PB foods can be increased in adults in Ireland in light of the shift towards a more PB diet for health and environmental benefits.
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    Novel ingredients and emerging processing technologies in the development of clean label, phosphate-reduced meat products
    (University College Cork, 2022-08) Palanisamy Thangavelu, Karthikeyan; Kerry, Joseph; Tiwari, Brijesh; Álvarez, Carlos; Teagasc
    Phosphate additives are used in numerous processed foods as stabilisers and emulsifiers. They are present in up to 65% of processed meat products. However, consumer preferences for more natural and less processed foods have resulted in clean-label growth trends, meaning shorter ingredient declarations avoiding ingredients unfamiliar to the consumer. Due to the unique characteristics of phosphates, their removal, while maintaining product quality, is challenging. As an initial study (Chapter 2), a survey assessing the Irish consumer’s (n=548) intention to purchase phosphate-reduced processed meat products employing the Theory of Planned Behaviour (TPB) was conducted. Results showed that Irish consumers positively intended to purchase phosphate-reduced processed meat products if widely available. Based on survey findings, this thesis research explored the possibilities of developing high-quality, phosphate-replaced/reduced processed meat products employing natural ingredients and additionally employing novel processing technologies. This objective was achieved by carrying out two important processes: modification of potential phosphate-replacers and meat structure modification using novel processing technologies and accomplished by carrying out four experimental studies. The first experimental study (Chapter 3) examined the phosphate-replacing ability of two dietary fibre-rich food co-product ingredients, namely; apple pomace (AP) and coffee silverskin (CSS), in Irish breakfast sausage formulations. A specialised response surface methodology developed using Mixture design software created 18 sausage formulations containing different sodium tripolyphosphate (STPP), AP and CSS concentrations. Results showed that the addition of ingredients improved WHC (P<0.001) and decreased the cook loss (P<0.001), hardness (P<0.001), chewiness (P<0.001) and day 9 TBARS (P<0.018) values. Software analysis of results predicted three optimised phosphate-reduced sausage formulations based on the desirability response method. Following chapter 3, efforts were made to enhance the functional properties of AP and CSS using Power Ultrasound (US) technology Chapter 4). This investigated the effect of US treatment of 20 kHz, 250 W at different time intervals of 15 and 30 minutes on the techno-functional properties of AP and CSS, such as water and oil absorption capacity (WAC and OAC), particle size, viscosity, colour and total fibre content. Results indicated that US treatment on ingredients for 15 and 30 minutes improved WAC and OAC of both ingredients (Significant only for AP). Observation showed that functionality improved with increased treatment duration. This demonstrated that US treatment can create beneficially-functional properties in food co-products or ingredients, such as with AP and CSS powders. Combining Chapters 3 and 4, a comparative study (Chapter 5) was conducted employing US-treated (30 minutes) ingredients in the three optimised phosphate-reduced sausage formulations obtained from the mixture design software. Results showed that the addition of US-treated AP and CSS to all the formulations increased WHC (P<0.05), emulsion stability (TEF %) (P<0.05), and decreased cook loss (P<0.05), demonstrating that the addition of US-treated AP and CSS can improve phosphate-reduced sausage quality. Finally, in Chapter 6, a strategy of using High-Pressure Processing (HPP) technology to alter meat functionality was employed for further sausage quality improvement. Study results showed that HPP (150 MPa for 5 mins) produced positive changes in the water holding capacity (WHC) (P<0.05) and cook loss (P<0.05) of sausage formulations when compared to non-HPP treated equivalents. In conclusion, there is potential to manufacture sausages with reduced phosphate concentration using novel processing technologies and clean label ingredients, such as those used in this study. Overall, the research presented showed the wide application scope that exists for non-thermal novel processing technology. With further optimisation, these ingredients and the processing technologies employed could be used to produce a wide range of healthier and higher-quality processed meat products.
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    Cold microfiltration as an enabler of innovative dairy protein ingredient composition and techno-functionality
    (University College Cork, 2022-08) France, Thomas C.; O'Mahony, Seamus Anthony; Crowley, Shane; Dairy Processing Technology Centre
    Microfiltration (MF) of skim milk at warm temperatures (i.e., 45-55 °C) is common practise in the dairy industry; however, high rates of fouling and short run times due to fouling and microbial quality can occur when operating at these temperatures. The adoption of cold temperatures (i.e., ≤20 °C) provides opportunities to improve efficiency and overall sustainability of the process. However, it can affect the protein, mineral and enzyme partitioning during MF which can ultimately impact the functional properties of the final ingredients, although this has not been sufficiently studied within the cold MF range. This thesis systematically studies the effects of different temperatures within the cold MF range on processing performance and fouling, protein, mineral and enzyme partitioning and some of the consequences on the physicochemical properties of the resulting process streams. Lower processing temperatures, in the range from 20 to 4 °C, resulted in significantly higher concentrations of β-casein in the permeate, with κ-casein, α-lactalbumin and β-lactoglobulin not significantly impacted by alterations in processing temperature. Lower processing temperature also resulted in a lower rate of permeate flux decline during MF although higher mechanical (pump) and thermal energy consumption were measured for the lower processing temperature (i.e., 4 °C). Altering processing temperature had minor effects on plasmin activity in permeate streams although extensive plasmin-mediated hydrolysis was observed on storage; such plasmin-mediated hydrolysis had significant impacts on the temperature-dependent self-association of β-casein. Extensive diafiltration (DF) with water was performed at 4 °C, resulting in a β-casein-depleted micellar casein retentate which displayed superior heat stability when compared to a micellar casein retentate produced at 50 °C. The learnings obtained were applied to the final study in which different DF media were used, i.e., water and two simulated milk ultrafiltrates (SMUF) designed to resemble the mineral profile of ultrafiltration permeate produced at 10 and 50 °C. The use of both SMUFs resulted in similar protein partitioning and significantly improved the heat stability of the micellar casein retentates generated, compared to when water was used as the DF medium. The findings presented in this thesis constitute a significant advance in the understanding of the effects of processing temperature within the cold MF range on parameters of relevance in the optimisation of next generation protein ingredient development in the dairy industry.
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    Characterisation of pulse protein ingredients produced using different protein sources and processing technology, and potential for application in milk alternatives
    (University College Cork, 2022-02-25) Vogelsang-O'Dwyer, Martin; Arendt, Elke K.; Horizon 2020
    In the face of the growing global population along with climate and food security concerns, there is currently much interest in developing plant protein ingredients from sustainable sources. Pulses are a valuable source of protein which could play an increased role in reducing our reliance on animal protein. Pulse protein ingredients can potentially provide the required functional properties (e.g., solubility, emulsifying, gelling, foaming) for a range of food applications. However, further development is necessary in order to increase our understanding and maximise the utility of pulse proteins as demand increases. This thesis addresses how protein source and processing can impact various properties of ingredients, including functional, nutritional and environmental aspects. In addition, the application of pulse proteins in high protein milk alternatives is examined. Furthermore, the impact of enzymatic hydrolysis on physicochemical and functional properties is explored. Protein isolates from blue lupin (Lupinus angustifolius) and white lupin (L. albus) were compared to assess the influence of protein source on various properties. Electrophoresis revealed major differences in molecular weight distribution. Solubility and foaming properties were similar for both isolates, while major differences in thermal gelling behaviour were found, with white lupin protein gelling at a lower concentration (7%) compared to blue lupin (23%). Both isolates were low in FODMAPs (fermentable mono-, di, oligosaccharides and polyols). In addition, the life cycle assessment (LCA) showed generally lower environmental impacts for the lupin isolates compared to milk powder per kg protein. Faba bean protein-rich flour (FPR) produced using dry fractionation was compared to faba bean protein isolate (FPI) produced using wet fractionation. Protein content of dry matter was lower for FPR (64.1%) compared to FPI (90.1%) Overall, superior functionality was found for FPR, including solubility and foaming properties. Wet processing (FPI) was found to be effective for removal of vicine, and trypsin inhibitors and FODMAPs. In the LCA, lower environmental impacts were found for FPR than FPI; however, both FPR and FPI had much lower impacts compared to milk powder. Milk alternatives were produced with blue lupin (BL) or white lupin (WL) protein isolate, with similar protein and fat content to low-fat cow’s milk. Both BL and WL milk alternatives had good colloidal stability and were suitable for low FODMAP diets. Increased homogenisation pressure (780 bar vs 180 bar) resulted in smaller particle size and increased stability for both BL and WL milk alternatives. WL milk alternative homogenised at 780 bar had the lowest separation rate, comparable to low fat cow’s milk, indicating good resistance to creaming. The effects of enzymatic hydrolysis on the physicochemical and functional properties of lentil protein isolate were assessed, in a comparison of three proteases. Hydrolysis with Alcalase or Novozym 11028 resulted in considerably higher solubility from pH 4–6, where the control showed poor solubility. Hydrolysis with Flavourzyme resulted in moderately increased solubility in this pH range, but slightly decreased solubility at neutral pH. Foaming properties were not impacted significantly by hydrolysis. Hydrolysis with Alcalase resulted in larger particle size and higher viscosity compared to the control. Overall, these studies provide useful insight into the properties of pulse protein ingredients which depend on pulse type and ingredient processing, modification with enzymatic hydrolysis, as well as their suitability for high protein milk alternatives.
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    Influence of dietary factors on the macro and micro-composition of bovine milk for use in protein ingredient powder manufacture
    (University College Cork, 2021-12) Magan, Jonathan B.; Kelly, Alan; O'Callaghan, Tom; McCarthy, Noel A.; Dairy Research Ireland; Teagasc
    The increasing frequency of “grass-fed” labelling claims in dairy product marketing, predicated in part on improved product quality and nutritional benefits associated therewith, has necessitated both rigorous experimental data to determine the relative differences in the composition of milk from grass-fed and non-grass-fed cows and robust methods for verifying these labelling claims. The “Grass-fed Standard” established by Bord Bia in 2020 is the first scientifically-backed standard in use internationally, which is founded on the somewhat unique pasture-based dairy production system practiced in Ireland. The compositional and functional benefits associated with products derived from pasture-fed cows have thus far been focused on business-to-consumer products. The effect of pasture-based production relative to the conventional indoor production system utilised most widely throughout the world on the composition and functional properties of “business-to-business” milk powder products, which represent a major aspect of Irish dairy production, remained to be established. Variation in the composition and functional properties of dairy products arises due to numerous factors, including feed composition, which can differ depending on the type of production system practiced. Therefore, the objective of this research was to investigate the effect of perennial ryegrass only (GRS), perennial ryegrass/white clover pasture (CLV) and indoor total mixed ration (TMR) feeding systems on the composition and functional properties of bovine milk-based protein ingredients. There was a significant effect of feeding system on the concentration of metabolite compounds and B vitamins in skim milk powder (SMP) and whey ingredients, which were distinguishable by liquid chromatography-mass spectrometry. Concentrations of vitamins B1, B2 and B7 were significantly higher in GRS and CLV samples than TMR samples, for which concentrations of vitamin B3 and B3-amide were higher than in CLV and GRS samples, respectively. Gross compositional parameters were similar between the feeding systems; however, the CLV and TMR systems were associated with high concentrations of non-protein nitrogen and high heat stability in whole milk powder and SMP samples. Some differences in total amino acid (AA) composition were also exhibited between WMP and SMP samples from each diet, which suggests that AA profile may be responsive to dietary variation. Yoghurts produced from GRS and CLV-derived WMP were typified by significantly higher gel strength and textural firmness than those derived from TMR, despite significantly higher concentrations of palmitic acid in TMR samples. Fatty acid (FA) profiles of WMP samples from each diet were similar to those in the literature produced from pasture or concentrate-based systems. The level of FA unsaturation and carotenoid content could also distinguish between pasture and TMR samples using Raman spectroscopy. The mineral composition of WMP, SMP and whey protein concentrate (WPC) samples from each diet did not vary significantly, with the exception of selenium and iodine, which were consistently, and significantly, higher in TMR samples than GRS and CLV samples. The viscosity of GRS-derived skim milk concentrate was significantly higher than that for TMR, but the effect of diet on the heat-dependent viscosity of dispersions of skim milk with WPC was not as substantial as the differences between WPC types, with micellar casein whey being most stable on heating, and acid WPC the least stable. Proteomic and peptidomic analysis of WMP and digested WMP samples determined qualitative and quantitative differences in proteins and peptides arising from each diet. In conclusion, this research demonstrated that the influence of bovine diet on milk components is not limited to gross compositional factors, but the micro-composition and functional properties, such as heat stability and acid-induced gelation, of value-added dairy products can also be influenced by feeding practices. This research will be of most interest to the manufacturers of dairy powder ingredients, such as SMP and WPC and premium WMP products in establishing the commercial point-of-difference for pasture or concentrate-derived products along with the unique compositional elements and functional behaviour associated with products from the three feeding systems investigated herein. Furthermore, this research will aid in ingredient selection for manufacturers of value-added dairy commodities, such as infant milk formula. Finally, this research contributes to the list of compositional variables which demonstrate potential for differentiation between feeding systems, providing preliminary information, relating to the establishment of robust analytical methods for verification of “Grass-fed” labelling claims for milk powder products to international entities responsible for policy implementation, such as Bord Bia.