Food and Nutritional Sciences - Doctoral Theses

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    Dietary quality of school-aged children and teenagers in Ireland by demographic characteristics and eating location
    (University College Cork, 2022-10) Rusu, Ioana; Kehoe, Laura; Flynn, Albert; Cashman, Kevin; Walton, Janette; O'Mahony, Jim; Department of Agriculture, Food and the Marine, Ireland
    Background: Childhood and the teenage years are distinctive life stages characterised by unique dietary needs. Data from nationally representative dietary surveys of children and teenagers across Europe have shown that intakes of key nutrients are not in line with recommendations. Furthermore, demographic characteristics such as sex, age, socio-economic status and weight status may have an influence on dietary quality in children and teenagers. It has also been shown that eating location can influence dietary quality, with some locations such as ‘home’ and ‘school’ being associated with better dietary quality than other locations, such as ‘restaurants’, ‘takeaways’ and ‘shops’. Objectives: The overall aim of this thesis was to examine the dietary quality of school-aged children and teenagers in Ireland by demographic characteristics and eating location using data from the National Children’s Food Survey II (NCFS II) (2017-18) and the National Teens’ Food Survey II (NTFS II) (2019-20). Methods: The analyses for this thesis were based on data from the NCFS II and the NTFS II which are two nationally representative dietary surveys of children (5-12 years, n 600) and teenagers (13-18 years, n 428) living in the Republic of Ireland. Dietary intake data were collected at brand level using a 4-day weighed food diary for both surveys. Dietary quality was determined using energy-adjusted (%E or /10MJ) intakes of nutrients and food groups. ‘Eating location’ was defined as the location where food was prepared or obtained, irrespective of where it was consumed. For eating location analysis, consumers were defined as those who consumed food at a given location at least once during the four-day recording period. Results: The overall dietary quality of children and teenagers in Ireland was found to be unfavourable and there were very few differences observed across sex, age groups, categories of socio-economic status and weight status. Intakes of key food groups were not in line with food-based dietary guidelines (FBDG) for either children or teenagers. In both children and teenagers, dietary intakes were driven by the ‘home’ location. While the majority of children (73%) and teenagers (78%) consumed food from ‘outside of the home’, most eating occasions took place at ‘home’ for both children (89%) and teenagers (85%), accounting for a large proportion of the energy consumed (88% in children and 81% in teenagers). The contribution of food consumed from ‘outside of the home’ was higher in teenagers than in children (19% vs. 12%). Younger children had higher intakes of energy from food consumed from ‘other homes’ than older children and both children and teenagers of parents with primary/intermediate education only had higher intakes of energy from food consumed from ‘fast food/takeaways’ than children and teenagers of parents with tertiary education. There were no other differences observed in these eating patterns across any other demographic characteristics examined. Food consumed from ‘home’ and the ‘participant’s own home’ was better in terms of dietary quality than food consumed from ‘outside of the home’ and ‘other homes’. Of all ‘out of home’ locations, ‘school’ provided the best dietary quality for children, but this was not seen in teenagers. Conclusion: This thesis has shown that the overall dietary quality of children and teenagers in Ireland was unfavourable and there were few differences found across demographic characteristics. Dietary intake was driven by the home environment, with ‘home’ and the ‘participant’s own home’ being associated with better dietary quality than ‘other homes’ and ‘outside of the home’. The findings of this thesis can be of use to policy makers when introducing healthy eating policies aimed at school-aged children and teenagers such as taxation on unhealthy foods and regulation around marketing of unhealthy foods.
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    Quantification of volatile compounds (oxidative and olfactory) in meat products and impact of seaweed addition on the sensory and volatile profiles of processed meat products
    (University College Cork, 2022-10) Garicano Vilar, Elena; Kerry, Joseph; O'Sullivan, Maurice; Kilcawley, Kieran; Teagasc
    Now more than ever consumers demand healthier food options, including meat products, with ‘clean-label’, sustainable and natural ingredients without compromising their sensory experience; hence a greater need for innovative concepts and approaches towards new product development is required. In this regard, seaweeds compose a credible source of functional ingredients with bioactive properties. There is a positive association between processed meat consumption and the risk of chronic diseases, such as cardiovascular disease, certain cancers or type II diabetes, due to their high levels of saturated fats and sodium. Processed meat refers to meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation (i.e., frankfurters, ham, and canned meat). The optimization of processed meat products through the reduction of fat and the partial replacement of salt could potentially offset the risk. However, the influence of matrix changes on the character aroma compounds and sensory perception of the developed products could adversely affect consumer acceptability. Therefore, this research aims to characterize the volatile organic compounds (VOC) and aroma profiles of processed meat products and seaweed, and to study seaweed-based processed meat products in terms of shelf life and consumer perception. This thesis has demonstrated the feasibility of generating valuable VOC and aroma profiles of processed meat products and seaweed using sophisticated extraction, separation, and identification gas chromatography mass spectrometry techniques (GC-MS); and of developing a novel method using headspace high capacity sorptive (HiSorb) extraction for quantification of target lipid oxidation compounds. This in-depth approach provides information on the sensory characteristics and shelf life of the processed meat products (frankfurters and beef patties), following reformulation and/or storage. The work in this thesis primarily employed HiSorb and thermal desorption (TD) GC-MS (HiSorb TD GC-MS) with polydimethylsiloxane (PDMS) probes and headspace solid phase microextraction GC-MS (HS-SPME GC-MS) for VOC profiling, but also the use of gas-chromatography olfactrometry (GC-O) applications. Chapter 1 provides an updated insight into the main extraction/concentration techniques that are available for the determination of the main odour-active volatiles in beef and pork. Aroma compounds are challenging to extract, concentrate, separate, identify and quantify due to the complexity of meat. The review highlights the potential pros and cons of the main approaches used to date but also, how advances in extraction, chromatography and olfactometry helps elucidate more key aroma compounds. However, many VOC have been identified in beef and pork to date. It is the use of GC-MS and olfactometry methodologies that enable us to increase our knowledge of the importance of the key volatiles impacting on consumer perception, either positively or negatively. The review in chapter 2 provided insights into the volatile analyses of six commercially important brown and red seaweed species used in the food industry and highlighted the need for more information regarding VOC in edible macroalgae and to identify those most likely to impact sensory perception. This is as important for those VOC that positively or negatively contribute to sensory perception. Such information could be used to aid new product development or widen applications of these seaweeds in the food sector, one of which is in meat product formulation. In that regard, chapter 3 investigated the volatile profiles of dried brown (Himanthalia elongata, Undaria pinnatifida, Alaria esculenta) and red (Porphyra umbilicalis, Palmaria palmata) seaweeds, and a brown seaweed extract (fucoxanthin) from Laminaria japonica, some of which had not previously been described. A chemometric approach was used to collate data from GC-MS, direct sensory aroma evaluation, and GC-O to obtain a better understanding of their volatile profile and sensory perception. Once the volatile profiles of the seaweed were characterized, chapter 4 investigated the impact of the inclusion of four selected seaweeds (1 % w/w) in reformulated frankfurters in which salt addition was reduced by 50 % compared to a control. The overall acceptability of reformulated frankfurters containing seaweed was greatly influenced by the type of added seaweed (also linked to dosage), but overall, the addition of seaweed enabled salt reduction and thus improved the nutritional quality. Further processing of seaweed prior to addition, optimization of dose rates, combinations of seaweeds and/or highlighting potential nutritional benefits will be necessary before such products are accepted by consumers unfamiliar with seaweeds in their diet. Lipids may cause both desirable and undesirable flavours and aromas in meat. However, progressive lipid oxidation adversely affects meat quality. Sophisticated techniques such as GC-MS can be used to identify and quantify individual VOC associated with lipid oxidation. Hence, the aim in chapter 5 was to develop a GC-MS method using HiSorb extraction for untargeted volatile profiling and to quantify targeted LOC in raw beef patties over refrigerated storage. Using this approach to determine the concentrations of VOC associated with lipid oxidation that adversely impact sensory perception provided insights into the production parameters that could maximise the oxidative shelf life stability and quality of meat products. It is essential to expand the knowledge on how to protect foods against lipid oxidation. Synthetic antioxidants have been used for many years to retard lipid oxidation in foods. However, there is growing interest in replacing synthetic antioxidants with natural ingredients. Seaweeds are not only a valuable source of bioactive compounds and a good salt content replacer, but also exhibit extraordinary antioxidant potential which can be harnessed for a broad variety of food applications. Therefore, the validated HiSorb GC-MS method outlined in chapter 5 was applied to profile the aroma of raw beef patties reformulated with seaweed, packed in MAP, and stored under refrigeration conditions in chapter 6. The method was combined with GC-O to detect VOC changes that could cause off-flavours in the product over time, along with changes in colour and TBARS values indicative of lipid oxidation. The antioxidant activity of the seaweed was also examined in an attempt to evaluate their effect against product deterioration. The antioxidant activity present in seaweed, attributable to polyphenols, flavonoids and other antioxidants, opens new possibilities of application of these in fresh meat products. Their use could potentially increase shelf life of food products due to their antioxidant capacity, and replace artificial food additives.
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    Sensorial, cultural and volatile properties of dairy powders, yoghurt and butter from pasture and non-pasture cow diets
    (University College Cork, 2022-12-14) Zeng, Cheng; O'Sullivan, Maurice; Kerry, Joseph; Kilcawley, Kieran N.; Teagasc
    Significant advances have occurred in the ability to extract and identify volatile aromatic dairy compounds that may influence sensory perception. In this Thesis volatile extraction techniques were optimised and evaluated in order to obtain a more representative volatile profile of selected dairy products, such as; whole milk powder, skim milk powder, yoghurt and salted butter. This information was also utilised with gas chromatography olfactometry (GC-O) and sensory analysis to determine which specific compounds are most likely influencing sensory perception. In addition the impact of cow diet was assessed in terms of the volatile and sensory profile on skim milk powder, whole milk powder and salted butter using milk from cows outdoors on pasture-fed diets (such as ryegrass, ryegrass and white clover) and cows indoors on trial mixed rations. Cross cultural sensory analysis was also undertaken on skim milk powder from these diets in order to determine if consumers and trained panellists perceived skim milk powder differently based on diet but also on product familiarity Chapter 1 provides an updated review of traditional and novel sensory methods used to evaluate milk, milk powders, yoghurt, and butter, as well as gas chromatography mass spectrometry and gas chromatography olfactometry extraction techniques to provide more complete profile of volatiles that impact sensory perception. Chapter 2 investigates the impact of pasture and non-pasture cow diets on the volatile cross cultural sensory perception of skim milk powder. The volatile profile and sensory properties of the skim milk powder were influenced by cow diet and Irish, Chinese and USA consumers as well as trained sensory panellists perceived products differently primarily based on familiarity. Chapter 3 investigated if yoghurt produced from three different starter cultures were perceived differently by Irish consumers, German consumers and trained assessors. German trained assessors found it more difficult to discern differences between some of the yoghurts than trained Irish assessors. Seventeen of the 24 volatiles compounds identified differed due to starter culture, which most directly or indirectly associated with lipid oxidation.The ability of headspace solid phase microextraction, thermal desorption, and high capacity sorptive extraction as a direct immersion and headspace extraction technique were compared with and without salting out and by a polar and non-polar gas chromatograph column for volatile profiling of whole milk powder in Chapter 4. The impact of three different diets on the sensory properties and volatile profile of whole milk powder was investigated in Chapter 5. Both the sensory perception and volatile profiles of whole milk powder differed significantly depending on the diet, with whole milk powder derived from rye-grass or rye-grass and white clover more similar than whole milk powder derived from total mixed ration. Most of the differences in volatiles due to diet were either directly or indirectly linked to fatty acid content. Chapter 6 outlines the development and optimisation of direct immersion high capacity sorptive extraction for the extraction, separation and identification of volatile compounds from salted butter from three different diets; rye-grass or rye-grass and white clover or from total mixed ration. This thesis has clearly demonstrated that cow diet influences the volatile and sensory characteristics of selected dairy products, which subsequently effects sensory perception on a cultural basis influenced by product familiarity. The benefits of optimising volatile extraction techniques on a product specific basis were clearly demonstrated along with using multiple techniques in order to achieve the most representative volatile profile as possible. Combining volatile analysis with olfactometry and / or sensory techniques enables a more comprehensive understanding of factors influencing sensory perception and choice that can be utilised for product quality, improvement and marketing.
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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.