Food and Nutritional Sciences - Doctoral Theses

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    Development and optimisation of food products low in FODMAPs: an investigation of dietary fibres in low FODMAP products and the reduction of FODMAPs via bio-technological processes
    (University College Cork, 2023) Atzler, Jonas J.; Arendt, Elke K.; Gallagher, Eimear; Department of Agriculture, Food and the Marine, Ireland
    Cereal-based products – a stable food source in the western world- are high in fructans and α-galactooligosaccharides (GOS). These carbohydrates belong to the group of fermentable oligo-, di-, monosaccharides and polyol (FODMAP), which were shown to trigger symptoms of irritable bowel syndrome. A diet low in FODMAPs is reported to relieve symptoms in over 70 % of patients However, the availability of nutritious and appealing food products (e.g., sufficient dietary fibre content and good techno-functional quality) suitable for that diet is very limited. Therefore, this thesis investigated two approaches and their potential for overcoming this challenge. Firstly, three enzymes (invertase, inulinase and α-galactosidase) were used to investigate the targeted degradation of fructans and GOS. Inulinase and invertase degrade both fructans and GOS, while α-galactosidase only degrades GOS. Inulinase was the most efficient in degrading both fructans and GOS since it led to the degradation of 90 % of both oligosaccharide types. However, the use of inulinase and invertase resulted in the production of two degradation compounds – fructose in excess of glucose and melibiose and its higher homologues- which have the potential to act as FODMAPs. The second approach was to fortify products with dietary fibres (DFs) beneficial for IBS-patients, based on substituting wheat flour with wheat starch and gluten. The application of two insoluble (bamboo fibre and cellulose) and two soluble-viscous DFs (psyllium and guar gum) was tested in bread and pasta. Two different concentrations of these DFs (3 g/ 100g and 6 g/100 g) were used to produce a bread. The application of these DFs in a bread system, highlighted that the effects on the bread quality significantly depend on both the DFs' solubility and viscosity. All DFs decreased the specific volume of breads and increased the hardness after 0 h and 24 h. Despite these effects, the techno-functional quality was similar to wheat bread fortified with DF (3 g/100 g and 6 g/ 100 g of wheat bran). Additionally, a dose dependency of these effects was found: using the DFs in a concentration of 6 g/100 g resulted in an enhancement of the observed effects. Ultimately, the addition of all fibres led to an improvement in the nutritional quality with reduced in vitro starch digestibility. All four DFs mentioned above were added to a pasta system in a concentration of 6 g/100 g. The effects on the techno-functional properties depended on the DF's solubility, viscosity, and particle size. Both cellulose and guar gum showed the most potential with acceptable techno-functional properties (e.g., hardness, optimal cooking time, cooking loss). The application of highly viscous DFs (especially guar gum) positively influenced the in vitro starch digestibility. For all DF fortified pasta, no significant difference in the sensory properties compared to the unfortified pasta was found, suggesting an acceptable sensory quality. Finally, a combination of three different DFs (resistant starch, cellulose and corn fibre rich in arabinoxylans) was used to produce a fibre-enriched low FODMAP biscuit. Using the response surface method (RSM) for finding the best combination of the three ingredients resulted in a biscuit with a DF content of ~15 % and an improved quality compared to the unfortified biscuit. The sensory quality of the optimised biscuit was similar to a wholemeal biscuit and the unfortified low FODMAP control biscuit. Furthermore, the fibre-enriched biscuits showed an improved in vitro starch digestibility. Overall, the findings of this thesis offer a set of tools for the developments of low FODMAP products. On the one hand the suitability of IBS-beneficial fibre for developing nutritious and appealing products suitable for a low FODMAP diet is a reliable approach, without the need of any further FODMAP reduction techniques. On the other hand, also the targeted use of FODMAP degrading enzymes is a promising approach; if native fructans and GOS are present (e.g., whole wheat or rye-based products) these can be efficiently degraded in combination with fermentation-based techniques.
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    Upcycling of brewing by-products using lactic acid bacteria fermentation technology and analysis of their behaviour in a cereal-based applications
    (University College Cork, 2023-05-19) Neylon, Emma; Arendt, Elke K.; Horizon 2020
    Barley rootlets (BR) and brewers spent grain (BSG) are by-products of the malting and brewing industries and are primarily used in animal feed and landfill. Due to the beneficial nutritional composition of BR and BSG (high fibre/protein) the current uses underestimate their maximum potential. BR are a relatively under explored material and review of the literature available on BR revealed extensive knowledge on the formation, processing, compositional quality, and potential applications of BR. In regard BSG, literature suggests high prospects for BSG in widely available cereal-based applications. However, further processing of BSG such as using lactic acid bacteria (LAB) fermentation technology are required to improve food product quality and further valorise BSG as a food ingredient. The incorporation of BSG and fermented BSG (FBSG) in a pasta matrix revealed inclusion of BSG and FBSG induced changes in gluten properties which depreciated pasta quality (reduced firmness and tensile strength) compared to semolina pasta. However, both BSG and FBSG pasta formulations performed more favourably than the wholemeal control from a techno-functional perspective. A greater reduction in the predicted glycaemic index with FBSG fortification compared to BSG suggested fermentation further enhances nutritional properties of BSG. A follow up study on the application of BSG and FBSG in a bread revealed similar defects to bread quality. Nonetheless, comparing BSG and FBSG breads, FBSG addition improved bread characteristics resulting in increased specific volume, reduced crumb hardness; restricted microbial growth rate over time; and slowed the release in reducing sugars over time during in vitro starch digestion. The success observed in the capability of LAB technology to functionalise BSG sparked interest in the application of LAB fermentation in BR processing. As a result, 5 fermented BR ingredients were developed and produced using Lactiplantibacillus plantarum FST 1.7 (BR-FST1.7), Lactobacillus amylovorus FST2.11 (BR-FST2.11), Weissella cibaria MG1 (BR-MG1), Leuconostoc citreum TR116 (BR-TR116) and Limosilactobacillus reuteri R29 (BR-R29). The changes in sugar/FODMAP/acid compositions; microbial metabolites and techno-functional properties of the developed BR ingredients identified each LAB fermentation imparted a unique set of characteristics to the BR ingredient, further affirming LAB fermentation technology as a functionalising processing technique. The developed BR ingredients were applied to a bread matrix to explore if characteristics of the LAB fermentation translated to the bread product. Inclusion of the fermented BR ingredients improved bread specific volume/reduced crumb hardness (BR-MG1, BR-TR116); substantially slowed microbial spoilage of breads (BR-R29); and produced breads with improved nutritional characteristics and varied sensory flavour profile (BR-FST2.11, BR-FST1.7). The outcome of this research thesis provides extensive knowledge on the effects of BSG and BR on pasta/bread quality as well as showcasing the potential of LAB fermentation technology as a valorisation technique for BR and BSG processing.
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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.