Browsing Food Institute - Masters by Research Theses by Issue Date
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- ItemThe glycaemic index of fresh and processed potatoes(University College Cork, 2020-10-16) Muldoon, Aine; O'Brien, Nora M.; O'Connor, Thomas P.; Department of Agriculture, Food and the Marine, IrelandPotatoes are an important staple food, which provide vital nutrition to millions of people globally every year. However, potatoes have a relatively high carbohydrate content as well as being generally considered as a high Glycaemic Index (GI) food. Research suggests that the consumption of potatoes or high GI foods can contribute to the onset of certain chronic conditions such as cardiovascular disease and type II diabetes. The supposed link between potatoes and negative health outcomes has led to a decline in their consumption in the developed world. The aim of this thesis was to assess the GI, glycaemic load (GL), and carbohydrate parameters of selected potato cultivars using an in-vitro method. The main objectives of the research were to employ various interventions in an attempt to reduce the GI and GL of the potatoes. Five potato cultivars commonly consumed in Ireland (Cultra, Gemson, Kerr’s Pink, Maris Piper, and Rooster) were tested. All varieties were found to have a medium or high GI. Evidence suggests that certain types of processing can reduce GI therefore each of the potato cultivars were then subjected to high pressure processing (HPP) at either 400Mpa or 600Mpa. In the potatoes which had the highest GI a decline in the GI was observed as the pressure was increased, however this decrease in GI was not seen in the potato varieties with a lower GI. Roosters were selected for further testing as they are the most widely produced and consumed potato variety in Ireland. To determine the effect of added fat on GI, a dose response was conducted by adding 10%, 15%, 20% or 25% (w/w) of rapeseed oil to potato and measuring GI. The GI of potato was also assessed following addition of butter, coconut oil, or olive oil at a concentration of 10% (w/w). No significant changes in GI or GL of the potato were observed following the addition of fat at any concentration; nor did the degree of saturation of the added fat impact GI or GL. The impact of combining Roosters with either cheese, peas, beans, or tuna on the GI of the resultant meal was investigated. Each meal consisted of 50g of available carbohydrates. Roosters alone had a medium GL, this was reduced to a low GL when they were included as part of a meal. The GI was also reduced for every meal in comparison to Rooster alone, apart from the potato-tuna meal. The greatest decrease in the GI was observed when Rooster were combined with beans which are a rich source of fibre. Consequently, the addition of three fibres; pectin, HPMC (hydroxypropylmethylcellulose), or inulin was investigated as a means of reducing the GI of Rooster potatoes. The fibres were tested at three concentrations 5%, 7% or 10% (w/w). The viscosity of the digesta as well as the carbohydrate parameters were measured. Pectin induced the greatest reduction to the GI out of all three fibres, whilst causing the highest increase in viscosity. HPMC had a similar but less pronounced effect, whilst inulin did not affect the GI. Finally, the impact of HPMC on carbohydrate parameters in sweet potatoes as well as the antioxidant potential of both Roosters and sweet potatoes was investigated. Ferric reducing antioxidant potential (FRAP), Oxygen radical absorbance capacity (ORAC), total phenol content (TPC), as well as ascorbic acid content were quantified. The addition of the fibre caused reductions in the FRAP and ascorbic acid content of the tubers however, ORAC and TPC values remained unchanged. Overall, our findings have identified methods to potentially reduce the GI of potatoes which could be useful for the food industry and have also demonstrated that in-vitro methods can be a convenient tool for the determination of GI and GL in potato and potato-based meals.
- ItemThe optimization of plant protein meat re-placers and clean label water binders in processed meat (white pudding and chicken)(University College Cork, 2021-10-31) Garvey O'Driscoll, Seán; O'Sullivan, Maurice; Kerry, Joseph; Ryan, SinéadReformulations and the development of bespoke vegetarian/vegan products, are becoming increasingly popular for a host of reasons, including health, environmental, economic and ethical concerns. Processed meat products have been under the spotlight for much of the recent past, with particular regard to their typically higher fat and salt contents and the health consequences of these, as well as the impact of meat production on the environment. Therefore, the interest in plant-based alternatives is continuing to grow. A sequential reduction of meat and animal fat with either chickpea or red lentil protein was performed in white pudding, with the overall goal of producing an acceptable 100% vegan product, or failing this, identifying the optimal replacement level that was acceptable to consumers and would not compromise on technological quality. The technological, compositional and sensory quality of the samples were analysed. Replacement was performed in 10% increments from 10% to 100%. Samples that contained more chickpea or red lentil protein than meat and animal fat (50% + replacement) were significantly (P<0.05) less acceptable from a sensory perspective, while they were also significantly (P<0.05) higher in protein content, lower fat content and lower in pH. Overall, a vegan sample was not a viable possibility under the parameters due to significant deterioration in sensory and technological quality and the optimum replacement level was identified at 20% for both proteins. Replacement was possible up to 40% for CP and 30% for RLP before quality started to deteriorate. Further optimisation of the formula and/or production method to achieve further replacement of the meat and animal fat. Recent years have seen an increase in demand for products that are perceived to be more “natural”, organic, containing less additives and preservatives or by utilising clean label ingredients. Phosphates, a common water binding agent, are one such food ingredient that consumers may actively seek to avoid. Sodium triphosphate (STPP) was sequentially replaced (25%, 50%, 75%, 100%) with Aquamin soluble, citrus fibre and carrageenan in a brine intended for injection into chicken breast fillets. The effect of the replacement on the technological, sensory and microbiological quality of the cooked chicken (in the form of restructured chicken hams) was investigated. The overall objective was to produce a phosphate-free brine system utilising Aquamin soluble as well as any other ingredients deemed necessary. Replacement yielded significantly (P<0.05) more acidic brines and cooked samples alongside a significant increase in WHC. The sensory quality was unaffected by replacement, with no significant differences in overall acceptability between samples. Similarly, no significant improvements or deterioration in microbiological quality were identified, though the acidic nature of the 75% and 100% replacement samples may have had a slight statistically nonsignificant antibacterial effect. Ultimately, the complete replacement of STPP yielded a cooked chicken sample that performed largely on par with one or two exceptions, most notably cook yield, in the quality parameters to the control. Further optimisation could be performed to address cook yield and protein solubilisation of the 100% replacement sample, as well as to attempt to produce a completely clean label brine, as carrageenan is not considered a clean label ingredient.
- ItemTemporal sensory liking methods: an investigation with beef steaks from different production systems(University College Cork, 2022) Corcoran, Linda; O'Sullivan, Maurice; Crofton, Emily; TeagascResearch on the impact of the diet of the animal on consumer liking of beef has yielded conflicting results. The aim of this study was to apply the traditional liking method and two temporal liking (TL) methods (free and structured) to determine consumer liking of beef derived from animals that were fed grain (GF), grass silage and grain (SG) or grazed grass (GG) during finishing and use different methods to determine the data quality and consumers variability. Three separate panels of regular beef-eating consumers (n=51; n=52; n=50) were recruited from students and staff at Teagasc Food Research Centre, Dublin, Ireland, to assess the liking of striploin steaks from animals fed either GF, SG, or GG, respectively. Results of chapter 2 revealed significant differences (p≤0.05) in liking between diets in terms of overall liking, juiciness, and tenderness using the free TL method. These effects were not observed using the structured TL or traditional liking methods. Further statistical analysis of the TL methods found that the free TL method yielded more discriminative data than the structured TL method, with significant differences (p≤0.05) found for both overall liking and juiciness. Consumers also found the free TL method easier to perform compared to the structured TL method. The evolution of scores over time (changes in consumer scores over the scoring period) was significant (p≤0.05) for all attributes using the free TL method. These results show that free TL may give rise to new opportunities to elicit more in-depth insight from consumer studies using meat. In addition to answering the research question, TL data also has the potential to give new insight into consumer behaviour in terms of how people approach temporal 8 sensory liking methods. Chapter 3 utilises this consumer behaviour approach to look at three temporal liking studies applying both structured and free TL in terms of data quality, presence or absence of temporality, and correlations between consumer response and self-reported difficulty. Interestingly, the assessment of temporality found that consumers who showed the ability to provide temporal data did not provide it for all attributes studied. The analyses have also demonstrated areas where fatigue and the natural variability in consumer responses may impact data quality. Chapter 4 further analyses data from study 2 from chapters 2 and 3 as this had no missing data. Studies 1 and 3 had missing data due to consumers not providing responses to all time points and attributes during sensory testing. Two TL methods (free and structured) and a traditional liking method were employed to generate data from consumers on their liking of beef steaks derived from a grain supplementation diet for four attributes (overall liking, flavour, tenderness, juiciness). Consumers spent the most time and gave the most responses to the attribute flavour. High levels of variability were found within each liking method. High correlations were also found between attributes within each liking method. For the structured TL, overall liking was found to be significant over time. In addition, the free TL and traditional liking were found to be significantly different from each other (p≤0.05) for liking and flavour attributes and the structured TL and traditional liking were found to be significantly different from each other for flavour. However, the two temporal liking methods did not differ from each other. Two clusters of consumers were found for each attribute, one who slightly liked the attribute and one who slightly disliked the attribute. Some consumers changed cluster groups between attributes. This study has shown that the choice of TL method may make a difference on the data elicited.