Optimisation of quality and nutritional value of reformed/restructured meat products for older adults developed using plant proteins

Literature has shown that the emerging ageing population are seeking healthy foods and ingredients that confer nutritional benefits and may prolong an active, healthy and independent quality of life. The aim of this thesis was to determine the physicochemical, nutritional and structural parameters and potential uses of plant-derived ingredients [pea protein isolate (PPI), rice protein (RP) and lentil flour (LF)] in a meat model using underutilised beef cuts. The meat model could then be extrapolated to a meat product such as beef patties and restructured beef products. The physicochemical properties of the inclusion of plant-derived ingredients in a beef pattie model were initially examined. Plant-derived ingredients are a nutritionally-dense source of amino acids and protein, as well as a source of vitamins and minerals. The inclusion of RP increased the protein content and improved cooking yields and reduced oxidative rancidity in beef patties. Acceptable textural parameters were observed with LF inclusion. The best performing ingredients (RP & LF) were used in the beef pattie formulation using a mixture design approach. An optimised formulation was predicted consisting of; (LF; 6.22% and 6.05%) and (RP; 3.63% and 3.95%). An optimised beef pattie formulation with enhanced protein and acceptable textural parameters was produced. Sensory analysis scores showed significant differences between optimised formulations for beef aroma and tenderness. The learnings from this study was then applied to develop a novel meat product using the same raw meat material and a novel processing technique. A novel restructured beef steak using transglutaminase enzyme [ActivaEB (TG) and TrangluseenTM-M (TS)] and phosphate (with/without) was developed using the Pi-Vac technology. The chemical and physical characteristics were investigated. Restructured beef steaks subjected to 18h chilling had a similar texture and colour attributes to the control. Cooking losses varied depending on phosphate inclusion. A good bind was achieved with TG, without the addition of phosphate. A follow on study examined the addition of PPI, RP and LF at 4% and 8%, phosphate at 0.2% and TG (1%) and TS (0.15%). When RP was added at 8%, protein content and hardness values increased. Cooking loss decreased with the addition of PPI, RP and LF. Inclusion of PPITG at 8% increased binding strength in comparison to the control. LF addition was positively associated with a tender restructured beef steak. The effect of TG on plant and meat protein was evaluated using in vitro digestion. Micrographs after intestinal digestion illustrated fragmentation of fibres and re-aggregation of protein molecules across all samples. Most soluble peptides had a molecular weight of < 500 Da, corresponding to peptides of less than 5 amino acids, regardless of food treatment. The combination of PPI, RP and LF was studied as potential ingredients using a response surface design to develop an optimised restructured beef steak. Simultaneously, PPI, RP and LF significantly increased protein content. The inclusion of RP had an adverse effect on moisture levels and cooking losses at levels greater than 7.5%. Using the optimisation tool, the optimised and validated formulation consisted of: 2% TG, 8% PPI, 9.35% RP and 4% LF. A consumer study of adults aged 65+ scored the optimised restructured beef steaks products with added plant proteins and seasoning less favourably than the control samples. The outcomes of this work in conjunction with the literature reviewed favours the conclusion that plant-based ingredients can be utilised without TG to improve technological and nutritional characteristics of novel meat products. The novel meat products could help fulfil the dietary protein requirements for older adults, thus reducing their risk of sarcopenia as well as other age-related conditions such as osteoporosis and cognitive impairments