Abstract
Consumption of apple (poly)phenols has been linked to protection from chronic diseases such as cancer, diabetes, cognitive decline and cardiovascular disease. The overall aim of this thesis was to establish and compare the (poly)phenol and ascorbic acid content, and antioxidant capacity of the Armagh Bramley, heritage apples and selected processed Armagh Bramley products, against a range of other apples and their products, available in Northern Ireland. Pomace (waste) from processing was also assessed as a source of bioactives.In 74 apple cultivars grown in/or imported to Northern Ireland (NI), the (poly)phenolic content ranged from 5.16 to 33.2 g kg-1 DW, with ascorbic acid from 0.03 to 1.4 g kg-1 DW. Lower bioactive content was observed in the imported dessert apples group compared to that of locally grown dessert, cider, culinary, and Irish heritage apples. Many old Irish cultivars contained a high bioactive content, with the Bramley’s Seedling cultivar containing the highest bioactive content of those currently available to consumers. When comparing the effect of different horticultural practices such as rootstock, orchard design and planting density on bioactive content, the Armagh Bramley was found to be a consistent product, however the highest values for cyanidin 3-galactoside and some flavonols were observed in southern facing apples. (Poly)phenolic content of apples grown on 5 and 60-year-old trees decreased throughout the growing season and remained consistent between harvest and after commercial storage (10 months).
Effects of processing on the Armagh Bramley apple were investigated in artisan, industrial and newly developed products, with the highest bioactive content retained in ‘screw cooked’ industrial products. Ascorbic acid was the most negatively affected bioactive on processing. (Poly)phenol content remaining in the pomace post-production was significant with potential for use in value-added co-products. High pressure processing (HPP) preserved more (poly)phenols than traditional pasteurisation in two products. Moreover, incremental sugar replacement with erythritol by up to 75% was possible without affecting sensory attributes.
An increase in consumption of health promoting bioactives could be achieved through apples and reduced-sugar apple products, which contain higher bioactive content than is currently available to consumers. Taken together with the value-added ‘waste’ pomace identified, results from this thesis will contribute to the sustainable growth of the NI apple industry.
Thesis is embargoed until 30 June 2027.
| Date of Award | Jun 2025 |
|---|---|
| Original language | English |
| Sponsors | Agri-Food & Biosciences Institute |
| Supervisor | Chris Gill (Supervisor) & Kirsty Pourshahidi (Supervisor) |
Keywords
- Armagh Bramley
- apple
- Irish heritage
- (poly)phenols
- ascorbic acid
- antioxidant
- processing
- novel processing
- high pressure pasteurisation
- sensory
- consumer acceptability