Bioactive compounds in Fruits & Vegetables
Antioxidants in fruits, vegetables and their products
Consumer demand for ready-to-use convenience foods has led to dramatic changes in the marketing of fruits, vegetables and their products. Minimal processing unit operations such as slicing and peeling as well full processing such as canning and high pressure processing place extra stress on in-product antioxidants and significant losses may occur. This FIRM project is operated in conjunction with the University of Limerick and will compare retention levels of antioxidants in fresh unprocessed fruits and vegetables with retention in fully processed products with the aim of providing integrated processing/packaging solutions to minimize losses. Preliminary results indicate that slicing results in a reduction in the antioxidant potential of berry fruits. In a short-term storage trial (3 days) neither storage time nor temperature (3 vs 8°C) adversely affected the antioxidant potential of berry fruits with increases occurring in some cases. Results also indicated that Golden Delicious apples are a relatively poor source of antioxidants with methanolic extracts of freeze dried samples having a lower antioxidant potential than berry fruits. No anthocyanins were detected in the apples. (nigel.brunton@teagasc.ie)
Polyacetylenes in minmally processed vegetables
Vegetables are increasingly being marketed as pre-prepared minmally processed convenience products with an extended shelf life. Peeling, cutting and other unit processes involved in producing minimally processed vegetables bring together oxidative enzymes and their substrates, which had previously been separated by sub-cellular partitioning. This practice can lead to extra stress on in-product bio-active compounds and significant losses may occur. The phytochemical molecule falcarinol (a polyacetylene) is a potent anti-tumour agent and occurs in some vegetables including carrots, parsnips and lettuce. Recent work indicated that the compound may have a more significant contribution towards the anti-cancer properties of carrots than well known contributors such as β-carotene. Despite this, little is known regarding the stability of falcarinol during storage or following unit operations such as slicing, dicing and cubing. The aim of this project is to assess the effect of minimal processing on the retention of falcarinol in a selection of vegetables currently on retail sale in minimally processed forms in cold cabinets. A HPLC-based procedure for the determination of falcarinol in hexane extracts of freeze dried carrots has been developed. Results indicate that short-term storage of carrots sticks results in a small decrease (~9%) in falcarinol content. (nigel.brunton@teagasc.ie)
Bioactives in apples and other tree fruits
This project is a component of a major EU Integrated Project (ISAFRUIT) (www.isafruit.eu) with the overall theme ‘healthy fruit for a healthy Europe’ and is in start-up phase. Activites have already been listed above under the sub-heading ‘Novel fruit products with emphasis on apples’. A major component of this project at AFRC is measuring the total antioxidant capacity of the fresh fruits but also of their minimally and fully processed counterparts. A range of bioactive agents will also be introduced into fresh fruit slices and also into processed fruit products thus making them potential functional foods. (ronan.gormley@teagasc.ie)
