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CONVERSION OF ENVIRONMENTALLY-UNFRIENDLY ONION WASTE INTO FOOD INGREDIENTS

Objective

The objectives of the project are :
- to reduce the environmental impact of onion waste disposal by converting
waste streams into useful products resulting in low-wastood production;
- to optimise existing, and to develop new food processes for extracting and
tailoring onion flavours; adapt for extraction from waste;
- to develop combination processes for the extraction and modification of
fructo-oligosaccharides, gelling pectins and dietary fibre (DF) from onion waste;
- to exploit the unique properties of onion parenchyma for producing fibre
supplements suitable for texturally-sensitive foods.

Over 450,000 tonnes of onion waste are produced annually in Europe mainly from onion processing industries in the UK, Holland, Spain, Italy. The waste makes poor fodder. Disposal commonly involves landfill (cost of 5-40 ECU per tonne) which is not suitable , environmentally, due to the rapid growth of phytopathogens e.g. Sclerotium cepivorum (white rot). Hence, there is considerable industrial and political pressure to convert the waste into useful products. This project will bring together European partners from the Food industry (SME's), Research Institutes and Universities to develop means for exploiting onion waste for the extraction of high quality, and commercially valuable onion oil, fructoligosaccharides (FOS), gelling pectins and low-lignin-dietary fibre for se in texturally sensitive foods.

Onion waste will be provided by partner 4 and 6 (SME's) and fractionated by partner 2. Onion flavour compounds, for which there is a considerable market, will be enhanced by tailoring the biochemistry of flavour release (P1) and extracted by steam distillation (P6) and supercritical CO2 (P2) (so far untried on onions). It is estimated that oil extraction will give a minimum value of 30 ECU/ton waste P6. In addition to containing significant quantities of fructo-oligosaccharides, the flavour-free residue will comprise mainly cell wall material. Unusually for fruit and vegetables, this will be almost devoid of lignin and phenolics making it ideal for the production of a range of dietary fibre supplements suitable for use in fibre-poor, texturally-sensitive foods including dairy products (SME sub-contractor S1), drinks, sauces and desserts (P5). There is a lack of commercially available DF for such products (S1). Such supplementation will help to enhance ingestion of functionally-important DF throughout the EU. Modification of the crude fibre will involve physico-chemical (e.g. extrusion (P1)) and biochemical treatments (P2, S2), individually and in combination processes. Process development will rely on feedback of rheological behaviour of the product in food (P5) and physicochemical properties of DF (P3). Additional gelling pectins will be extracted from onion skins (further 70 ECU per ton waste (P1)). Profitability from onion waste will support agriculture and the food industry in the EU.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

BBSRC Institute of Food Research
Address
Norwich Research Park Colney Lane
NR4 7UA Norwich
United Kingdom

Participants (5)

ATO - DLO - AGROTECHNOLOGICAL RESEARCH INSTITUTE
Netherlands
Address
Bornsesteeg, 59 - P.o. Box 17
6700 AA Wageningen
British Onion Producers Association Ltd
United Kingdom
Address
133 Eastgate
LN11 9QG Louth
HERBSTREITH & FOX KG, PEKTIN-FABRIK NEUENBÜRG
Germany
Address
Turnstraße, 37
75305 Neuenbürg
TRIUMFUS ONION PRODUCT FLAVOURS B.V.
Netherlands
Address
Korenhalmdijk, 17 - P.o. Box 1
4430 AA 'S-gravenpolder
UNIVERSIDAD AUTONOMA DE MADRID
Spain
Address
Ciudad Universitaria - Cantoblanco
28049 Madrid