Food Waste and Catering Waste; Focus on Valorisation of Used Cooking Oil and Recovered Triglycerides - The Economic Utilisation of Food Co-Products - page 91

and quality control is a challenging task, inflected by technical, cultural and
regulatory issues. For instance, the threshold for quality control differs in
different countries. The EU stipulates a polar content below 25 wt.% and a
smoke point above 170 1C for oil to be usable for frying, when in the US the
limit is given by an FFA value below 2 wt.%. In other countries such as Japan,
Acid Value 2.5) and carbonyl value (50) is used to decide when UCO should be
discarded. There are as many types of recovered oils and fats as there are
processes where they are employed or recovered; therefore it is di cult to
propose a specific classification for these materials. 26 A number of rapid
analysis techniques (of viscosity primarily) have been proposed to evaluate
shelf-life in order to establish the quality of a product.
In addition, the shelf-life and period of use for the oil introduce further
variability to the quality of the remaining UCO, where the main driver for
regulators and industry is to deliver acceptable standards for the use of
vegetable oil in frying and food preparation. Generally, there is a direct rela-
tionship between the fatty acid profile, fatty-acid content and degree of
refinement with the potential for degradation of the oil. 27
The critical parameters to classify oils and fats according to its composition
are;

d n 9 r 3 n g | 0

d y y f n n 3 .

fatty acid profile;
free fatty acid content;
polar and eluteable content.

It is dicult to establish a general classification for UCO, frying oils and fats
solely on the basis of composition. It makes more sense to produce generic
specifications based on critical parameters such as viscosity, melting points and
oxidative stability, 28

in order to facilitate the utilisation of recovered fats and

oil as raw materials.

6.3.3 Analysis for UCO
The determination of specifications for UCOs and fats is important when
determining the end application.
Frying-oil specifications are completely aligned with the need to ensure food
quality when frying, 29 therefore any new processes or applications utilising
UCO and fats as a raw material will have to adapt to the variable quality of the
available material. The clearest example of this is the production of biodiesel,
where preprocessing (drying, deodorisation, esterification, etc.) and adequate
downstream processing (additivation, distillation, etc.) are required to deliver a
quality product.
Therefore the key driver to monitor quality and shelf-life of UCOs and fats
for both the food and biofuel industry are the following:

Moisture and impurities, generally determined by centrifuging aided by
titrimetric techniques such as volumetric Karl Fischer (moisture titration). 30