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Jan 29, 2020 Publication

Metrology: Glaze measurement method for frozen broccoli - Technical Report


PROFEL completed 5 years of research work by carrying out a series of trials at Nouvelles Vagues, Boulogne-Sur-Mer, with their French professional partner CTCPA. These trials, funded by PROFEL members, were carried out during August, 2019 with a WELMEC presence to both view and constructively comment upon the methods being employed. The previous work had culminated in two methodologies for deglazing broccoli being considered, and these latest trials compared the two methodologies, namely the PROFEL M1 Method employing an immersion time of 60 secs in water at 27C, and the Modified New WELMEC M4 Method employing an immersion time of 180 secs in water at 37C.

The overall objective for all parties was to establish a robust, accurate and reproducible methodology whilst removing any subjective elements that could obviously be interpreted differently by each processing site / country.

These two methodologies were used to deglaze broccoli florets that had been hand glazed in the laboratory in order to determine which method gave the most accurate measurement of the known weight of glaze that had been applied. Several sources of broccoli florets were used as it was recognised that origin and sizing could have an effect on the results.

Full details of this work, including tabulated results, graphs and photographs can be found in the accompanying Technical Report.

The conclusion from this work is that the Modified New WELMEC M4 Method is more likely to measure a correct glazing rate in ‘blind’ samples, where the glazing level is not known, as will be the case in official controls employing the methodology.

However, a note of caution has to be considered when interpreting the results of any enforcement action. A correction factor has to be applied to take account of both the amount of water consistently found to be retained within unglazed broccoli florets, and the measurement uncertainty factor inherent when following the determination protocol. It also has to be recognised that broccoli is a natural product such that any testing will have an inherent variability due to parameters including, maturity, origin, variety, climatic growth conditions, processing conditions, size and density that will influence both the freezing and glazing characteristics of the florets. The overall measurement uncertainty of deglazed broccoli has proved to be larger than the permitted allowance found within the e-marking Directive, so in order not to unfairly penalise processors it should be considered that for any determination the first 5% should be set aside and not regarded as glaze. For example, if a glazing level of 8% absolute is determined then the reported glaze level is 8-5 = 3% added glaze.

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