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Detection of selected fruit species in plant-based foodstuffs through instrumental analysis and methods of molecular biology
Ondruch, Petr ; Langová, Denisa (referee) ; Fialová, Lenka (advisor)
Food is often subject to adulteration, including fruit products containing strawberries. This work deals with the detection of strawberries in model and real fruit products, so that possible falsification can be detected. The aim of the work was the preparation of model and real fruit products, their analysis using selected instrumental and molecular-biological methods and mutual comparison of the results of these methods. Model mixtures of fruit products were prepared and commercial ones were purchased. The content of polyphenols and flavonoids was determined by UV-VIS spectrophotometry, which were characterized in more detail by HPLC. DNA was isolated from the fruit purees, suitable primers confirmed the amplifiability and formation of a specific product for strawberry, and this product was verified by electrophoretic control. In the instrumental part, certain substances were detected by extraction from model and commercial mixtures and the HPLC method, and the amount of selected substances was determined. The lowest amount of strawberry DNA that could be detected by selected primers in the PCR method was 0.7 ng /µl, in commercial mixtures this DNA could not be detected. In the HPLC method, the strawberry was detected in all samples by focusing on a particular fingerprint and the amount of pelargonidin-3-glucoside in the samples. The instrumental method can be considered more suitable in this case.
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Využití spektrofotometrických metod ke kontrole falšování potravin
Pytel, Roman
The theme od this dissertation is " Application of Spectrophotometric methods for inspection adulteration of food". In the theoretical part, there are stated chapters regarding adulteration of food (in general), adulteration of honey, quality requirements on honey, spectroscopy and its categories. The dissertaion is focused on spectrophotometric measurements of honey and sugar syrup samples where colour and consistence of honey was monitored. The techniques used for the analysis are NIR spectrophotometry and UV/VIS spectrophotometry. The results gained were statistically and graphically processed. It follows from the outcome that using FT-NIR for adulteration of honey detection is an appropriate method for honey inspection. The least effective method for proving adulteration of honey is the spectrophotometry specification of the colour of honey. Using this method, it is not possible to prove the links between colour of honey and colour of sugar syrup.
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