Vsebnosti hidrofilnih vitaminov v izbranih živilih in prehranskih dopolnilih - Veber, Katja (2020)
Živila so na Evropskem trgu regulirana, a veliko manj strogo kot zdravila, zato se pristnost sestave izdelkov redno ne preverja. V magistrski nalogi smo preverjali dejansko vsebnost hidrofilnih vitaminov (vitamin C in B kompleks) v živilih in prehranskih dopolnilih. Ugotavljali smo, v kolikšni meri živila sploh vsebujejo, kar je navedeno in odstopanja od navedb na ovojnini izdelkov. V ta namen smo uporabili predhodno razvito metodo UHPLC z detektorjem DAD. Metodo smo najprej validirali v skladu s smernico ICH za potrditev, da služi svojemu namenu. V nadaljevanju smo razvili in optimizirali postopek priprave vzorcev iz živil in prehranskih dopolnil v različnih oblikah. Analizirali smo naslednje skupine vzorcev: vode z dodanimi vitamini, energijske pijače, šumeče tablete, sokove, instantne napitke in bonbone. Priprava vzorcev je bila odvisna od kompleksnosti posameznega vzorca. Po optimizaciji postopka za ekstrakcijo smo metodo uporabili za vrednotenje kakovosti 36 različnih prehranskih izdelkov z vidika vsebnosti dodanih hidrofilnih vitaminov. Ugotovili smo dejansko vsebnost vitaminov v izdelkih, jo primerjali z navedeno vsebnostjo in ugotavljali odstotek ujemanja. Vitamina B7 in B12 sta bila izdelkom dodana v nizkih (μg) količinah, zato njune vsebnosti pogosto nismo uspeli kvantitativno ovrednotiti. Zaradi ohlapnejših regulatornih zahtev za živila smo med navedeno in ugotovljeno vsebnostjo vitaminov zaznali večja nihanja. Proizvajalci so v izdelke večinoma dodali več vitaminov kot jih navajajo. To je verjetno zaradi nestabilnost nekaterih vitaminov med izdelavo in shranjevanjem z namenom zagotavljanja vsebnosti blizu navedene znotraj roka uporabnosti izdelka. Ugotovljene vsebnosti vitaminov so najpogosteje presegale navedeno vsebnost za 15-35%. V določenih primerih smo zaznali tudi odstopanja v obratno smer, ugotovljena je bila nižja količina vitaminov kot je navedeno (vitamin C v 78% izdelkov) oz. navedenih vitaminov sploh nismo zaznali (vitamin B6 v dveh izdelkih). V splošnem je bilo manj odstopanj pri tekočih kot pri trdnih izdelkih. Pri prehranskih dopolnilih smo potrdili manj odstopanj od tolerančnih mej kot pri živilih. Z izjemo nekaterih prehranskih dopolnil proizvajalci večinoma niso jasno navajali katera oblika vitaminov je v izdelku. Rezultati magistrske naloge so uporabni za potrošnike, ki sami ne morejo preveriti sestave in kakovosti izdelkov in so dobra podlaga za nadaljnje raziskave. Foods sold on the European market are regulated, but much less strictly than medicines, which is why the authenticity of the products composition is not regularly controlled. We investigated the actual content of hydrophilic vitamins (vitamin C and B complex) in foods and food supplements. We determined whether the tested products contain the vitamins stated, in which concentrations and how obtained results correlate with the label claims. For this purpose, we used a previously developed UHPLC method with DAD detection. The method was initially validated according to the ICH guideline to confirm its suitability for the proposed use. Hereinafter, we developed and optimized sample preparation procedure for vitamins extraction from food and food supplements in various forms. We analysed different groups of samples: waters with added vitamins, energy drinks, effervescent tablets, juices, powdered drink mixes, and candies. The sample preparation procedure was adjusted to the composition and complexity of each sample. The developed analytical procedure was used to evaluate the quality of 36 different commercial products containing hydrophilic vitamins. We determined the actual vitamins contents and compared it with the contents indicated on the packaging. Vitamins B7 and B12 are added to the products in very low (μg) amounts, so their concentrations were often not quantitatively determined. Due to less strict regulations for foods, significant variations between the declared and the contents of determined vitamins were observed. In general, vitamin contents were higher than declared. This is mostly associated with instability of vitamins during production and storage. Therefore, manufacturers usually add overages in order to ensure proper vitamin contents at the expiration life. The found vitamins overages were mostly 15-35%. On the other hand, some vitamins were determined in lower amounts than stated, e.g. vitamin C in the majority of the tested products (78%) or were labelled but not detected (vitamin B6 in two products). In general, fewer deviations from the label claims were observed among liquid than solid products. Content tolerance limits were more frequently exceeded in foods. Except for some food supplements, manufacturers rarely specified the added vitamin form. The obtained results of the analysis are useful for consumers, who cannot check the composition and quality of products themselves, and are a good basis for further research.