Vitamins form a heterogeneous chemical group having different stability. In foodstuffs some of them might be bound to matrix components. In the case of vitamin supplemented food products, since the vitamins are not strongly embedded in the matrix a general extraction method could be fit for purpose. The aim of this study was the simultaneous determination of the most common water-soluble vitamins, i.e. ascorbic acid (C), riboflavin (B ₂), niacin (B ₃), pyridoxine (B ₆), folic acid (B ₉) in enriched food products. Sample preparation based on the European Standard (CEN, 2003) was optimised for further LC-MS compatible chromatography. The separation of the vitamins was achieved by reversed-phase liquid chromatography. Detection was carried out with a photodiode array detector at four different wavelengths. The chromatographic method and the sample preparation were successfully applied for vitamin-enriched cereal, instant cacao powder and fruit juice samples.

Water is a major component of drinking water, beverages, and most foodstuffs. In this study, an effort has been made to employ selected properties of water for: (1) evaluation of interactions of water with other food components; (2) discussion on the effects of water properties on food and beverage products; (3) applications of water properties in food technology; and (4) comparison of water properties with corresponding properties of similar substances. This study provides the following major conclusions: (i) unusual properties of water are mostly due to its high permanent dipole moment, partial ionic character of O–H covalent bonds, and extensive hydrogen bonds; (ii) different properties of many foodstuffs are strongly related to various properties of water; (iii) the properties of food products change depending on water availability and temperature; (iv) preparation of drinking water is a prerequisite for production of any safe drinks and foodstuffs; (v) water contributes important roles in quality, flavor, and shelf-life of foods; and (vi) water is used in food industries as a fluid for heat transfer; as a medium for temperature moderation in food processing; as a solvent for sugars, salts, water-soluble vitamins, and acids; as a dispersing agent for hydrophilic food components; as a dispersed phase for emulsified products; or as a reactant for several reactions in food processing.

The expanding demands of consumers requires food quality control to be improved all the time. Higher concentration of biogenic amines can lead to food toxicity, for example they can cause migraine headaches in people who consume products rich of serotonin or tyramine. Methylxanthines (caffeine and metabolites) can also have side effects to human comfort – high doses can lead to unrest, irritation or insomnia. Most vitamins are supplied to humans only as a part of food meals or dietary supplements. Knowledge about their concentration in food can be useful for composing various diets. In this work specification of complete sample preparation parameters for extraction of the compounds from food matrices has been reviewed. Particular attention was given to the preparation stage as well as to extraction methods that have been used. The second part of the work presents data from chromatographic methods for determination and separation of selected biogenic amines, methylxanthines and water-soluble vitamins in food. Stationary and mobile phases, detection methods as well as validation data have been reviewed. This publication is a comprehensive compendium of analytical procedures for food analyses of the previously mentioned compounds.