ABSTRACT
Epidemiological studies have established a relation between vegetable consumption and better health (Steinmetz and Potter 1996, Lampe 1999). Since World War II, the demand for food presenting additional properties to their traditional nourishment has increased. This type of food is called functional food. To satisfy these societal demands, it is necessary to ‚nd new natural sources of ingredients that offer health bene‚t in addition to their nutritive value. For instance, the cyanobacterium Spirulina, consumed since the times of pre-Columbian America (Paniagua-Michel et al. 1993; for centuries around Lake Tchad in Africa; Tremblin G, pers. comm.), is now seen as a functional food due to its antioxidant, antimicrobial, and fatty content (Eriksen 2008, Benedetti et al. 2010). Among the long list of bioactive compounds taken up from a diet rich in plant products, tetrapyrroles have been traditionally overlooked despite being present in high amounts compared to other phytochemicals. The tetrapyrrole family of compounds can be divided into two subfamilies: (i) the closed tetrapyrroles such as chlorophylls (Chl) and (ii) the open-chain tetrapyrroles such as phycobilins (Figure 30.1). Chl molecules are probably the most ubiquitous tetrapyrroles. Many tetrapyrroles are colored, making the environment attractive and, therefore, constituting an appealing force for the consumers because color modi‚cations are often associated with inferior quality. Besides their natural presence in photosynthetic organisms, tetrapyrroles are extracted and used as natural colorants (Roman et al. 2002, Soni et al. 2006, Prasanna et al. 2007) and/or antioxidants to restore the natural level of these molecules in food products and food supplements (Benedetti et al. 2010) or to prepare forti‚ed and functional products (Ayadi et al. 2009). According to the European regulation, Chl and their direct derivatives are designated as E140, E140i, and E140ii, the latter two designating liposoluble Chl derivatives and hydrosoluble chlorophyllins (Na+- or K+-chlorophyllins), respectively. These molecules could be chemically modi‚ed, for example, by replacement of Mg2+ with Cu2+, and are designated as E141, E141i (Cu-Chl), and E141ii (Cu-chlorophyllins) (Anonymous 2 1994). According to the local legislation, the use of these compounds can be restricted or completely prohibited. For instance, the Food and Drug Administration (FDA) restricted the use of E141 compounds to citrus-based dry beverage mixes and in concentrations never exceeding 2%.
