Anthocyanins are group of polyphenols, responsible for the colours of yellow, orange, red, pink and blue of most of the flowers and fruits. The major drawback of their use and competitiveness ...compared to synthetic colorants is their colour instability, which may result in degradation of colour during processing and storage. The overall goal of the Ph. D. work was to develop a product, a natural colorant on anthocyanin base with adequate colour stability, which can be an alternative replacement for synthetic colorants in food and drug industry. Extraction of anthocyanins from grape marc, a by-product of the winery industry, was investigated considering their potential use as natural colorants. The optimal conventional extraction conditions were investigated with three different varieties of grape marc native to Slovenia. For comparison, experiments with a fresh (non-by-product) material -elder berry- were performed. The investigated operating parameters were: extraction solvent, solvent concentration and temperature. Influence of the pH value of the extraction media was investigated regarding the yield and degradation of anthocyanins. The stabilities of the obtained extracts during storage were compared. Supercritical fluid extraction (SFE) using carbon dioxide (CO2), was investigated for the pre-treatment of natural materials. Co-pigments influence the stability and colour of the anthocyanins. Therefore, the obtained extracts were analyzed on the content of some flavonoids. The second major part of the Ph.D. work focused on product formulation and stabilization of the anthocyanin extracts by using several high pressure techniques. Product formulation with SCF techniques, namely Concentrated Powder Form (CPFT), Particles from Gas Saturated Solution (PGSST) and Supercritical Antisolvent Precipitation (SAS) were carried out. Different anthocyanin-concentrates and carrier materials were tested. The products were analyzed for their colour properties (Lightness, Hue angle and Chroma values). The stability of the colour was monitored during prolonged storage.
Type of material - dissertation
; adult, serious
Publication and manufacture - Maribor : [T. Vatai], 2009
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