[6-1015-A] Functional/Wellness Foods & Nutrition (2)

[6-1015-A-05] Stability of Plant Pigments and Antioxidant Activities in Juice Model during Processing and in vitro Gastrointestinal Digestion

*Titikan Liangpanth¹, Rungarun Sasanatayart¹ (1. School of Agro-Industry, Mae Fah Luang University(Thailand))

Keywords:Anthocyanins , Carotenoids , Betalains, Chlorophylls, in vitro gastrointestinal digestion, Antioxidant

Due to the changing perceptions of consumers to consume natural products, there is an increasing interest in the use of natural antioxidant pigments as substitutes for synthetic food colorants. Plant pigments exert antioxidant activities, providing health benefits. However, there are challenges related to color losses during food processing, storage, and commercialization due to a low stability of natural pigments compared to synthetic colorants. In this study, four pigment powders extracted from selected plant parts including butterfly pea flower rich in anthocyanins (TAC), dragon fruit peel containing betalains (TBC), turmeric rhizome containing curcuminoids (TCC) and pandan leaves rich in chlorophylls (TCPC) were compared. To examine the stability through processing, juice model samples containing 10% (w/v) glucose, 0.1M citric acid and coloring with 1.0-3.0% (w/v) color powder were prepared. The samples were adjusted to pH 3 and 7 and subjected to three different heat treatments including (1) No heat (control), pasteurization (75°C for 15 min) and sterilization (121°C for 15 min). All samples were measured for color parameters (L*, a*, b*, hue and ΔE) whilst, antioxidant properties were measured in terms of total phenol content (TPC) and antioxidant activities based on FRAP and DPPH assays. Results showed that pH and heat treatments played a critical role on stability of pigment compounds, resulting in change in visual color and color parameters which could limit food uses. Overall, pasteurization of juice model samples rich in plant pigments at both pH 3 and 7 was better than sterilization in retaining initial color and maximize level of bioactive compounds and related antioxidant properties. To assess stability and bioaccessibility of antioxidant properties during simulated in-vitro gastrointestinal digestion, all pasteurized juice model solutions at pH 3 were compared. During digestion, all juice model solutions showed different stability of pigments compound, TPC and antioxidant activities based on FRAP and DPPH. Overall, trends observed were the increased stability of bioactive compounds and their related antioxidant activities from oral phase (G0) to gastric phase (G30) but subsequently decreased stability along intestinal phase (I0-I120). All pigment compounds, TAC, TBC, TCC and TCPC showed the less correlation with antioxidant activities based on FRAP and DPPH than did TPC. Results suggested that the concentration of pigment compounds and the antioxidant capacity before digestion might not reflect the after digested concentration. Data of this study provided relevant information on antioxidants reflecting stability and activity during digestion which supports the potential use of plant pigments in natural foods and beverages.