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QUALITY PARAMETERS OF LYOPHILIZED CAROB POD EXTRACTS AS A FUNCTION OF DIFFERENT PRE- TREATMENT APPROACHES

Due to the safety and toxicity related to different types of synthetic antioxidants, there is an increasing interest in developing potent but safe natural based antioxidant preparations. Carob seems to be a promising raw material for the purpose, mainly because of its low cost and high content of polyphenolic compounds. Therefore, in the frameworks of this study we investigated the impact of different pre-treatment approaches on the quality parameters of lyophilized carob pod extract to be validated as a natural antioxidant. Native carob flour (NC), carob flour roasted at 165 °C for 5 minutes (RC), sugar free carob flour (SFC) and roasted sugar free carob flour (RSFC) were used as starting materials for the preparation of carob water extracts that were subsequently lyophilized. The following four extracts were prepared from the same starting materials but with the addition of β- cyclodextrin (NCβ, RCβ, SFCβ and RSFCβ respectively). Obtained extracts were than analyzed in terms of total phenolic and total flavonoid content, different types of in vitro antioxidant activity (ABTS and ORAC antiradical activity) and stability, which was assessed by thermogravimetric analysis (TGA). Lyophilized carob pod extracts contained significant amounts of polyphenols and were characterized with significant antiradical efficiency. Addition of β-cyclodextrin during extraction significantly increased total polyphenolic yields (3.1-12.3%). Significant impact of β-cyclodextrin on flavonoid yields, ABTS- and ORAC antioxidant activity was observed only in sugar free extracts (in SFC 8.6 %, 3.1% and 35.5% respectively ; in SFCβ 25, 9 %, 26.9% and 18.9% respectively). Roasting significantly increased phenolic content (15.0- 51.8%), flavonoid content (41.4-81.6%) and ABTS antiradical activity (27.7-62.3%) in all analyzed samples while significant positive effects on ORAC antioxidant activity were only noticed in sugar free extracts. By comparing the TGA curves of lyophilised carob extracts, it might be concluded that removal of the native sugars prior to extraction significantly improved thermal stability, and the effect was further improved by the addition of β- cyclodextrin. This showed that removal of natural sugars and the use of a suitable carrier molecule would gain in samples with superior thermal stability. Carob pods can be used for the development of natural extracts with high antioxidant activity. Roasting and removal of native sugars prior to extraction as well as the use of β- cyclodextrin during the extraction can significantly improve quality and stability of the final product. Future investigations should be focused on the testing of obtained extracts in different food- and biological model systems.

antioxidant; β-cyclodextrin; carob; roasting; thermogravimetric analysis

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