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Impact of different roasting conditions on antiradical and reductive activity of carob pods

Recent literature data clearly show that carob pod can be considered as a valuable food source of polyphenols and other antioxidants and that if included to diet in sufficient amounts, can provide beneficial health effects. Therefore, one possible approach to utilizing carob in creating novel foods or nutraceuticals is the formulation of carob pod extracts that could be used as the powerful natural antioxidants in the wide variety of food products. Although it is already known that roasting of carob pods significantly changes some of its nutritional and sensory characteristics, an impact of processing roasted carob powder using different time-temperature combinations on its in vitro antiradical and reductive capacity hasn´t been investigated to date. With the aim to optimize the roasting of carob in terms of achieving maximal antioxidant activity carob pods were roasted at 130 °C (5, 10, 15 30 and 45 min), 150 °C (5, 10, 15 and 30 min) and 165 °C (5, 10 and 15 min) and extracted using 60 minute reflux cooking with water. Results of analyzing obtained water extracts show that roasting process significantly influences antioxidant activity of processed carob powders. The increase of ABTS antiradical activity correlated well with the increase of temperature ; however prolonged duration of roasting at high temperatures led to decrease of measured antioxidant activity. The increase of reducing power of analyzed samples occurred only in the case of short roasting (5 or 10 min) at temperatures of 150 °C and 165 °C. Both, antiradical and reductive efficiency were the highest in carob powder roasted at 165°C for 5 minutes. Statistically significant correlations were observed between antiradical activity of obtained extracts and total phenolic content indicating that polyphenols can be considered as important carriers of antiradical activity of roasted carob pods (Figure 3). On the other hand, reductive capacity of roasted carob powders was significantly affected by roasting, independently on the changes of phenolic content, probably due to formation of certain compounds during roasting (such as certain classes of Maillard reaction products) that can be considered as principal carriers of reductive activity of roasted carob.

carob water extract; antiradical activity; reductive activity

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