Journal of Food Processing & Technology

Abstract

Effects of Green Tea Extracts on the Caffeine, Tannin, Total Polyphenolic Contents and Organoleptic Properties of Milk Chocolate

Aroyeun SO and Jayeola CO

Chocolate and green tea contains antioxidants that may be used as health promoting foods. A new product incorporating green tea in Chocolate and termed green tea chocolate was developed in this project. Green tea was produced using the Chinese method viz: Plucking, Fixing, Rolling and Drying. The green tea produced was milled into powder and mixed at different ratios: 10:90, (GTCE) 20:80 (GTCD), 30:70 (GTCC), 40:60 (GTCB) and 50:50 (GTCA) (w/w) of the green tea powder to the Chocolate. Conventional milk chocolate (GTCF) without green tea served as the control for the production of chocolate followed by the standard method. Proximate Analysis, Total Phenol and antioxidant properties were determined using standard methods; Sensory Analysis was done by panel of tasters who measured the Taste, Odour, flavour and general acceptability. The average protein of the control chocolate was 8.05 which varied between 7, 24% (10% supplementation) and 8.39% (50% supplementation). The % crude fibre for the control chocolate was 1.17% and for other supplemented levels, it varied from 0.93% for 10% green tea addition to 1,23%. All the crude fibre increased significantly (p < 0.05) on increasing the green tea in the chocolate. It was found that at 10% inclusion of green tea, there were increases of 9.7%, 9.6%, 4.4% and 3.2% in crude fibre as compared to the control. This may be due to higher contents of dietary fibre in the green tea. The percentage total ash of the control was 2.43% and increased significantly and consistently from 2.28 at 10% level of inclusion to 2.55 at the 50% green tea supplementation. The chocolate containing the smallest quantity of green tea powder seemed to have the lowest amount of crude fat and rose steadily with increase in the green tea supplementation. Although at these levels the effect of the crude fat on the chocolate was not significant while the significance was observed only at 50% green tea inclusion. The control chocolate had 162.39 mg/100 g gallic acid equivalent and it increased significantly (p < 0.05) with rise in green tea powder in the recipe. This study also established that at the organoleptic threshold of 10%, green tea supplementation, there was no significant difference in the polyphenol content of the chocolate. It became significant at higher level of inclusion, i.e. 40-50% at which the taste of the chocolate and the overall acceptability and colour and sweetness became impaired. The caffeine content increased with increase in green tea powder in the chocolate. Green tea inclusion at 20%, 30%, 40% and 50% were showing significantly better chelating properties than the control samples and the 10% samples. The iron chelating ability increased with high contents of green tea and in the order 50% > 40% > 30% > 20% > control > 10%. The L* value reduced significantly from 10% to the 50% green tea powder. In conclusion, replacement of cocoa nibs with green tea powders up to 20-50% impaired the taste of the chocolate.