Development of an instant tea product from pomelo peel and herbs

Abstract

Peel of pomelo (Citrus grandis (L.) Osbeck) is considered to have a variety of health benefits and commonly used in aromatherapy, pharmaceutical and food industries. Peels, seeds, and pulp usually produced as the primary by-products in the processing industries account for approximately 50% of the whole fruit mass. The project’s content in particular was (1) to evaluate the treatment of pomelo peel (including freezing/ thawing and roasting for improvement the tea infusion); (2) to preliminarily develop a recipe of an instant tea from pomelo peel and other ingredients such as licorice, sweet leaf, reishi mushroom, and mint that suited the sensory acceptability and quality evaluation. In this study, the improvement of tea infusion was based on comparing the effects of the time of slow-freeze condition (1, 2, 3, and 7 days), the time of roasting (5, 7.5, 10, 12.5, 15 minutes at 100°C), and their combination. The extraction of polyphenols, naringin, and antioxidation capacity was determined to find the best treatment. After that, the recipe of the tea was preliminarily development. Sensory evaluation of the product based on ranking test and TCVN 7975:2008. According to the results, the best treatment of pomelo peel to improve the tea infusion was the combination of 1 day slow-freezing and roasting at 100oC in 7.5 minutes with the TPC content and naringin content were 4.726 ± 0.046 mg GAE/g DW and 1.792 ± 0.022 mg NE/g DW, in particular. The recipe that suited the sensory acceptability was containing 50% pomelo peel, 15% licorice, 15% sweet leaf, 10% reishi mushroom, 10% mint. The point of final product was 14.41, corresponding to fair evaluation, with the TPC content, naringin content, antioxidant capacity were 8.156 ± 0.192 mg GAE/g DW, 0.822 ± 0.085 mg NE/g DW, and 4.620 ± 0.016 mg AAE/g DW, in particular. Practically, this study had potential to develop new instant tea product using pomelo peel as the main ingredient. Keywords: Pomelo (Citrus grandis (L.) Osbeck) peel, polyphenols, naringin, antioxidant capacity, instant tea.