Impact of adsorbent Amberlite XAD-16 in reducing bitterness of Pummelo juice

Pummelo [Citrus grandis (L.)] Osbeck, is an important underutilized fruit crop grown mainly in the states of the North Eastern region of India. The juice of pummelo fruit is an excellent source of antioxidant and health-promoting compounds. However, it is not very popular among consumers due to its unbearable bitterness. This bitter taste is due the presence of bittering compounds (limonin and naringin) which gets extracted during juice extraction. It is the main reason for the poor organoleptic attributes and acceptability of pummelo juice among the consumers. It is also one of the limiting factors for commercial production and processing of pummelo based fruit juices. This investigation was therefore, aimed at reducing bitterness by reducing the concentration of bittering compounds (limonin and naringin) by using an adsorbent, Amberlite XAD-16, and optimization of the same in terms of quantity (mg/100 mL) and reaction time (seconds) for debittering purposes using response surface methodology (RSM). The impact of independent variables (quantity of adsorbent and reaction time) on dependent variables (quantity of limonin and naringin) and the extent of reduction in bitterness of pummelo juice were studied. Effects of quantity of adsorbent and reaction time were found to be significant (p < 0.05) for dependent variables. The Amberlite XAD-16 resin was found to be very effective in reducing limonin and naringin as it reduced limonin by 88% and naringin by 40% in the juice resulting in reduced bitterness in pummelo fruit juice.