Effect of High Hydrostatic Pressure on the Content of Phytochemical Compounds and Antioxidant Activity of Prickly Pears (Opuntia ficus-indica) Beverages

Prickly pear beverages prepared with 10 % peel and 90 % pulp (Cristal and Rojo San Martin varieties) either with (A) or without (N) the incorporation of acids and antimicrobials (0.3 g sodium benzoate, 0.15 g sodium sorbate, 1.4 g fumaric acid, 0.4 g tartaric acid and 0.3 g sodium citrate per liter of beverage) were treated with high hydrostatic pressure (HHP, 400 or 550 MPa, room temperature, 0-16 min), or heat sterilization (131 A degrees C/2 s). The effect of these treatments on the content of vitamin C, total phenolic (TP), flavonoids and betalains, as well as the antioxidant activity (AOX) was evaluated. Prickly pear beverages prepared from Cristal (A) and Rojo San Martin (A and N) varieties processed at 550 MPa/t a parts per thousand yen 2 min showed significant increase (p < 0.05) in TP (16-35 %) and AOX (8-17 %), no significant changes in kaempferol and isorhamnetin contents, and 3-15 % losses of vitamin C. Beverages formulated from the Rojo San Martin variety (A) treated at 550 MPa/t a parts per thousand yen 2 min showed significant increase in betaxanthins (6-8 %) and betacyanin (4-7 %). On the other hand, heat sterilization caused significant losses (p < 0.05) of vitamin C (46-76 %), TP (27-52 %), flavonoids (0-52 %), betalains (7-45 %) and AOX (16-45 %). These results show that HHP treatments retains, and can even increase, the content of most phytochemical compounds of prickly pear beverages when compared to untreated samples, thus yielding products with higher nutraceutical quality than fresh or heat treated beverages.