Block freeze concentration assisted by centrifugation applied to blueberry and pineapple juices

Retention of Ascorbic Acid and Solid Concentration via Centrifugal Freeze Concentration of Orange Juice

“…A progressive increase in the percentage of concentrate was observed after the concentration cycles for orange juice and reached 60%, which was close to the values reported in the literature [21,32]. This work of the percentage of concentrate is similar to the value (approximately 50%) reported by Bonilla-Zavaleta et al [16] for centrifugal assisted cryoconcentrated pineapple juice and is similar to the general 50% concentrate obtained by block freeze concentration [15].…”

“…During the third cycle, the efficiency decreased, and the solids content in the ice augmented to 12 ∘ Brix. These results were better than those obtained previously in our laboratory [21], where the solids concentration increase of 2.5 and 2.7 times was obtained after the third freeze concentration cycle of blueberry and pineapple juices, respectively. This difference can be explained because, in the present study, differently sized tubes were used (45 ml versus 12 ml), which could provoke some stratification or movement of the solids in the freezing step that favors later separation.…”

“…The evolution of the concentrations along the freeze concentration cycles from orange juice was comparable to performance reported when using block cryoconcentration for maple sap [13], whey milk [30], cherry and apricot juices [14], blueberry and pineapple juices [21], and, recently, strawberry juice [23].…”

“…Freezing and centrifugation were carried out by the method of Petzold et al [21], with minor modifications. Orange juice (45 ml) in centrifugal tubes (internal diameter = 22 mm) was frozen in a static freezer at −20 ∘ C for 12 h. The external surfaces of the tubes were covered with foamed polystyrene (8 mm, thermal conductivity = 0.035 W m −1 K −1 ) so that the heat transfer during freezing occurred primarily in a unidirectional manner.…”

“…Thus, centrifugation was used by Bonilla-Zavaleta et al [16] for the concentration of frozen pineapple juice, whereas Luo et al [17] used this technique to desalinate water. Virgen-Ortíz et al [18,19] used this assisted technique to cryoconcentrate protein solutions, Petzold and Aguilera [20] presented a centrifugal cryoconcentration method using a sugar solution, and Petzold et al [21] proposed the application of this assisted technique to blueberry and pineapple juices.…”