Influence of block freeze concentration and evaporation on physicochemical properties, bioactive compounds and antioxidant activity in blueberry juice

Abstract

This study investigated the impacts of centrifugal block freeze concentration (CBFC) and evaporation processes on physicochemical properties, bioactive compounds and antioxidant activity applied to fresh blueberry juice. After three concentration cycles, the solutes were approximately 3.6 times to the initial condition (12 °Brix) and the final color (ΔE*>4.7) was darker than the fresh juice. In all cycles, CBFC obtained higher bioactive compound concentration than evaporation, with values, in the last cycle, close to 610 mg GAE/100 mL, 57 mg M3G/100 mL and 279 mg CEQ/100 mL for total polyphenol, anthocyanin and flavonoid content, respectively, causing a retention over 70%. Similarly, as the cycles progressed, DPPH assay presented values from 1916 to 5700 μmol Trolox equivalents/L, which were higher than those reported by the treatment at high temperatures (1916 to 4600 μmol Trolox equivalents/L), resulting in good antioxidant activity in the cryoconcentrates achieved at low temperatures. Moreover, a significant correlations between CIELab parameters, bioactive compounds and antioxidant activity were observed. Thus, CBFC is an interesting and novel technique to preserve important quality properties from fresh fruit juices.

Quality Attributes of Cryoconcentrated Calafate (Berberis microphylla) Juice during Refrigerated Storage

“…This contrary performance has been linked to the TSS and their values cycle by cycle, i.e., as TSS increased, an increase in the organic acid content was generated, affecting the pH and TA values [ 37 ]. Besides, the results are in accordance with those obtained in CC applied to pineapple juice [ 16 ], apple juice [ 17 ] and blueberry juice [ 38 ], in which all the cryoconcentrated juices had antagonistic values in pH and TA with the increase in solutes as the cycles passed.…”

“…The values (r) between 0.9 to 1.0, indicating the direct and proportional results between TBC and TAA, i.e., each component increased or decreased, as the cycles or the days under storage progressed, respectively. A similar trend was distinguished by Casas–Forero et al [ 38 ] and Correa et al [ 57 ], who reported a high correlation (0.9 to 1.0) between antioxidant activity and bioactive compound in CC applied to blueberry juice and aqueous coffee extract, respectively.…”

“…At day 0, the TBC values significantly increased as the cycles progressed, with an increase of approximately 1.2, 2.0 and 2.7, 1.1, 1.9 and 2.5 and 1.1, 1.8 and 2.4 times in relation to the initial TBC value, for TPC, TAC and TFC, for cycle 1, cycle 2 and cycle 3, respectively. Various studies showed a similar upward trend for TBC in the cryconcentration of orange juice [ 10 ], maqui juice [ 14 ], strawberry juice [ 15 ], pineapple juice [ 16 ], apple juice [ 17 , 32 ], blueberry juice [ 38 ] and broccoli extract [ 54 ], i.e., since as liquid food was concentrated at low temperatures, the thermolabile components were highly protected in comparison to high thermal concentration technology as evaporation, which seriously affects the bioactive composition of the liquid food due to the high processing temperatures [ 6 ].…”

Effect of Freeze Crystallization on Quality Properties of Two Endemic Patagonian Berries Juices: Murta (Ugni molinae) and Arrayan (Luma apiculata)

“…Therefore, our values indicate that the human eye can perceive visual differences between the original sample and each cryoconcentrated sample, since all the ∆E* values were higher than 13 CIELab units. All the data and visual color had similar trend to the results reported in various studies on FC applied to fresh juices [ 27 , 31 , 43 ].…”

“…Additionally, the TPCC retention represents the TPCC retained from the fresh juice in the cryoconcentrated solution. The TPCC retention was determined by Equation (2) [ 31 ]. where C o is the initial TSS; C c is the TSS at each cycle in the cryoconcentrated fraction; TPCC c is the value of TPC, TAC, and TFC at each cycle; and TPCC o is the initial value of TPC, TAC, and TFC.…”