Effect of freezing and freeze/thaw cycles on lycopene stability encapsulated in alginate beads containing sugars and biopolymers

AGUIRRE CALVO, TATIANA; SANTAGAPITA, PATRICIO R.

Concordia, Entre Ríos

Conferencia; III International Conference on Food InnovaTION, FoodInnova 2014; 2014

Universidad Nacional de Entre Ríos // FoodInnova

Lycopene (ψ,ψ-carotene, C40H56) is a highly unsaturatedcarotenoid present in tomato, watermelon, papaya, and pink grapefruit, among others. Generally, it is used as an antioxidant in dietary supplements and as a natural colorant. However, carotenoids could be degraded by light, O2 and thermal treatments, and then, suitable matrices should be used for their stabilization. Encapsulation of active compounds (like lycopene) is used to preserve them, besides of giving controlled release and adequate dosage. The purpose of this work was to study the stability of a lycopene extract encapsulated in alginate beads subjected to continuous freezing and freeze/thaw cycles(-18°C for 30 days and four f/t cycles at -196/25°C, respectively). Grapefruit (Citrus paradisi, red variety) was obtained from Jujuy, Argentina (being this country its higher producer in South America). Lycopene was extracted fromfreeze-dried pulp by using extra-virgin olive oil (1:2). Afterwards emulsions were preparedby Ultraturraxusing different hydrocolloids as alginate, pectin, chitosan, or commercial and natural gums, as well as sugars (trehalose and β-cyclodextrin) (2:1 lycopene extract:excipients solution). Then, alginate-Ca(II) beads were prepared by dropping the emulsions in CaCl2 (2.5%w/v).The effect of freezing was evaluated on both concentration and stability of lycopene. In addition, the progress of crystallization of water and oil was monitored using transversal relaxation times (T2) determined by low field-NMR, obtaining isothermal curves at different temperatures.Alginate beads containing trehalose with β-cyclodextrin, guar, arabic or espina corona gums retained a high lycopene content (>80%) after freezing, regardless of the freezingmethod. Instead, beads containing only alginate showed lycopene losses between 50 and 75%. Greater losses of lycopene were obtained during the continuous freezing, besides of affecting its stability, with respect to f/t cycles. Isothermal studies revealed lower amount of crystallized water in beads containing trehalose (with or w/o other excipient), reducing also the time to arrive at the 50% of crystallization during freezing. The size of the beads increased after freezing, while circularity dependedon the composition. The results of this work can contribute to the selection of excipients for the encapsulation of labile biomolecules in alginate beads subjected to freezing.