Evaluation of physicochemical and rheological properties of reconstituted beverage from dried apricot

Abstract:
Background and objectives: Fruit-based drinks is secured antioxidants, carotenoids, vitamins and other nutrients necessary for human health. Apricot juice is especially consumed in the warm days of the year due to high nutritional value. it is a seasonal fruit. In order to prepare the juice, in the first step, apricot fruit juice is extracted by an extractor and then concentrated by evaporation. In other seasons, apricot juice is prepared by using concentrated juice. This study is devoted to examine the possibility of the production of beverage from dried apricot owing to the high costs of concentrate preparation (equipment and energy consumption) along with the reduction of minerals of fresh fruit by removing the parts of the pomace and skin of apricot.
Materials and Methods: Apricot fruit was purchased from local market and after washing, the fruit was dried with a laboratory oven (70 °C), then used in the formulation of beverage. The effect of formulation parameters, consist of pectin percentage (0.1-0.3 %), the amount of sugar (8-12 %) and amount of citric acid (0.3-0.7 %) on physicochemical (viscosity, Brix, suspended solids and sediment content) and rheological properties of the reconstituted beverage, evaluated. The flow behavior of the samples was investigated by a power law and Herschel-Bulkley models. Response surface methodology base on the rotatable central composite design was used to predict the effect of formulation variables on the qualitative characteristics of the apricot beverage.
Results: The Brix and viscosity of beverage increased with simultaneous increasing of pectin and sugar due to enhancement of concentration of the sample. The analysis of the rheological behavior of the samples demonstrated that the flow index (n) was less than one that the samples exposed a shear-thinning behavior. According to the statistical indices, Herschel-Bulkley model with the highest correlation coefficient was selected as the best model for describing the rheological behavior. Results of process optimization indicated that the best conditions for reaching the minimum viscosity and suspended solids were obtained at levels of 0.1, 0.7 and 8.978 % for pectin, citric acid & sugar respectively: for maximum desirability of 0.885.
Conclusion: The current study was developed to produce beverages from dried apricot flakes. This technique is low-cost compared to the concentration and reconstitution method in the preparation of beverages, also reduces the fruit damage. With respect to the high content of minerals and fibers in the dried slices of apricot compared to the fresh fruit, the prepared beverage also obeys this trend. The results of this investigation indicated that the implementation of natural compounds (citrus pectin) in the formulation of beverages may inhibit the undesirable phase separation process.