Production Optimization of Low-Calorie Orange Nectar Using Stevioside Sweetener and Evaluation of Its Physicochemical Properties during Storage

Nowadays low-calorie products are increasingly becoming popular. One of the methods to produce low-calorie food is replacement of sugar (sucrose) with low-calorie sweeteners such as stevioside. This compound is isolated from the leaves of the Paraguayan plant، Stevia rebaudiana Bertoni. Since orange juice is a popular beverage with an important role in human nutrition، production of low-calorie orange nectar (containing 60% natural juice) and optimization of formulation parameters using response surface methodology (RSM) was the purpose of this study. Three levels of independent variables، sugar، stevioside and pectin were used to optimize formulation and two responses of brix and viscosity were evaluated. After the determination of the best formula، they were produced and stored at refrigerator (4°C) and ambient (25°C) temperatures for 60 days and their physicochemical properties were measured in 20 days intervals. The results showed that after 60 days of storage، stevioside content was reduced (5%). Sucrose، turbidity and viscosity were reduced during storage but brix did not indicate a notable change over the course of the study. These changes were greater at the higher storage temperature (except brix). At the end of the storage، optimal treatment had higher turbidity and total phenolic contents than the blank sample. Results showed that it is possible to produce orange nectar with 70% decrease in its sugar content by using 0. 06% of stevioside and 0. 03% of pectin، without any significant effects on physicochemical and sensory properties.