Optimization of Dates Puree Pastilles Formulation Based on Concentrated Whey, Agar and Xanthan Hydrocolloids Using Response-Surface Methodology (RSM)

The aim of this study was to investigate the feasibility of producing a pastilles based on dates puree and concentrated whey and optimizing its formulation. In order to optimize the production conditions of pastilles based dates and concentrated whey,response- surface methodology was used.In this study,the conditions of production of pastilles product(concentration of xanthan gum (0.1-0.5%)and agar(0.3-0.9%) as well as concentration of whey(5-15%)were optimized to achieve maximum protein and total acceptability and total color index.According to the results of the statistical analysis of the data,a linear model for moisture, water activity, pH and total color index and a quadratic model for total acceptability were selected.The results showed that the concentration of whey had a significant effect on all responses.Increased concentration of whey had a positive effect on moisture of the samples and had a reverse effect on water activity,pH and total color index.The overall acceptability index did not show a steady trend,with a 10% increase in concentrated whey increasing and then decreasing.As the xanthan gum and agar gum content increased, the moisture content of the samples increased,but water activity decreased.The overall acceptability index also showed the highest value in average percentages for the two gums(as was the case for whey).The optimum operating conditions obtained for the jelly production process included xanthan gum concentration of 0.36% (w / w),agar gum concentration of 0.46% (w / w) and concentrated whey 13.92% (w / w).The predicted responses under these conditions were 36.62% moisture content, 0.66% water activity, 3.25 pH, 1.17 protein content,overall acceptability score of 6.56 and total color index of 45.94%.After the evaluation,it was found that the actual results were very close to the model estimates,indicating accurate model prediction.