evaluation of effective factors on juice extraction process from variety of date-palm fruit kaluteh and optimization using response surface methodology

of a large amount of date palms cultivated and harvested in iran, only about 11 – 12 annual percent is used in food processing and packaging industries. due to the poorq uality of produced dates, it is regarded as waste and is mainly used as feed stocks. thus, through producing syrup and liquid sugar from date palm of low quality could be regarded as a new opportunity to convert waste dates to a higher value product in order to reduce imports of similar products and also to export it in large quantities. in the present study, the face-center central composite design of response surface methodology was used to investigate the influence of temperature (60-80 °c), ph (4-7), time (1-5 h) and water-to-date pulp ratio (1:3-1:5) on yield and absorbance of juice extraction from grade ii date of the kaluteh variety and its optimization. the results revealed that all the investigated independent variables have significant influence on the process, but the effect of time was not significant on the absorbance. also, the main influencing parameter on the extraction process of palm was observed to be the water-to-date pulp ratio. the results showed that the extraction yield increased at elevated temperatures, higher mixing ratios, longer times and lower ph, whereas increasing temperature and decreasing ph had a negative impact on clarity of syrup. the optimum conditions obtained for the extraction process were temperature of 77.45 °c, time of 5 h, mixing ratio of 1:4 and ph= 4. at the optimum conditions, the yield and absorbance were found to be 62.5 % and 0.28, respectively.