Performance of Two Types of Solar Dryers on Some Physico-chemical and Textural Properties of Two Varieties of Al-Ahsa Dates

Abstract

Dates fruits of the date palm (Phoenix dactylifera L.) have a great economic importance and they are valuable food in the Arab countries that produce and consume dates. The date producing countries are interested in research that support and assist the development and preservation of the fruits, and the one of the most prominent countries is the Saudi Arabia Kingdom, which had been and still taking great care and attention to this fruit. Date palm is becoming an important commercial crop in the producing countries with significant increase in yield. However, date processing industries have not advanced at the same pace. Drying method and process conditions may affect significantly physicochemical and textural properties of dates. The objectives of present study were: 1) performance evaluation of the two solar dryers; direct dryer (GHD) and indirect dryer (IND) and 2) investigation of the solar drying process effect, by using the two solar dryer, on some physicochemical and textural properties of date fruits for two cultivars namely, Khalas and Ruzeiz. Two solar dryers namely, greenhouse dryer (GHD) and indirect solar dryer (IND) were constructed from local materials and were used in the dates drying. All experiments of the study were carried out at The Agricultural and Veterinarian Training and Research Station of King Faisal University. Results showed that the daily average overall thermal efficiencies of the two solar dryers during the experimental period were 63.2% and 55.6% for GHD and IND, respectively. The drying took place predominantly in the falling rate period which indicated that diffusion was the main physical mechanism governing moisture movement in date palm fruits. The results of the study concerning the physic-chemical and textural properties of date by showed that generally under the experiment conditions of the solar drying process some properties were affected by the drying process such as; mass, pH and hardness properties, while the other properties were not affected.