~ 433 ~ Journal of Pharmacognosy and Phytochemistry 2020; 9(4): 433-439 E-ISSN: 2278-4136 P-ISSN: 2349-8234 www.phytojournal.com JPP 2020; 9(4): 433-439 Received: 07-05-2020 Accepted: 09-06-2020 Gitanjali Behera Department of Agricultural Engineering, Centurion University of Technology & Management, Odisha, India Kalpana Rayaguru Department of Agriculture Processing and Food Engineering, College of Agricultural Engineering, OUAT, Odisha, India Corresponding Author: Gitanjali Behera Department of Agricultural Engineering, Centurion University of Technology & Management, Odisha, India Comparative evaluation of the quality characteristics of the osmo-dehydrated star fruit slices using hot air, solar and sun drying Gitanjali Behera and Kalpana Rayaguru Abstract The star fruit (Averrhoa carambola) belonging to family Oxalidaceae is one of the earliest known tribal fruit being grown in abundance in India. It is a multipurpose, drought resistant evergreen tree which is gaining lot of importance for its therapeutic potentials. Due to lack of technical knowledge most of these fruits are not effectively utilised. The present study was an effort to perform a quality characteristics evaluation of osmo-dehydrated star fruit slices subjected to hot air drying (HAD), Solar drying (SOD) and sun drying (SD). The star fruit slices were subjected to microwave blanching, Osmo-dehydrated and the process was optimized. Final samples were prepared at that optimum conditions and subjected to hot air drying, solar drying and sun drying. Quality analysis of the dried sample was done for ascorbic acid (AA), oxalic acid (OA), rehydration ratio (RR). The sensory (colour and shape) analysis was also carried out. Drying time taken was 6-13 hrs, 7-11 hrs and 11-18 hrs for HAD, SOD and SD. The solar dryer achieved considerable reduction of 75% in drying time as compared to that of conventional sun drying. The samples undergone microwave blanching and osmo-dehydration lost part of AA and OA during heat treatments. The sun dried samples showed very low sensory score (5 to 6) which was much lower than those of HAD and solar dried samples. Osmo-solar process may be recommended to be practiced at rural level for dehydration of star fruit slices as a compromise method between HAD and SD considering both the quality parameters of finished product and from energy consumption point of view. Keywords: Solar drying, sun drying, rehydration ratio, ascorbic acid, oxalic acid 1. Introduction The star fruit (Averrhoa carambola) belonging to family Oxalidaceae is popularly known as tribal fruit of India. The evergreen tree can be used for multipurpose and is very much resistant to drought. Though the fruits and plant parts are traditionally used for various diseases, the fruit is the most usable part of the plant. Due to lack of technical knowledge most of these fruits are not effectively utilised. The fruit contains vitamin C, total phenolics, antioxidants, dietary fibres and mineral in a huge amount which helps in health promoting [1, 2] . Fruit contains soft, fleshy, yellow and edible pulp, with the flavor of a green, sour apple [3] . The fruit is used for preparation of jelly, jam and beverages. And sometimes, it is also used in curry to give a sour taste. The presence of moisture above 90% wb makes the fruit perishable and the utilization becomes limited due to the seasonal availability. Therefore, it is necessary to preserve this nature’s gift by doing proper processing with efficient nutrition retention. The fruit has a very unique star shape and market potential is very high due to the ripen golden colour. It is used for garnishing of salads and other products prepared by value addition [4, 5] . A huge portion of this fruit is getting wasted at production point due to lack of transpiration facilities, storage and processing. Keeping in view of the above stated problem, development of in-expensive processing methods is necessary for storage of this nutritious fruit. Dehydration is the process of removal of water from agricultural products and essential methods for storing this fruit with minimum spoilage [6] . Finding the standard optimum processing parameters is also very much essential for producing product with highest quality and with efficient nutrition. The standardized processing parameter can be directly used by the rural farmers and industries [7] . Different types of methods are being constantly used for drying different products having their own benefits and limitations. Conventional hot air drying is more efficient compared to sun drying; gives uniformly dried with better quality product. With all these advantages, the hot air dryer is costly and it is not affordable by rural farmers. The renewable energy sources can be used for this purpose for saving the major processing cost. Solar energy is the abundantly available energy source which generally used for drying operations of agricultural commodities [8] . Solar drying reduces the drying time considerably and improves the product quality with better taste, colour and texture compared