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ThesisItem Open Access STUDIES ON OSMOTIC BASED DRYING OF PINEAPPLE CUBES WITH DIFFERENT DRYING METHODS(DBSKKV., Dapoli, 2016-11) Patil, Yogesh; Swami, S. B.ABSTRACT ------------------------------------------------------------------------------------------------------ STUDIES ON OSMOTIC BASED DRYING OF PINEAPPLE CUBES WITH DIFFERENT DRYING METHODS by Yogesh Vasantrao Patil College of Agricultural Engineering and Technology, Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli Dist. - Ratnagiri, Maharashtra. 2016 ---------------------------------------------------------------------------------------------------------------- Research Guide : Dr. S. B. Swami Department : Agricultural Process Engineering ---------------------------------------------------------------------------------------------------------------- In the present research work, ―Studies on osmotic based drying of pineapple cubes with different drying methods ‖ was done from pineapple. Osmotic dehydration kinetics of pineapple cubes (10mm×10mm×10mm) was studied over a range of sugar concentration (40, 50 and 600B) and soaking temperature (30, 45 and 600C) of osmotic solution. The cubes were further dehydrated by convective hot air drying at 40, 50 and 600C. Osmotic dehydration kinetics indicated that both water loss and solids gain increased with increase of syrup soaking temperature and concentration, the former having much more effect for the range of values tested. After the osmotic treatment, the moisture content of fruits and vegetable are usually reduced by 316.24-399.54(%db). The effect of drying conditions (air temperature) on the osmo-convective dehydrated pineapple cubes on of dried product quality (TSS, pH, acidity, reducing sugar, non-reducing sugar, total sugar) was also evaluated. The drying took place in the falling rate period. The drying rate decreases with the decreases in the moisture content and it reaches to zero at the final moisture content of the osmo-convective dried of pineapple cubes. The Hendersons and Pabis Model was well fitted to the experimental data r2≥0.753. The effective diffusion coefficients for water and solute diffusion were determined, considering pineapple as slab thickness 1 cm. The effective diffusion coefficients for water as well as solute were empirically correlated with sugar concentration, soaking temperature and xxii convective hot air temperature. The effective diffusivity was found to be in the range of 6.301×10-8 to 3.4635×10-7 m2/s. The activation energy for pineapple cubes, which was estimated by using Arrehenius equation was be in the range 220.39 to 278.84 kJ/mole. Overall score of sensory characteristics ranged from 6.3 to 8.7 for all drying temperature. The quality characteristics of dried pineapple cubes i.e. TSS, pH, acidity, Reducing sugar, Non-reducing sugar, total sugar were significant at p≤0.05. The best sample of pineapple cubes was, the cubes soaked at 60oB sugar concentration and exposed to 600C resulted the best sensory score and the quality characteristics are as follows TSS 32.42%, pH 4.53%, Acidity 0.651%, Reducing sugar 19.09%, Non-Reducing sugar 41.79% and Total sugar 60.87% respectively. Drying of pineapple by microwave-vacuum (MW-V) with osmotic dehydration (OD) as a pretreatment was studied. The effect of sugar concentration (40, 50, and 60 Brix), soaking temperature 30, 45, 60 0C and magnetron ON/OFF time-15s/30s, 20s/30s, 25s/30s of the microwave vacuum dryer on TSS, pH, acidity, reducing sugar, non-reducing sugar and total sugar was evaluated. After the osmotic treatment, the moisture content of fruits are usually reduced by 316.24-399.25(%db) from initial moisture content. The Hendersons and Pabis Model was well fitted to the experimental data r2≥0.9464. The effective diffusion coefficients for water and solute diffusion were determined, considering pineapple as slab of thickness 10 mm. The effective diffusion coefficients for water as well as solute were empirically correlated with sugar concentration, soaking temperature and magnetron ON/OFF time. The effective diffusivity was in the range of 2.91×10-7 to 7.58×10-7 m2/s. The activation energy for pineapple cubes, which was estimated by using Arrehenius equation was in the range 13.79 to 94.77 kJ/mole. Overall score of sensory characteristics ranged from 6.3 to 8.7 for all magnetron ON/OFF timei.e. 15s/30s, 20s/30s, 25s/30s ON/OFF time of the magnetron. The quality characteristics of dried pineapple cubes i.e. TSS, pH, acidity, reducing sugar, non-reducing sugar, total sugar were significant at p≤0.05. Osmo-microwave vacuum dried pineapple cubes indicated that the best sample could be prepared at cubes soaked in at 600B sugar concentration at 600C soaking temperature and dried at 20 sec on time of magnetron and 30 sec off time of the magnetron resulted best sensory scores and the nutritional analysis indicated that the pineapple cubes dried at these condition have TSS 32.37%, pH 4.44%, xxiii acidity 0.605%, reducing sugar 21.87%, non-reducing sugar 46.08% and total sugar 67.96% etc. Pineapple has been identified as a valuable source of nutrients and antioxidants, which are beneficial for human health. To preserve the nutritional properties after drying, appropriate storage specifications should be considered. This study aimed to investigate the quality and stability of osmo-convective and osmo-microwave vacuum dried pineapple cubes in terms of quality characteristics during storage for up to 2 months in two packaging materials: aluminum and polypropylene. Packaging in aluminium pouches under ambient conditions was found to better preserve quality characteristics of dried pineapple cubes. The packaging and storage study of osmo-convective dried pineapple cubes indicated that the pineapple cubes can be stored in good condition in aluminium pouch packaging material up to 60 days; The sensory scores were in the range of colour 6.8, texture 8.2, taste 8.2, flavour 6.5 and overall acceptability 8.2. The nutritional retention of osmo-convective dried pineapple cubes stored up to 60 days was TSS 31.85%, pH 4.02, acidity 0.579%, reducing sugar 18.82%, non reducing sugar 42.86% and total sugar 61.67%. The packaging and storage study of Osmo-microwave vacuum dried pineapple cubes stored up to 60 days indicated that the pineapple cubes can be stored in good condition in aluminium pouch packaging material up to 60 days; The sensory scores were for osmo-microwave vacuum dried pineapple cubes stored up to 60 days range of colour 7.5, texture 7.0, taste 8.2, flavour 7.5 and overall acceptability 8.0. The nutritional retention was TSS 32.22%, pH 3.97, acidity 0.503%, reducing sugar 25.83%, non reducing sugar 46.40% and total sugar 72.23%. (Keywords: Pineapple, Osmotic dehydration, convective drying, microwave vacuum, Drying characteristics, nutritional analysis, sensory analysis, Packaging and storage.)