Studies on Mass Transfer Characters of Osmo Dehydrated Aloe Gel Shymi Cherian 1, Geetha Lekshmi P.R 2 and Mini C. 3

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1 Studies on Mass Transfer Characters of Osmo Dehydrated Aloe Gel Shymi Cherian 1, Geetha Lekshmi P.R 2 and Mini C. 3 1 PG scholar, Department of Processing Technology, College of Agriculture, Vellayani 2 Assistant Professor, Department of Processing Technology, College of Agriculture, Vellayani, 3 Professor and Head, Department of Processing Technology, College of Agriculture, Vellayani, Abstract Aloe vera (Aloe barbadensis Miller) cubes of 1cm 3 size were osmosed for 4 h and 6 h in sugar osmotic of 30, 40 and 50 Brix concentration at 40 C at constant osmotic to fruit ratio of 5:1. The water loss, solid gain and weight reduction were recorded during experiments. and osmotic affected the water loss, solid gain and weight reduction. Water loss, solid gain and weight reduction increased with increase in osmotic concentration and immersion time and aloe gel osmosed in 50 0 B osmotic concentration and 6 h immersion time recorded the highest SG (10.68%), WL (68.82%) and WR (63.45%). Keywords: Aloe vera, Osmosis, Solid gain, Water loss,weight reduction I. INTRODUCTION Aloe vera (Aloe barbadensis Miller), a traditional medicinal plant, member of Liliaceae family is used in food, pharmaceutical and cosmetic industries. The parenchymatic tissue of Aloe vera leaves (gel) contains over 98 99% water and more than 60% of the dry matter is made up of polysaccharides 1 2 Aloe vera is an industrial crop and in the food industry it has been utilized for the preparation of health food drinks. 3 The gel is protected from evaporation by a film of a substance known as aloe, composed mainly of resins and aloins 4. Taking advantage of all of its medicinal proprieties various food products, in which aloe has been used as a main ingredient or as an additional component, have been developed in recent years. In the production of aloe products, Aloe vera has been used as a raw material in its concentrated juice or freeze-dried form. But the substances that really play a healthy role in aloe gel are damaged and spoiled on heating. 5 The potential use of aloe products often involves some type of processing, e.g. heating and/or dehydration. Improper processing procedures may cause irreversible modifications to the polysaccharides, affecting their original structure, which may promote important changes in the proposed physiological and pharmacological properties of these active ingredients 5. 6 evaluated the main effects of the drying temperature on the physico-chemical properties of the main type of polysaccharide, present in Aloe vera parenchyma. dehydration is the process of water removal, with low energy consumption at low temperature. This provides minimum thermal degradation of nutrients due to low temperature water removal process. 7 The osmotic process variables (pre-treatment, temperature, concentration of the solution, agitation, additives, immersion time) have been reported to have influence on mass transfer and on the product quality. 8 The osmotic process has received considerable attention as a pretreatment so as to reduce energy consumption and improve food quality 9 10.Besides reducing the drying time, the osmotic dehydration as a pretreatment also inhibits enzymatic growing, retains natural colour and retains volatile aroma during the subsequent drying 11. dehydration process has been studied for many fruits and vegetables and studies on dehydration of aloe vera was done by 12. Therefore, the objective of the study was to investigate All rights Reserved Page 210

2 effect of osmotic concentration and immersion time on water loss (WL), solid gain (SG) and weight reduction (WR) of aloe gel cubes. II. MATERIALS AND METHODS Aloe vera (Aloe barbadensis Miller) leaves were procured from farmer s field in Thiruvananthapuram. Fresh aloe vera leaves of 30 and 50 cm length from 3 to 4 year old plants were washed under tap water to remove adhering materials. The spikes along the margins were removed and the leaves were steam blanched for two minutes. After air drying of the blanched leaves the top and bottom rind of aloe leaves were removed by using sharp knife and the gel was extracted. The extracted gel was cut into cubes of 1 cm 3 size and was freshly prepared on each day of experiment. Sugar osmotic of desired concentration was prepared by dissolving required amount of sugar in distilled water. ] dehydration The solute used for osmotic dehydration was sugar. The sucrose selected for osmotic dehydration were 30, 40 and 50 Brix. The osmotic dehydration was carried out at 4 h and 6h immersion time at constant osmotic to fruit ratio of 5:1 and the temperature was maintained at 40 0 C. The cubes were then immersed in osmotic solution and potassium metabisulphite (0.1%) and citric acid (0.1%) were added to the osmotic solution and the ph was adjusted to 3.0 to 3.5. The osmotic dehydration experiments were carried out in a glass beaker placed in a hot water bath with thermostatcontrolled heaters. The samples were weighed and their moisture content was determined by using moisture analyser. All the experimental measurements were replicated 4 times. Water loss The WL was the net loss of water from aloe vera cubes on an initial mass basis. Weight of fresh fruit prior to osmosis and after osmosis was recorded in electronic balance (Shimadzu 0.1mg- 200g). Dry mass of fresh fruit and dry mass after osmosis were recorded and water loss in terms of percentage was calculated by the method described by 13 using following formula Wo Wt St So WL (%) 100 Wo W o = Initial weight of fruit slices W t = Weight of fruit slices after osmotic dehydration S 0 = Initial dry mass of fruit slices S t = Dry mass of fruit slices after osmotic dehydration Solid gain The dry matter gain is related to solid gain (SG) and hence, the SG was the net gain in total solids by aloe vera cubes on the initial mass basis. Solid gain (%) was determined using the procedure followed by 14. SG (%) = S t - S i 100 m i S t = mass of dry body at time t, S i = Initial mass of dry body (of fresh) and m i = initial mass of wet All rights Reserved Page 211

3 Weight reduction Weight reduction in terms of percentage was calculated using the method described by 15. Mo M WR (%) 100 Mo Mo = Initial mass of fruit slices prior to osmosis (g) M = Mass of fruit slices after osmosis (g) III. RESULTS AND DISCUSSION In this experiment, the effects of different osmotic and immersion time on mass transfer characters were studied. Mass transfer characters viz., SG, WL and WR of osmosed aloe gel are summarized in Table 1, 2 and 3. Solid gain is an indicator of movement of solute into the aloe cubes and it increased with increase in osmotic concentration. SG of osmo dehydrated aloe gel in different osmotic and immersion time are depicted in Fig 1. and immersion time significantly differed in SG. Osmo dehydrated aloe gel in 50 0 B osmotic concentration and 6 h immersion time recorded the highest SG of % and it was 9.72 % for aloe gel in 50 0 B osmotic concentration and 4 h immersion time and the lowest SG of 8.52 % was recorded for osmo dehydrated aloe gel in 30 0 B osmotic concentration and 4 h immersion time. WL of osmo dehydrated aloe gel increased with increase in osmotic concentration and immersion time. The highest WL of 68.82% was recorded for osmo dehydrated aloe gel in 50 0 B osmotic concentration and 6 h immersion time and % for 50 0 B osmotic concentration and 4 h immersion time. Osmo dehydrated aloe gel in 30 0 B osmotic concentration and 4 h immersion time recorded the lowest WL of 46.25%. Weight reduction of osmo dehydrated aloe gel in different osmotic and immersion time are depicted in Fig 2. WR of osmo dehydrated aloe gel increased with increase in osmotic concentration and immersion time. The highest WR of % was recorded for osmo dehydrated aloe gel in 50 0 B osmotic concentration and 6 h immersion time and % for 50 0 B osmotic concentration and 4 h immersion time. Osmo dehydrated aloe gel in 30 0 B osmotic concentration and 4 h immersion time recorded the lowest WR of %. Moisture loss during osmosis may be resulted in WR of aloe gel. Results of the study revealed that mass transfer characters viz., SG, WL and WR was highest for aloe gel osmo dehydrated in 50 0 B osmotic concentration and 6 h immersion time. SG, WL and WR increased with increase in osmotic concentration and immersion time. These results are inconformity with the results of. 16 who reported highest sugar gain was with 50 0 B osmotic treatment of aloe gel and microstructure especially porosity of aloe contributed to the change in solid gain velocity. Higher concentration of osmotic solution and immersion time increased the solid gain on osmotic dehydration of pineapple reported that SG and WL increase with increased solute concentration due to high rate of diffusion of solute and water exchange reported SG and WL of aloe gel cubes increased with the increase in sugar concentration and temperature. Table 1. Effect of osmotic concentration and immersion time on solid gain (%) of aloe gel Solid gain (%) T 1 (4 h) T 2 (6 h) Mean S 1 (30 0 B) S 2 (40 0 B) S 3 (50 0 B) Mean CD (0.05) S T SxT - All rights Reserved Page 212

4 Table 2. Effect of osmotic concentration and immersion time on water loss (%) Water loss (%) T 1 T 2 Mean S 1 (30 0 B) S 2 (40 0 B) S 3 (50 0 B) S 1 (30 0 B) CD (0.05) S T SxT Table 3. Effect of osmotic concentration and immersion time on weight reduction (%) of aloe gel Weight reduction (%) T 1 (4 h) T 2 (6 h) Mean S 1 (30 0 B) S 2 (40 0 B) S 3 (50 0 B) Mean CD (0.05) S T SxT Figure. 1. Solid gain (%) of osmo dehydrated aloe All rights Reserved Page 213

5 Figure 2. Weight reduction (%) of osmo dehydrated aloe gel BIBLIOGRAPHY [1] McAnalley, B.H., Process for Preparation of Aloe Products. European Patent WO 89/ [2] Femenia, A., Sánchez, E., Simal, S., Rosselló, C., Compositional features of polysaccharides from Aloe vera (Aloe barbadensis Miller) plant tissues. Carbohyd. Polymers 39 (2), [3] Seoshin, Y., Lee, K.S., Lee, J.S.,and Lee, C.H Preparation of yoghurt added with aloe vera and its quality characteristics. J. Korean Soc. Food Nutr. 24: [4] Vega, A., Ampuero, N., Díaz, L., and Lemus, R El Aloe Vera (Aloe barbadensis Miller) como componente de alimentos funcionales. Revista Chilena de Nutrición 32 (3): [5] Eshun, K. and He, Q Aloe vera: a valuable ingredient for the food, pharmaceutical and cosmetic industries. A review. Crit. Reviews Food Sci. Nutr. 44: [6] Femenia, A., García-Pascual, P., Simal, S., and Rosselló, C., Effects of heat treatment and dehydration on bioactive polysaccharide acemannan and cell wall polymers from Aloe barbadensis Miller. Carbohyd. Polymers 51 (4): [7] Shi, J.X., Maguer, M.L., Wang, S.L., and Liptay, A Application of osmotic treatment in tomato processingeffect of skin treatments on mass transfer in osmotic dehydration of tomatoes. Food Res. Int. 30(9): [8] Rastogi, N.K., Nayak, C.A., Raghavarao, K.S.M.S Influence of osmotic pretreatment on rehydration characteristic of carrots. J. Food Eng. 65: [9] Jayaraman, K.S., Das Gupta, D.K dehydration of fruits and vegetables: recent development in principles and techniques. Drying Technol. 10:1 50. [10] Karthanos, V.T., Kastaropoulus A.E., and Saravacos, G.D Air-drying behaviour of osmotically dehydrated fruits. Drying Technol. 13 (5 7): [11] Pokharkar, S.M., Prasad, S., and Das, H A model of osmotic concentration of banana slices. J. Food Sci. Technol. 34: [12] Simal, S., Femenia, A., Llull, P., and Rossello, C Dehydration of aloe vera: simulation of drying curves and evaluation of functional properties. J. Food Eng. 43: [13] Sridevi, M. and Genitha, T. R Optimization of osmotic dehydration process of pineapple by response surface methodology. J. Food Processing Technol. 3: 173. [14] Kowalski, S.J. and Mierzwa, D Influence of preliminary osmotic dehydration on drying kinetics and final quality of carrot (Daucus carota L). Chem. Process Eng.32(3): [15] Yadav, B. S., Ritika, B., and Jatain, M Optimization of osmotic dehydration conditions of peach slices in sucrose solution using response surface methodology. J. Food Sci. Technol. 49(5): [16] Garcia-Segovia, P., Mognetti, C., Andres-Bello,A., and Martinez-Monzo, J dehydration of Aloe vera (Aloe barbadensis Miller). J.Food Eng. 97: [17] Kumar, S. P. and Devi, P Optimization of some process variable in mass transfer kinetics of osmotic dehydration of pineapple slices. Int. Food Res. J. 18: [18] Chavan, U. D dehydration process for preservation of fruits and vegetables. J. Food Res. 1(2): [19] Pisalkar, P. S., Jain, N. K., and Jain, S. K Osmo-air drying of aloe vera gel cubes. J. Food Sci. Technol. 48(2): [20] Pisalkar, P. S., Jain, N. K., Pathare, P. B., Murumkar, R. P., and Revaskar, V.A dehydration of aloe vera cubes and selection of suitable drying model. Int. Food Res. J. 21(1): All rights Reserved Page 214