Effect of Different Osmotic Pretreatments on Weight Loss, Yield and Moisture Loss in Osmotically Dehydrated Guava

The osmotic dehydration is that the water diffuses from dilute solution to concentrated solution (hypertonic solution) through a semi-permeable membrane until concentration equilibrium is reached. The driving force is the water activity gradient caused due to the osmotic pressure. In the present investigation, higher weight loss and solid gain were observed in Allahabad Safeda slices than the Pink Flesh. Higher moisture loss was observed in osmosed Pink Flesh slices than Allahabad Safeda. Maximum effect on the weight loss 34.55 per cent, moisture loss 53.24 per cent, solid gain 13.97 per cent, were observed when guava slices were pre treated with 70o Brix syrup for 24 hours (T9). It was also observed that an increase in duration of osmosis and syrup concentration increased weight loss, moisture loss and solid gain in slices of both Allahabad Safeda and Pink Flesh. The osmosed slices prepared from Pink Flesh variety recorded lower (43.91%) moisture content than the Allahabad Safeda (46.81%). Dried yield was highest in Allahabad Safeda (34.73%) than Pink Flesh (33.79%). In case of variety Allahabad Safeda the drying ratio of osmotically dehydrated slices ranged from 2.58:1 to 3.02:1. In case of variety Pink Flesh the drying ratio of osmotically dehydrated slices ranged from 2.46:1 to 3.23:1. Osmotic treatment of guava slices 70o Brix syrup for 24 hours (T9) resulted in highest yield and lowest drying ratio.