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|Title: ||Dehydro-freezing – a potential technology for preservation of tropical fruit slices|
|Authors: ||R B, Tiwari|
|Issue Date: ||2010|
|Citation: ||R.B.Tiwari and Sarojini Jalali, 2010. Dehydro-freezing – a potential technology for preservation of tropical fruit slices. International Conference on Greening Food Processing Sector for sustainable safe food supply. IICPT, Thanjavur Oct. 30-31.|
|Abstract: ||Freezing is a widespread commercial method for long-term preservation of perishable foods because of high product quality and convenience. Freezing is a process of bringing down the temperature of the food below its freezing point and storage at -18°C temperature. Fruits like mango, banana, pineapple pulps and juices of citrus fruits are traded in frozen form throughout world. The potential application of freezing preservation of fruits and vegetables particularly tropical products, has been increasing recently in developing countries including India. Freezing rate affects strongly the quality of frozen foods, in which the predominantly water content should quickly be frozen in a fine-grain crystal structure in order to prevent the damage to cellular tissues and to inhibit rapidly the spoiling microbiologic and enzymatic processes. Dehydrofreezing is the recently developed an innovative freezing technology. Dehydrofreezing is a variant of freezing in which a food is dehydrated to a desirable moisture level and then frozen. Fresh fruits and vegetables contain more water and their cellular structure could be susceptible to damaged by large ice crystal formed in freezing. Although increasing freezing rate can reduce the possibilities of the formation of large ice crystal, the tissue damage is still inevitable due to the presence of large amount of water. Dehydrofreezing provides a promising way to preserve fruits by removing part of water from food materials prior to freezing. A reduction in moisture content leads to reduction in the amount of water to be frozen, thus lowering refrigeration load during freezing. In addition, Dehydrofrozen products could lower cost of packaging, distribution and storage, and maintain product quality comparable to conventional products. Partial dehydration constitutes the first stage of dehydrofreezing, whereas it influences the freezing process and quality of final products. Presently more attention is being paid to osmotic dehydration as a pretreatment, which has advantages over air drying, such as adaptability to a wide variety of products and less-energy requirement. At IIHR, mango and pineapple fruit slices have been successfully preserved through osmo-dehydrofreezing. Osmotic pre-treatment of mango and pineapple slices improved texture, yield and quality of osmodehydro-frozen product. However, care should be taken when choosing the aqueous solution of high osmotic pressure since solute uptake often leads to substantial modification of the product composition with a negative impact on sensory characteristics. It is concluded that application of osmo-dehydrofreezing technology for fruit freezing can reduce post-harvest losses, extend shelf-life and improve the quality of frozen foods besides energy saving.|
|Appears in Collections:||Post Harvest Technology|
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