Osmotic dehydration of Amorphophallus paeoniifolius slices & it’s phyto-chemical investigation

Amorphophallus paeoniifolius known as Elephant foot yam is a highly potential tropical tuber crop of Areace family. The tubers are rich in nutrients. It is a healthy low-fat food containing a good source of protein as well as starch. It is a natural product that is high in fiber, rich in potassium, calcium (50 mg g-1), phosphorus (34 mg g-1) vitamin A (260 IU g-1), vitamin B6, as well as with trace minerals like selenium, zinc and copper. Fresh yams are difficult to store and deteriorate on storage. Various drying operations like freeze drying, sun drying has been reported for developing a stable form of dried Yam products but the effect of these food processes are not reported. In this investigation the yam slices were osmo-dehydrated after pretreatment i.e at 4oC for 12 hours, prior to this dehydration the phytochemicals levels as well as enzymes like protease and cellulase activity was checked.The effect the osmotic substance, time, temperature of this dehydration process on enzyme activity after rehydration is studied. Key-Words: Amorphophallus, Osmotic dehydration, Sugar solution Introduction It is already well known fact that bulk of the vegetables and fruits grown only during predetermined season and there is a need to increase the shelf life of these perishable natural resources. Dehydration is one of the most common natural and reliable method where vegetables and fruits in its dehydrated form are preserved for a longer period and are made available during off-season Osmotic dehydration is used to improve the economics of dehydration processes for extension of the sustainability of fruit and vegetable drying. The aim of osmotic dehydration is a partial removal of water from the material to obtain a better quality final product. Tomato, potato, pumpkin, carrot,onions are some vegetables that are good example of osmotic dehydration.( Le Maguer 1988,Filipčev, B etal;2008) In this process first, fruits and vegetables are dipped in a hypertonic aqueous solution of sugars, salts or a combination of both and multicomponent mass transfer occurs through the semi permeable cell wall due to difference in osmotic pressure of water in the plant tissue and hypertonic aqueous solution leading loss of water from fruits and vegetables. Diffusion of solute from osmotic solution into fruits and vegetables is also seen. (Koprivica, G., 2009) * Corresponding Author E.mail: [email protected] Diffusion of cell juices from the plant tissue into the osmotic solution also occurs this is known to affect the the nutritive value of osmo-dehydrated fruits and vegetables (Mizrahi, S., S. Eichler, J.L.;2001) Osmodehydrated fruits and vegetables are partially dehydrated which can be directly used in human nutrition or as a intermediate material for further drying to the form a product can be used as components of cereals or snacks for direct consumption with appropriate moisture content(Lenart, 1996; Filipčev, B., Lj. Lević, O. Šimurina, T. Kuljanin ;2006 and Torreggiani, D. Bertolo, G.; 2001) Dehydration process parameters and osmotic agent used can modify the quality traits and nutritional value of osmodried fruits and vegetables (Mandala et al., 2005; Chiralt and Talens, 2005)Main factors effecting the mass transfer rate in this process are temperature of the osmotic solution, agitation of the osmotic solution, concentration of the osmotic solution, type of osmotic agent, time duration, geometry (size) of the food material, variety of the food material, physico-chemical properties of the food materials and operating pressure. Advantage of this process is quality improvement, Packaging and distribution cost reduction, influence on the principal drying method, product stability during storage, no chemical requirement, shortening of the drying process, resulting in lower energy requirements. (Lenart and Lewicki, 1988) Since heat is not applied in Research Article [Singh & Wadhwa, 3(7): July, 2012] CODEN (USA): IJPLCP ISSN: 0976-7126 Int. J. of Pharm. & Life Sci. (IJPLS), Vol. 3, Issue 7: July: 2012, 1797-1801 1798 this process, which leads to higher retention of initial food characteristics, like colour, aroma, nutritional constituents, and flavour compounds (Beaudry 2001). Amorphophallus paeoniifolius is a good source of protein as well as starch Commercially cultivation of this crop is due to its production potential (50-80 t ha1 )and popularity as a vegetable in various Indian cuisines. In India, it is cultivated in Andhra Pradesh, West Bengal, Gujarat, Kerala, Tamil Nadu, Maharashtra, Uttar Pradesh, and Jarkhand. The net economic return is over 1 lakh rupees per ha. It has a great export potential since its commercial cultivation is not in other countries (Misra and Shivalingaswamy, 1999; Misra et al., 2001). In India, Sree Padma, Gajendra, Sree Athira (a hybrid),Bidhan Kusum and NDA-9 are some of the high yielding Amorphophallus varieties released for cultivation (AICRP,2006). Osmotic dehydration of Amorphophallus can be a useful technique to preserve and obtain new processed products of interest to the consumer. This study was aimed to produce a novel shelf stable high quality dried Amorphophallus cubes using combination of pretreatment, osmotic dehydration and conventional hotair drying. The effect of different concentration of sugar, dehydration time, dehydration temperature on the rate of dehydration and its effect on enzyme activity and phytochemicals is studied.Process condition was optimized in order to produce good quality product. Material and Methods Fresh Amorphophallus tubers were purchased from the local market. Prior to the treatment, the elephant foot yam were thoroughly cleaned and cut into square shapes of, 2cmx2cm. Osmotic solution used was table sugar aqueous solutions (solid content: 50%, 60% 70% and 80%) that were prepared by mixing sugar in deionized water (30oC) to complete dissolution. Prior to osmotic dehydration of cubes were kept at 4oC for 12 hours as their pretreatment Osmotic dehydration was carried out at constant temperature (55oC) in the water bath with minor shaking, under atmospheric pressure. After measuring the initial mass, Amorphophallus cubes were dipped into different concentrations of the hypertonic sugar solutions.Sugar solutions had a concentration of 50% (indicated as S1), 60 %( S2), 70% (S3), 80 %( S4). The material to hypertonic solution ratio was kept constant at 1:10. The evenly sliced samples were kept for dehydration and samples were removed after 0 min, 60min, and 150 min. The slices were then washed with water blot dried for 15 min to remove excessive water, oven dried at 65 oC for 2 hours until constant weight was attained. During the process the values the changes in weight and in the content of dry matter observed. The following parameters were calculated: water loss (WL), weight reduction (WR), dry matter growth (SG) (Le Maguer, M.1988) WR [g/g] = wo w [1]