Thesis

"Elephant apple (Dillenia indica L) is both nutritionally as well as therapeutically important plant of tropical areas. It was originally found in Indonesia and also grow in southeastern Asia (India, Sri Lanka, China, Thailand, Malaysia. In India it is found plentily in north-eastern states, West Bengal, Odisha, Bihar, and South India. The ripe fruits are harvested while the sepals get thickened. It is rich in vitamin-C, anti-oxidant and anti-inflammatory properties, fiber with fairly high amount of calcium and phosphorus. These are sour in taste and widely used in flavoring curries and in the preparation of jam and jelly. The fruit sepals have hard peel along with central gummy, mucilaginous materials, which make it difficult to be used by hand. Therefore, it is one of the most neglected wild fruits in the region which has the potential to provide an excellent source of income generation activities if properly utilized. Since the fruit is seasonal, it is not available to the people throughout the year. It is reported to have excellent processing attributes. Manufacturing of value added products may be useful in effective utilization of the fruits year round. Value added products prepared during the peak period are expected to be consumed throughout the year. The present study was an effort to optimize the process variables of osmo-convective drying of Dillenia indica fruit slices with respect to quality characteristics using response surface methodology. The effect of packaging materials on shelf-life of osmo-dehydrated slices were studied. Trial was also made to utilize the resulting osmotic solution for preparation of value added beverage. Ripe Elephant apple fruits were collected from a particular farmer and cleaned properly by washing it with water. After primary processing (cutting and peeling) the usable product was separated. The slices of peeled sepals were subjected to microwave blanching followed by osmo-covective drying. Experiments were planned to optimize the process parameters of osmo-convective drying of elephant apple slices using response surface method (RSM). Box-Behnlean design for three factors with three levels was used to design the experiments. The three independent variables were SC (40, 50 and 60° Brix), IT (2, 4 and 6h) and DT (50, 60 and 70°C). The plan consisted of 15 experimental runs with three experiments at centre point. The dependent quality attributes of slices considered were water loss(WL), solid gain(SG), Rehydration ratio(RR), Antioxidant activity(AOA), Ascorbic acid(AA) and Total phenolics(TP The experimental data were analyzed to develop response functions and the input variables were optimized for best outputs. A complete second order polynomial model was fitted to the data of all responses using multiple regression technique. The adequacy ofthe model was tested considering R2 (The coeff of multiple determination) and Fischer's F-test. The models were then used to interpret the effect of input variables on the response. Final samples were prepared at that optimum conditions and stored in packs of LDPE (Low density polyethylene) and MPP ( Metalised polyester polyethelene) for a period of 4 months. Quality analysis of the dried sample was carried out for antioxidant property, total phenolics, rehydration ratio and ascorbic acid. Two types of ready-to-serve beverage (RTS) were prepared namely RTS-I was using fresh fruit and sugar syrup and RTS-2 using the left over sugar syrup of osmo-dehydration along with some more fresh fruit by which the nutritional and therapeutic value could be preserved in addition to the reuse of sugar present in the residual fluid. Shelf life of both the beverages were evaluated with respect to quality characteristics and sensory properties using ANOV A, composite scoring and fuzzy logic. The primary processing of elephant apples give rise to 47 % of usable part for further value addition. Using multiple responses optimization technique for osmoconvective drying of elephant apple slices, a set of compromised process parameters to satisfy all the response functions within the acceptable range was determined to be SC, IT, DT as 60° Brix, 4 h, 55°C. Corresponding to these values of process variables, the value ofWL, SO, RR, AA, AOA, TP were 45.7, 7.76, 1.75, 90.01, 2951.4 and 503.09 respectively. The overall desirability was 0.985.Multiple regression analysis of experimental values for osmo-convective drying using Box-Behnken design of res po rise surface methodology (RSM) revealed that the proposed second order models for WL, SO, RR, AA, AOA, TP were adequate and satisfactory with 0.984, 0.974, 0.993, 0.999, 0.905, and 0.995 as coefficient of determination respectively.The regression coefficients of second order model and the probability of factors influencing the response at linear, quadratic and interactive level has been analysed thoroughly. Sugar concentration and immersion time has most significant effect on all the responses; however, drying temperature had no influence on osmotic properties i.e. WL and SO of the slices. In order to have a better flexibility in the selection of operating range, superimposed contour plots having common feasible zone of all the responses for osmo-convective drying have been plotted for any two variables keeping the third variables at fixed optimum values. RTS-2 (Beverage using residual osmotic syrup) was evaluated to be better acceptable than the RTS-I prepared from fresh fruit except the colour as evidenced by both composite scoring method and fuzzy logic. Both the samples remained acceptable after 4 months of storage and could retain substantial amount of biochemical and therapeutic qualities with no significant difference between the samples hence, use of residual osmotic syrup may be recommended which otherwise would be wasted. Using 100 kg of fresh fruits, 250 lit ofRTS beverage (RTSI) may be produced. Using Osmo-convective drying and residual osmotic syrup 7 Kg of dried slices and 165 lit of RTS beverage (RTS-2) may be prepared out of 100 Kg of fruits. Storage experiment of dried samples suggested to use MPP as packaging material for storage of osmo-dehydrated slices up to a period of 4 months without significant loss in therapeutic qualities."

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