The rheological behaviour of clarified mango juice was measured at temperatures 15–85C and concentrations 15–66 °Brix, using a rotoviscometer. Mango juice free of pectin and pulp behaves as a Newtonian fluid. The effect of temperature can be described by an Arrhenius‐type equation. The activation energy for viscous flow was in the range of 1.64–8.44 kcal/g‐mol, depending on the concentration. The effect of concentration was modelled better by an exponential relationship than a power‐law relationship. Simple equations are proposed for describing the combined effect of temperature and soluble solids content on the juice viscosity.

Flour producedfiom steamed and unsteamed unripe bananas was analyzed to determine the effect of steaming on physicochemical properties. Steaming of bananas prior to dehydration slowed dehydration of banana slices, increased water uptake, density and solubility of flour and decreased viscosity, setback, breakdown, discoloration and vitamin C content. Banana flour produced with predehydration steaming gives pastes of low paste bulk density, which is desirable for weaning and supplementary foods.

Osmotic dehydration of cauliflower as influenced by temperature (40‐90 C), salt concentration (5‐25%), ratio of brine to material (2‐4, w/w) and time (5‐180 min), was studied through central composite rotatable design (CCRD) under response surface methodology. Responses of weight loss (%) and salt pickup (%) were fitted to polynomials of second degree requiring 6 and 7 terms, respectively, with multiple correlation coefficients of 0.97 and 0.98. the fitted functions were optimized for maximum weight loss and with 4% salt pickup using a flexible polyhedron search method. Out of four such optimum sets one was selected based on the actual weight losses in the verification experiments with larger batch sizes, color and appearance, texture and rehydration properties of the dried materials. the optimum conditions required the material to be processed at 80C for 5 min in 2 times (w/w) of 12% brine. the selected optimum as well as two other optimum sets also inactivated polyphenol oxidase which causes enzymatic browning.

A B S T R A C TThe dynamics of aroma separation from some tropical fruit juices and pulps was studied using a thin film evaporator. In the case of mango (Mangifera indica Linn, Alphonso and Totapuri varieties) and guava (Psidium guajava Linn) pulps, 90% of each of the volatile .fraction, esters, carbonyls and alcohols, was removed at 30-3.5 % evaporation of the water in a single pass.I n the case of pineapple (Ananas sativa Schult F ) juice, 90 "/, separation of esters and carbonyls required about 80 % and 47 : < evaporation, respectively.However, the behaviour of alcohols in pineapple juice was found to be similar to that of mango and guava. Mango pulp j o m Alphonso and Totapuri uarieties on 60 % evaporation showed a loss in oxygenated terpenes of 80 % and 63 %, respectively, while guava pulp lost about 58 % oxygenated terpenes on 60 % concentration.The dynamics of the total aroma volatiles separation )om the fruit juices and pulps showed that, in a single pass evaporation, 85-90 % volatiles were removed at a juice evaporation degree of 60 % water, while the same extent of aroma removal occurred at 32-35% total evaporation by multiple pass.

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