CHANGES IN COLOUR AND TEXTURE DURING OSMOTIC DEHYDRATION OF GREEN BANANA
Green banana is a complex carbohydrates source, mainly of resistant starch, that escapes from digestion the small intestine of healthy individuals. The aim of this research was to verify the effects of osmotic dehydration on the texture and colour of green banana (Musa cavendishii). The osmotic dehydration of green banana was carried out at 25 °C with glycerol and sorbitol solutions 60 g/100 g and also with a 60 g/100 g mixture of both solutes at 30:30 proportion. The samples were immersed in osmotic solutions up to 2 and 4 h. Colour parameters (L*, a* and b*) were measured and colour difference total (ΔE*) was determined. Biaxial compression until 40 % deformation was determined and was analyzed stress, Hencky strain rate, biaxial extensional viscosity and apparent modulus of elasticity. Independent of the solute employed, osmotic dehydration caused colour variation in the samples, in general, values L* parameter decreased, and values of a* and b* have increased when compared to untreated samples, however this behavior caused lower average values in ΔE* (5,45-8,07). Values of mechanical properties of osmodehydratred samples such as stress, biaxial extensional viscosity and apparent modulus of elasticity were lower and strain rate values did not vary significantly regarding as fresh samples. The graphical representation of the biaxial viscosity versus rate deformation showed that the samples dehydrated with glycerol, and a mixture preserved better these parameters regarding as fresh samples. Results indicate that the osmotic dehydration with non caloric solutions maintained colour obtaining a product less viscous and rigid.