Microscopic features, mechanical and thermal properties of osmotically dehydrated guavas

Characterisation and performance assessment of guava (Psidium guajava L.) microencapsulates obtained by spray-drying

“…On the other hand, DSC profiles for these samples are very complex and involve a first process of glass transition below 50°C (Iijima, Nakamura, Hatakeyama, & Hatakeyama, 2000;EinhornStoll & Kunzek, 2009) that indicates a likely re-organisation of pectin polymeric-chains contained in guava (1.52 g/100 g fresh fruit), since this curve-decline could not be observed in the DSC profile of pure maltodextrin . Also, a continuous and broad endothermic peak centred on 150°C (but showing a shoulder at 210°C) was observed in both cases (MD and AGMD-1 samples) due to the melting point of pectin contained in guava (Iijima et al, 2000;Pereira et al, 2009). A strong endothermic peak centred on 240°C, detected for the MD sample, clearly can be assigned to the melting point of maltodextrin .…”

“…The mass of the MD sample is very stable until 160°C, but a pronounced loss of mass was observed after 200°C for both MD and AGMD-1 samples. Loss of mass in these materials along this temperature range can be understood as a possible degradation or thermal decomposition of one or more components (polysaccharides) and their subsequent volatilization (Mothé & Rao, 2000;Einhorn-Stoll & Kunzek, 2009;Pereira, Carmello-Guerreiro, & Hubinger, 2009). So, it is very important that MD sample surpasses the 100°C without loss of mass, because this is a typical temperature for sterilisation processes in food industries.…”

Thermal, Structural, and Physical Properties of Freeze Dried Tropical Fruit Powder

“…Thermal stability of freeze dried fruit powder was investigated by thermogravimetric analysis. The TGA-DSC curve of guava, sapota, and papaya fruit powder is shown in Figure ∘ C dehydroxylation, demethoxylation, and decarboxylation reactions should be occurring on pectin and similar polysaccharides (pectin is the main component of dehydrated guava) [21][22][23]. The total loss of weight for samples is 69.52% at 545 ∘ C; the residue left after incineration at 980 ∘ C is 14.32%, indicating the thermal stability of guava powder.…”

Recent Developments in Osmotic Dehydration

“…Pereira et al (2009) studied the effects of different osmotic solutions (sucrose and maltose solutions, 40 and 60 Brix) on the microscopic features and some mechanical and thermal properties of guava tissue. The osmotic process, by using both the solutions, resulted in severe structural damage to the guava tissue.…”