Novel ready-to-eat mango product using gellan gum as gelling agent: physico-chemical, microbial and sensory characteristics

Este trabalho foi efectuado com o apoio da Universidade de Lisboa, Instituto Superior de Agronomia com o Centro de Engenharia dos Biossistemas (CEER

The development of novel food products designed to maximise both the health benefits and enjoyment of the consumer’s eating experience is an important area of research nowadays. Fruits and vegetables are also increasingly recognized as important components of a healthy diet. Within this context, the work in this thesis aimed the development of a novel convenient food product – fresh like mango bars - based on mango (Mangifera indica L) and gellan gum, designed to have sensory quality similar to that of fresh mango, to be of easy consumption and to have an extended shelf-life. The influence of gellan concentration and of the ratio of L (low acyl)/H (high acyl) gellan on the rheological and microstructural properties of mango/gellan gels was studied. This allowed optimising the concentration of gellan. The effect of the L/H ratio on texture, microstructure, syneresis and sensory acceptance was evaluated. Results separated bars into two sets: one showing a higher hardness and lower syneresis (only L gellan and L/H in the ratios of 75/25 and 50/50); and the other with bars having a higher proportion of H, with a softer structure with higher cohesiveness and syneresis (L/H25/75 and only H gellan). Through sensory analysis the bar with L/H 25/75 was identified as the preferred one. An edible coating was developed to improve the characteristics of the product. Its optimization was performed by the use of experimental design and mathematical modelling. Results showed that the coating improved appearance and firmness of bars, and reduced syneresis and volatiles loss during storage. Thermal and high hydrostatic pressure preservation treatments were applied on packaged products. Both treatments had similar performance considering microbial content and aroma release. Thermally treated bars were stored at 5 °C during 21 days, without changing significantly their texture, colour, microbial loading and sensory attributes. Overall results show that the process allows producing a stable ready-to-eat mango bar product appreciated by the sensory panellists.

Fundação para a Ciência e a Tecnologia (FCT)- (SFRH/BD/64341/2009); FCT-MCTES funding the projects PTDC/AGR-ALI/114706/2009 and PEst – OE/AGR/UI0245/2014