Evaluation of the effects of focused microwave processing on liquid foods
| Grant number: | 14/25041-4 |
| Support type: | Scholarships in Brazil - Master |
| Effective date (Start): | March 01, 2015 |
| Effective date (End): | February 28, 2017 |
| Field of knowledge: | Agronomical Sciences - Food Science and Technology |
| Cooperation agreement: | Coordination of Improvement of Higher Education Personnel (CAPES) |
| Principal Investigator: | Jorge Andrey Wilhelms Gut |
| Grantee: | Tiago Augusto Bulhões Bezerra Cavalcante |
| Home Institution: | Escola Politécnica (EP). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Associated research grant: | 13/07914-8 - FoRC - Food Research Center, AP.CEPID |
Abstract Thermal pasteurization processes and commercial sterilization are widely used for the processing of fruit-based liquid foods, such as pulp and juice, with some deterioration of sensorial and nutritional quality associated with the high temperature. The emerging technology of focused microwaves brings the advantage of the rapid volumetric heating without surface overheating, which can reduce the impacts caused by the passage of the product in a heat exchanger. In addition, studies report non-thermal effects of microwaves on the inactivation of enzymes, the main targets of thermal processes of these products, which would allow the operation under milder conditions. However, confirmation of non-thermal effects is still controversial in the scientific literature. Thus, the objective of this research is to investigate thermal and non-thermal effects of microwaves on the inactivation of enzymes polyphenoloxidase (PPO), pectinesterase (PE) and peroxidase (POD), which are relevant for the processing of fruit-based products. To eliminate sources of variability, commercial enzymes in standardized media that simulates liquid foods will be subjected to conventional (immersion bath) and microwave (mini-reactor for microwave chemical synthesis) treatments, with record of temperature history and residual enzyme activity. The numerical integration of the lethality function of each test linked to an optimization problem to adjust kinetic parameters will allow greater reliability, avoiding the influence of the heating rate. First order kinetic models with one or two components and temperature dependency expressed by Arrhenius or Z value will be tested. Results will be compared with data reported in the literature for evaluation of reliability and consistency. The comparison between results obtained by conventional and microwave processes will allow the quantification of possible non-thermal effects of microwaves on the activity of the enzymes tested, providing important information for the design of production processes products such as orange juice, juice apple and coconut water. (AU) | |