Microwave and microwave-vacuum drying of peruvian carrots: influence of process on the quality and kinetic parameters

Abstract

Many studies have been conducted to better understand the mechanisms of microwave drying of food, and to evaluate the quality parameters of these products. The behavior of the microwaves depends on the dielectric properties of each food matrix. Peruvian carrot is an Andean root that triggers a special interest by food science researchers and industry because it has a wide range of culinary applications and great amount of resistant starch and bioactive compounds (carotenoids, phenolic compounds and minerals). However, trade and consumption of Peruvian carrots are restricted due to its perishability. Microwaves can be used for drying roots, extending the shelf life of foods and promoting a fast drying process. The advantage of microwave use is associated with the volumetric heating mechanism, which assists in the development of products with aggregated value by preserving thermosensitive compounds. Vacuum microwave drying increases the product moisture transfer and preserves the oxidative molecules from oxygen action. The aim of this work is studying the behavior of Peruvian carrots during microwave and microwave-vacuum drying, analysing the influence of microwave power level at kinetics parameters and quality attributes. The power level increases the drying rate, sample surface temperature, energy consumption, reduces the drying time, and improves chip quality compared to convective drying. The research observes that higher microwave power level use increased rehydration and crispness, reduced hardness and shrinkage characteristics and preserved β -carotene content. The vacuum application preserved phenolic compounds, β -carotene and color changes. However, it did not influence the physical characteristics of chips. At the end of the drying, Microwave power level did not influenced the drying rate, which can be reduced without loose in the kinetic parameters. In the treatments with two levels of power, the temperature and the energy consumption were reduced and contributed to preserves carotenoids and phenolic compounds of restructured Peruvian carrots chips. In conclusion, microwave power level and vacuum use affect the final characteristics of the product, and behavior during dehydration.