FLOUR FROM YELLOW AND SWEET PASSION FRUIT PEELS: BIOACTIVE COMPOUNDS, PHYSICAL AND TECHNOLOGICAL PROPERTIES AND HYGROSCOPIC BEHAVIOR

Passion fruits are fruits especially appreciated for the production of juices, but the pulp corresponds to a small percentage of the mass and total volume of the fruit. The peels, which account for most of the volume, are raw materials with a mild flavor, containing fibers and bioactive principles that make them a fully usable material, mainly for incorporation into other flours. The work was carried out with the aim of determining the bioactive compounds, physical and technological properties and hygroscopic behavior in the flours from the peel of passion fruit of the yellow (Passiflora edulis) and sweet (Passiflora alata) species. The passion fruit peels were ground in a processor, placed in stainless steel trays in a 0.5 cm thick layer and dehydrated in an oven with forced air circulation at temperatures of 50, 60, 70 and 80 °C and air velocity from 1.0 m/s to constant mass. After drying, the samples were crushed in a processor, transforming them into flour. The bioactive compounds, total phenolics (TPC), tannins, flavonoids and anthocyanins were determined in the flours; physical and technological properties Hausner factor (FH), Carr index (CI), solubility, water and oil absorption capacity; and the moisture adsorption isotherms in a dew point hygrometer at 25 oC. All experiments and analyzes were performed in triplicate. It was observed that there was a significant influence of drying temperature and specie on the levels of bioactive compounds in the flours. TPC and tannins had higher levels in flour obtained at higher temperatures and flavonoids and anthocyanins at lower temperatures. The TPC contents of the yellow passion fruit flour were higher than that of the sweet passion fruit at the drying temperatures of 50 and 60 oC, while the tannins were the opposite with the highest contents of the yellow passion fruit flours at the temperatures of 70 and 80 oC compared to the sweet passion fruit flour. Higher levels of flavonoids and anthocyanins were detected in yellow passion fruit flour. The flours of both species showed low Carr and Hausner indices, corresponding to low cohesiveness and very good fluidity. In sweet passion fruit flours, higher solubility, hygroscopicity and oil absorption capacity were determined; and in yellow, greater water absorption capacity. The water adsorption isotherms of the flours were classified as type II and III and well fitted with the GAB model. Yellow and sweet passion fruit peel flours proved to be a source of bioactive compounds with good fluidity, which can be used as ingredients in foods.