Nutritional, technological and functional characterization of freeze dried tropical fruit pomaces.
Tropical fruit, industrial waste, phytochemicals, thermal treatment.
The dietary consumption of fruit is associated with beneficial health effects due the presence of fiber, vitamins and bioactive compounds, especially phenolic compounds (PC) and vitamins antioxidant activity. Brazil has a diversified production of tropical fruits such as acerola, guava and cashew usually processed and forming large amounts of agro-industrial pomaces. Thus, this study aimed to characterize freeze-dried acerola pomace (ACE), guava (GUA) and cashew (CAS) as their nutritional, technological and functional aspects associated with the thermal-treatment study of the bioactive content. The residues have high values of dietary fiber, especially insoluble in GUA (40.6%) and soluble in ACE (14.2%). The protein value (13.8%) and lipids (9.2%) was higher for the GUA, but in general, all pomaces have reduced calorie content. The featured minerals were potassium, calcium and magnesium, especially in CAS (K: 83.5 mg/g) and ACE (Ca: 31.9 mg/ g and Mg: 2.8 mg/g). As the technological aspects, all residues showed low hygroscopicity and promising water holding capacity (4,4 – 12,0 g/g) and oil (3,0 – 5,4 g/g). The ACE was the higher total PC (5331.7 mg AGE/ 100g), total flavonoid (760.9 mg CE/ 100g) and antioxidant activity (688.1 μmol TE/g in ORAC) and GUA presented higher proanthocyanidins (217.8 mg PA2/ 100g). The ACE has the outstanding phenolic profile, with salicylic acid (3503.4 mg/ 100g), myricetin (929.4mg / 100g) and catechin (498.2 mg/ 100g). No residue showed antibacterial activity to the studied microorganisms. The ACE was more sensitive to heat treatment with retention of total PC reaching 29% at 150 °C. However, the antioxidant activity showed higher retention to all pomaces and temperatures (above 70%). In the case of CAS an increase up to 133% at 150 ° C was detected, which may be related to the formation of melanoidins in all pomaces (with variations up to 582%). All these data conclude that the freeze dried pomaces have a high nutritional, technological and bioactive potential, including in the fortification of other food matrices.