STABILITY OF MANGO PEEL FLOUR OBTAINED BY CONVENTIONAL AIR DRYING ALONG STORAGE AT DIFFERENT TEMPERATURES

Mango is a widely consumed tropical fruit throughout the world due to its exotic and outstanding taste, and is also an important source of nutrients. Mango peel is a major by-product obtained during the processing of mango products, containing high levels of vitamins, minerals, antioxidants and fibers. The inappropriate disposal of co-products becomes a potential cause of environmental problems and also implies loss of valuable nutrients. The new consumers’ demands have required the development of foods regarding healthiness and well-being aspects, through the use of natural ingredients. Therefore, processing of mango peel into flours represents an excellent alternative to add value to these fruit by-products, answering the new food trends, besides reducing postharvest losses and increasing the sustainability of food chain. The drying of fruit co-products results in a more stable ingredient, but process conditions may affect the stability of bioactive compounds due to chemical and enzymatic degradation, losses by volatilization and/or thermal decomposition. In this context, the purpose of this work was to study the stability of mango peel flour stored at different temperatures during 6 months, evaluating the degradation of vitamin C, carotenoids and color parameters throughout storage. Drying experiments were performed in a tray dryer with air circulation (velocity of 1.5 m/s) at 65°C during 5 hours. Then, dried samples were milled to fine powder using a grinder mill and mesh sieves of 1.25 µm particle size. The flours were placed in polyester/aluminum/low-density polyethylene (PET/Al/LDPE) bags with 70 μm nominal thickness and stored at 10, 25 and 35ºC for 180 days at 60% RH. Samples were periodically analyzed with respect to color parameters, vitamin C, phenolic compounds, total carotenoids and antioxidant activity. Furthermore, powders were also subjected to morphological analyses at 0 and 180 days of storage. Antioxidant activity was practically maintained for all the samples throughout storage time (around 320 µmol TE/g). The initial phenolic compounds content was about 2500 mg GAE/g and their reduction varied from 10 to 20% after 180 days. The degradation of vitamin C and the variation in chroma parameter (C*) were adjusted to first order kinetic models with Q10 ranging between 0.89 and 2.07 and R2 > 0.93. At the beginning of stability study, vitamin C and total carotenoids contents were about 370 mg/100g and 14 mg beta-carotene/100g. As temperature increased, higher losses of vitamin C and beta-carotene were observed. Regarding morphology, mango peel flour stored at 35ºC presented a high level of agglomeration after 180 days. Mango peel flour stored at lower temperatures showed good retention of vitamin C, besides high antioxidant capacity and total polyphenols content. These powders can be used as a potential ingredient in the development of innovative food products, attending the current demand for healthier products.

Financial support: The authors are grateful for FAPESP (Process number 2015/12303-3) and CAPES for the financial support.