Development of films from mango peel pectin added with phenolic antioxidants


Abstract: México is the fourth producer of mango around the world with ~1,767,653 tons/year nevertheless it has to face loss of almost 30 % of production. Mango peels (MP) represent about 16-19 % of the total weight of the fruit. These peels are mostly thrown into nature or used for animal feeding, but is an important source of pectin, fiber and polyphenols (TPMP). Conventional packaging films, plastics, have led to serious ecological problems due to their non-biodegradability. A new alternative is the use of natural polymeric materials that has been studied to replace the conventional packaging materials. Also, these edible films have been reported as a carrier of natural additives. In this context, this Thesis aimed to provide added value to natural materials from by-products. In particular, the research undertaken was directed to the extraction and partial characterization of pectin and polyphenols from MP and their use to manufacture of edible films. The objective was related to determine the effect of pectin, glycerol and candelilla wax concentration on water vapor permeability (WVP) of edible films. Three concentrations of each component were tested. For each film the WVP, thickness, moisture, film transparency and light transmission rate were measured. For Mango var. Ataulfo, the dry peels represent 2.66 % of the fresh mango and the yield of pectin using a microwave-assisted hydro-extraction was up to 10.43 % dry weight with low degree of esterification. Also, MP are an important source of total polyphenols (72.61 mg/g dry peels) with higher content of hydrolysable tannins (427.06 mg GAE/g TPMP), antioxidant capacity (72.18, 37.73 and 39.23 ppm of TPMP to inhibit DPPH, ABTS and LO reactions in 50 %) and antifungal activity against C. gloeosporioides, Mucor sp., S. sclerotiorum (703.23, 757.17, 1275.70 ppm to inhibit 50 % radial growth, respectively) and F. oxysporum (930.07 to inhibit 33.33 % radial growth). The optimized film formula on the basis of the lowest WVP was: 1.0093 % w/v of pectin, 0.1646 % w/v candelilla wax and 0.3282 % v/v of glycerol to obtain a WVP. This edible film was added with TPMP and it showed to improve the shelf life of mangoes up to 14 days at room temperature in comparison with the control. In conclusion, pectin, candelilla wax, glycerol and TPMP can be used as edible coatings for application on mango, turning these coatings into promising alternative of packaging materials.

Tesis Romeo Rojas