Coproduto da própolis como inibidor da oxidação lipídica em biscoitos de polvilho

Abstract

The anti-inflammatory, antimicrobial, immunostimulating and, in particular, antioxidant properties of propolis, are largely due to the presence of phenolic compounds. The correlation of bioactive compounds with propolis's antioxidant properties and, the maintenance of these in the coproduct of the commercial extraction of propolis, stimulate studies on the use of the coproduct. In the area of food, one of the challenges for taking advantage of the potential antioxidant properties of the propolis co-product is to be considered in the perspective of analyzing its use as a lipid oxidation (OL) inhibitor in food products made up of oils or fats and subject to cooking. Thus, the objective of this study was to evaluate the effects of the addition of lyophilized (LFCP) and microencapsulated (MECP) extracts of the propolis co-product on the inhibition of the lipid oxidation of starch biscuits made with canola oil. For this, the hydroalcoholic extraction of the propolis co-product was carried out and, from this, lyophilized extracts (LFCP) and microencapsulated by spray drying (MECP) were prepared, which were added to the starch biscuits. In this way, 4 formulations of polvilho biscuit were elaborated, which differ according to the antioxidant employed: F1 - polvilho biscuit free of antioxidant (control); F2 - starch biscuit containing butyl hydroxytoluene (BHT); F3 - starch biscuit containing microencapsulated extract of the propolis co-product (MECP); and F4 - starch biscuit containing the lyophilized extract of propolis by-product (LFCP). The antioxidant potential of the extracts was evaluated by the method of free radical scavenging (ABTS and DPPH) and by the iron reducing power (FRAP). In addition, the phenolic compounds in the extracts were identified by high performance liquid chromatography with electrospray ionization coupled to mass spectrometry (HPLC-ESI-MS). The production of malonaldehyde (MDA), a product of lipid oxidation (OL) by the method of thiobarbituric acid reactive substances (TBARS) and the fatty acid profile determined by gas chromatography coupled to the flame ionization detector (GC-FID) were evaluated in the cookies fortnightly, during 45 days of storage at room temperature (25 °C). The LFCP and MECP extracts had a total phenolic compound content of 199.78 and 69.28 mg EAG g-1 of sample (EAG: equivalent in gallic acid), respectively. The LFCP extract showed antioxidant activity superior to the values achieved by the MECP extract by all the methods employed. The microencapsulation process showed good efficiency, equal to 62.97%. This result shows that the process parameters and the encapsulating material used were adequate. The characterization of phenolic compounds by HPLC-ESI-MS analysis allowed the identification of three phenolic compounds (cumáric acid, pyrocatechol and siringic acid), compounds already mentioned in propolis characterization studies. Through the analysis of fatty acids by GC-FID it was possible to identify the main fatty acids present in canola oil (C16:0, C18:0, C18:1n-9, C18:2n-6 and C18:3n-3), by which the verification of the maintenance of their contents with the storage time is positive. In addition, the TBARS values found in the starch biscuits and the fatty acid profile observed in the samples during the storage period give rise to a positive effect of the application of LFCP and MECP in the inhibition of lipid oxidation.