(160c) Aloe Vera Gel As Natural Additive to Improve Oxidative Stability in Refrigerated Beef Burger Stored in Aerobic and Vacuum Packaging

Beef burger has stood out in the face of new consumer demands for convenience products in food industry. However, beef burger commercialization is limited by its high perishability and reduced shelf life. Quality deterioration in meat, besides microbial growth, mostly occurs because of oxidative reaction, namely lipid oxidation and myoglobin (Mb) oxidation. These reactions lead to change in organoleptic characteristics in burgers and thus consumer rejection. Lipid oxidation results in formation of many hydrocarbons, especially malondialdehyde, which promotes off-flavors development. In Mb oxidation, Mb is oxidized forming metmyoglobin (MMb), leading changes in meat color. The use of vacuum packaging and formulation of burger with active agents are two alternatives which can be used to reduce oxidative reactions. Moreover, the combination of these two technologies may result in even better effects. Aloe vera gel is a potential additive to be used in burger formulation because of its antioxidant activity, besides it is a natural agent. Given the importance, this work aimed to evaluate the influence of interaction of packaging atmosphere and use of different concentrations of Aloe vera gel as natural additives on the shelf life of beef burger during refrigerated storage at 4 °C. A complete factorial experimental design 2² was carried out, to verify the influence of packaging atmosphere (atmospheric pressure and vacuum) and concentration of Aloe vera gel (2% and 4%). Control Samples were also prepared. The burgers were formulated, packaged and submitted to refrigerated storage at 4 °C for 7 days, and their quality was evaluated on days 0 (when the burgers were prepared), 3, 5 and 7 of storage. The Aloe vera was extracted from Aloe vera through maceration, after removal of Aloin. The parameters evaluated were lipid oxidation (TBA value, in mg MDA.kg^-1burger), pigment oxidation (through metmyoglobin formation, in % of total pigments) and color (a* value), all in duplicate. The Statistica 7.0 software was used to evaluate the results, through Tukey's test with 5% significance. Lipid oxidation at the beginning of the experiment was 0,26 mg MDA.kg^-1burger. During the storage period, TBA value increased (statistical significance) for all treatments. Vacuum packaging and the addition of Aloe vera gel reduced lipid oxidation, especially after day 5 of storage, and differences (statistical significance) from Control Samples had grown with storage period. Beef burgers stored formulated with 2% and 4% Aloe and in aerobic packaging presented a decrease in oxidation of 43,6% and 52,6%, respectively, while burgers stored in vacuum presented a decrease of 53,9% (2% Aloe vera) and 60,8% (4% Aloe vera), compared with the worst condition, which was control sample in aerobic packaging. Comparing only control samples, vacuum packaging reduced lipid oxidation in 18%. Vacuum packaging reduces oxidative reactions by reducing oxygen availability in packaging. The active agent, especially in higher concentration (4%) also showed to be very effective in improving lipid stability. Aloe vera contains a large amount of bioactive compounds, as polyphenols, which have stronger free radical scavenging abilities. So, bioactive compounds of Aloe can act in the second phase (propagation) of lipid oxidation, reacting with radicals present in burger, thus forming stable products and avoiding the formation of undesirable ones. MMb content also presented significant changes during storage. At day 0, beef burger presented a MMb content of 12,15%. Control Sample stored in vacuum and burger formulated with 2% Aloe were the treatments which presented the highest initial increasing, presenting in day 3 a content of 23,19% e 24,23% (no statistical difference between these samples). Low oxygen partial pressure inside the packaging in the firsts days of experiment may had favored the transformation of Mb in MMb, while high concentrations of Aloe presented an antioxidant effect, reducing MMb formation. In the following days, due to oxygen permeation through packaging, MMb content in beef stored in vacuum packaging was reduced, especially in beef formulated with additives. Control sample stored in aerobic packaging was the treatment which presented the highest MMb content (27,6%) at the end of the storage, followed by Control Sample stored in vacuum (21,5%). Microbial growth is the main cause of MMb formation in aerobic packaging. The addition of Aloe vera gel reduced (statistical significance) MMb formation, particularly high concentrations of Aloe vera (13,27%). The lowest level found, however, was in burgers formulated with 4% Aloe vera gel and stored in vacuum (12,06%). Analyzing meat color, particularly a* value, is also very important, since color is a key factor in product purchase decision and read color is seen by consumers as an indicative of freshness. Fresh meat (day 0 of storage) presented an a* value of 30,45. At the third day of storage, Control Sample stored in vacuum presented the highest change in a* value (-12,24 0,07), which coincides with the highest MMb content is this day. At the end of the storage, Control sample stored in aerobic (-12,5 2,51) and vacuum (-7,40 1,30) presented the greatest changes in a*, which also corresponds to the greatest changes in MMb. The conditions which most improved the maintenance of a* value were high concentration of Aloe and aerobic packaging (-2,15 0,00), and low (-0,21 1,92) and high concentration (-0,21 1,92) of Aloe in burgers stored in vacuum packaging. No statistical differences were found among a* value of these three samples at day 7. As could be noted, the combination of vacuum packaging and Aloe vera gel as active agent in beef burger formulation, is a potential alternative to reduce deteriorative reaction in beef burger. Results of this work can be used as primary information for the improvement and development of technologies in meat industry, collaborating with the global need to reduce food waste. This study was financed in part by the Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina - Brasil (FAPESC).