Orientadora: Profa. Dra. Andresa Carla Feihrmann

Data da Defesa: 26/02/2021


Consumers believe that health is directly related to food, so the interest in “functional foods”, which help in the prevention of diseases, is considered an opportunity for the industry to improve the quality of meat products. Currently the application of probiotics in the preparation of fermented meat products has become an alternative in the development of healthy products, since probiotics are considered live microorganisms that confer benefits to the host, when administered in adequate amounts of 106 CFU/g.
The benefits of probiotic strains are many, they can act beneficially to lactose intolerants, allergies, respiratory tract infection, aging, immune system modulation, among others. The species Bifidobacterium animalis a gram-positive, anaerobic and non-spore forming bacillus, while Lactiplantibacillus plantarum stands out due to its adaptability, in addition to the ability to produce several and potent bacteriocins and Lactobacillus acidophilus stands out for its ability to survive conditions considered adverse effects on the gastrointestinal tract.
Several studies have already carried out the incorporation of probiotic strains in fermented meat matrices, but their incorporation depends on several factors, such as the composition of the product and whether it undergoes heat treatment, which is considered a challenge since the bacteria probiotics are sensitive to heat. Thus, encapsulation can be an alternative to immobilize or trap the microorganism, protecting its cells, preventing loss of viability and enabling the application in several products.
The objective of this study was the production of burgers with the addition of the probiotics Bifidobacterium animalis ssp. Lactis Bb-12®, Lactiplantibacillus plantarum Lp-115® and Lactobacillus acidophilus LA-5® encapsulated, evaluating the physicochemical, microbiological properties, viability of probiotics in raw and cooked products and after simulation of gastrointestinal digestion, frozen at –18 ° C for 60 days.
Material and methods
This work started with the production of microcapsules, the probiotic bacteria Bifidobacterium animalis ssp. Lactis, Lactiplantibacillus plantarum and Lactobacillus acidophilus were used individually and added to the encapsulating solution, the microencapsulation was performed in a mini spray dryer (MSD 1.0 Labmaq, São Paulo, Brazil). For the production of burgers, 80% of beef and 20% of ground pork fat were used. The meat was added to the probiotic strains, with an initial count of 7 log CFU.g-1, and then the burgers were molded. Five treatments were developed, the control formulation (C) without probiotics, B with Bifidobacterium animalis ssp. Lactis, P with Lactiplantibacillus plantarum, A with Lactobacillus acidophilus and BPA with the mixture of the three probiotics. Finally, the burgers were vacuum-packed and stored at freezing temperature (- 18ºC) for 60 days for further analysis. Then moisture, protein content and ash content of the treatments were analyzed according to AOAC (2005). The lipid content was determined using the methodology of Bligh and Dyer (1959). The pH was obtained with a portable digital pH meter (Hanna, HI-99163, Romania). The determination of water activity (Aw) was performed by direct reading on AquaLab 4TEV (Meter Group, USA). The previous analyzes were performed on days 0, 30, and 60 in triplicate, on raw and cooked burgers. The analyzes of substances reactive to thiobarbituric acid (TBA) were carried out according to the methodology described by Wang et. al. (2002). The texture profile analysis (TPA) was performed on the cooked burgers, according to the methodology of Bourne (1978) and the technological parameters were obtained by weighing and measuring the raw burgers, and after cooking, cooling to room temperature was expected (25 °C) and then the products were weighed and measured again, on day 60 of storage. The color of the samples was measured using a colorimeter (Konica Minolta, CR-400, Japan), previously calibrated on a white plate. Three parameters were measured: L * (brightness), a * (red intensity) and b * (yellow intensity) in three different sample locations. Microbiological analyzes were performed on days 0, 30 and 60 of storage. The counting of coliforms at 45 ° C, Salmonella sp., Staphylococcus aureus coagulase positive and reducing clostridia sulfites were performed according to BRASIL (2003). The viability of probiotic microorganisms present in the samples was carried out using serial decimal dilutions, followed by depth inoculations in a specific selective medium, on days 0, 15, 30 and 60. Gastrointestinal digestion in vitro was simulated according to Correa et al. (2017). The data were submitted to descriptive analysis, analysis of variance and Tukey test, at 5% significance level, where different treatments and storage periods were considered fixed effects, with the aid of software R version 1.2.5019 (R Core Team, 2016).
Results and discussion
The humidity of the raw products was not influenced by the application of probiotics, with no significant difference between the formulations (P> 0.05), however in the cooked products there was a reduction in humidity, and a significant difference was observed (P <0.01) between the formulation BPA (58.6%), and formulations B (52.8%), P (52.6), A (53.8%). As expected, with the decrease in humidity after cooking, the values of proteins, ash and lipids increased. The protein content in the raw products varied from 19.8% to 22.2%, with no significant difference between the formulations (P> 0.05), as well as the ash content. There was a significant difference in the pH values (P <0.05) in the raw and cooked samples, in the last there was an increase in pH on day 30 for all formulations (P <0.05), followed by a drop at the end of storage (P < 0.05). According to some authors, this decrease in pH during the storage of meat products is attributed to the production of lactic acid by the lactic acid bacteria, however, as in this study the probiotics were encapsulated, their participation in the reactions was probably small and that is why it is possible that other lactic acid bacteria naturally present in meat may have caused this effect. In this study, Aw values ranged from 0.97 to 0.99 for raw burgers, while for cooked products these values were 0.96 to 0.99. There was a significant difference (P <0.05) in the TBARS values of the burger samples compared to the control. In this sense, raw formulations A and P during storage were those that had the highest mean values, 0.18 and 0.13 mg malonaldehyde/kg, respectively, in relation to the control. After cooking, there was no significant difference (P> 0.05) between the probiotic treatments and the control until the 30th day of frozen storage. However, on day 60 all treatments showed an increase in TBARS values and were different from C (P <0.05), although lipid oxidation is a temperature-dependent reaction, freezing is not necessarily sufficient to prevent oxidation from occurring, despite that, the values are within the acceptable value for consumption. In general, the products showed a small weight loss, showing a statistical difference (P <0.001) between all treatments, ranging from 17.93 to 24.26%. There was a significant difference in the values of diameter reduction compared to the control (P <0.05), with the exception of BPA. The hardness values ranged on average from 22.21 to 40.18 N, the addition of Lb. plantarum to the burger decreased the values of the hardness parameter (22.21 N), differing statically (P <0.001) from all other formulations. It is possible that release may have occurred Lb. plantarum present in sample P and this produced a small amount of acids that acted in a lesser hardness. Formulation P showed the lowest mean values of cohesiveness, elasticity and chewability, 0.30, 0.57 and 3.91, respectively. The Brightness parameter (L *) showed no significant difference (on day 30) between formulations in relation to the control (P> 0.05) and at 60 days all formulations showed a decrease in brightness compared to day 0, except for BPA, as expected, in the cooked products there was a reduction in luminosity possibly resulting from the non-enzymatic reaction during the cooking process. The a* values of the raw samples showed no difference on day 0 regardless of the probiotic used (P> 0.05). Regarding the b * values in general, the cooked samples showed higher values (~ 19.87) than the raw ones (~ 11.25). While the h * values ranged from 24.64º to 69.50º in raw and cooked formulations, respectively, the color variation being from red to reddish- orange. The result of the microbiological analyzes showed absence of Salmonella spp. For Staphylococcus aureus positive coagulase and reducing sulfite clostridia, counts below 2 log CFU/g were obtained, for thermotolerant coliforms at 45 ºC the counts were below 3.0 MPN/g. Regarding viability, at the beginning of storage it is possible to verify that the counts of BB-12 (raw product) varied by an average of 8.44 CFU log. g-1 in the BPA formulation and 10.03 CFU log. g-1 in formulation B, and at the end of storage both treatments showed values above 8 CFU log. g-1. Lb. plantarum counts were higher (P <0.05) in the BPA formulation on days 0, 15 and 30, while on day 60 the P treatment showed an Lb. plantarum value of 9.75 CFU log. g-1 (P <0.05). The counting of L. acidophilus was possible to verify that A showed greater viability (P <0.05) at the end of the storage period (60 days). All formulations had counts above 7 CFU log. g-1 in the cooked product. Whereas the consumption of burger is carried out after thermal processing, the burgers in this study can be considered potentially probiotic products. After passing through the gastrointestinal tract, it was found that Bifidobacterium Bb-12 had a count of 6.60 CFU log. g-1, Lb. plantarum was 6.00 CFU log. g-1 and L. acidophilus of 6.53 CFU log. g-1, and the probiotic must survive the journey from mouth to colon after consumption in order to exercise its probiotic functions.
The results showed that it is possible to produce a functional meat product with the application of Bifidobacterium animalis ssp. lactis, Lactiplantibacillus plantarum and Lactobacillus acidophilus. Microencapsulated probiotics were resistant to cooking and simulation of gastrointestinal digestion.
Keywords: Probiotics, burger, functional meat products, in vitro digestion

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