Aplicação de extrato de café em iogurte probiótico: efeito nas propriedades químicas, físico-químicas, microbiológicas e sensoriais

Abstract

Dairy products such as yogurts have a high nutritional value, being susceptible to the action of deteriorating and pathogenic microorganisms, which makes it important to develop alternatives to reduce or eliminate the undesirable microbiota in these products. The use of substances of natural origin, such as coffee extract, is an interesting option because it has antimicrobial potential, in addition to providing an appreciable flavor by consumers. This work aimed to evaluate the effect of adding roasted Coffea canephora extract on the growth of pathogenic and spoilage microorganisms in probiotic yogurt, in addition to the starters and probiotic bacteria. Yogurt formulations were produced with the addition of 5.0% Coffea canephora extract (EC) and probiotic cultures of Lactobacillus acidophilus (La) and/or Bifidobacterium animalis subsp. lactis (Bal). Eight assays were obtained, one corresponding to the standard (P) without coffee extract or the presence of probiotic microorganisms (P, PEC, PLa, PLaEC, PBal, PBalEC, PLaBal and PLaBalEC). The eight formulations were repeated with strains of Salmonella enterica serovar Typhimurium ATCC 14028 and Escherichia coli ATCC 43888, which corresponded to the positive control. Samples without contaminating microorganisms corresponded to the negative control. Microbial growth was evaluated for seven weeks (42 days) by counting the lactic cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus; of the probiotic microorganisms Lactobacillus acidophilus and Bifidobacterium animalis subsp. lactis; in addition to Escherichia coli, Salmonella sp. and molds and yeasts. For the negative control assays, the characterization of the chemical composition, physical-chemical properties, texture and viscosity profile, microbiological quality and sensory evaluation was carried out. It was identified that there was the maintenance of the viability of the microorganisms of the starter cultures and probiotics in the presence of the coffee extract. However, the coffee extract acted as a growth inhibitor for Escherichia coli and Salmonella enterica serovar Typhimurium after 6 to 7 weeks of storage. Therefore, it can be said that there was an antimicrobial effect of the roasted Coffea canephora extract on the growth of pathogenic microorganisms without affecting the viability of starter cultures and probiotics in the formulated yogurt. It was also verified that the yogurts complied with the Brazilian legislation for the contents of lipids, proteins and acidity. The physical-chemical properties, texture profile and viscosity analyzed remained under the technological aspects for the development of yogurts. Regarding the sensory attributes of appearance, color, flavor, texture and overall impression evaluated in P, PEC, PLaBal and PLaBalEC, the tests with coffee extract (PEC and PLaBalEC) had lower acceptability indices, except for the aroma attribute, where the probiotic yogurt with the addition of coffee extract showed a higher acceptability index. Considering the overall impression, the four tests showed values greater than 70%, admitted as a minimum percentage of the acceptability index. The results indicate that the canephora coffee extract can be applied as an alternative antimicrobial agent in the control of pathogens in dairy products containing probiotic microorganisms, and also indicate its potential from the technological point of view, for application in other food matrices.