OPTIMIZATION OF PROCESS VARIABLES AND SENSORY EVALUATION OF PROBIOTIC “REQUEIJÃO” ENCAPSULATED BY SPRAY DRYER

The incorporation of probiotic bacteria in foods has increased lately due to their beneficial effects on intestinal microflora. Traditionally, probiotics have been added to dairy products. However, to date no work has focused on the use of probiotic microorganisms in "requeijão". Thus, the aim of this study was to develop a new probiotic product with "requeijão" containing Lactobacillus rhamnosus ATCC 9595 and evaluate the influence of process variables as well as evaluate the acceptance of product. For this purpose, Lactobacillus rhamnosus ATCC 9595 was inoculated in the 10% (w / v) (1010 CFU.mL-1) "requeijão", kept in a water bath at 40 °C for 4 hours and stored under refrigeration (8±2 °C) for 24 hours prior to encapsulation. The mixture was then encapsulated using a mini spray dryer Labmaq model MSD 1.0. The 11 assays were performed according to the completely experimental design 23. In order to evaluate the influence of independent variables: air inlet temperature (90 to 140 °C), feed flow rate (0.40 a 0.80 L/h) and encapsulating agent concentration (10% maltodextrin DE 10 + 0.5% to 1% gelatin) on the dependent variables: water activity, moisture content, hygroscopicity and microbial viability count. The sensory evaluation was performed with 100 untrained panelists. The formulation of the probiotic "requeijão" in powder been subjected to acceptance and purchase intent test. Results showed, the variables that influenced the final product water activity (0.10 to 0.25) and moisture content (1.36% to 3.20%) were the temperature, the feed flow rate and gelatin, that is, higher percentage of gelatin, higher temperature and lower feed flow rate resulted in a powder with lower water activity and moisture content. The hygroscopicity of powders ranged from 8.92 to 10.79 g/100g-1. Lower percentage of gelatin and lower temperature conferred lower hygroscopicity to the powder. An increase in the inlet temperature results in an increase of the hygroscopicity, because high temperatures promote greater evaporation of the water, reducing the humidity of the powders and, conversely, it increases its hygroscopicity that is, increasing its capacity to adsorb the humidity of the environment. Although there was a variation of the microbial viability values (7.41 to 9.20 CFU.mL-1) all the powders presented viable cell counts above 6.0 log CFU.mL-1, which is the minimum recommended level for probiotics in food products necessary to for produce therapeutic benefit. Since temperature was the only variable, that significantly influenced cell viability, the lower the temperature the greater the viability. Sensory analysis data showed an acceptability index greater than 80% and higher frequency purchase intent to "certainly and probably buy" the product (87.78%). With the results of the experimental design and the sensorial tests the best process condition was air temperature 90 ºC, mass feed flow rate 0,40 L/h and maltodextrin 10% and gelatin 1%. Thus, the "requeijão" have been suggested as novel and appropriate media for probiotic bacteria cultivation, demonstrating to be an option for food industry.