Influência da adição de diferentes culturas de lactobacilos sobre as características de soro de queijo de cabra tipo coalho atomizado (pó) reconstituído fermentado

Abstract

The goat milk whey is a by-product of cheese production and often discharged without any kind of treatment as effluent, becoming a source of pollution. Instead, the use of whey to produce dairy drinks has been a very attractive option, remarkably because of its nutritional value. Probiotic cultures contain microorganisms that bring health benefits to the host by improving its intestinal balance, and they can be used in fermented beverages. This study aimed to evaluate the influence of different potential probiotic lactobacilli cultures on the physicochemical and microbiological features, and also on the pattern of protein degradation on reconstituted and fermented goat Coalho Cheese whey powder. The fermentation process was performed in four trials, C1, C2, C3 and C4, added, respectively, of Lactobacillus casei BGP93, Lactobacillus paracasei BGP1, L. paracasei and Lactobacillus rhamnosus LPC37 LR32, all of them also added of Streptococcus thermophilus TA40 as starter culture. Titratable acidity, pH values, and viability of both S. thermophilus and Lactobacillus sp. were monitored in the reconstituted whey after adding cultures before fermentation (TI), after fermentation (TF), and after 1 (D1) and 7 (D7) days of storage at 4 °C. The use of near infrared spectroscopy (NIR) was evaluated as an alternative method for the determination of Lactobacillus sp. populations. The analyses of proteolysis by the method o-phthaldialdehyde (OPA), ultrafast reversed phase high-performance liquid chromatography (RP- UFLC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS- PAGE) were performed to evaluate the protein degradation in samples throughout the processing and storage period. The whey added of L. rhamnosus (C4) obtained the lowest pH (4.83) and the highest acidity (lactic acid 0.637g / 100 g) after 7 days of storage. The viability of Lactobacillus sp. in all trials (C1, C2, C3 and C4) obeyed the Brazilian criteria for probiotic foods, remaining above 9 log CFU in the recommended daily serving portion (200 ml). The calibration procedure for Lactobacillus sp. values in NIR analysis was adequate; however, it is required additional samples of each trial to improve the performance of calibration models and the construction of prediction models to be performed in future studies. The protein content was around 25 mg/g in all treatments over all sampling periods and, therefore, no significant difference between them was verified (p > 0.05). The chromatograms of the reconstituted whey without addition of cultures showed differences from those obtained for the TI, TF, D1 and D7 sampling periods in all trials, probably due to the thermal treatment of samples prior to the addition of cultures. The degree of proteolysis did not differ significantly between treatments (p > 0.05); however, according with the analysis of all the results, including electrophoresis and chromatography data for the C1 trial, in which low molecular weight fraction was formed, there was a trend towards of higher proteolytic activity in goat cheese whey added of the probiotic culture L. casei BGP93.