Dados do Trabalho

Título

BEHAVIOUR OF AUTOCHTHONOUS LACTIC ACID BACTERIA IN FERMENTED MILK SUPPLEMENTED WITH SUGAR SUBSTITUTE

Introdução

The objective was to evaluate the growth kinetics of the potentially probiotic strain Lactococcus lactis GV103 in coculture with commercial strain Streptococcus thermophilus STI-12 in fermented milk with sugar substitute. Furthermore, syneresis and water retention capacity (WRC) were assessed.

Material e Métodos

The experiments were carried out with three different carbohydrate sources: sucrose (control-CT), sucrose added with xylitol (XIL), and sucrose added with artificial sweetener (sodium cyclamate and potassium acesulfame) (AD). The formulations were 12% skim milk, 5% sucrose, 2% xylitol e, 0.05% sodium cyclamate, and potassium acesulfame. The sugar substitutes were added separately, according to the experimental plan. The LAB population was counted every 30 minutes until pH 4.6. The effect on syneresis and WRC was evaluated at the end of fermentation of the final product and after 14 and 28 days of storage at 5°C. The Baranyi & Roberts model (1994) was published in the DMFIT online edition for microbial parameters estimation. All experiments were carried out in triplicate. The statistical differences were evaluated by Tukey's test (p<0.05).

Resultados e Discussão

The growth potential (δ) for GV103 varied from 1.73, 0.88, and 2.07log CFU/mL for CT, XIL, and AD, respectively. Growth rates(μ) ranged from 0.77 to 1.73h-1 in XIL and CT, respectively. The lag time varied from 3.64h to 5.38h in AD and CT, respectively. The R² of the models ranged from 0.68 to 0.90, showing a good fit. The syneresis was 58.28%, 58.35%, and 61.83% in AD, XIL, and CT, respectively, after 28 days. These results showed no significant difference between samples (p<0.05). However, in WRC, there was a difference in samples supplemented with artificial sweeteners (AD). In this treatment, the WRC decreased from 37.66% to 16.91%. Conversely, the WRC for treatments of CT and XIL did not show differences after 28 days of storage.

Conclusão

Despite the impact on microbial growth parameters, supplementation with xylitol may be an alternative to reduce the sugar content in fermented dairy products. Even after the effects on microbial growth parameters, the final population was kept above 7.00log CFU/mL and in the shelf life. These results suggest that xylitol is a promising sugar substitute for fermented products.