Development of a potential probiotic fresh cheese using two Lactobacillus salivarius strains isolated from human milk

Abstract

Cheeses have been proposed as a good alternative to other fermented milk products for the delivery of probiotic bacteria to the consumer. The objective of this study was to assess the survival of two Lactobacillus salivarius strains (CECT5713 and PS2) isolated from human milk during production and storage of fresh cheese for 28 days at 4°C. The effect of such strains on the volatile compounds profile, texture, and other sensorial properties, including an overall consumer acceptance, was also investigated. Both L. salivarius strains remained viable in the cheeses throughout the storage period and a significant reduction in their viable counts was only observed after 21 days. Globally, the addition of the L. salivarius strains did not change significantly neither the chemical composition of the cheese nor texture parameters after the storage period, although cheeses manufactured with L. salivarius CECT5713 presented significantly higher values of hardness. A total of 59 volatile compounds were identified in the headspace of experimental cheeses, and some L. salivarius-associated differences could be identified. All cheeses presented good results of acceptance after the sensory evaluation. Consequently, our results indicated that fresh cheese can be a good vehicle for the two L. salivarius strains analyzed in this study.

Figure 1

Flowchart of the cheese making process.

Figure 2

Viable counts (log₁₀ cfu/g) of starter Lc. lactis ESI153 (○) and L. salivarius CECT5713 (□) and PS2 (■) in fresh cheese during storage at 4°C.

Figure 3

DGGE profiles of 16S rRNA gene V6–V8 regions obtained from samples of cheese manufactured with L. salivarius CECT5713 using universal primers U968-GC-f and L1401-r (a) and L. salivarius PS2 using Lactobacillus-specific primers Lab159f and Uni-515-GCr (b) during storage at 4°C. (a): lane 1: marker (L. salivarius CECT5713 and Lc. lactis ESI153); lane 2: Lc. lactis ESI153; lane 3: L. salivarius CECT5713; lane 4: 1-day cheese; lane 5: 7-day cheese; lane 6: 14-day cheese; lane 7; 21-day cheese; lane 8: 28-day cheese. (b) Lane 1: marker (L. salivarius PS2 and Lc. lactis ESI153); lane 2: Lc. lactis ESI153; lane 3: L. salivarius PS2; lane 4: 1-day cheese; lane 5: 7-day cheese; lane 6: 14-day cheese; lane 7; 21-day cheese; lane 8: 28-day cheese.

Figure 4

Graphical charts of the sensory profile of control cheese (○) and cheeses containing L. salivarius CECT5713 (■) and PS2 (▲) after 28 days at 4°C. (a) Odour related attributes. (b) Flavour and taste related attributes. (c) Texture and appearance descriptors.