Nora Sabbag

Reggianito Argentino cheese: influence of Lactobacillus helveticus strains isolated from natural whey cultures on cheese making and ripening processes

Abstract Reggianito Argentino cheeses were manufactured with three defined single strains Lactobacillus helveticus cultured in sterile whey, and one “natural” whey starter. Gross composition of cheeses did not significantly differ, and viable starter cell counts were similar for all cheeses. Soluble nitrogen at pH 4.6 was also alike for cheeses made with natural or selected starters, but soluble nitrogen in trichloroacetic acid 12% and phosphotungstic acid 2.5% showed significant differences. Electrophoretograms showed that γ casein bands increased during ripening, while β casein band decreased; α s1 casein was also cleaved to α s1 -I. Acid degree values of fat for control and experimental 0-day old cheeses were slightly different, but were similar at 90 and 180 days of ripening. All cheeses were good quality Reggianito, but control and experimental samples differed in aroma and texture. Natural whey starter replacement by selected single starter of Lactobacillus did not alter cheese making and primary proteolysis or lipolysis, but it modified secondary proteolysis and sensory characteristics.

Technological, rheological and sensory characterizations of a yogurt containing an exopolysaccharide extract from Lactobacillus fermentum Lf2, a new food additive

Lactobacillus fermentum Lf2, an autochthonous strain isolated as a non starter culture in Cremoso cheese, produces high EPS levels (~1g/L) in optimized conditions (SDM broth, pH6.0, 30°C, 72h). Technological (texture profile and rheological analysis) and sensory properties of non-fat yogurts with 300 and 600mg EPS/L were studied at 3 and 25days after manufacture. Yogurts with different EPS concentrations showed higher hardness values than the control group at both periods of time, being the only significant difference that remained stable during time. The consistency index was also higher for the treated samples at both times evaluated, being significantly different for samples with 300mg/L of EPS extract, while the flow behavior index was lower for EPS-added yogurts. The thixotropic index was lower (P<0.05) for samples with the highest EPS extract concentration at the end of the storage time. Regarding the sensory analysis, those yogurts with 600mg/L of EPS extract presented the highest values of consistency at 3days of storage. No considerable differences for defects (milk powder, acid, bitter and cooked milk flavors) were perceived between treated and control samples at both times evaluated. Syneresis was also studied and samples with 600mg/L of EPS extract presented the lowest syneresis values at 25days of storage, which considerably decreased with the time of storage. In conclusion, the EPS from L. fermentum Lf2, used as an additive, provided yogurt with creamy consistency and increased hardness, without the presence of unwanted defects and improving the water holding capacity of the product. All the analysis done showed the potential of this extract to be used as a technofunctional natural ingredient, and it should be considered its positive impact on health, according to previous studies.