Influence of Fermentation and Storage Conditions on the Sensory Properties of Plain Low Fat Stirred Yogurts

Abstract

Influence of strain association, temperature, pH and storage on the sensory properties of low fat stirred yogurt was studied through a factorial design including three associations of thermophilic lactic acid bacteria (one Lactobacillus delbrueckii subsp. bulgaricus, one ropy and one nonropy Streptococcus thermophilus strains), three incubation temperatures (39C, 42C and 45C), two final fermentation pH (4.4 and 4.8) and two storage times (7 and 21 days). The 36 formulated yogurts were assessed by Quantitative Descriptive Analysis and by instrumental measurements: apparent viscosity (modified funnel of Posthumus), lactate and pH. Texture perceptions and acid taste, rather than other flavor properties, gave the best discrimination between samples according to strain association, temperature and final pH. Significant two‐factor interaction displayed the concomitant influence of strain association and temperature on the sample texture properties. Instrumental parameters correlated best with thickness and acid taste (pH and lactate) and mouthcoating (apparent viscosity).

Effect of inulin on growth and acidification performance of different probiotic bacteria in co-cultures and mixed culture with Streptococcus thermophilus

“…Finally, the highest values of pH and less lactic acidity obtained with St-Lr and St-Bl with respect to the other two co-cultures are consistent with the heterolactic nature of both Lr (Jyoti et al, 2003) and Bl (Bongaerts et al, 2005), and the lower pH after D7 with St-Lb compared with StLr to the formation of acetic acid instead of ethanol (Bongaerts et al, 2005). The values of pH after D1 are not so far from those reported by Moreira et al (2000) (3.76-4.39), who analyzed samples of milk fermented by different strains of L. bulgaricus and S. thermophilus, and by Martin et al (1999) after 30-day storage at 5°C (4.18-4.36). Besides, Damin et al (2006) detected an average lactic acidity in commercial yoghurts (10.1 mg g À1 ) practically coincident to the average value of this work after D7.…”

Effect of inulin as prebiotic and synbiotic interactions between probiotics to improve fermented milk firmness

“…Oliveira et al (2001) observed an increase in firmness from 0.12 to 0.20 N when milk was supplemented with whey and from 0.71 to 0.86 N with milk proteins. The above enforcing effect of storage at 4°C is in agreement with the viscosity increase observed by several authors mainly during the first week of storage (Barrantes et al, 1994;Martin et al, 1999;Zourari et al, 1991). On the other hand, no report is available in the literature about the effect of a complex probiotic cocktail on yoghurt firmness, to which the last part of this work has been addressed.…”

Effect of microparticulated whey protein with varying content of denatured protein on the rheological and sensory characteristics of low-fat yoghurt

“…In addition, the mass change per time unit (Dm/Dt) versus mass was plotted and linear regression was performed using procedure PROC REG in SAS version 9.1. From the regression equations, the negative reciprocal value of the slope was defined as the flowing time coefficient (FTC) and used as parameter for further studies, i.e., FTC4mm and FTC8mm (Martin et al, 1999). Finally, the efflux time or time necessary to collect 280 g of yoghurt was termed as t280g4mm or t280g8mm.…”

“…Prior to the measurement, the yoghurts were tempered to 13 C. Thereafter, the funnel was filled and yoghurt was allowed to flow through the orifice. The material exiting the conical part was collected in a beaker whose weight was measured every second by a scale interfaced to a computer Martin, Skokanova, Latrille, Beal, & Corrieu, 1999). The flow curves of weight (g) versus time (s) were fitted to a second-degree polynomial, where the corresponding Table 1 Schematic overview of the experimental design used.…”