Growth characteristics of Saccharomyces rouxii isolated from chocolate syrup

Abstract

We investigated the growth parameters of Saccharomyces rouxii isolated from spoiled chocolate syrup. The optimum pH range for S. rouxii was 3.5 to 5.5, whereas the minimum and maximum pH values that permitted growth were 1.5 and 10.5, respectively. For cells grown in 0 and 60% sucrose the optimum water activity (a,) values were 0.97 and 0.96, respectively. The optimum temperature for S. rouxii increased with a decreasing a, regardless of whether glucose or sucrose was used as the humectant. The optimum temperatures for S. rouxii were 28°C at an a. of >0.995 and 35°C at an a, of 0.96 to 0.90 in 2x potato dextrose broth with sucrose. Increasing the sorbate concentration (from 0.03 to 0.10%) caused the growth of S. rouxii to become more inhibited between a,s of >0.995 and 0.82. S. rouxii did not grow when the sorbate level was 0.12% (wt/vol). At lower sorbate levels, the effect of sorbate on the growth of S. rouxii depended on

Sugar‐ and salt‐tolerant yeasts

“…Onishi (1959) reported that many sugar-and salt-tolerant yeasts were able to grow at a high temperature such as 40°C in a saline medium, but not in a conventional medium. Restaino et al (1983) showed that the optimum temperatures for growth of Z. rouxii increased with a decreasing a,, regardless of whether glucose or sucrose was used as humectants. Jermini and Schmidt-Lorenz (1987b) investigated the cardinal temperatures for growth of six yeast species at different a, adjusted with glucose, and found that minimum, optimum and maximum temperatures for growth shifted toward higher values as the a, decreased.…”

“…The effects of propionic, acetic and lactic acids on the growth of several yeast species have been investigated (Noda et al 1982;Moon 1983). The activity of benzoic acid and its sodium salt, sorbic acid and its potassium salt against yeast is well recognized (Takeuchi et al 1963;Hanaoka 1967;Lloyd 1975a;Beuchat 1981;Bills et al 1982;Restaino et al 1982Restaino et al , 1983. Jermini and Schmidt-Lorenz (1987~) reported the effectiveness of sodium benzoate and ethyl-paraben against 18 sugar-and salt-tolerant yeast strains at different a , and pH.…”

Combined Effects of pH and Sugar on Growth Rate of Zygosaccharomyces rouxii , a Bakery Product Spoilage Yeast

“…Foods that contain high sugar concentrations and thus have low a w values are spoiled first by Zygosaccharomyces rouxii (7). In addition, Z. rouxii is able to grow at a wide range of pH values, such as pH 1.8 to 8.0 in the presence of high concentrations of glucose (28) or pH 1.5 to 10.5 in 12% glucose medium (25). In his well-documented review of spoilage yeast, Fleet (7) mentioned that a high sugar concentration may either increase or decrease the low-pH tolerance of yeast and emphasized that further study of these influences would be needed to clarify the discrepant observations that have been described.…”

Combined Stress Effects on Growth of Zygosaccharomyces rouxii from an Intermediate Moisture Papaya Product

“…English (1954) reported a high tolerance of this yeast to a wide range of acidity. Restaino et al (1983) found an optimum pH range of 3.5 to 5.5, much wider than that reported by Tilbury. In our study, a pH of 3.0 had a more inhibitory effect indicated by significantly (P I 0.05) smaller counts of the yeast at that pH, than those at pH 4.0 or 3.5.…”

“…OSMOTOLERANT YEASTS can spoil foods with low to intermediate water activity, high acidity, low redox potential, high carbon/nitrogen ratio foods, and do not compete much with other microorganisms in nonselective environments (Restaino et al, 1983). Thus, such yeasts are important in spoilage of foods where such stress factors are used to control microbial growth, as with intermediate moisture products.…”