Department of Biology. University of Lavras (UFLA), Lavras, MG, Brazil.
Food Science Department, University of Lavras (UFLA), Lavras, MG, Brazil.
Food Res Int. 2019 Nov;125:108620. doi: 10.1016/j.foodres.2019.108620. Epub 2019 Aug 18.
The demand for new probiotic products has shown recent increases alongside a growing interest in studying starter cultures of cheeses. This study thus aims to evaluate the ability to survive under simulated gastrointestinal conditions and impact of Torulaspora delbrueckii B14 and Kluyveromyces lactis B10 as single and mixed inocula for cheese production. These two yeast strains were subjected to simulated gastrointestinal tracts and tested for self-aggregation, hydrophobicity, pathogen inhibition, antibiotic resistance, and β-galactosidase production. The yeast strains were also assessed for their ability to survive in different NaCl concentrations (2.5%, 5%, and 10% w/v), multiple temperatures (4 °C and 40 °C), and used as single and mixed starter cultures for cheese production. Yeasts population levels were monitored by YPD plating and MALDI-TOF and metabolites were analyzed by HPLC and GC-MS over the course of the 21 days cheese maturation process. T. delbrueckii B14 and K. lactis B10 both showed >80% viability after the passage through the simulated gastrointestinal tract, had self-aggregation rates >90%, and displayed β-galactosidase activities of 0.35 U/g and 0.53 U/g, respectively. Both yeasts survived at 2.5%, 5%, and 10% NaCl for 21 days and showed growth at 4 °C. In cheese, the single inoculum of K. lactis B10 and mixed inoculum showed the highest levels of lactose consumption. HS-SPME GC-MS analysis of cheese samples allowed the identification of 38 volatile compounds. The highest concentrations of most of these compounds were observed after 21 days of maturation for the cheese produced with mixed inoculum. The most abundant acids detected were hexanoic and decanoic acid; the most abundant alcohols were 2,3-butanediol, 2-phenylethanol and isoamyl alcohol, and the most prevalent ester compounds were isoamyl acetate and phenethyl acetate. Our results therefore show that T. delbrueckii B14 and K. lactis B10 are interesting yeasts for further studies in the context of probiotics and positively impact the composition of desirable volatile compounds in cheeses, particularly when used as mixed inoculum.
对新型益生菌产品的需求最近有所增加,同时人们对奶酪发酵剂的研究兴趣也日益浓厚。因此,本研究旨在评估毕赤酵母 B14 和乳克鲁维酵母 B10 作为单一和混合接种物用于奶酪生产时在模拟胃肠道条件下的生存能力以及对其的影响。将这两种酵母菌株进行模拟胃肠道处理,并测试其自聚集、疏水性、抑制病原菌、抗生素耐药性和β-半乳糖苷酶的产生。还评估了这些酵母菌株在不同的 NaCl 浓度(2.5%、5%和 10%w/v)、多个温度(4°C 和 40°C)下的生存能力,并将其用作单一和混合起始培养物用于奶酪生产。通过 YPD 平板和 MALDI-TOF 监测酵母菌株的种群水平,并通过 HPLC 和 GC-MS 在 21 天奶酪成熟过程中分析代谢物。毕赤酵母 B14 和乳克鲁维酵母 B10 在通过模拟胃肠道后均显示出 >80%的存活率,自聚集率>90%,并且分别显示出 0.35 U/g 和 0.53 U/g 的β-半乳糖苷酶活性。两种酵母在 2.5%、5%和 10%的 NaCl 中都能存活 21 天,并在 4°C 下生长。在奶酪中,乳克鲁维酵母 B10 的单一接种物和混合接种物显示出最高的乳糖消耗水平。通过 HS-SPME GC-MS 对奶酪样品进行分析,共鉴定出 38 种挥发性化合物。在使用混合接种物生产的奶酪成熟 21 天后,这些化合物的大部分浓度最高。检测到的最高浓度的酸是己酸和癸酸;最丰富的醇是 2,3-丁二醇、2-苯乙醇和异戊醇,最普遍的酯化合物是异戊酸乙酯和乙酸苯乙酯。因此,我们的研究结果表明,毕赤酵母 B14 和乳克鲁维酵母 B10 是益生菌研究中很有前途的酵母,并且对奶酪中理想挥发性化合物的组成有积极影响,特别是在用作混合接种物时。