• 한국축산식품학회지
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• 제40권4호
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• pp.541-550
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• 2020

The use of yeast assist kefir fermentation, but also can cause food spoilage if uncontrolled. Hence, in this study, the microbial composition of an existing commercial kefir starter was modified to produce a functional starter, where Lactobacillus acidophilus KCNU and Lactobacillus brevis Bmb6 were used to replace yeast in the original starter to produce non-yeast kefir-like fermented milk. The functional starter containing L. acidophilus KCNU and L. brevis Bmb6 demonstrated excellent stability with 10¹⁰ CFU/g of total viable cells throughout the 12 weeks low-temperature storage. The newly developed functional starter also displayed a similar fermentation efficacy as the yeast-containing control starter, by completing the milk fermentation within 12 h, with a comparable total number of viable cells (10⁸ CFU/mL) in the final products, as in control. Sensory evaluation revealed that the functional starter-fermented milk highly resembled the flavor of the control kefir, with enhanced sourness. Furthermore, oral administration of functional starter-fermented milk significantly improved the disease activity index score by preventing drastic weight-loss and further deterioration of disease symptoms in DSS-induced mice. Altogether, L. acidophilus KCNU and L. brevis Bmb6 have successfully replaced yeast in a commercial starter pack to produce a kefir-like fermented milk beverage with additional health benefits. The outcome of this study provides an insight that the specific role of yeast in the fermentation process could be replaced with suitable probiotic candidates.

• Journal of Microbiology and Biotechnology
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• 제22권7호
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• pp.960-966
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• 2012

The diversity and composition of yeast populations may greatly impact wine quality. This study investigated the yeast microbiota in two different types of wine fermentations: direct inoculation of a commercial starter versus pied de cuve method at an industrial scale. The pied de cuve fermentation entailed growth of the commercial inoculum used in the direct inoculation fermentation for further inoculation of additional fermentations. Yeast isolates were collected from different stages of wine fermentation and identified to the species level using Wallersterin Laboratory nutrient (WLN) agar followed by analysis of the 26S rDNA D1/D2 domain. Genetic characteristics of the Saccharomyces cerevisiae strains were assessed by a rapid PCR-based method, relying on the amplification of interdelta sequences. A total of 412 yeast colonies were obtained from all fermentations and eight different WL morphotypes were observed. Non-Saccharomyces yeast mainly appeared in the grape must and at the early stages of wine fermentation. S. cerevisiae was the dominant yeast species using both fermentation techniques. Seven distinguishing interdelta sequence patterns were found among S. cerevisiae strains, and the inoculated commercial starter, AWRI 796, dominated all stages in both direct inoculation and pied de cuve fermentations. This study revealed that S. cerevisiae was the dominant species and an inoculated starter could dominate fermentations with the pied de cuve method under controlled conditions.

• Journal of Microbiology and Biotechnology
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• 제24권5호
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• pp.661-666
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• 2014

Both lactic acid productivity and cell growth were linearly correlated with yeast extract supplementation in batch fermentation. During conventional continuous operation, although fresh feed was introduced into the bioreactor with a significantly low dilution rate (0.04 $h^{-1}$), the amount of yeast extract employed was not enough to maintain the growth of microorganism. However, when the fresh feed contained 100 g/l glucose and 2 g/l yeast extract during cell-recycle continuous operation at a dilution rate of 0.04 $h^{-1}$, more than 90 g/l lactic acid was continuously produced, with the average productivity of 3.72 $g/l{\cdot}h$. In this experiment, 82 g of yeast extract (77% of reduction yield) could be reduced for the production of 1 kg of lactic acid compared with batch fermentation of a similar volumetric productivity.

• 한국식품과학회지
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• 제52권5호
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• pp.529-537
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• 2020

본 연구에서는 재래누룩을 사용한 막걸리의 미생물 군집을 차세대 염기서열 분석기법(NGS)을 활용하여 조사하고, 미생물 군집이 막걸리의 품질에 미치는 영향을 구명하고자 효모 첨가에 따른 품질특성을 확인하였다. 발효 스타터로 효모의 첨가는 재래누룩 막걸리의 미생물 군집 분포에 영향을 주어 결과적으로 막걸리의 품질 차이를 나타냈다. 무첨가구의 경우 발효 초기의 진균류는 Saccharomycopsis fibuligera가 대부분이었고, 세균류는 Pediococcus pentosaceus, Weissella confusa, Pantoea vagans의 증식으로 인하여 총산 및 젖산 함량이 높게 나타났다. 첨가구는 발효 시작 전부터 Saccharomyces cerevisiae가 우점하여 알코올 생성 속도가 빠르고, 발효 초기의 높은 알코올 농도로 인해 재래누룩에서 기인한 젖산 생성 bacteria의 생육을 억제하는 것으로 나타났다. 따라서 재래누룩으로 막걸리를 제조할 때, 알코올 생성능이 우수한 효모의 첨가가 막걸리 시어짐의 원인이 되는 젖산균의 성장을 억제함으로써 산미를 낮추고 제품의 균일성을 확보할 수 있을 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제29권2호
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• pp.211-218
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• 2016

This study evaluated the effect of Candida norvegensis (C. norvegensis) viable yeast culture on in vitro ruminal fermentation of oat straw. Ruminal fluid was mixed with buffer solution (1:2) and anaerobically incubated with or without yeast at $39^{\circ}C$ for 0, 4, 8, 16, and 24 h. A fully randomized design was used. There was a decrease in lactic acid (quadratic, p = 0.01), pH, (quadratic, p = 0.02), and yeasts counts (linear, p<0.01) across fermentation times. However, in vitro dry matter disappearance (IVDMD) and ammonia-N increased across fermentation times (quadratic; p<0.01 and p<0.02, respectively). Addition of yeast cells caused a decrease in pH values compared over all fermentation times (p<0.01), and lactic acid decreased at 12 h (p = 0.05). Meanwhile, yeast counts increased (p = 0.01) at 12 h. C. norvegensis increased ammonia-N at 4, 8, 12, and 24 h (p<0.01), and IVDMD of oat straw increased at 8, 12, and 24 h (p<0.01) of fermentation. Yeast cells increased acetate (p<0.01), propionate (p<0.03), and butyrate (p<0.03) at 8 h, while valeriate and isovaleriate increased at 8, 12, and 24 h (p<0.01). The yeast did not affect cellulolytic bacteria (p = 0.05), but cellulolytic fungi increased at 4 and 8 h (p<0.01), whereas production of methane decreased (p<0.01) at 8 h. It is concluded that addition of C. norvegensis to in vitro oat straw fermentation increased ruminal fermentation parameters as well as microbial growth with reduction of methane production. Additionally, yeast inoculum also improved IVDMD.

• Food Science and Biotechnology
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• 제15권1호
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• pp.77-81
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• 2006

The dextransucrase activity of microorganisms which were identified as contributing to the fermentation of jeungpyeon made with yeast was measured. The dextran generated during fermentation was quantified and the viscosity changes were measured. The mechanism of network structure formation was clarified by observing the inside of the network structure over the fermentation periods ranging from 1 to 7 hr using scanning electron microscopy (SEM). The pH of jeungpyeon batter decreased significantly as the fermentation proceeded, whereas the viscosity increased. The identified lactic acid bacteria (LAB) were Leuconostoc mesenteroides subsp. mesenteroides, Pediococcus pentosaceus, Tetragenococcus halophilus, and Leuconostoc mesenteroides subsp. dextranicum. The yeast was identified as Saccharomyces cerevisiae A/Tor. Pretorien. The dextransucrase extracted from those microorganisms showed high activity. On the other hand, the amount of dextran generated from the batter increased significantly beyond 2 hr of fermentation, and the viscosity increment showed a similar trend. The SEM photos showed that the most homogeneous fine network structure was observed in the batter fermented for 2 hr. Therefore, we assumed that the dextran that was generated by microorganisms during fermentation interacted with the components of the batter to increase the stability of the network structure.

• Mycobiology
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• 제40권1호
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• pp.35-41
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• 2012

A repeated batch fermentation system was used to produce ethanol using $Saccharomyces$ $cerevisiae$ strain (NCIM 3640) immobilized on sugarcane ($Saccharum$ $officinarum$ L.) pieces. For comparison free cells were also used to produce ethanol by repeated batch fermentation. Scanning electron microscopy evidently showed that cell immobilization resulted in firm adsorption of the yeast cells within subsurface cavities, capillary flow through the vessels of the vascular bundle structure, and attachment of the yeast to the surface of the sugarcane pieces. Repeated batch fermentations using sugarcane supported biocatalyst were successfully carried out for at least ten times without any significant loss in ethanol production from sugarcane juice and molasses. The number of cells attached to the support increased during the fermentation process, and fewer yeast cells leaked into fermentation broth. Ethanol concentrations (about 72.65-76.28 g/L in an average value) and ethanol productivities (about 2.27-2.36 g/L/hr in an average value) were high and stable, and residual sugar concentrations were low in all fermentations (0.9-3.25 g/L) with conversions ranging from 98.03-99.43%, showing efficiency 91.57-95.43 and operational stability of biocatalyst for ethanol fermentation. The results of the work pertaining to the use of sugarcane as immobilized yeast support could be promising for industrial fermentations.

• 한국산학기술학회논문지
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• 제16권5호
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• pp.3361-3369
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• 2015

본 연구의 목적은 효모균주와 발효조건 등을 달리하여 머루를 첨가하여 복분자 와인의 품질을 향상시키는데 있다. 효모별 복분자 와인 술덧 품질에 미치는 영향 연구에서는 Y1(Lalvin 71B)효모가 젖산, 퓨젤유 성분을 발효후에 타 효모에 비해 유의적으로 높게 생성하였으며, 술덧의 산도를 낮추고 복분자 와인의 아로마를 강화하는데 효과가 있는 것으로 분석되었다. 또한 발효온도가 복분자 와인 술덧에 미치는 영향 연구에서는 고온발효($25^{\circ}C$)에서 Y1 효모를 이용하여 발효한 술덧에서 낮은 온도($15^{\circ}C$)에서 발효한 술덧에서보다 아로마 성분(에틸 아세테이트 및 고급알코올)이 유의적으로 높게 생성되었다. 본 연구를 통해 머루를 첨가한 복분자 와인제조시 Y1 효모를 이용하고 고온에서 발효하는 것이 복분자 와인의 맛과 아로마를 강화하는데 효과가 있는 것으로 나타났다.

• 한국식품영양학회지
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• 제32권4호
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• pp.371-378
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• 2019

This paper investigated the effects of the percentages of yeast and fermentation time as well as the top and bottom temperature of oven on the baking properties of rice bread. The specific volume of the dough decreased as the amount of added yeast and fermentation time increased. When 1.5% yeast was added at 60 min of fermentation time, the shape of the rice bread showed the largest volume, high appearance and a round shape. The top and bottom temperature of the oven on the baking characteristics of rice bread were affected by the baking time. When the top and bottom temperature of the oven at 200 and $140^{\circ}C$, and 200 and $170^{\circ}C$, the baking time was 20 min. When the top and bottom temperature of oven at 140 and $170^{\circ}C$, the baking time was 40 min. When the top and bottom temperature of the oven were 170 and $170^{\circ}C$, the shape of the rice bread indicated the largest volume, high appearance and a round shape. The results of this study revealed that the replacement of rice flour with 1.5% yeast, 60 min of fermentation time, and the top and bottom temperature of oven at $170-170^{\circ}C$ are effective for rice bread.

• 한국식품저장유통학회지
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• 제18권5호
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• pp.779-785
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• 2011

본 연구에서는 참외를 이용한 알코올 발효과정에서 효모에 따른 발효 특성을 비교 조사하였다. 그 결과 pH, 총산도 및 당도는 효모에 따른 큰 차이를 보이지 않았으며 발효과정에서 pH는 일정하게 유지되었으나 총산도는 증가하는 경향으로 나타났다. 당도는 발효 3일째부터 급격하게 감소하여 발효 후 약 7 $^{\circ}Brix$로 감소하였다. 유기산 함량은 모든 구간에서 lactic 및 citric acid의 함량이 가장 높게 나타나주요 유기산으로 나타났다. 유리당 함량은 발효가 진행됨에 따라 서서히 감소하여 발효 9일째는 대부분 검출되지 않았다. 알코올함량은 (C) S. cerevisiae RC-212에서 14.20%로 가장 높았으며 나머지 구간에서도 12%이상의 알코올이 생성되어 효모 종류에 따른 알코올 함량은 큰 차이가 없었다. 알코올 성분에서 acetaldehyde의 함량은 (E) S. cerevisiae K1-V1116에서 가장 높았으며 methanol함량은 (C) S. cerevisiae RC-212와 (D) S. bayanus EC-1118에서 비교적 높았다. Fusel oil류인 n-propanol, 2-methyl-1-propanol 및 isoamyl alcohol은 발효 3일째부터 대부분 생성되어 점차 증가하였다. 이상의 결과 참외 알코올 발효에서 효모에 따른 이화학적 품질특성에는 큰 차이가 나타나지 않았다.