EP-4739767-A1 - FREEZE-DRIED COMPOSITION COMPRISING NON-SACCHAROMYCES YEAST

Abstract

The present application is in the field of dry compositions for non-Saccharomyces yeasts, a process for preparing such compositions through freeze-drying and compositions which may be prepared by the processes. The processes are characterized in that the lyoprotectants comprise maltodextrin, antioxidant(s) and disaccharide(s), and that the dry matter weight ratio of lyoprotectants to yeast biomass is between 0.5:1 and 4:1, preferably between 0.5:1 and 3:1.

Inventors

• BISGAARD-FRANTZEN, HANS
• GRUENERT, Philipp Paul
• Pohl, Sebastian
• ERIKSSON, EMIL
• HAMM, Duncan

Assignees

• Chr. Hansen A/S

Dates

Publication Date

20260513

Application Date

20240621

Claims (15)

1. 1 . A freeze-dried composition of non-Saccharomyces yeast, preferably Pichia spp. or Pichia kluyveri, comprising maltodextrin, antioxidant(s) and disaccharide(s) as lyoprotectants, and wherein dry matter weight ratio of lyoprotectants to yeast biomass is between 0.5:1 and 4:1 .
2. 2. The freeze-dried composition according to claim 1 , wherein the disaccharide is non-reducing disaccharide, preferably trehalose or sucrose, and/or wherein the antioxidant is ascorbic acid, citric acid, beta-carotene, vitamin E and glutathione, and/or derivatives thereof.
3. 3. The freeze-dried composition according to any one of claims 1-2, further comprising modified starch.
4. 4. The freeze-dried composition according to any one of claims 1-3, wherein the maltodextrin has a dextrose equivalent (DE) between 5 and 30, preferably between 10 and 20.
5. 5. The freeze-dried composition according to any one of claims 1 -4 comprising from 10 7 to 10 12 cfu/g yeast cells.
6. 6. The freeze-dried composition according to any of any one of claims 1-5, wherein the yeast is Pichia spp., preferably Pichia kluyveri.
7. 7. The freeze-dried composition according to claim 6, wherein the Pichia kluyveri is DSM 28484 or PK-KR1 .
8. 8. The freeze-dried composition according to any one of claims 1-7, further comprising excipients.
9. 9. Use of the freeze-dried composition according to any one of claims 1-8 to prepare fermented food products, preferably beverages.
10. 10. A process for preparing a freeze-dried composition of non-Saccharomyces yeasts, comprising the following steps: (1) providing non-Saccharomyces yeast cells, (2) growing the yeast cells and harvesting the yeast cells to obtain a yeast cell concentrate, wherein the concentrate comprises 10 8 to 10 11 cfu/g dry matter of yeast cells, (3) adding lyoprotectants to the yeast cell concentrate to form a suspension, wherein the lyoprotectants comprise maltodextrin, antioxidant(s) and disaccharide(s), (4) freezing the suspension, (5) drying the suspension, and (6) obtaining freeze-dried non-Saccharomyces yeast composition. wherein the dry matter weight ratio of lyoprotectants to yeast biomass is between 0.5:1 and 4:1 , preferably between 0.5:1 and 3:1 , more preferably between 0.7:1 to 2.5:1 .
11. 11 . The process according to claim 10, wherein the obtained composition comprises 10 9 to 10 13 cfu/g yeast cells.
12. 12. The process according to any one of claims 10-11 , wherein the drying is carried out at a vacuum pressure of from 0.01 to 2 millibar(mbar) and/or the temperature during drying is controlled such that the vacuum pressure is kept constant.
13. 13. The process according to any one of claims 10-12, wherein in freezing step (4) the suspension is frozen in liquid nitrogen to form pellets or is frozen on a tray.
14. 14. The process according to any one of claims 10-13, further comprising washing the cells after harvesting in step (2).
15. 15. The process according to any one of claims 10-14, wherein the lyoprotectants further comprise modified starch.

Description

FREEZE-DRIED COMPOSITION COMPRISING NON-SACCHAROMYCES YEAST FIELD The present application generally relates to the field of yeast, in particular freeze-dried yeast compositions and uses thereof to prepare fermented food and beverage products. Furthermore, the present application relates to processes of manufacturing freeze-dried yeasts. BACKGROUND Microorganisms such as yeasts are involved in numerous industrially relevant processes. For instance, yeast cultures are essential in the making of fermented food, including fermented beverages, wine, beer, fermented juice etc. In most cases, it is important that the microorganisms remain viable after prolonged storage in order for these to impart their beneficial effect. There is a recent and growing interest in the application of non-Saccharomyces yeasts in fermented foods. From the 1990s, interest in non-Saccharomyces yeasts began to increase, and after three decades, the non-Saccharomyces went from being an undesirable yeast associated with spoilage to microorganisms that could improve aromatic profiles of products. In wine fermentation, co-cultures of non-Saccharomyces yeast of interest with Saccharomyces yeasts are often used for various purposes, such as to generate other aromatic compounds through enzymatic reactions, decrease ethanol content, increase glycerol production, decrease acidity, and stabilize color, etc. In beer, another widely consumed alcoholic beverage, also there is also a growing interest in non-Saccharomyces yeasts, primarily focused on aromatic complexity. This interest is directly related to the development of an artisanal beer market, which seeks to develop products with new and original aromatic notes. In other beverages obtained from different fruits (pineapple, lychee, papaya, bilberry, among others) the possibility of using non-Saccharomyces yeasts has also been studied. In other fermented foods, such as dairy or dairy analogue products as well as food or beverage prepared from cocoa beans or coffee beans, the use of starter cultures with non-Saccharomyces yeasts have been gaining interests. WO2011/134952 discloses frozen starter culture comprising non-Saccharomyces wine yeasts for direct inoculation. However, the use of frozen culture requires an unbroken cold chain during transport, which may be expensive and cumbersome. Lyophilization, also known as freeze-drying, is a dehydration method used to preserve cells in a dry state to permit their storage preferably at room temperature. Freeze-drying is a harsh process which negatively affects both viability and physiological state of the yeasts. The formation of ice crystals induces mechanical damage that leads to cellular death during freezing and has impact on viability. For example, survival rates of Saccharomyces yeast have been investigated after freeze-drying and preserving in a vacuum at 5°C. The survival rates of the yeast were only at 10% or less. Miyamoto-Shinohara, Yukie, et al. "Survival rate of microbes after freeze-drying and long-term storage." Cryobiology 41.3 (2000): 251-255. To our knowledge, non- Saccharomyces yeast has not been satisfactorily preserved yet using freeze- drying techniques at an industrial level. Most documented lyophilization processes involving non- Saccharomyces yeasts have not been scaled to an industrial level. Thus, there is a need for freeze-dried yeast compositions, in particular non- Saccharomyces yeast compositions since they are becoming increasingly popular as fermenting microorganisms. There is a particular need to provide manufacturing processes which may be scaled to an industrial level and allows good preservation and process survival of yeast cells. Preferably, such compositions exhibit good stability and can be transported without requiring cold chain. SUMMARY OF THE INVENTION Lyophilization is a process which is known to trigger thermal, osmotic and oxidative stress in yeasts. The present inventors have discovered that yeast cells can be preserved effectively and with good process storage stability and survivability by using lyoprotectants comprising maltodextrin, antioxidant(s) and disaccharide(s). The weight ratio of the lyoprotectants to yeast (dry matter) in the compositions is in a range preferably between 0.5 and 4. It has been observed that the prepared yeasts have high survivability overthe freeze-drying step, and the obtained compositions are storage stable for prolonged time and can be transported at low temperature or even ambient temperature. The present application provides freeze-dried yeast compositions, particularly freeze-dried non- Saccharomyces yeast, such as Pichia spp. A first aspect of the application provides a freeze-dried composition of non-saccharomyces yeast, preferably Pichia spp., comprising a mixture of maltodextrin, antioxidant(s) and disaccharide(s) as lyoprotectants with predetermined weight ratio of the lyoprotectants to yeast biomass (dry matter). This weight ratio is also referred to as encapsu