Journal of Dairy Science and Biotechnology

Korean Society of Dairy Science and Biotechnology (한국낙농식품응용생물학회)
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Changes in the Viability of Lactic Acid Bacteria during Storage of Freeze-Dried Yogurt Snacks

저장기간에 따른 동결건조 농후 발효유 내 유산균 생균수 변화

  • 임예서 (서울우유협동조합 중앙연구소) ;
  • 홍식 (서울우유협동조합 중앙연구소) ;
  • 신용국 (서울우유협동조합 중앙연구소) ;
  • 강신호 (서울우유협동조합 중앙연구소)
  • Received : 2015.09.10
  • Accepted : 2015.09.18
  • Published : 2015.09.30
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Abstract

The majority of food drying processes are based on the use of thermal energy. However, such methods may deteriorate the quality of the final product. Freeze-drying is one of the most useful processes for drying thermosensitive substances. Food that contains beneficial bacteria, for example, is susceptible to heat treatment, but during freeze-drying beneficial bacteria are preserved in these food items. The primary goals of this study were to develop yogurt snacks and to compare the viability of lactic acid bacteria (LAB) in yogurt snacks under different freeze-drying temperatures. In addition, the survival of LAB during storage was investigated. Survival of LAB in freeze-dried yogurt snacks gradually decreased over 16 weeks of storage. LAB had a residual viability of 25.5% after 16 weeks of storage at room temperature. LAB survived better in freeze-dried plain yogurt snacks than in freeze-dried strawberry yogurt snacks during storage. Freeze-dried yogurt snacks contained 11.9% fat, 57.1% carbohydrate, and 18.7% protein. In conclusion, the viability of LAB in freeze-dried yogurt snacks depends on the temperature during freeze-drying: the higher the freeze-drying temperature, the lower the viability of LAB in yogurt snacks. The viability of LAB in yogurt snacks was also dependent on the moisture content and nutritional value.

본 연구에서는 동결건조 공정에 의한 유산균의 생균수 감소를 최소화 할 수 있는 농후 발효유를 개발하고자 하였다. 이를 위해 농후 발효유 제조에 첨가되는 당의 종류 및 구성을 달리하여 동결 건조 전후의 유산균 생존율을 비교 분석하였다. 그 결과, 포도당의 일부를 이소말토올리고당으로 대체하였을 때, 발효유 내 초기 유산균 생균수 및 동결건조 공정 이후의 유산균 생존율 또한 높아졌다. 또한 동결 건조 시 열판 온도가 낮을 경우, 건조 효율은 떨어지지만, 동결건조 이후의 동결건조 농후 발효유 내 초기 유산균 생존율이 높았다. 16주간의 저장기간에 따른 유산균 생균수 변화를 살펴본 결과, 상온보관 조건에서 유산균은 지수적으로 감소하였다. 하지만 16주가 경과한 후에도 $1.63{\times}10^8CFU/g$의 생균수를 유지하여 약 0.6 g 이상의 동결건조 농후 발효유만 섭취하여도 체내에서 유산균 증식 및 유해균 억제 배변활동 원활 등의 건강기능성을 가질 수 있는 수준이었다. 하지만 본 연구에서는 식품 매트릭스에 따른 동결방지 효과를 파악할 때, 유산균 생균수를 유일한 지표로 삼았다는데 한계가 있다. 유산균 생균수뿐만 아니라, 유산균의 활성을 살펴보기 위해 동결건조 이후의 젖산 생성능력이나 실질적으로 체내에 들어갔을 때 위액이나 담즙액에 대한 저항성 측면에서의 추가 연구가 필요할 것으로 사료된다.

Keywords

References

  1. Abadias, M., Benabarre, A., Teixido, N., Usall, J. and Vinas, I. 2001. Effect of freeze drying and protectants on viability of the biocontrol yeast Candida sake. Food Microbiol. 65:173-182. https://doi.org/10.1016/S0168-1605(00)00513-4
  2. Abraham, A., De Antoni, G. and Anon M. 1990. Effect of calcium on the cryopreservation of L. bulgaricus in different freezing media. Cryobiology 27:336. https://doi.org/10.1016/0011-2240(90)90033-Z
  3. Bansal, T. and Garg, S. 2008. Probiotics: From functional foods to pharmaceutical product. Curr. Pharm. Biotechnol. 9:267-287. https://doi.org/10.2174/138920108785161587
  4. Blanquet, S., Garrait, G., Beyssac, E., Perrier, C., Denis, S., Hebrard, G. and Alric, M. 2005. Effect of cryoprotectants on the viability and activity of freeze dried recombinant yeasts as novel oral drug delivery system assessed by an artificial digestive system. Eur. J. Pharm. Biopharm. 61:32-39. https://doi.org/10.1016/j.ejpb.2005.03.009
  5. Brian, C. S. To and Etzel, M. R. 1997. Spray drying, freeze drying, or freezing of three different lactic acid bacteria species. J. Food Sci. 62(3):576-578. https://doi.org/10.1111/j.1365-2621.1997.tb04434.x
  6. Capela, P., Hay, T. K. C. and Shah, N. P. 2006. Effects of cryoprotectants, prebiotics and microencapsulation on survival of probiotic organisms in yoghurt and freeze-dried yoghurt. Food Res. Int. 39:203-211. https://doi.org/10.1016/j.foodres.2005.07.007
  7. Carvalho, A. S., Silva, J., Ho, P., Teixeira, P., Malcata, F. X. and Gibbs, P. 2004. Effects of various sugars added to growth and drying media upon thermotolerance and survival throughout storage of freeze dried Lactobacilli delbrueckii ssp. Bulgaricus. Biotechnol. Progr. 20:248-254.
  8. Carvalho, A. S., Silva, J., Ho, P., Teixeira, P., Malcata, F. X. and Gibbs, P. 2003. Effect of various growth media upon survival during storage of freeze-dried Enterococcus faecalis and Enterococcus durans. J. Appl. Microbiol. 94:947-952. https://doi.org/10.1046/j.1365-2672.2003.01853.x
  9. Castro, H. P., Teixeira, P. M. and Kirby, R. 1995. Storage of lyophilized cultures of Lactobacillus bulgaricus under different relative humidities and atmospheres. Appl. Microbiol. Biot. 44:172-176. https://doi.org/10.1007/BF00164498
  10. Gardiner, G. E., O'Sullivan, E. and Kelly, J. 2000. Comparative survival rates of human-derived probiotic Lactobacillus paracasei and L. salivarius strains during heat treatment and spray drying. Appl. Environ. Microb. 66(6):2605-2612. https://doi.org/10.1128/AEM.66.6.2605-2612.2000
  11. Gwak, H. J., Lee, N. R. and Park, H. W. 2014. Use of food-grade protective agents to improve the viability of freeze-dried lactic acid bacteria. Korean J. Food Sci. Technol. 46(5):655-659. https://doi.org/10.9721/KJFST.2014.46.5.655
  12. Leonie, J. M., Linders, W. F., Wolkers, F. A. and Hoeskstra, Klaas van’t Riet. 1997. Effect of added carbohydrates on membrane phase behavior and survival of dried Lactobacillus plantarum. Cryobiology. 35:31-40. https://doi.org/10.1006/cryo.1997.2021
  13. Leslie, S. B., Israeli, E., Lighthart, B., Crowe, J. H. and Crowe, L. M. 1995. Trehalose and sucrose protect both membranes and proteins in intact bacteria during drying. Appl. Environ. Microb. 61(10):3592-3597.
  14. Mellor, J. D. 1978. Fundamental of freeze drying. London: Academic Press. pp. 257-288.
  15. Otero, M., Espeche, M. and Nader-Macias, M. 2007. Optimization of the freeze-drying and survival throughout storage of freeze dried Lactobacillus gasseri and Lactobacillus delbrueckii subsp. delbrueckii for veterinarian probiotic applications. Process Biochem. 42:1406-1411. https://doi.org/10.1016/j.procbio.2007.07.008
  16. Schrezenmeir, J. and de Vrese, M. 2001. Probiotic, prebiotics, and synbiotics. Am. J. Clin. Nutr. 73(suppl):361S-4S. https://doi.org/10.1093/ajcn/73.2.361s
  17. Schwab, C., Vogel, R. and Gänzle, M. G. 2007. Influence of oligosaccharides on the viability and membrane properties of Lactobacillus reuteri TMW1. 106 during freeze-drying. Cryobiology 55:108-114. https://doi.org/10.1016/j.cryobiol.2007.06.004
  18. Selmer-Olsen, E., Birkeland, S. E. and Sorhaug, T. 1999. Effect of protective solutes on leakage from and survival of immobilized Lactobacillus subjected to drying, storage and rehydration. J. Appl. Microbiol. 87:429-437. https://doi.org/10.1046/j.1365-2672.1999.00839.x
  19. Zayed, G. and Roos, Y. H. 2004. Influences trehalose and moisture content on survival of Lactobacillus salivarius subjected to freeze-drying and storage. Process Biochem. 39:1081-1086. https://doi.org/10.1016/S0032-9592(03)00222-X